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Syntheses, crystal structures, spectroscopic, fluorescence and thermal propertiesof silver(I) 5,5-diethylbarbiturato complexes with some aminopyridines

Fatih Yilmaz a, Veysel T. Yilmaz b,*, Eda Soyer b, Orhan Buyukgungor c

a Department of Chemistry, Faculty of Arts and Sciences, Rize University, 53100 Rize, Turkeyb Department of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkeyc Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayis University, 55139 Samsun, Turkey

a r t i c l e i n f o

Article history:Received 31 March 2010Accepted 24 May 2010Available online 1 June 2010

Keywords:5,5-DiethylbarbiturateSilver(I)2-Aminopyridine2-Aminomethylpyridine2-(Dimethylaminomethyl)-3-hydroxypyridine

a b s t r a c t

Three new silver(I) complexes of 5,5-diethlybarbiturate (barb), [Ag(barb)(apy)]�H2O (1), {[Ag(l-ampy)][Ag(l-barb)2]}n (2) and [Ag(barb)(dmamhpy)] (3) [apy = 2-aminopyridine, ampy = 2-aminometh-ylpyridine and dmamhpy = 2-(dimethylaminomethyl)-3-hydroxypyridine] have been synthesized andcharacterized by elemental analysis and FT-IR. Single crystal X-ray diffraction analyses showed that com-plexes 1 and 3 are mononuclear. In 1, the silver(I) ion is linearly coordinated by a barb anion and a ampyligand, while a bidentate dmamhpy ligand together with an N-coordinated barb anion forms a trigonalcoordination geometry around silver(I) in 3. Complex 2 is a one-dimensional coordination polymer inwhich silver(I) ions are bridged by ampy ligands, leading to a cationic chain ½AgðampyÞ�þn. The[Ag(barb)2]� units contains two N-bonded barb ligands, bridging the silver centers in the cationic andanionic units via the carbonyl O atoms. Thus, complex 2 contains two-coordinated and four-coordinatedsilver ions. All complexes display hydrogen-bonded network structures and exhibit appreciable fluores-cence at room temperature. Thermal analysis (TG–DTA) data are in agreement with the structures of thecomplexes.

� 2010 Elsevier B.V. All rights reserved.

1. Introduction

Barbiturates are derivatives of barbituric acid (malonylurea or4-hydroxyuracil) and form a group of medically important com-pounds used as central nervous system depressants, sedative-hypnotics, anticonvulsants and anesthetics. Most of them exert asedative effect in small doses and a hypnotic effect in larger doses.The medicinal properties of barbiturates mainly depend on the sidegroups attached to the C5 atom of the pyrimidine ring [1].

The coordination chemistry of barbiturates is interesting andbegins with the preparation of a crystalline copper(II) complex of5,5-diethylbarbituric acid (barbH) with pyridine (py), [Cu(barb)2-(py)2] in 1931 [2]. The methods used to identify barbiturates bycomplexing with transition metal ions are of substantial analyticalvalue. On the other hand, barbituric acids are weak acids and read-ily deprotonate in solutions, forming corresponding barbiturateanions. The donor atoms such as amine N and carbonyl O atomsmake them polyfunctional ligands. The copper(II) complexes of12 different clinically important barbiturates containing py wereprepared and identified by elemental and IR spectral analysis [3].

Among them, metal complexes of barbH have received muchattention, probably due to its easy complexation with various me-tal ions [4–7]. X-ray crystal structures showed that in the first re-ported complexes, barb anion is N-coordinated through thedeprotonated N atom.

As a continuation of our work on the synthesis and structuresof metal complexes of 5,5-diethylbarbiturate (barb), also clinicallyknown as barbital or veronal, we synthesized a number of metalcomplexes of barb [8–15]. These studies showed that the barbmonoanion exhibits monodendate (N), bidentate chelating (N,O) and bridging coordination modes, forming complexes frommononuclear to coordination polymers. Moreover, it sometimesacts as a counter-ion remaining outside the coordination sphere.In some cases, the barb ligand loses its second amin hydrogenatom and forms a barb dianion which behaves as a tetradentatebridging ligand [16]. We have now extended this work to includebarb-silver(I) complexes with three aminopyridines such as 2-aminopyridine (apy), 2-aminomethylpyridine (ampy) and 2-(dimethylaminomethyl)-3-hydroxypyridine (dmamhpy), namely[Ag(barb)(apy)]�H2O (1), {[Ag(l-ampy)][Ag(l-barb)2]}n (2) and[Ag(barb)(dmamhpy)] (3). The paper reports the synthesis, char-acterization and crystal structures of these complexes. Further-more, thermal and fluorescent properties of 1–3 are alsoevaluated.

