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F U L L P A P E R

Monomeric, one- and two-dimensional networks incorporating (2,6-Me2C6H3S)2Pb building blocks

Sarah E. Appleton,a Glen G. Briand,*a Andreas Deckenb and Anita S. Smithaa Department of Chemistry, Mount Allison University, Sackville, New Brunswick,

Canada E4L 1G8. E-mail: gbriand@mta.ca; Fax: (+506) 364 2313; Tel: (+506) 364 2346b Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick,

Canada E3B 6E2

Received 7th July 2004, Accepted 15th September 2004First published as an Advance Article on the web 29th September 2004

The amine coordination of lead(II) has been examined through the preparation and structural analysis of Lewis base adducts of bis(thiolato)lead(II) complexes. Reaction of Pb(OAc)2 with 2,6-dimethylbenzenethiol affords (2,6-Me2C6H3S)2Pb (6) in high yield. The solubility of 6 in organic solvents allows for the preparation of the 1 : 2 Lewis acid–base adduct [(2,6-Me2C6H3S)2Pb(py)2] (7), and 1 : 1 adducts [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ (8) and [(2,6-Me2C6H3S)2Pb(l2-pyr)]∞ (9) (where py = pyridine, bipy = 4,4-bipyridyl and pyr = pyrazine) from reaction with an excess of the appropriate amine. In contrast to 7, reaction of (C6H5S)2Pb (1) with pyridine afforded the 2 : 1 adduct [(C6H5S)4Pb2(py)]∞ (10). Compounds were characterized via elemental analysis, FT-IR, solution 1H and 13C{1H} (6) NMR spectroscopy, and X-ray crystallography (7–10). The structures of 7–9 show the thiolate groups occupying two equatorial positions and two amine nitrogen atoms occupying axial coordination sites, yielding distorted see-saw coordination geometries, or distorted trigonal bipyramids if an equatorial lone pair on lead is considered. The absence of intermolecular contacts in 7 and 8 result in monomeric and one-dimensional polymeric structures, respectively. Weak PbS intermolecular contacts in 9 result in the formation of a two-dimensional macrostructure. In contrast, the structure of 10, shows extensive intermolecular PbS interactions, resulting in five- and six-coordinate bonding environments for lead(II), and a complex polymeric structure in the solid state. This demonstrates the ability of the 2,6-dimethylphenylthiolate ligand to limit intermolecular lead–sulfur interactions, while allowing the axial coordination of amine Lewis base ligands.

IntroductionThe study of self-assembled molecular frameworks has become of wide spread interest over the past number of years, due to their potential as functional solid materials.1 For metal-medi-ated supramolecular architectures, network topologies may be manipulated through both the selection of metal centers with desirable coordination geometries and the chemical structure of organic ligands. As of yet, research regarding these systems has typically focused on the incorporation of s- and d-block metal ions as coordination centers for Lewis base ligands,1a–c while significantly less consideration has been given to the metals of the p-block.

The heavy elements of the p-block have proven to exhibit interesting coordination geometries due to their extensive Lewis acid properties.2,3 This is a result of their large atomic radii, high nuclear charges, and variable stereochemical activity of the lone pair in N-2 oxidation state centers (where N is the number of valence electrons). More specifically, lead(II) has a potentially extensive array of coordination geometries2a,4 by virtue of its valence lone pair and empty p-orbital (Fig. 1). Due to the lack of identification of suitable lead(II) coordination complexes, however, structural data remains relatively limited. Homoleptic organolead(II) complexes containing Pb–C bonds are unstable in the absence of very bulky groups, and undergo disproportion-ation to R3Pb–PbR3 compounds and elemental lead.2b Lead(II) dithiolate complexes, on the other hand, are stable with respect to disproportionation, as well as hydrolysis. However, these compounds are typically very insoluble in non-coordinating solvents, which precludes the isolation of crystalline materials.

