diverse coordination of polynuclear copper(ii) complexes constructed from benzene tetracarboxylates

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Diverse coordination of polynuclear copper(II) complexes constructed from benzenetetracarboxylates

Salah S. Massoud a,⇑, Franz A. Mautner b,⇑, Febee R. Louka a, Serhiy Demeshko c, Sebastian Dechert c,Franc Meyer c,⇑a Department of Chemistry, University of Louisiana at Lafayette, P.O. Box 44370 Lafayette, LA 70504, USAb Institut für Physikalische and Theoretische Chemie, Technische Universität Graz, A-8010 Graz, Austriac Institut für Anorganische Chemie, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany

a r t i c l e i n f o

Article history:Received 1 October 2010Received in revised form 30 January 2011Accepted 9 February 2011Available online 16 February 2011

Keywords:CopperPolynuclear complexesBenzene tetracarboxylate bridgeCrystal structureMagnetic properties

a b s t r a c t

The reaction of aqueous solutions of the preformed 1:1 Cu(ClO4)2-polydentate amine with tetrasodium1,2,4,5-benzene tetracarboxylate (Na4bta) afforded three different types of polynuclear compounds.These include the tetranuclear complexes: [Cu4(Medpt)4(l4-bta)(ClO4)2(H2O)2](ClO4)2�2H2O (1),[Cu4(pmdien)4(l4-bta)(H2O)4](ClO4)4 (2), [Cu4(Mepea)4(l4-bta)(H2O)2](ClO4)4 (3), [Cu4(TPA)4(l4-bta)]-(ClO4)4�10H2O (4) and [Cu4(tepa)4(l4-bta)](ClO4)4�2H2O (5), the di-nuclear: [Cu2(DPA)2(l2-bta)(H2O)2]�4H2O (6), [Cu2(dppa)2(l2-bta)(H2O)2]�4H2O (7) and [Cu2(pmea)2(l2-bta)]�14H2O (8) and the trinuclearcomplex [Cu3(dppa)3(l3-bta)(H2O)2.25](ClO4)2�6.5H2O (9) where Medpt = 3,30-diamino-N-methyldipro-pylamine, pmedien = N,N,N0 ,N00,N00-pentamethyldiethylenetriamine, Mepea = [2-(2-pyridyl)-ethyl]-(2-pyridylmethyl)methylamine, TPA = tris(2-pyridylmethyl)amine, tepa = tris[2-(2-pyridyl)ethyl)]amine,DPA = di(2-pyridymethyl)amine, dppa = N-propanamide-bis(2-pyridylmethyl)amine and pmea = bis(2-pyridylmethyl)-[2-(2-pyridylethyl)]amine. The complexes were structurally characterized by elementalanalyses, spectroscopic techniques, and by X-ray crystallography for complexes 1, 2, 4, 6, 7 and 9.X-ray structure of the complexes reveal that bta4� is acting as a bridging ligand via its four deprotonatedcaboxylate groups in 1, 2 and 4, three carboxylate groups in 9 and via two trans-carboxylates in 6 and 7.The complexes exhibit extended supramolecular networks with different dimensionality: 1-D in 2 and 4due to hydrogen bonds of the type O–H��O, 2-D in 1 and 7, and 3-D network in 6 as a result of hydrogenbonds of the types N–H��O and O–H��O. Magnetic susceptibility measurements showed very weak anti-ferromagnetic coupling between the CuII ions in 1–5, 7–9 (|J| = 0.02–0.87 cm�1) and weak ferromagneticcoupling for 6 (J = 0.08 cm�1).

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1. Introduction

The synthesis and design of metal–organic-frameworks (MOFs)and metal–organic coordination compounds with special geomet-rical and topological arrangement is becoming an attractive topicin the ‘‘crystal engineering’’ field of material sciences. In thesecompounds the metal sites play a major role in adapting certainchemical and physical characteristics that make them interestingfor a wide range of potential applications that include molecularrecognition processes in biological systems and in medicine [1],hydrogen storage [2], gas adsorption [3], catalytic reactions [4],electrical conductivity [5], guest exchange [6], nonlinear optics

[7], and magnetism [8]. The industrial applications of MOFs havebeen recently reviewed by Müller and co-workers [9]. The natureof coordinating metal ion and the selection of a suitable ligandwith certain features such as flexibility or rigidity, versatile bindingmodes and the ability to form hydrogen bonds are now consideredto be crucial parameters in the construction of polymeric metalcomplexes [10,11]. In fact, the assembly of divalent transition me-tal ions [7,8,10–17], and Zn2+, Cd2+ and Sr2+ ions [18,19] as well aslanthanides [20,21] with organic ligands yielded a new generationof polynuclear and multi-dimensional networks [2,7,8,10–21].

In the last decade, considerable efforts have been devoted to theformation of polycarboxylate assemblies, and rigid ligands derivedfrom symmetric and asymmetric aromatic multicarboxylic acidswere shown to be the most promising candidates for the construc-tion of novel metal complexes with interesting networks[8,11,12,14–21]. In addition to the ability of these compounds toaccommodate several metal ions, they can act as bridging ligands[11,12,14–21]. Among various organic ligands which have been

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⇑ Corresponding authors. Tel.: +1 337 482 5672; fax: +1 337 482 5676 (S.S.Massoud), tel.: +43 316 873 8234; fax: +43 316 4873 8225 (F.A. Mautner), tel.: +49551 393012; fax: +49 551 393063 (F. Meyer).

E-mail addresses: [email protected] (S.S. Massoud), [email protected] (F.A. Mautner), [email protected] (F. Meyer).

Inorganica Chimica Acta 370 (2011) 435–443

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widely used in this area are benzene tricarboxylates (1,3,5- and1,2,4-benzene tricarboxylic acid = 1,3,5-H3btc and 1,2,4-H3btc)[15,17–19] and benzene tetracarboxylate (1,2,4,5-benzenetetra-carboxylic acid = H4bta) [8,11,16,17,20,21]. Several interestingcharacteristics have been found in these compounds includingthe diversity in the binding modes and the possibility that one ormore of the carboxylate group(s) can be out of the plane of thephenyl ring upon complexation with the metal ions [22]. In thesecompounds, the carboxylic acid groups may be completely or par-tially deprotonated, a property which makes these ligands to serveas H-bond acceptor and H-bond donor depending on the number ofdeprotonated groups. The high symmetrical nature of 1,3,5-btc3�

and 1,2,4,5-bta4� carboxylate anions may also be helpful in thecrystal growth of the product.

In this paper, we report the synthesis, characterization andmagnetic properties of a novel series of polynuclear copper(II)complexes bridged by the tetradeprotonated 1,2,4,5-benzene-tet-racarboxylate, bta4� in the presence of linear tridentate- (Medpt,pmdien, DPA, Mepea) and tripod tetradentate (TPA, tepa, pmea,dppa) amines.1 The structural formulas of the pyridyl amine deriva-tives used in this study are illustrated in Chart 1.

2. Experimental

2.1. Materials and methods

The compounds 2-picolylchloride hydrochloride, (2-pyridyl-methyl)amine, 2-vinylpyridine and 2-(2-aminoethy)pyridine and2-(2-methylaminoethyl)pyridine were purchased from AldrichChem. Comp. Di(2-pyridylmethyl)amine and acrylamide were ob-tained from TCI-America whereas 3,30-diamino-N-methyldipropyl-amine and N,N,N0,N00,N00-pentamethyl-diethylenetriamine werepurchased from Strem Chemicals, USA. All other chemicals were re-agent grade quality. 2-Vinylpyridine was distilled and purified bycolumn chromatography before using. The pyridyl amine ligands

TPA, tepa, pmea, dpapa, and Mepea (Chart 1) were synthesizedand characterized according to published procedures [23–26].