0020-1693/$ - see front matter � 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.ica.2010.05.050

* Corresponding author.E-mail address: [email protected] (V.T. Yilmaz).

Inorganica Chimica Acta 363 (2010) 3165–3171

Contents lists available at ScienceDirect

Inorganica Chimica Acta

journal homepage: www.elsevier .com/locate / ica


2. Experimental

2.1. Materials and instrumentation

Commercially available chemicals were used without furtherpurification. Elemental analyses were carried out by the analyticalservices of BUTAL. IR spectra were recorded with a Thermo Nicolet6700 FT-IR spectrophotometer as KBr pellets in the 4000–400 cm�1

range. Excitation and emission spectra were recorded at roomtemperature in 1 � 10�3 M acetonitrile (MeCN)/H2O/2-propanol(PrOH) solutions (1/1/1) with a Varian Cary Eclipse spectropho-tometer equipped with a Xe pulse lamp of 75 kW. Thermal analysiscurves (TGA and DTA) were obtained using a Seiko Exstar 6200thermal analyzer in a dynamic air atmosphere with a heating rateof 10 K min�1 and a sample size of ca. 10 mg.

2.2. Synthesis of the silver(I) complexes

Complex 1 was prepared by the following procedure. A 10 mlaqueous solution of Na(barb) (5,5-diethylbarbituric acid sodiumsalt) (0.21 g, 1 mmol) was added to a 10 ml aqueous solution ofAgNO3 (0.17 g, 1 mmol) with stirring at room temperature. Then,the solution immediately became milky. The addition of 2-amino-pyridine (apy) (0.09 g, 1 mmol) together with a mixture of ethanoland MeCN (1:1) (10 mL) to the milky suspension resulted in a clearsolution. The resulting solution was allowed to stand in darkness atroom temperature and colorless crystals of 1 were obtained after4 days.

Complexes 2 and 3 were synthesized using the same method byemploying 2-aminopyridine (ampy) and 2-(dimethylamino-

methyl)-3-hydroxypyridine (dmamhpy), respectively. In the caseof 2, to clarify the milky solution, it was gently heated after addi-tion of ampy and PrOH.

[Ag(barb)(apy)]�H2O (1): Yield 64%. M.p. 127–134 �C (decompo-sition). Anal. Calc. for C13H19N4O4Ag: C, 38.8; H, 4.3; N, 14.0. Found:C, 39.1; H, 4.2; N, 14.3%. IR (Solid KBr pellet) m (cm�1): 3410m,3379w, 3350m, 3187sb, 3081m, 3032w, 2970m, 2929w, 2872w,1716s, 1679vs, 1638vs, 1601vs, 1487s, 1442vs, 1422vs, 1368vs,1319vs, 1258s, 1152w, 1042w, 993w, 944w, 850m, 776s, 698w,641w, 539m, 444w.

{[Ag(l-ampy)][Ag(l-barb)2]}n (2): Yield 52%. M.p. 172–174 �C(decomposition). Anal. Calc. for C22H30N6O6Ag2: C, 38.3; H, 4.4; N,12.2. Found: C, 38.0; H, 4.5; N, 12.4%. IR (Solid KBr pellet) m(cm�1): 3273w, 3189m, 3125w, 3087w, 2968m, 2935w, 2876vw,1711s, 1676vs, 1636vs, 1602vs, 1459m, 1421vs, 1368vs, 1318vs,1257s, 1166w, 1039w, 947w, 931m, 837w, 796w, 765m, 696w,542m, 466w.

[Ag(barb)(dmamhpy) (3): Yield 60%. M.p. 273 �C (decomposi-tion). Anal. Calc. for C16H23N4O4Ag: C, 43.4; H, 5.2; N, 12.6. Found:C, 43.6; H, 5.6; N, 12.8%. IR (Solid KBr pellet) m (cm�1): 3420b,3187m, 3085m, 3032vw, 2966m, 2929w, 2868m, 1716vs, 1679vs,1638vs, 1593vs, 1499m, 1458s, 1418vs, 1360vs, 1315vs, 1275sh,1254vs, 1185m, 1168m, 1103m, 1042m, 1009s, 968w, 837s,809s, 760s, 735w, 690w, 625m, 568m, 543s, 449m.