Despite their insolubility in organic solvents, crystals of (C6H5S)2Pb (1),5 (4-MeC6H4S)2Pb (2)6 and (ethanedithiolato)lead (3)7 suitable for X-ray structural analysis have been prepared from solutions containing RS− ligands. Solid-state structures of these complexes show extensive PbS intermolecular inter-actions. This results in the formation of coordination polymers in the solid state, accounting for the observed insolubilities, and yields a variety of bonding environments for lead(II). Similar extended structures and high coordination numbers have been observed for thiolates of other p-block metals {e.g. [(PhCH2S)Tl]∞

8 and [(tBuS)2Sn]∞9}.3a,10 The introduction of

2,6-substituted aryl ligands on lead(II) has resulted in the for-mation of the soluble complexes (2,6-iPr2C6H3S)2Pb (4) and (2,4,6-tBu3C6H2S)2Pb (5).11 Although sterically bulky groups

Fig. 1 The valence lone pair and empty p-orbital of a lead(II) dithiolate molecule.

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3 5 1 6 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 3 5 1 7

solution 1H NMR spectrum of 10 in dmso-d6 shows shifts corres-ponding to those of 1 and pyridine in the same solvent. These data therefore suggest the absence of significant lead–nitrogen interactions in thf (7–9) or dmso (10) solution.

X-ray structures

Crystals of suitable quality for X-ray analysis were obtained for compounds 7–10. X-ray structures of 7–10 are shown in Figs. 2–5. Crystallographic data are summarized in Table 1. Selected bond distances and angles are given in Tables 2 and 3.

have proven effective in prohibiting intermolecular contacts in p-block metal complexes,11,12 a trimeric structure is observed for 4 in the solid state.

In this context, the goal of this research was to manipulate the coordination at lead, by preventing polymerization via PbS interactions and effecting a controlled interaction of mononuclear units. Herein, we report the synthesis and structural characterization of (2,6-Me2C6H3S)2Pb (6) and the monomeric 1 : 2 pyridine adduct [(2,6-Me2C6H3S)2Pb(py)2] (7) (where py = pyridine). The solubility of 6 in organic solvents has also facilitated the isolation of the 1 : 1 adducts [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ (8) and [(2,6-Me2C6H3S)2Pb(l2-pyr)]∞ (9) with bifunctional ligands 4,4-bipyridyl (bipy) and pyrazine (pyr). Finally, the bis(phenylthiolato)lead(II)–pyridine adduct [(C6H5S)4Pb2(py)]∞ (10) has been prepared and structurally characterized for comparison with 7.

Results and discussionSyntheses and solution NMR studies

The reaction of lead(II) acetate with two equivalents of 2,6-dimethylbenzenthiol in aqueous ethanol results in the forma-tion of the bis(2,6-dimethylbenzenethiolato)lead(II) (6) as a red–orange powder in high yield (87%). This synthetic approach to homoleptic lead(II) thiolates has been employed previously to prepare a number of alkyl-, aryl- and mono-substituted aryl-complexes.13 Further, this method is a desirable alternative to that employed for the preparation of the 2,6-disubstituted com-plexes (RS)2Pb (R = 2,6-iPrC6H3 4; 2,4,6-tBuC6H2 5), which cur-rently requires the preparation of Pb[N(SiMe3)2]2 or the lithium thiolate salt as synthetic intermediates.11

Compound 6 shows solubility in a number of organic sol-vents, including thf, chloroform, dichloromethane, toluene and pyridine. While still facilitating solubility in non-coordinating solvents, the 2,6-Me2C6H3S ligand provides the advantage over 2,6-iPr2C6H3S (4) or 2,4,6-tBuC6H2S (5) of decreased steric bulk at the lead center. Reaction of 6 with pyridine results in the for-mation of the 1 : 2 adduct [(2,6-Me2C6H3S)2Pb(py)2] (7). Despite its insolubility in non-coordinating organic solvents, the unsub-stituted phenylthiolate analogue (C6H5S)2Pb (1) was found to be very soluble in pyridine. Interestingly, however, the reaction resulted in isolation of the 2 : 1 adduct [(C6H5S)4Pb2(py)]∞ (10).