Infrared spectra were recorded on JASCO FT/IR-480 plus spec-trometer as KBr pellets. Electronic spectra were recorded using Agi-lent 8453 HP diode UV–Vis. spectrophotometer. 1H and 13C NMRspectra were obtained at room temperature on a Varian 400 NMRspectrometer operating at 400 MHz (1H) and 100 MHz (13C). 1Hand 13C NMR chemical shifts (d) are reported in ppm and were refer-enced internally to residual solvent resonances (DMSO-d6: dH = 2.49,dC = 39.4 ppm). Elemental analyses were carried out by the AtlanticMicrolaboratory, Norcross, Georgia USA. Thermogravimetry mea-surements were performed by the Analytical Laboratory of the Insti-tute of Inorganic Chemistry at Georg-August-University Göttingenwith a STA 409PS device (NETZSCH). Susceptibility measurementswere carried out with a Quantum-Design MPMS-5S SQUID magne-tometer. The powdered samples were contained in a gel bucketand fixed in a nonmagnetic sample holder. Each raw data file forthe measured magnetic moment was corrected for the diamagneticcontribution from the gel bucket and the sample.

Caution! Salts of perchlorate and their metal complexes arepotentially explosive and should be handled with great care andin small quantities.

2.2. Synthesis of the complexes

A general method was used to synthesize the copper(II) com-plexes: To a pre-heated equimolar molar mixture of Cu(ClO4)2�6H2O(0.190 g, 0.50 mmol) and the amine ligand (0.50 mmol) dissolved in20 mL H2O, an aqueous solution of 1,2,4,5-benzene tetracarboxylatetetrasodium salt (0.95 g, 0.25 mmol) was added. The resulting in-tense blue solution was heated on a steam-bath for 15 min, filteredthrough Celite and then allowed to crystallize at room temperature.The crystalline solid which separated over a period of 4–15 days wascollected by filtration, washed with 2-propanol, ether and air dried.Crystallization from H2O afforded single crystals suitable for X-raystructure analysis.

2.2.1. [Cu4(Medpt)4(l4-bta)(ClO4)2(H2O)2](ClO4)2�2H2O (1)The complex was isolated as shiny blue crystals with an overall

yield: 91%. Characterization: Anal. Calc. for C38H86Cl4Cu4N12O28

(1555.16): C, 29.43; H, 5.51; N, 10.81. Found: C, 29.35; H, 5.57;

N

N

NNH2

O

HN

N

N

N

CH3

N

N

NN

N

NN

N

NN N

NN

N

TPA pmea tepa

DPA Mepea dppa

Chart 1. Structural formulas of the polypyridyl amine ligands used in this study.

1 Ligand abbreviations: Medpt, 3,30-diamino-N-methyldipropylamine, pmedien,N,N,N0 ,N0 0 ,N0 0-pentamethyldiethylenetriamine; DPA, di(2-pyridymethyl)amine;Mepea, [2-(2-pyridyl)ethyl]-(2-pyridylmethyl)methylamine; TPA, tris(2-pyridyl-methyl)amine; tepa, tris[2-(2-pyridyl)ethyl)]amine; pmea, bis(2-pyridylmethyl)-[2-(2-pyridylethyl)]amine; dppa, N-propanamide-bis(2-pyridylmethyl)amine.

436 S.S. Massoud et al. / Inorganica Chimica Acta 370 (2011) 435–443


N, 10.81%. Selected IR bands: m = 3445 (s) [(O–H) stretching],m = 1571 (vs), 1486 (w), 1414 (m), 1368 (s) [m(CO)], m = 1142 (s),1115 (s), 1091 (vs) [m(O–Cl) (ClO4

�) (split)] cm�1. UV/Vis (H2O):kmax, nm (emax) = 618 (511 M�1 cm�1).

2.2.2. [Cu4(pmedien)4(l4-bta)(H2O)4](ClO4)4 (2)This was isolated as dark blue crystals with an overall yield of

84%. Characterization: Anal. Calc. for C46H102Cl4Cu4N12O28

(1667.48): C, 33.14; H, 6.17; N, 10.08. Found: C, 33.27; H, 6.09; N,10.27%. IR bands (cm�1): m = 3378 (m, br) [m(O–H) stretching],m = 1578 (s), 1474 (s), 1405 (m), 1365 (s) [m(CO)], m = 1091 [m(O–Cl)(ClO4

�)] cm�1. UV/Vis (H2O): kmax, nm (emax) = 658(1050 M�1 cm�1).

2.2.3. [Cu4(Mepea)4(l4-bta)(H2O)2](ClO4)4 (3)Blue crystals were isolated in an overall yield of 69%. Character-

ization: Anal. Calc. for C66H74Cl4Cu4N12O26 (1847.37): C, 42.91; H4.04; N, 9.10. Found: C, 43.18; H, 4.02; N, 9.11%. IR bands (cm�1):m = 3463 (m) [m(O–H) stretching], m = 1609 (s) [m(C@N)+m(C@C)],m = 1579 (s), 1488 (m), 1448 (m), 1399 (m), 1353 (s) [m(CO)], m =1093 (vs) [m(O–Cl) (ClO4

�)] cm�1. UV/Vis (H2O): kmax, nm(emax) = 620 (602 M�1 cm�1) and 740 (sh).

2.2.4. [Cu4(TPA)4(l4-bta)](ClO4)4�10H2O (4)The complex was isolated as torques long needles in an overall

yield: 78%. Characterization: Anal. Calc. for C82H94Cl4Cu4N16O34

(2243.74): C, 43.90; H, 4.22; N, 9.99. Found: C, 44.41; H, 4.07; N,10.45%. Selected IR bands (cm�1): m = 3423 (vs) [m(O–H) stretch-ing], m = 1607 (vs) [(C@N)+m(C@C)], m = 1571 (m), 1480 (m), 1439(m), 1378 (m) [m(CO)], m = 1142 (m), 1120 (vs), 1091 (vs) [m(O–Cl)(ClO4

�) (split)] cm�1. UV/Vis (H2O): kmax, nm (emax) = 620(977 M�1 cm�1), 660 (sh), � 860 (977) and in CH3CN: 660 (sh),�852 (975 M�1 cm�1).

2.2.5. [Cu4(tepa)4(l4-bta)](ClO4)4�2H2O (5)Blue crystals were isolated in an overall yield of 74%. Character-

ization: Elemental analysis: Anal. Calc. for C94H102Cl4Cu4N16O26

(2267.93): C, 49.78; H, 4.53; N, 9.88. Found: C, 49.51; H, 4.45; N,9.85%. Selected IR bands: m = 3422 (s,br) [m(O–H) stretching],1608 (vs) [m(C@N)+m(C@C)], m = 1488 (s), 1446 (s), 1364 (s), 1320(s) [m(CO)], m = 1091 (s) [m(O–Cl) (ClO4

�)] cm�1. UV/Vis (H2O): kmax,nm (emax) = 637 (458 M�1 cm�1).

2.2.6. [Cu2(DPA)2(l2-bta)(H2O)2]�4H2O (6)Dark blue crystals were isolated in an overall yield of 84%. Char-

acterization: Anal. Calc. for C34H40Cu2N6O14 (883.82): C, 46.21; H,4.56; N, 9.51. Found: C, 46.18; H, 4.52; N, 9.47%. IR bands:m = 3422 (s) [m(O–H) stretching], m = 1610 (vs) [(C@N)+m(C@C)];m = 1583 (s), 1485 (m), 1443 (m), 1411 (s), 1371 (s) [m(CO)]. UV/Vis (H2O): kmax, nm (emax) = 624 (br) and 735 (sh).

2.2.7. [Cu2(pmea)2(l2-bta)]�14H2O (8)Shiny blue micro crystals were isolated in an overall yield of

75%. Characterization: Anal. Calc. for C48H70Cu2N8O22 (1240.25):C, 46.46; H, 5.69; N, 9.03. Found: C, 45.98; H, 5.44; N, 8.64%. IRbands: m = 3407 (s,br) [m(O–H) stretching], m = 1609 (s)[(C@N)+m(C@C)], m = 1563 (vs), 1470 (s), 1488 (m), 1445 (m),1419 (m), 1382 (vs) [m(CO)]. UV/Vis (H2O): kmax, nm(emax) = 620 nm. (452 M�1 cm�1).