2.3. X-ray crystallography

The intensity data of complexes 1–3 were collected using aSTOE IPDS 2 diffractometer with graphite-monochromated MoKa radiation (k = 0.71073) at 295 K. The data reduction and numer-ical absorption correction were performed using the X-RED program[17]. The structures were solved by direct methods using the SHEL-

XS-97 program and refined on F2 with the SHELXL-97 program [18].All non-hydrogen atoms were found from the difference Fouriermap and refined anisotropically. Hydrogen atoms bonded to Cand N atoms were refined using a riding model, with C–H = 0.96–0.97 Å and N–H = 0.86–0.91 Å. The constraint Uiso(H) = 1.2Ueq (Cand N) or 1.5Ueq (methyl C) was applied. The details of datacollection, refinement and crystallographic data are summarizedin Table 1.

Table 1Crystal data and structure refinement details for 1–3.

1 2 3

Empirical formula C13H19N4O4Ag C22H30N6O6Ag2 C16H23N4O4AgFormula mass 403.19 690.26 443.25Crystal system monoclinic monoclinic triclinicSpace group P21/c P21/c P�1a (Å) 10.1704(5) 12.5383(12) 7.4647(5)b (Å) 7.0214(3) 20.0524(15) 10.2438(6)c (Å) 24.2669(13) 11.2219(11) 13.1233(8)a (�) 90 90 111.783(4)b (�) 110.549(4) 104.795(8) 98.159(5)c (�) 90 90 94.740(5)V (Å3) 1622.65(14) 2727.9(4) 912.36(10)Z 4 4 2Dcalc (g cm�3) 1.650 1.681 1.613l (mm�1) 1.265 1.482 1.133F(0 0 0) 816 1384 452Crystal size (mm3) 0.45 � 0.35 � 0.28 0.48 � 0.26 � 0.14 0.60 � 0.57 � 0.52h range (�) 1.79–26.50 1.68–26.50 2.16–26.50Index range (h, k, l) �12/12, �8/8, �24/30 �15/15, �25/25, �14/14 �9/9, �12/12, �16/16Reflections collected 9071 30928 9937Reflections independent 3357 (Rint = 0.0324) 5651 (Rint = 0.0469) 3790 (Rint = 0.0285)Absorption correction numerical numerical numericalData/parameters/restraints 3357/206/3 5651/325/0 3790/231/1Goodness-of-fit (GOF) on F2 1.058 1.045 1.020R1/wR2 [I > 2r(I)] 0.0286/0.0721 0.0305/0.0767 0.0204/0.0538R1/wR2 (all data) 0.0336/0.0748 0.0391/0.0796 0.0233/0.0548Dqmaximum/minimum (e Å�3) 0.443/�0.505 0.505/�0.873 0.398/�0.525

NHHN

O

O O

barbH apy dmamhpy

N NH2 NNH2

NN

OH

ampy

3166 F. Yilmaz et al. / Inorganica Chimica Acta 363 (2010) 3165–3171


3. Results and discussion

3.1. Synthesis and characterization

The reaction of Na(barb) with AgNO3 in the presence of the apy,ampy and dmamhpy ligands yielded complexes 1–3 in moderateyields (over 50%). All complexes are air-stable and highly solublein a mixture of water/EtOH (1:1) at room temperature.

Selected FTIR data for complexes 1–3 are summarized in Table2. The broad absorption bands over 3400 cm�1 are assigned to theabsorption of the O–H vibrations of the lattice water molecule in 1and the hydroxyl group of dmamhpy in 3. The symmetric andasymmetric absorption bands of the NH2 group of apy in 1, andampy in 2 are observed in the frequency range 3125–3380 cm�1,while the m(NH) stretching of the NH group of the barb ligands

Table 2Selected IR and VIS spectral data for 1–3.a

1 2 3

m(OH) 3410m – 3420bm(NH2)amine 3379w, 3350m 3273w, 3125w –m(NH)barb 3187sb 3189m 3187mm(CH) 3081m–2876w 3087w–2876vw 3085m–2868mm(CO) 1716s, 1679vs,

1638vs1711s, 1676vs,1636vs

1716vs, 1679vs,1638vs

m(CN) 1601vs 1602vs 1593vs

b = broad; w = weak; vs = very strong; s = strong; m = medium.a Frequencies in cm�1.