The increased solubility of 6 versus lead(II)alkyl–, phenyl– (1) and 4-methylphenylthiolates (2) has permitted the reaction of the compound with bridging amine bases. The reaction of 6 with four equivalents of 4,4-bipyridyl in thf or dichloro-methane results in the crystallization of the 1 : 1 adduct [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ (8). Similarly, the reaction of 6 with four equivalents of pyrazine in thf yielded crystals of the 1 : 1 adduct [(2,6-Me2C6H3S)2Pb(l2-pyr)]∞ (9). Although the prepara-tion of 8 and 9 involved the addition of excess amine, the 1 : 2 adducts were not isolated from either reaction mixture.

Solution 1H NMR spectra of the adducts 7–9 in thf-d8 show similar shifts to those of 6, as well as those of the corresponding free amine base ligands in the same solvent. Analogously, the

Compound 7 (Fig. 2) shows the lead(II) center bonded to two cis thiolate groups through sulfur atoms [S(1)–Pb(1)–S(2) = 89.31(3)°] and two trans pyridine ligands via their nitrogen atoms [N(1)–Pb(1)–N(2) = 178.58(9)°]. The Pb–S bond dis-tances [2.6078(9) and 2.6079(9) Å] are similar to those observed in other lead(II) dithiolates [2.554(4)–2.895(3) Å].5,6,7,11 The Pb–N bond distances [2.689(3) and 2.695(3) Å] are longer than those observed for mono-pyridine lead(II) adducts [2.502(4)–2.55(4) Å]14 and the bis-pyridine complex cis-(py)2PbI2 (11a) [2.55(2) Å].15 These values are, however, closer to those observed in trans-(py)2PbI2 (11b) [Pb–N 2.66(2) Å].15 Further, the S–Pb–S and S–Pb–N bond angles all approximately 90°, which is typical for bonding at heavy main group centers.

The solid-state structure of 8 (Fig. 3a) shows two unique lead centers [Pb(1) and Pb(2)] with similar bonding environ-ments to those observed in 7. The presence of a second basic nitrogen in 4,4-bipyridyl allows the ligand to act as a bridge between two lead centers. The result is the formation of two independent one-dimensional [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ polymers, composed of alternating 4,4-bipyridyl and lead thio-late units (Fig. 3b). The chain containing Pb(1) is parallel to the ab-diagonal, whereas the chain containing Pb(2) is parallel to the b-axis. The closest possible bonding contacts between poly-mers are via open face PbPb interactions [Pb(1)Pb(1) = 4.3743(7) Å; Pb(2)Pb(2) = 4.4292(8) Å], which are outside of the van der Waals’ radii of 4.0 Å.16 The Pb–N bond distances for Pb(2) [2.652(8) and 2.668(7) Å] are identical within experimental error and similar to those observed in trans [Pb(l2-bipy)(l2-X)2]∞ (X = Br, I) [2.66(1) Å].17 Conversely, the Pb(1)–N(2) [2.652(7) Å] and Pb(1)–N(1) [2.814(7) Å] bond distances are significantly different, resulting in an unexpected closer association of the bridging 4,4-bipyridyl ligand to one lead center.

Compound 9 (Fig. 4a) also shows a similar bonding environment to 7 at lead. The presence of a second nitrogen functionality in pyrazine again facilitates the formation of one-dimensional [Pb(SR)2(l2-LL)]∞ coordination polymers. Unlike 8, however, the thiolate groups of adjacent (2,6-Me2C6H3S)2Pb units are located on alternating sides within each chain. Further, the polymers in 9 are subsequently linked into two-dimensional sheets via weak PbS intermolecular interactions [3.743(3) Å] (sum of van der Waals’ radii = 3.8 Å)16 (Fig. 4b). These inter-chain interactions are similar to those observed in the solid state structure of the unsubstituted bis(phenylthiolato)lead(II) 15 (vide

Fig. 2 X-ray structure of 7 (30% probability ellipsoids). Hydrogen atoms are removed for clarity.