2.2.8. [Cu2(dppa)2(l2-bta)(H2O)2]�4H2O (7) and [Cu3(dppa)3(l3-bta)(H2O)2.25](ClO4)2�6.5H2O (9)

To an equimolar amounts of Cu(ClO4)2�6H2O (0.380 g, 1 mmol)and N-propionamide-bis(2-pyridylmethyl)amine, dppa (0.270 g,1 mmol) in H2O (25 mL), tetrasodium benzene-1,2,4,5-tetracarbox-ylate (0.172 g, 0.5 mmol) was added. The reaction mixture was

heated on a steam bath for 10 min, filtered through Celite and thenallowed to crystallize at room temperature. Dark blue well shapedcrystals were separated after two days. These were collected by fil-tration and air dried (yield: 160 mg, 30% based on the amine).Characterization for 9: Anal. Calc. for C55H73.5Cl2Cu3N12O27.75

(1590.66): C, 41.53; H, 3.55; N, 10.57. Found: C, 41.08; H, 3.82;N, 10.42%. Selected IR bands (cm�1): m = 3401 (s,br) [m(O–H)stretching], m = 1668 (m) [m(C@N-amide], m = 1611 (vs) [m(C@C)],m = 1569 (s), 1488 (m), 1447 (m), 1413 (m), 1385 (m), 1362 (m)[m(CO)], m = 1096 (vs) [m(O-Cl) (ClO4

�)] cm�1. UV/Vis (H2O): kmax,nm (emax) = 637 (310 M�1 cm�1). The complex loses its crystallinitywhen washed with MeOH or 2-propanol. When the mother liquorof the reaction was allowed to stand at room temperature for 7–10 days, a second batch of blue crystals were obtained. These werecollected by filtration, and air dried (yield: 0.096 g, 18%). Charac-terization of 7: Anal. Calc. for C40H50Cu2N8O16 (1025.98): C,46.83; H, 4.91; N, 10.92%. Found: C, 46.42; H, 4.94; N, 10.68%. Se-lected IR bands (cm�1): m = 3414 (s,br) [m(O–H) stretching],m = 1647 (m) m(C@N-amide), m = 1611 (m) [m(C@C)], m = 1563 (vs),1485 (m), 1447 (m), 1415 (m), 1373 (s), 1314 (m) [m(CO)].

2.3. Crystal data collection and refinement

The X-ray single-crystal data of compounds 1, 2, 4, and 6 werecollected on a Bruker SMART APEX CCD diffractometer, with graph-ite-monochromated Mo Ka radiation. Lorentz-polarization andabsorption corrections using the SMART, SAINT and SADABS softwareprograms [27]. The crystallographic data, conditions retained forthe intensity data collection and some features of the structurerefinements are listed in Table 1. The structures were solved by di-rect methods, and refined by full-matrix least-squares methods,using the SHELX program package [28]. All non-hydrogen atomswere refined anisotropically. The hydrogen atoms bound to C andN atoms were located on calculated positions, and their isotropicdisplacement factors were set 1.2 (or 1.5) times the value of theequivalent isotropic displacement parameter of the correspondingparent atom. Hydrogen atoms of aqua ligands or lattice water mol-ecules were located from difference Fourier maps and subse-quently included in the final refinement cycles on calculatedpositions. In case of 4 split occupancies of 0.62 for O6–O8 and0.38 for O26–O28, respectively, were applied for the disorderedO atoms of a perchlorate anion. X-ray data for 7 and 9 were col-lected on a STOE IPDS II diffractometer (graphite monochromatedMo Ka radiation, k = 0.71073 Å) by use of x scans at �140 �C.The structures were solved by direct methods and refined on F2

using all reflections with SHELX-97 [28]. Non-hydrogen atoms wererefined anisotropically. Hydrogen atoms which are not involved inhydrogen bonding were placed in calculated positions and as-signed to an isotropic displacement parameter of 0.08 Å2. In caseof 7 the coordinating carboxylate moiety is disordered, which re-sults in two different coordination modes. In one mode two oxygenatoms of the carboxylate group are bound to the copper atom. Thesecond type features only one oxygen atom bound to the copperatom. Additionally one water molecule completes the coordinationsphere of the copper atom. Atoms of the disordered parts were re-fined at half occupancy. A DFIX restraint was applied for all O–Hdistances in 7 (dO–H = 0.82 Å). A fixed isotropic displacementparameter of 0.08 Å2 was assigned to the hydrogen atoms boundO8. Otherwise the isotropic displacement parameters of the oxy-gen or nitrogen bound hydrogen atoms were refined freely. In 9one ClO4

� and one water molecule were found to be disorderedabout a twofold rotation axis. Atoms were refined at half occu-pancy. Furthermore a second ClO4

� and two atoms (C10 and O8)of one carboxylate moiety were found to be disordered abouttwo positions (occupancy factors ClO4

�: 0.897(3)/0.103(3); –CO2:0.881(4)/0.119(4)). SADI restraints (dCl–O, dO��O) and EADP

S.S. Massoud et al. / Inorganica Chimica Acta 370 (2011) 435–443 437


constraints were used to model the disorder of the ClO4�. Addition-

ally DFIX (dCar–C = 1.51 Å), DELU and SIMU restraints were used incase of the carboxylate group. A DFIX restraint was applied forall N–H distances in 9 (dN–H = 0.86 Å). Nitrogen bound hydrogenatoms were refined with fixed isotropic displacement parameterof 0.08 Å2. Oxygen bound hydrogen atoms could not be located.Face-indexed absorption corrections for 7 (Tmin/Tmax = 0.6339/0.8424) and 9 (Tmin/Tmax = 0.6530/0.8222) were performed numer-ically with the program X-RED [29].

3. Results and discussion

3.1. Synthesis of the complexes

The syntheses of the 1,2,4,5-benzenetetracarboxylato-bridgedcopper(II) complexes: [Cu4(Medpt)4(l4-bta)(ClO4)2(H2O)2](ClO4)2�2H2O (1), [Cu4(pmdien)4(l4-bta)(H2O)4](ClO4)4 (2), [Cu4(Mepea)4-(l4-bta)(H2O)2](ClO4)4 (3), [Cu4(TPA)4(l4-bta)](ClO4)4�10H2O (4),[Cu4(tepa)4(l4-bta)](ClO4)4�2H2O (5), [Cu2(DPA)2(l2-bta)(H2O)2]�4H2O (6), and [Cu2(pmea)2(l2-bta)]�14H2O (8), was straight for-ward. The complexes were obtained in reasonably good yield(70–90%) by the reaction of an aqueous mixture containing equi-molar amounts of Cu(ClO4)2�6H2O and the amine ligand, and 0.50equivalent of 1,2,4,5-benzene tetracarboxylate tetrasodium salt.Under similar conditions two different compounds were isolatedwith N-propionamide-bis(2-pyridylmethyl)amine (dppa) namelythe trinuclear complex [Cu3(dppa)3(l3-bta)(H2O)2.25](ClO4)2�6.5H2O (9) and the corresponding dinuclear complex [Cu2(dppa)2-(l2-bta)(H2O)2]�4H2O (7) which was obtained from the motherliquor. Crystals suitable for X-ray analysis were produced by slowevaporation of the complexes from dilute aqueous solutions atroom temperature or by crystallization from H2O. The synthesizedcomplexes were characterized by elemental analyses, IR and UV–Vis spectroscopy and by X-ray crystallography (1, 2, 4, 6, 7 and9). Complex 3 showed no X-ray diffraction, and twinned crystalswere obtained from 8. The thermogravimetric and magnetic prop-erties were also examined.