Fig. 1. (a) A molecular view of 1, (C–H hydrogen atoms were omitted for clarity). (b) A two-dimensional layer in 1 viewed down a.

Table 3Selected bond and hydrogen bonding geometry for 1.

Bonds lengths (Å) and angles (�)Ag1–N1 2.129(2) N1–Ag1–N3 165.28(7)Ag1–N3 2.127(2)

Hydrogen bondsa

D–H��A D–H (Å) H��A (Å) D��A (Å) D–H��A (�)

O1W–H1W��O3 0.82(2) 2.04(2) 2.856(3) 174(4)O1W–H2W��O3i 0.83(2) 2.01(2) 2.837(3) 171(4)N2–H2A��O1Wii 0.86 2.12 2.968(3) 169N2–H2B��O2iii 0.86 2.21 3.061(3) 172N4–H4A��O1iv 0.86 1.98 2.829(2) 169

a Symmetry codes: (i) �x + 1, y � 1/2, �z + 1/2; (ii) �x + 1, y + 1/2, �z + 1/2; (iii) x,�y + 3/2, z + 1/2; (iv) �x, �y + 2, �z.

F. Yilmaz et al. / Inorganica Chimica Acta 363 (2010) 3165–3171 3167


Fig. 2. (a) Asymmetric unit of 2, (C–H hydrogen atoms were omitted for clarity). (b) View of a fragment of the polymeric chain in 2. (c) Packing of chains in 2 viewed down b.



appears at ca. 3187 cm�1 as a single band. The carbonyl groupvibrations of the barb ligands are observed as three distinctabsorption bands in the frequency range 1635–1715 cm�1, beingin agreement with the presence of three different carbonyl groups.Moreover, the C–N stretching vibrations occur as strong bands cen-tered at ca. 1600 cm�1. The bands with various intensity below1600 nm are due to the C–C and C–H vibrations.

3.2. Description of crystal structures

The molecular structure of complex 1 with the atom labeling isshown in Fig. 1a. The selected bond lengths and angles together

with the hydrogen bonding geometry are given in Table 3. Complex1 crystallizes in the monoclinic space group P21/c. The molecule of1 is mononuclear in which the silver(I) ion is coordinated by a barbligand and an apy ligand, forming a slightly distorted linear AgN2

coordination with an N–Ag–N angle of 165.28(7)�. The bendingin the N–Ag–N angle may be a consequence of the relatively strongion-dipole interaction of the lattice water molecule with the sil-ver(I) ion (Ag��O = 2.927(2) Å]. The rings of barb and apy are tiltedwith a dihedral angle of 33.07(5)�. The apy ligand acts as a mono-dentate ligand via the py N atom, whereas the amine N atom is notinvolved in coordination as observed in [{Ag(pts)}2(2-apy)4](pts = p-toluenesulfonate) [19], [Ag(l-X)(2-apy)(PPh3)]2 (X = Cl,Br), and [Ag(l-ONO2)(2-apy)(EPh3)]2 (E = P, As) [20]. Two Ag–Nbond distance are identical and the Ag–N(barb) bond distance issimilar to those of the previously reported silver(I)-barb complexes[10,12,15,16]. On the other hand, the Ag–N(apy) bond distance issignificantly shorter than those found in the Ag–apy complexes[19,20]. The molecules of 1 are connected by OW–H��O and N–H��O hydrogen bonds to form a two-dimensional layer along thecrystallographic bc-plane (Fig. 1b), which is further extended to athree-dimensional supramolecular network.