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3 5 1 6 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 3 5 1 7

and 2.699(2) Å] and three longer PbS contacts [2.993(2)–3.268(1) Å], forming a distorted square pyramidal bonding environment. The presence of an empty coordination site at this center suggests the presence of a stereochemically active lone pair. The second unique lead center [Pb(2)] shows three shorter Pb–S bonding interactions [2.720(2)–2.836(2) Å] in a facial arrangement and two longer PbS interactions [3.212(2) and 3.422(1) Å]. A sixth coordination site is occupied by a weakly bound pyridine nitrogen atom [2.842(5) Å], giving a distorted octahedral bonding environment at lead. The absence of an open coordination site suggests the lone pair is stereochemically inactive in this case. Each of the four unique sulfur atoms in the structure is three- or four-coordinate, having one or two long

Fig. 3 (a) X-ray structure of one of the independent molecules of 8 (30% probability ellipsoids). Hydrogen atoms are removed for clar-ity. Symmetry transformations used to generate equivalent atoms: () x, y + 1, z. (b) One-dimensional polymeric structure of 8 containing Pb(1).

Fig. 4 (a) X-ray structure of 9 (30% probability ellipsoids). Hydrogen atoms are removed for clarity. Symmetry transformations used to generate equivalent atoms: () −x, −y, −z + 1; () −x + 1, −y, −z + 2; () x + 1, y, z. (b) Two-dimensional sheet structure of 9.

Fig. 5 X-ray structure of 10 showing the skeletal atoms of the poly-meric structure (30% probability ellipsoids). All carbon and hydrogen atoms are removed for clarity. Symmetry transformations used to generate equivalent atoms: () −x + 1, −y + 1, −z; () −x, −y + 1, −z; () x − 1, y, z; () x + 1, y, z.

infra). As for Pb(1) of 8, the Pb–N bond distances [2.614(9) and 2.848(9) Å] are significantly different.

The presence of open coordination sites in the structures of 7–9 suggests the presence of a stereochemically active lone pair in each case. If the lone pair and two sulfur atoms are consid-ered to occupy cis equatorial sites and the two nitrogen atoms are viewed as filling axial positions, the geometry at lead(II) in each case is distorted trigonal bipyramidal. This expands to octahedral for 9 if the long PbS interaction is considered. Observed structures of 7–9 may therefore be explained using a simple bonding model (Fig. 1), which requires electron donation by the nitrogen Lewis bases into the empty p-orbital on lead(II). The limitation to bis-nitrogen coordination in excess amine, and the absence of intermolecular PbS interactions to the empty and sterically unencumbered equatorial sites in 7 and 8, suggests that the lead(II) center is a weak Lewis acid.

The structure of the unsubstituted lead(II) phenylthiolate–pyridine adduct 10 (Fig. 5) differs significantly from that of 7. The first of the two unique lead centers in the structure [Pb(1)] is five coordinate with two short cis Pb–S bonds [2.696(2)

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3 5 1 8 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 3 5 1 9

SPb contacts, respectively. In this case, both independent lead atoms are part of the same chain, and the overall structure may be viewed as two chains bound together via short and long Pb–S contacts along S(1)–Pb(1)–S(4)–Pb(2). In comparison to 7, therefore, compound 10 shows extensive PbS bonding in the absence of 2,6-substitution on the phenyl thiolate ligand. This intermolecular bonding arrangement is similar to that observed for Pb(SC6H5)2 (1).5 In the case of 1, however, each [Pb(l2-SC6H5)2]∞ chain is bound to two neighbouring chains via alternating PbS contacts, giving a two dimensional sheet-like structure.

ConclusionsThe high yield synthesis and solubility of (2,6-Me2C6H3S)2Pb (6) has facilitated the preparation and structural characterization of the Lewis acid–base adducts [(2,6-Me2C6H3S)2Pb(py)2] (7), [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ (8) and [(2,6-Me2C6H3S)2Pb(l2-pyr)]∞ (9) (where py = pyridine, bipy = 4,4-bipyridyl and pyr = pyrazine). The structures of 7–9 are based on a simple bonding model for lead(II), in which the amine nitrogen atoms donate electron density into the empty p-orbital on lead. The absence of PbS intermolecular contacts result in the formation of a monomeric system for 7. The bridging nature of bipy and pyr

results in one-dimensional polymeric structures for 8 and 9, the latter of which forms two-dimensional sheets via PbS con-tacts. Further, the structural characterization of the pyridine adduct [(C6H5S)4Pb2(py)]∞ (10) shows a polymeric double-chain structure via lead–sulfur interactions, with weakly bound amine ligands on alternate lead centers. This exhibits the ability of the 2,6-dimethylphenylthiolate ligand to preclude extensive intermolecular lead–sulfur interactions. These results demon-strate the potential of 6 as a building block for self-assembled, extended molecular frameworks using a variety of other organic Lewis base ligands.