3.2. Infrared spectra

IR spectral data of the complexes under investigation displaysome common features characteristic to the coordinated aquaand lattice water molecules over the range 3420–3450 cm�1 andto the presence of H-bonding (3500–3350 cm�1). The perchlorateions in complexes 1–5 and 9 displayed strong bands over the range1090–1140 cm�1 whereas no bands were detected in the same re-gion for complexes 6–8. The broadening or the split of the perchlo-rate band in these complexes may be attributed to the interactionof the ClO4

� ions with the lattice water and/or with the aqua watermolecules (see X-ray section). Most probably, this interaction leadsto the reduction of the ClO4

� ion symmetry of from Td to C3v or toC2v. The complexes [Cu4(Mepea)4(l4-bta)(H2O)2](ClO4)4 (3), [Cu4(-tepa)4(l4-bta)](ClO4)4�2H2O (5) and [Cu3(dppa)3(l3-bta)(-H2O)2.25](ClO4)2�6.5H2O (9) revealed their strong perchloratebands at 1093, 1091 and 1096 cm�1, respectively. The non-splitof these bands is most likely attributed to the presence of ClO4

�

as counter ions. The complexes gave also a series of absorptionbands between 1650 and 1310 cm�1 assigned to the stretching fre-quencies of the asymmetric, mas(COO�) and symmetric, ms(COO�)vibrations of the carboxylate groups. The split of these groupsand their extensive involvement in H-bonding with lattice waterand in some cases with coordinated aqua molecules (7) did not al-low the prediction of their modes of bonding [30].

3.3. Electronic spectra

The visible spectral data of the copper(II) complexes 1–6, 8, and9, recorded in H2O reveal the presence of a rather broad d-dabsorption band in the 600–900 nm region. In general, this featureis characteristic for five-coordinate copper(II) complexes which of-ten may be associated with a low-, or high-energy shoulder, oroccasionally, two distinct absorption maxima. The presence ofthe broad band in the 550–650 nm range (dxz, dyz ? dx2�y2 ) witha low-energy shoulder indicates a square pyramidal (SP) geometrywhereas, a single d–d band at k > 800 nm (dxy, dx2�y2 ? dz2 ) with a

Table 1Crystallographic data and structure refinement details for 1, 2, 4, 6, 7 and 9.

Compound 1 2 4 6 7 9

Empirical formula C38H86Cl4Cu4N12O28 C46H102Cl4Cu4N12O28 C82H94Cl4Cu4N16O34 C34H40Cu2N6O14 C40H52Cu2N8O17 C55H56Cl2Cu3N12O27.75

Molecular mass 1555.19 1667.40 2243.73 883.82 1043.98 1590.64T (K) 100(2) 100(2) 100(2) 100(2) 133(2) 133(2)Wavelength [Å] 0.71073 0.71073 0.71073 0.71073 0.71073 0.71073Crystal system Triclinic Triclinic Monoclinic Monoclinic Triclinic MonoclinicSpace group P�1 P�1 C2/c P21/c P�1 C2/ca (Å) 8.239(2) 9.684(2) 39.460(8) 8.169(2) 8.4276(4) 34.2117(6)b (Å) 14.405(3) 12.438(3) 13.463(3) 11.663(2) 10.6703(5) 21.5066(5)c (Å) 15.153(3) 15.033(3) 19.815(4) 19.431(4) 14.2948(7) 24.0347(5)a (�) 115.45(3) 86.26(3) 90 90 100.461(4) 90b (�) 94.14(3) 73.00(3) 115.93(3) 101.85(3) 103.173(4) 131.060(1)c (�) 100.81(3) 82.62(3) 90 90 112.136(3) 90V (Å3) 1571.2(8) 1716.5(7) 9467(4) 1811.8(7) 1107.24(9) 13334.3(5)Z 1 1 4 2 1 8qcalc (g m�3) 1.644 1.613 1.574 1.620 1.566 1.585l (mm�1) 1.595 1.466 1.092 1.253 1.044 1.122Crystal size (mm3) 0.30 � 0.23 � 0.15 0.32 � 0.22 � 0.17 0.34 � 0.22 � 0.13 0.30 � 0.26 � 0.22 0.30 � 0.24 � 0.19 0.50 � 0.34 � 0.15hmax (�) 26.37 26.37 25.00 26.38 26.73 25.65Reflections collected 12641 12117 29523 13908 14338 53334R(int) 0.0197 0.0268 0.0868 0.0308 0.0330 0.0216Data 6332 6960 8323 3697 4690 12573Parameters 402 446 667 274 352 974Goodness-of-fit (GOF) 1.080 1.087 1.167 1.073 1.036 1.047Ra [I > 2r(I)] 0.0391 0.0362 0.0607 0.0306 0.0308 0.0377R2xb (all data) 0.1036 0.0871 0.1371 0.0767 0.0856 0.1024Residual extrema (e Å�3) 1.585/�0.643 0.551/�0.391 1.067/�0.654 0.485/�0.268 0.405/�0.628 0.963/�0.583

a R(Fo) =PoF3

o � 3Foc=P 3Fo .

b R2x(Fo)2 = {P

[x((Fo)2 � (Fc)2)2]/P

[x((Fo)4]}1/2.



high-energy shoulder (spin forbidden, dxz, dyz ? dz2 ) is typical fortrigonal bipyramidal (TBP) stereochemistry [31]. Thus, based onthis criterion, the electronic spectral data of the complexes withthe exception of 4 can be described by SP geometry around thecentral CuII ions, where the absorption maximum band observedin the visible region results from a 2B1 2E transition. On the otherhand, the aqueous and acetonitrile solution spectrum of 4{kmax = 660 (sh) and 860 or 852 nm, respectively} clearly demon-strates the TBP environment around the CuII center [23–25,32].However, intermediate geometries that are slightly distorted fromthe ideal SP (1–3, 5, 6, 8 and 9), or TBP (4) may exist. Inspection ofthe kmax positions for complexes 5 and 8 which display the same SPgeometry and are derived from tripodal tris-pyridyl ligands (seeexperimental section) clearly indicates that the ligand fieldstrength of pmea (kmax. = 620 nm) is stronger than tepa (kmax. =637 nm).

3.4. Crystal structures

3.4.1. [Cu4(Medpt)4(l4-bta)(ClO4)2(H2O)2](ClO4)2�2H2O (1)A perspective view of 1 is given in Fig. 1. The structure of com-

plex 1 consists of centrosymmetric [Cu4(Medpt)4(l4-bta)(ClO4)2-(H2O)2]2+ complex cations, perchlorate counter ions and latticewater. Within the complex cation, the CuII centers behave differ-ently. Cu(1) is surrounded by three N atoms of the Medpt blockingligand and two O atoms supplied by the carboxylato group and anaqua ligand. The Cu(1)N3O2 chromophore is a square pyramid (SP)(s = 0.005) [33] with O(6) of the aqua ligand is in the apical site[Cu(1)–O(6) = 2.260(2) Å]. The basal Cu(1)–N/O bond lengths arein the range 1.980(2)–2.065(3) Å, and the Cu(1) atom deviates by0.186 Å from the basal Cu(1)N3O plane. Cu(2) is six-coordinatedwith an elongated trans-octahedral geometry. The equatorial sitesof the Cu(2)N3O3 chromophore are occupied by the three N- donoratoms of the Medpt ligand and O(13) of the carboxylato group[equatorial Cu(2)–N/O bond lengths ranges from 1.990(3) to2.050(2) Å]. The hexa-coordinate geometry is completed byO(14) of the carboxylato group and O(10) of a ClO4

� anion

[Cu(2)–O(14) = 2.492(2), Cu(2)–O(10) = 2.530(2) Å, O(14)–Cu(2)–O(10) = 156.08(8)�]. The bta4� anion is located at an inversioncenter. It coordinates to Cu(1) and Cu(10) in a bridging bis-mono-dentate mode and to Cu(2) and Cu(20) in a bridging bis-bidentatemode. The mean plane of the central benzene ring of btc4� formsdihedral angles of 19.4 and 102.8� with the monodentate and thechelating carboxylato groups, respectively. Dihedral angles of48.0 and 29.8� are also formed with the basal Cu(1)N3O and equa-torial Cu(2)N3O planes, respectively. The Cu(1) and Cu(2) centersdeviate by +1.017 and �0.500 Å, respectively, from the mean planeof the central benzene ring. The metal–metal distances withinthe tetranuclear complex unit are: Cu(1)��Cu(2) = 7.0297(18),Cu(1)��Cu(20) = 8.518(2), Cu(1)��Cu(10) = 11.181(3), Cu(2)��Cu(20) =10.906(3) Å, and the shortest inter-tetranuclear Cu��Cu separationis 5.0827(13) Å. Selected bond lengths and bond angles are given inTable S1 (Supplementary Section). Hydrogen bonds of the typeN–H��O and O-H��O form a supramolecular 2-D system orientedalong the a- and c-axis of the triclinic unit cell are also given inTable S2, respectively.