The asymmetric unit of complex 2 with the atom labeling isshown in Fig. 2a. The selected bond lengths and angles togetherwith the hydrogen bonding geometry are given in Table 4. Complex2 is a coordination polymer in which silver(I) ions are bridged byampy ligands through the two N atoms, leading to a one-dimen-sional cationic chain of ½AgðampyÞ�þn, and the anionic [Ag(barb)2]�

units are doubly coordinated to the silver centers of the polymeric


Bonds lengths (Å) and angles (�)Ag1–N1 2.094(2) N1–Ag1–N3 178.52(10)Ag1–N3 2.098(2) N5–Ag2–N6i 168.91(9)Ag2–N5 2.163(2) O1–Ag2–N5 97.72(9)Ag2–N6i 2.173(2) O1–Ag2–N6i 93.29(9)Ag2–O1 2.637(2) O1–Ag2–O6 107.70(7)Ag2–O6 2.649(2) O6–Ag2–N5 92.20(9)

O6–Ag2–N6i 83.11(9)Hydrogen bondsa


N2–H2��O5ii 0.86 2.11 2.952(3) 167N4–H4��O2iii 0.86 2.06 2.916(3) 171N5–H5C��O4i 0.90 2.12 3.002(3) 166N5–H5D��O3i 0.90 2.06 2.951(3) 169

a Symmetry codes: (i) x, �y + 1/2, z � 1/2; (ii) x + 1, y, z; (iii) x � 1, y, z.

Fig. 3. (a) A molecular view of 3, (C–H hydrogen atoms were omitted for clarity). (b) View of hydrogen-bonded chains of 3.



chain via the carbonyl O atoms (Fig. 2b). The silver(I) ion in the[Ag(barb)2]� unit is linearly coordinated by two barb ligands[N–Ag–N = 178.52(10)�]. Both pyrimidine rings are almostco-planar and each barb anion acts as a bidentate bridging ligandbetween the silver centers via the carbonyl O and the negativelycharged N atoms. The silver(I) ions in the polymeric chain arefour-coordinated with two N atoms from two bridging ampyligands and two O bonds from two barb ligands. However, thecoordination sphere around silver(I) does not conform to neithertetrahedral nor square-pyramidal geometry. The Ag–N(barb) bonddistances are equal and also similar to that of 1, while theAg–N(ampy) bonds are significantly shorter than those found in[Ag(sac)(ampy)] [21]. On the other hand, the Ag–O(barb) distancesare much longer than those reported for [Ag2(barb)(pipet)]n

(pipet = N-piperidineethanol) [16]. The polymeric chains in 2 runparallel to the c axis and are doubly connected by the N–H��Ohydrogen bond involving the NH and carbonyl groups of the barbligand in the neighboring chains, leading to a two-dimensional net-work extended along the ac-plane (see Fig. 2c).

As shown in Fig. 3a, the silver(I) ion in complex 3 is coordinatedby a dmamhpy ligand and a barb ligand, forming a significantlydistorted T-shaped AgN3 coordination with one N–Ag–N angle at169.39(6)� (Table 5). The dmamhpy ligand behaves as a bidentatechelating ligand, forming a five-membered ring, while barb is N-coordinated. The bite angle of the bpy ligand is 72.38(6)� and sig-nificantly contributes to the distortion of the coordination geome-try around the silver(I) ion. The dihedral angle between the rings ofpy and barb is 65.85(5)�. The Ag–N(barb) bond distance is in therange of the reported Ag–barb complexes [10,12,15,16], while theAg–N(dmamhpy) bond distances are comparable to those of [Ag(d-mamhpy)(sac)] [22]. The individual molecules of 3 are doublylinked into dimers by Ag��Cpy interactions between silver(I) ionsand py rings of the adjacent molecules. The Ag��C distance is3.358 Å, which are noticeably shorter than the sum of van derWaals radii of the Ag(I) ion and the carbon atom (3.42 Å). In addi-tion, the dimeric units are further connected by the N–H��O and O–H��O hydrogen bonds leading to one-dimensional hydrogen-bonded chains running along the c axis (see Fig. 3b). These chainsare held together by C–H��p(py) interactions (C��Cg = 2.89 Å) toform a three-dimensional network.

3.3. Photoluminescence

In the MeCN)/H2O/PrOH solution, complex 1 exhibits dualabsorption bands centered at 258 and 321 nm, while complexes2 and 3 show single absorptions at 280 and 295 nm, respectively.These absorptions correspond to the p–p* transitions of the aro-matic py moiety. All complexes show fluorescence emission bandsin the range 340–351 nm upon excitation at the absorption bandsin solution (see Fig. 4). The free ligands display emission maximasimilar to those observed for the metal complexes. Since the emis-sions of the metal complexes are not shifted compared to free li-gands, the emissions of complexes 1–3 are attributed to the p–p*intraligand transitions [23].

3.4. Thermal behavior

The TG and DTA curves of complexes 1–3 are illustrated in Fig. 5and the corresponding thermoanalytical data are listed in Table 6.In general, in the decomposition of these complexes, the


Bonds lengths (Å) and angles (�)Ag1–N1 2.1381(14) N1–Ag1–N3 169.39(6)Ag1–N3 2.2008(16) N1–Ag1–N4 118.12(5)Ag1–N4 2.4859(15) N3–Ag1–N4 72.38(6)

Hydrogen bondsa


N2–H2��O1i 0.86 2.03 2.888(2) 172O4–H4��O1ii 0.82 1.98 2.795(2) 170

a Symmetry codes: (i) �x + 2, �y + 1, �z + 2; (ii) �x + 1, �y, �z + 1.

Fig. 4. Emission spectra of complexes 1–3 in the acetonitrile/water/2-propanolsolution (1:1:1) at room temperature.

Fig. 5. DTA and TG curves of 1–3.



elimination processes of barb and other ligands overlap and it is,therefore, impossible to distinguish the decomposition range andmass loss for the individual ligands. A violently exothermic DTApeak in the temperature range 350–550 �C is characteristic forthe degradation of the barb ligands in air. In all cases, the totalmass loss values are consistent with the calculated values andthe final decomposition product is estimated as metallic silverfor 1 and 2, but Ag2O for 3.

Complex 1 dehydrates between 85 and 148 �C and then, theanhydrous complex begins to decompose in two stages in the tem-perature range 150–404 �C. An endothermic peak at 235 �C corre-sponds to the elimination of apy, whereas the highly exothermicpeak centered at 398 �C is related to the decomposition of the barbmoiety. Complex 2 decomposes in two stages. The DTA peaks at212 and 237 �C are due to the removal of the aepy ligand, whilethe exothermic peak at 365 �C are originated from the decomposi-tion of the barb moieties. Among these complexes, complex 3exhibits a high thermal stability beginning to decompose at269 �C. The decomposition ends at 520 �C. The DTA peaks at 317and 407 �C correspond to the decomposition of the dmamhpyand barb ligands, respectively.

4. Conclusion

Three new silver(I)-barb complexes with three aminopyridinessuch as apy, ampy and dmamhpy have been synthesized and char-acterized. The structures of complexes have been determined bysingle-crystal X-ray analysis. In the mononuclear complexes of 1and 3, the barb ligand is monodentate through the negativelycharged N atom, while apy and dmamhpy act as mono- and biden-tate ligands, respectively. However, complex 2 is a coordinationpolymer, in which both ampy and barb ligands behave as bidentatebridging ligands. All complexes are fluorescent in room tempera-ture and complex 3 exhibits a high thermal stability compared tothe others.

Acknowledgment

We thank the research fund of Uludag University for the finan-cial support given to the research project (F-2008/56).

Appendix A. Supplementary material

CCDC 771811, 771812 and 771813 contain the supplementarycrystallographic data for 1, 2 and 3, respectively. These data canbe obtained free of charge from The Cambridge CrystallographicData Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplemen-tary data associated with this article can be found, in the onlineversion, at doi:10.1016/j.ica.2010.05.050.

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Zangrando, D. Das, Polyhedron 27 (2008) 2452.

Table 6Thermoanalytical data for 1–3.

Stage Temp. range(�C) DTAmax (�C)a Mass loss (%)b Total mass loss (%)b Solid residue

1 1 85–148 107(+), 137 (+) 4.4 (4.5) [Ag(apy)(barb)]2 150–268 235 (+) 45.33 320–404 398 (�) 23.0 72.4 (73.2) Ag

2 1 167–277 212 (�), 237(+) 58.3 Ag2 277–400 365 (�) 12.2 70.5 (68.8)

3 1 269–380 317 (+) 60.22 380–520 407 (�) 10.5 70.7 (73.9) Ag2O

a (+) and (�) donate endothermic and exothermic processes, respectively.b Calculated values are given in parentheses.


syntheses, crystal structures, spectroscopic, fluorescence and thermal properties of silver(i)...

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