3.4.2. [Cu4(pmdien)4(l4-bta)(H2O)4](ClO4)4 (2)An ORTEP plot of 2 with the atom numbering scheme and se-

lected bond lengths and bond angles are presented in Fig. 2 andTable S1, respectively. The structure consists of centrosymmetric[Cu4(pmedien)4(l4-bta)(H2O)4]4+ complex cations and perchloratecounter ions. All CuII centers are ligated by three N atoms of thepmedien amine ligand and two O atoms; one from the carboxylatogroup and one from an aqua ligand. The CuN3O2 chromophoreshave distorted SP geometry [s-values: 0.096 and 0.143, for Cu(1)and Cu(2), respectively] with O atoms of the aqua ligands arelocated in the apical sites [Cu(1)–O(13) = 2.241(2), Cu(2)–O(14) =2.192(2) Å]. The basal Cu–N/O bond lengths range from 1.969(2)to 2.066(2) Å. The CuII ions are shifted by 0.232 and 0.255 Å out oftheir basal CuN3O planes for Cu(1) and Cu(2), respectively. The cen-trosymmetric bta4� ligand coordinates to the four CuII ions in abridging tetra-monodentate mode via the four deprotonated car-boxylic acid groups. The dihedral angles of the Cu(1)N3O andCu(2)N3O basal planes, the O(1)–C(4)–O(2) and O(3)–C(5)–O(4)carboxylic groups with the central bridging bta phenyl ring are163.1�, 31.9�, 116.7� and 133.9�, respectively. Cu(1) and Cu(2)

Fig. 1. ORTEP diagram (40% probability thermal ellipsoids) of the tetranuclear cationof 1 showing the atom numbering scheme. Symmetry code: (0): �x, �y + 1, �z + 1.

Fig. 2. ORTEP diagram (40% probability thermal ellipsoids) of the tetranuclear cationof 2 showing the atom numbering scheme. Symmetry code: (0): �x, �y + 1, �z.



deviate by 1.099 and 0.675 Å, respectively, from the plane of thecentral phenyl ring. The metal–metal distances within the tetranu-clear complex cation are: Cu(1)��Cu(20) = 7.6925(19),Cu(1)��Cu(2) = 8.232(2), Cu(1)��Cu(10) = 11.281(3),Cu(2)��Cu(20) = 11.253(3) Å, and the shortest inter-tetranuclearCu��Cu separation is 6.2942(16) Å. Hydrogen bonds of the type O–H��O form a supramolecular 1-D system oriented along the [1 1 0]direction of the triclinic unit cell (Table S2).

3.4.3. [Cu4(TPA)4(l4-bta)](ClO4)4�10H2O (4)The tetranuclear unit of 4 together with the atom numbering

scheme are presented in Fig. 3, and selected bond parameters aregiven in Table S1. The structure consists of centrosymmetric[Cu4(TPA)4(l4-bta)]4+ complex cations, ClO4

� counter ions and lat-tice water molecules. Both crystallographically independent CuII

centers are ligated by four N atoms of the TPA blocking ligandand one O atom from the coordinated carboxylato group. TheCuN4O chromophores display a distorted TBP geometry [s-values:0.852 and 0.803 for Cu(1) and Cu(2), respectively]. The equatorialsites are occupied by the three pyridyl N atoms of the TPA ligands[Cu–Npy ranges from 2.045(4) to 2.110(5) Å]. The axial sites areoccupied by the tertiary amine N of the TPA [Cu(1)–N(4) =2.027(4), Cu(2)–N(6) = 2.028(4) Å] and the O atom supplied bythe deprotonated monodentate carboxylato group [Cu(1)–O(1) =1.925(3), Cu(2)–O(4) = 1.932(3) Å]. The dihedral angles of the car-boxylic groups O(1)–C(18)–O(2) and O(3)–C(22)–O(4) with thecentral phenyl ring of the bta bridging ligand are 44.8� and 55.5�,respectively. The copper atoms deviate from the plane of the cen-tral phenyl ring by �1.643 and +2.152 Å for Cu(1) and Cu(2),respectively, The metal–metal distances within the tetranuclearcomplex unit are: Cu(1)��Cu(2) = 5.4960(16), Cu(1)��Cu(20) =9.446(2), Cu(1)��Cu(10) = 10.987(3), Cu(2)��Cu(20) = 10.870(3) Å,and the shortest inter-tetranuclear Cu��Cu separation is6.3039(18) Å. A supramolecular 1-D system oriented along the c-axis of the monoclinic unit cell similar to that described in 2 resultsfrom O–H��O hydrogen bonding (Table S2).

3.4.4. [Cu2(DPA)2(l2-bta)(H2O)2]�4H2O (6)Perspective views of the dinuclear unit of 6 with the atom label-

ing scheme are given in Fig 4 and the relevant bond parameters are

presented in Table S1. The structure of compound 6 consists ofneutral centrosymmetric dimeric unit [Cu2(DPA)2(l2-bta)(H2O)2]and lattice water molecules. Cu(1) is surrounded by three N atomsof the DPA blocking ligand, O(1) of a carboxylato group and O(5) ofan aqua ligand. The CuN3O2 chromophore has distorted SPgeometry [s = 0.277] with O(5) of the aqua ligand in the apical site[Cu(1)–O(5) = 2.235(2) Å]. The basal Cu(1)–N/O bond lengths arein the range from 1.9645(13) to 2.005(2) Å, and the Cu(1) atom isplaced by 0.138 Å out of the basal CuN3O plane. The centrosym-metric bta4� ligand coordinates to the two CuII centers in abridging trans bis-monodentate mode via two of the four deproto-nated carboxylic groups. The dihedral angles of the basal CuN3Oplane, the coordinated and uncoordinated carboxylic groupswith the central phenyl ring are 117.9�, 30.8� and 66.4�,respectively.

3.4.5. [Cu2(dppa)2(l2-bta)(H2O)2]�4H2O (7)Complex 7 (Fig. 5) is build up from neutral dimeric centrosym-

metric units [Cu2(dppa)2(l2-bta)(H2O)2] and lattice water mole-cules. Cu(1) is surrounded by N(1), N(2), N(3) and O(5) of theblocking ligand, and O(1) of the carboxylato group. The CuN3O2

chromophore has distorted SP geometry [s = 0.106] with O(5) ofthe dppa ligand in the apical site [Cu(1)–O(5) = 2.1943(12) Å].The basal Cu(1)–N/O bond lengths ranges from 1.9641(12) to2.0378(16) Å, and the Cu(1) atom is shifted by 0.118 Å out of thebasal CuN3O plane. Additional semi-coordinative Cu–O bond dis-tances are observed to O(9) [2.727(4) Å] of aqua ligand and O(2A)[2.719(4) Å] of the carboxylate group [both O atoms have occu-pancy of 0.5]. The centrosymmetric bta4� ligand binds the two CuII

ions in a fashion that is similar to 6. The dihedral angles of the basalCuN3O plane, O(1)–C(4)–O(2B) of the coordinated and O(3)–C(5)–O(4) of the uncoordinated carboxylate groups with the central phe-nyl ring are 95.4, 30.7 and 76.2�, respectively. The relevant bondparameters of the complex are given in Table S1.

In both structures 6 and 7, the Cu(1) deviate by 0.800 Å and1.230 Å, respectively from the plane of the central phenyl ring.The intra-dinuclear Cu(1)��Cu(10) distances are 11.054(3) Å and10.9327(6) Å, respectively whereas the corresponding shortest in-ter-dinuclear Cu��Cu separations are 6.8673(17) Å and 7.2860(4) Å.The relevant bond parameters of the two complexes are given inTable S1. Hydrogen bonds of type N–H��O and O–H��O are foundin the two compounds and lead to the formation of a supramolec-ular 3-D network in 6 and to a 2-D system oriented along the[0 1 1] and [1 0 0] directions of the triclinic unit cell in 7 (TablesS2 and S3).

Fig. 3. ORTEP diagram (40% probability thermal ellipsoids) of the tetranuclearcomplex cation of 4 showing the atom numbering scheme. Symmetry code: (0): �x,�y + 2, �z + 1.

Fig. 4. ORTEP diagram (40% probability thermal ellipsoids) of the dinuclear unit of 6showing the atom numbering scheme. Symmetry code: (0): �x + 1, �y, �z + 1.



3.4.6. [Cu3(dppa)3(l3-bta)(H2O)2.25](ClO4)2�6.5H2O (9)The trinuclear cation of 9 together with atom labeling scheme,

and selected bond parameters are presented in Fig. 6 and TableS1, respectively. The structure consists of [Cu3(dppa)3(l3-bta)-(H2O)2.25]2+ complex cations, partially disordered ClO4

� counterions and lattice water molecules. The geometry around each ofthe three Cu(II) centers may be described as 4 + 1 + 1. Each of theCu(II) atoms is bound to three of the four N atoms of the dppablocking ligand and to one O atom of the monodentate carboxylategroup in the equatorial sites [equatorial Cu–N/O bond lengths varyfrom 1.9483(18) to 2.047(2) Å]. The axial positions are occupied bythe carbonyl O atom of the dppa ligand [Cu(1)–O(11) = 2.2606(19),Cu(2)–O(21) = 2.334(2), Cu(3)–O(31) = 2.2260(18) Å] and by Oatom of an aqua ligand with semi-coordinative bond distances ofCu(1)–O(41) = 2.822(2), Cu(2)–O(42) = 2.731(2) and Cu(3)–O(43) = 2.670(9) Å [occupancy of O(43) is 0.25] in the later case.The bta4� ligand coordinates to the three CuII centers in a bridgingtris-monodentate mode via three of the four deprotonated carbox-ylate groups of bta4� ligand. Each of the three carboxylates isbound to CuII ions in the equatorial site and the remaining non-coordinated carboxylate group in position 6 of the central benzenering shows disorder with two split orientations. The dihedral

angles O(1)–C(7)–O(2), O(3)–C(8)–O(4), O(5)–C(9)–O(6) andO(7)–C(10A)–O(8A) of the carboxylate groups with the centralphenyl ring of the bta bridging ligand are 93.1�, 53.7�, 69.5� and17.0�, respectively, Also, the CuN3O equatorial planes form dihe-dral angles of 22.3�, 16.1� and 3.4�, for Cu(1)–Cu(3), respectively,with the phenyl ring. As indicated in the previous complexes, theCu centers deviate from the mean plane of the phenyl ring by+1.203, +1.205 and �1.070 Å, for Cu(1), Cu(2) and Cu(3), respec-tively. The Cu–Cu distances within the trinuclear complex unitare: Cu(1)��Cu(2) = 8.4187(5), Cu(2)��Cu(3) = 7.2091(6),Cu(1)��Cu(3) = 11.1750(7) Å whereas, the shortest inter-nuclearCu��Cu separation is 6.9400(4) Å. The–NH2 groups of the dppa ligands are not coordinated to the metalcenters but form hydrogen bonds of type N–H��O (Table S3).

Attempts were made to solve the molecular structure of [Cu2-(pmea)2(l2-bta)]�14H2O, 8 (detailed description of the structureis given in the supplementary section, ORTEP plot is shown inFig. S1 and crystallographic parameters are given in Table S4).Briefly, each CuII center is coordinated to the four N atoms of thepmea and one O atom from a carboxylato group in distorted SPgeometry. The bta4� bridges the two Cu atoms in trans bis-mono-dentate mode via two of the four deprotonated carboxylate groups.The intra-dinuclear Cu(1)��Cu(2) distance is 11.005(3) Å, and theshortest inter-dinuclear Cu��Cu separation is 7.323(2) Å.

3.5. Magnetic properties

Magnetic susceptibility measurements were carried out oncomplexes 1–9 at a magnetic field of 0.5 T in the temperaturerange 295–2.0 K. The temperature dependence of the magneticmoment leff are shown in Fig. 7 (for 1, 6, 7 and 9) and Fig. S2(for 2–5 and 8).

The magnetic moment leff at r.t. is around 3.7 lB for tetranu-clear, 3.25 lB for trinuclear and 2.6 lB for dinuclear complexes,which is close to the expected values for four (3.64 lB), three(3.15 lB), or two (2.57 lB) uncoupled CuII ions (S = ½, g = 2.10). leff

remains almost constant over a large temperature range, butdecreases at very low temperatures for all complexes with theexception of 6. Such behavior suggests the presence of very weakantiferromagnetic coupling between the CuII ions in 1–5, 7–9 andweak ferromagnetic coupling for 6.

According to the molecular structures of these tetra- and trinu-clear complexes, three interaction pathways are possible. However,in view of the weakness of the interaction this situation leads totwo problems in magnetic data analysis: (i) mutual dependence

Fig. 5. ORTEP diagram (40% probability thermal ellipsoids) of the dinuclear unit of 7showing the atom numbering scheme. Symmetry code: (0): �x, �y, �z.

Fig. 6. ORTEP diagram (40% probability thermal ellipsoids) of 9 showing the atomnumbering scheme.

Fig. 7. Plot of leff vs. temperature for 1, 6, 7 and 9 at 0.5 T. The solid line representsthe calculated curve fit.



of the coupling constants in the fitting procedure and (ii) assign-ment of obtained values to the different coupling pathways. There-fore we applied a simple dimer model for all complexes in order toestimate the magnitude of exchange interaction. Experimentaldata for all complexes were modeled by using a fitting procedureto the appropriate Heisenberg–Dirac–van-Vleck (HDvV) spin Ham-iltonian for isotropic exchange coupling and Zeeman splitting, Eq.(1) [34].

H ¼ �2JS1 � S2 þ glBðS1 þ S2ÞB ð1Þ

Temperature-independent paramagnetism (TIP) and a Curie-behaved paramagnetic impurity (PI) with spin S = ½ were includedaccording to vcalc = (1 � PI)�v + PI�vmono + TIP [35]. Results of themagnetic data analyses for 1–9 are compiled in Table 2. In orderto check the validity of the dimer model for estimating the magni-tude of the coupling in the tri- and tetranuclear complexes, an alter-native model with two coupling constants according to Chart 2 hasbeen applied to the magnetic data analysis of 1.

This model gives a nearly equally good fit (see Fig. S3) withg = 2.15, J1 = �0.55 cm�1, J2 = �0.55 cm�1, q = 0.8% (fixed), andTIP = 77 � 10�6 cm3 mol�1. However, the values of J1 and J2 aredependent on the starting parameters of the fitting procedure. Itshould be noted that assignment of J1 and J2 to the meta- andortho-pathways is arbitrary due to the symmetry of the Hamilto-nian. In view of the possible mutual dependence of the couplingconstants, the 3D error surface for the pair J1–J2 was calculated(Fig. S4). Indeed any minimum can be observed, indicating thatthese two parameters are strongly interdependent; hence the useof the dimer model seems to by a reasonable approach for thiscase.

From the structural point of view the pathway for the magneticexchange in the tetracarboxylate-bridged dinuclear complexes 6–8should be very similar to that in terephthalate-bridged dinuclearcopper(II) complexes. Indeed, the observed coupling constants in6–8 provide new evidence that the 1,2,4,5-benzenetetracarboxyla-to ligand in the para-bridged modes is unable to mediate any sig-nificant intramolecular coupling, as has previously been concludedfor terephthalate-bridged dinuclear copper(II) complexes [36]. Itshould be noted that such very small coupling constants may alsobe caused by intermolecular through-space (dipole–dipole) inter-actions [37]. Tri- and tetranuclear complexes should have availablefor exchange interactions meta- and ortho- in addition to para-pathways, but also these pathways do not mediate any noticeablemagnetic interactions (Table 2). This is in accordance with

previously reported results for phthalato- and isophthalato-bridged copper(II) complexes, where the intramolecular interac-tion through the phenyldicarboxylate bridges is negligibly small[38]. In some previous cases sizeable coupling in phenyldicarboxy-late bridged copper(II) complexes has been attributed to intermo-lecular through-bond interactions (e.g. via a spin polarizationmechanism mediated through hydrogen bonding between carbox-ylic groups, or because of loss of water molecules with ensuing car-boxylate bridging) [37a,38].

3.6. Thermogravimetric analysis

Thermogravimetric analyses of complexes 1, 2 and 7 show theloss of water over the wide temperature range: 70–140 �C (massloss: exp. 4.7%, calcd. 4.6% for 4 H2O), 125–170 �C (mass loss:exp. 4.0%, calcd. 4.3% for 4 H2O) and 125–170 �C (mass loss: exp,6.2%, calcd. 7.0% for 4 H2O). The TG profile for the water loss in 1shows a shoulder at 100 �C and a maximum at 114 �C, but doesnot show any intermediate step in 2 (Tmax = 118 �C) and 7(Tmax = 152 �C).

4. Conclusions

Three different types of polynuclear copper(II) complexesbridged by 1,2,4,5-benzene tetracarboxylate (bta4�) were isolatedby varying the nature of the coordinating polydentate amine coli-gands. Tetranuclear compounds were isolated with the aminesMedpt (1), pmedien (2), Mepea (3), TPA (4) and tepa (5), di-nuclearcomplexes were obtained with DPA (6), dppa (7) and pmea (8) andtrinuclear with dppa ligand (9). This reflects the diverse coordina-tion properties of the bta4� ligand in binding several metal ionswith the possibility of formation of extended structures with dif-ferent dimensionality [15,16,21], probably via hydrogen bondingand/or by careful selection of the building block coligands. Mag-netic susceptibility measurements revealed the very weak antifer-romagnetic interaction between Cu(II) ions in all complexes except6 which showed very weak ferromagnetic coupling. Also, the mag-netic coupling constants determined in this series of complexesclearly indicate that although the bridged bta4� ligand has severalcarboxylate groups which can accommodate several Cu(II) ions, itis still unable to mediate any significant intramolecular interaction.A result which was previously demonstrated in copper(II) com-plexes bridging by 1,4- and 1,3-benzene dicarboxylates [13,38].

Acknowledgments

This research was financially supported by the Department ofChemistry-University of Louisiana at Lafayette and the DeutscheForschungsgemeinschaft(SFB 602, project A16; F.M.). S.S.M. thanksDean B. Clark (UL-Lafayette), and F.A.M. thanks Dr. J. Baumgartner(TU-Graz) for assistance.

Appendix A. Supplementary material

Description of the molecular structure of [Cu2(pmea)2(l2-bta)]�14H2O (8), an ORTEP figure (Fig. S1) and its crystallographicparameters (Table S3) as well as H-bonding schemes of compounds1, 2, 4, 6, 7, and 9 are given in Tables S1 and S2. CCDC 790570,790571, 790572, 790573, 790574, and 790575 contain the supple-mentary crystallographic data for compounds 1, 2, 4, 6, 7, and 9,respectively. These data can be obtained free of charge from TheCambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this articlecan be found, in the online version, at doi:10.1016/j.ica.2011.02.019.

Table 2Parameters obtained from simulation of magnetic data for complexes 1–9.

Complexes g J (cm�1) PI (%) TIP/10�6 (cm3 mol�1)

1 2.14 �0.87 0.8 1242 2.14 �0.55 0.7 873 2.15 �0.44 0.7 1164 2.15 �1.04 0.5 (fixed) 3215 2.14 �0.56 0.3 2226 2.14 +0.08 0.9 547 2.11 �0.09 0.1 1808 2.12 �0.02 0.9 529 2.16 �0.31 0.2 50 (fixed)

Chart 2. Alternative coupling scheme for 1.



References

[1] B.I. Chen, M. Eddaoudi, S.T. Hyde, M. O’Keeffe, O.M. Yaghi, Science 291 (2001)1021.

[2] L.J. Murray, M. Dinca, J.R. Long, Chem. Soc. Rev. 38 (2009) 1294.[3] (a) S. Xiang, X. Wu, J. Zhang, R. Fu, S. Hu, X. Zhang, J. Am. Chem. Soc. 127 (2005)

16352;(b) M. Eddaoudi, J. Kim, N. Rossi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi,Science 295 (2002) 469.

[4] (a) H.K. Chae, D.Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A.J. Matzger, M.O’Keeffe, O.M. Yaghi, Nature 427 (2004) 523;(b) J.S. Seo, D. Whang, H. Lee, S.I. Jun, J. Oh, Y.J. Jeon, K. Kim, Nature 404 (2000)982;(c) J. Bi, L. Kong, Z. Huang, J. Liu, Inorg. Chem. 47 (2008) 4564.

[5] C.N.R. Rao, A. Rangnathan, V.R. Pedireddi, A.R. Raju, Chem. Commun. (2000) 39.[6] H.K. Chae, D.Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A.J. Matzger, M.

O’Keeffe, O.M. Yaghi, Nature 378 (1995) 703.[7] (a) W. Lin, L. Ma, O.R. Evans, Chem. Commun. 22 (2000) 2264;

(b) W. Lin, Z. Wang, L. Ma, J. Am. Chem. Soc. 121 (1999) 11249;(c) W. Lin, O.R. Evans, R.-G. Xiong, Z. Wang, J. Am. Chem. Soc. 120 (1998)13272.

[8] (a) M. Sanselme, J.M. Grenèche, M. Fiou-Cavllec, G. Férey, Chem. Commun.(2002) 2172;(b) V.V. Pavlishchuk, I.A. Koval, E. Goroshink, A.W. Addison, G.A. Albada, J.Reedijk, Eur. J. Inorg. Chem. (2001) 297.

[9] A.U. Czaja, N. Trukhan, U. Müller, Chem. Soc. Rev. 38 (2009) 1284.[10] B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1620.[11] C.S. Hong, S.K. Son, Y.S. Lee, M.J. Jun, Y. Do, Inorg. Chem. 38 (1999) 5602.[12] B. Chen, M. Eddaoudi, T.M. Reineke, J.W. Kampf, M. O’Keeffe, O.M. Yaghi, J. Am.

Chem. Soc. 122 (2000) 11559.[13] (a) F.A. Mautner, R. Vicente, F.R. Louka, S.S. Massoud, Inorg. Chim. Acta 361

(2008) 1339;(b) S.S. Massoud, K.T. Broussard, F.A. Mautner, R. Vicente, M.K. Saha, I. Bernal,Inorg. Chim. Acta 351 (2008) 123;(c) S.S. Massoud, F.A. Mautner, R. Vicente, B.M. Rodrigue, Inorg. Chim. Acta 359(2006) 3321.

[14] (a) L. Cañadillas-Delgado, O. Fabelo, J. Pasán, F.S. Delgado, F. Lloret, M. Julve, C.Ruiz-Pérez, Inorg. Chem. 46 (2007) 7458;(b) S. Dalai, P.S. Mukherjee, E. Zangrando, F. Lloret, N.R. Chaudhuri, DaltonTrans. (2002) 822;(c) S. Zhou, Y. Ke, H. Zou, T. Liu, F. Zhu, J. Chen, A. Xie, Z. Naturf. Sect. B 63(2008) 1339;(d) S.-T. Zheng, J. Zhang, G.-Y. Yang, Angew. Chem., Int. Ed. 47 (2008) 3909.

[15] (a) J. Mrozinski, A. Bienko, P. Kopel, V. Langer, Inorg. Chim. Acta 361 (2008)3723;(b) D. Zacher, J. Liu, K. Huber, R.A. Fisher, Chem. Commun. (2009) 1031;(c) J.-D. Lin, C.-C. Jia, Z.-H. Li, S.-W. Du, Inorg. Chem. Commun. 12 (2009) 558;(d) G.-B. Che, C.-B. Liu, B. Liu, Q.-W. Wang, Z.-L. Xu, CrystEngComm 10 (2008)184.

[16] (a) L.-M. Zhao, B. Zhai, D.-L. Gao, W. Shi, B. Zhao, P. Cheng, Inorg. Chem.Commun. 13 (2010) 1014;(b) De-Qing Chu, J.-Q. Xu, L.-M. Duan, T.-G. Wang, A.-Q. Tang, L. Ye, Eur. J. Inorg.Chem. (2001) 1135;(c) L.-J. Zhang, J.-Q. Xu, Z. Shi, X.-L. Zhao, T.-G. Wang, J. Solid State Chem. 32(2003) 32;(d) L.-J. Zhang, J.-Q. Xu, Z. Shi, W. Xu, T.-G. Wang, Dalton Trans. (2003) 1148.

[17] L.-P. Zhang, J. Yang, J.-F. Ma, Z.-F. Jia, Y.-P. Xie, G.-H. Wei, CrystEngComm 10(2008) 1410.

[18] (a) A.D. Burrows, C.G. Frost, M. Kandiah, L.L. Keenan, M.F. Mahon, T.C. Savarese,J.H. Warren, Inorg. Chim. Acta 366 (2011) 303;(b) Z.-H. Zhang, G.-X. Liu, T.-A. Okamura, W.-Y. Sun, N. Ueyama, Struct. Chem.17 (2006) 3;(c) J. Meng, X. Wang, E. Wang, Y. Li, C. Qin, X. Xu, Inorg. Chim. Acta 361 (2008)2447;

(d) S.-W. Liang, M.-X. Li, M. Shao, H.-J. Liu, Inorg. Chem. Commun. 10 (2007)1347;(e) M.A. Braveman, R.M. Supkowski, R.L. LaDuca, J. Solid State Chem. 180(2007) 1852;(f) J. Guo, T. Zhang, J. Zhang, Y. Liu, W. Yu, R. Wu, Struct. Chem. 17 (2006) 577;(g) D.T. Tran, D. Chu, A.G. Oliver, S.R.J. Oliver, Inorg. Chem. Commun. 12 (2009)351;(h) G.-H. Wei, J. Yang, J.-F. Ma, Y.-Y. Liu, S.-L. Li, L.-P. Zhang, Dalton Trans.(2008) 3080.

[19] J. Yao, Z.-D. Lu, Y.-Z. Li, J.-G. Lin, X.-Y. Duan, S. Gao, Q.-J. Meng, C.-S. Lu,CrystEngComm 10 (2008) 1379.

[20] (a) R. Cao, D. Sun, Y. Liang, M. Hong, K. Tatsumi, Q. Shi, Inorg. Chem. 41 (2002)2087;(b) M.-J. Ren, Z. Zhang, P. Zhao, J. Zhang, Asian J. Chem. 20 (2008) 3687.

[21] L.-P. Zhang, J.-F. Ma, J. Yang, Y.-Y. Pang, H.-C. Ma, Inorg. Chem. 49 (2010) 1535.[22] F.-P. Huang, J.-L. Tian, W. Gu, S.-P. Yan, Inorg. Chem. Commun. 13 (2010) 90.[23] (a) Z. Tyeklár, R.R. Jacobson, N. Wei, N.N. Murthy, J. Zubieta, K.D. Karlin, J. Am.

Chem. Soc. 115 (1993) 2677;(b) U. Mukhopadhyay, I. Bernal, S.S. Massoud, F.A. Mautner, Inorg. Chim. Acta357 (2004) 3673.

[24] F.A. Mautner, F.R. Louka, T. LeGuet, S.S. Massoud, J. Mol. Struct. 919 (2009) 196.[25] F.A. Mautner, J.B. Soileau, P.K. Bankole, A. Gallo, S.S. Massoud, J. Mol. Struct.

889 (2008) 271.[26] M. Schatz, M. Becker, F. Thaler, F. Hampel, S. Schindler, R.R. Jacobson, Z.

Tyeklár, N.N. Murthy, P. Ghosh, Q. Chen, J. Zubieta, K.D. Karlin, Inorg. Chem. 40(2001) 2312.

[27] (a) SMART (Control) and SAINT (Integration) Software, Version 5.0. Bruker AXSInc., Madison, WI, 1997.;(b) G.M. Sheldrick, SADABS, Program for Scanning and Correction of AreaDetector Data, University of Göttingen, Göttingen, Germany, 1997.

[28] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.[29] STOE & CIE GmbH, X-RED, Darmstadt, Germany, 2002.[30] B.G. Deacon, R.J. Philips, Coord. Chem. Rev. 33 (1980) 227.[31] A.B.P. Lever, Inorganic Electronic Spectroscopy, Elsevier, Amsterdam, The

Netherlands, 1984.[32] (a) B.J. Hathaway, in: G. Wilkinson, R.D. Gillard, J.A. McCleverty (Eds.),

Comprehensive Coordination Chemistry, vol. 5, Pergamon Press, Oxford,England, 1987, p. 533.;(b) S.S. Massoud, F.A. Mautner, R. Vicente, F.R. Louka, Eur. J. Inorg. Chem.(2008) 3709;(c) S.S. Massoud, F.A. Mautner, R. Vicente, J.S. Dickens, Inorg. Chim. Acta 361(2008) 299;(d) S.S. Massoud, F.A. Mautner, Inorg. Chim. Acta 358 (2005) 3343;(e) S.S. Massoud, F.A. Mautner, Inorg. Chem. Commun. 7 (2004) 559.

[33] A.W. Addison, T.N. Rao, J. Reedijk, J.V. Rijin, G.C. Verschoor, J. Chem. Soc.,Dalton Trans. (1984) 1349.

[34] O. Kahn, Molecular Magnetism, Wiley-VCH, Publishers Inc., 1993.[35] E. Bill, Simulation of the Experimental Magnetic Data with a Full-matrix

Diagonalisation of Exchange Coupling and Zeeman Splitting was Performedwith the JULX Program, Max-Planck Institute for Bioinorganic Chemistry,Mülheim/Ruhr, Germany.

[36] (a) J. Cano, G. De Munno, J.L. Sanz, R. Ruiz, J. Faus, F. Lloret, M. Julve, A.Caneschi, J. Chem. Soc., Dalton Trans. (1997) 1915.;(b) S.S. Massoud, F.A. Mautner, R. Vicente, N.S. Hunter, Inorg. Chim. Acta 359(2006) 1489.

[37] (a) L.M.B. Napolitano, O.R. Nascimento, S. Cabaleiro, J. Castro, R. Calvo, Phys.Rev. B 77 (2008) 214423;(b) T. Yamase, H. Abe, E. Ishikawa, H. Nojiri, Y. Ohshima, Inorg. Chem. 48(2009) 138.

[38] (a) S.K. Shakhatreh, E.G. Bakalbassis, I. Brüdgam, H. Hartl, J. Mrozinski, C.A.Tsipis, Inorg. Chem. 30 (1991) 2801;(b) E.G. Bakalbassis, D.G. Paschalidis, Inorg. Chem. 37 (1998) 4735;(c) W.-Z. Shen, X.-Y. Chen, P. Cheng, S.-P. Yan, B. Zhai, D.-Z. Liao, Z.-H. Jiang,Eur. J. Inorg. Chem. (2005) 2297.


diverse coordination of polynuclear copper(ii) complexes constructed from benzene tetracarboxylates

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