ExperimentalReagents

Benzenethiol 97%, 2,6-dimethylbenzenethiol 95%, pyridine 99+%, pyrazine 99+%, and 4,4-bipyridyl 98% were used as received from Aldrich. Lead(II) acetate trihydrate was used as received from Fisher. (C6H5S)2Pb (1) was prepared according to the literature procedure.13

Instrumentation

Melting points were recorded on an Electrothermal MEL-TEMP melting point apparatus and are uncorrected. Infrared spectra were recorded as Nujol mulls on a Mattson Genesis II FT-IR spectrometer in the range 4000–400 cm−1.

Table 1 Crystallographic data for 7–10

7 8·0.5CH2Cl2 9 10

Formula C26H28N2PbS2 C26.5H27ClN2PbS2 C20H22N2PbS2 C29H25NPb2S4

FW 639.81 680.26 561.71 930.12Crystal system Monoclinic Triclinic Triclinic MonoclinicSpace group P2(1)/n P1 P1 P2(1)/ca/Å 11.0004(7) 11.256(1) 5.3732(9) 8.9709(6)b/Å 18.2989(11) 12.368(1) 11.828(2) 14.551(1)c/Å 12.8936(8) 21.812(2) 15.587(3) 22.231(2)a/° 90 94.508(2) 90.884(3) 90b/° 107.661(1) 96.628(2) 92.637(2) 98.177(1)c/° 90 116.205(1) 96.783(2) 90V/Å3 2473.1(3) 2677.4(5) 982.5(3) 2872.4(3)Z 4 4 2 4F(000) 1248 1324 540 1736qcalcd./g cm−3 1.718 1.688 1.899 2.151l/mm−1 7.007 6.574 8.804 12.017T/K 198(1) 198(1) 198(1) 198(1)k/Å 0.71073 0.71073 0.71073 0.71073R1 a 0.0287 0.0450 0.0440 0.0270wR2

b 0.0731 0.1224 0.1132 0.0493

a R1 = [R||Fo| − |Fc||]/[R|Fo|] for [Fo2 > 2r(Fo

2)]. b wR2 = {[Rw(Fo2 − Fc

2)2]/[Rw(Fo4)]}1⁄2.

Table 2 Selected bond distances (Å) and angles (°) for 7–9

7 8·0.5CH2Cl2 9

Pb(1)–S(1) 2.6078(9) 2.595(3) 2.599(3)Pb(1)–S(2) 2.6079(9) 2.598(3) 2.595(3)Pb(2)–S(21) 2.598(3)Pb(2)–S(22) 2.602(3)Pb(1)–N(1/1) 2.695(3) 2.814(7) 2.848(9)Pb(1)–N(2) 2.689(3) 2.652(7) 2.614(9)Pb(2)–N(21) 2.652(8)Pb(2)–N(22) 2.668(7)Pb(1)S(1) 3.743(3)

S(1)–Pb(1)–S(2) 89.31(3) 84.33(8) 87.8(1)S(1)–Pb(1)–N(1/1) 90.55(7) 90.0(2) 85.8(2)S(2)–Pb(1)–N(1/1) 88.04(7) 93.4(2) 86.0(2)S(1)–Pb(1)–N(2) 88.04(8) 88.0(2) 86.3(2)S(2)–Pb(1)–N(2) 91.78(8) 90.8(2) 85.9(2)N(1/1)–Pb(1)–N(2) 178.58(9) 175.1(3) 168.9(3)S(21)–Pb(2)–S(22) 87.67(8)S(21)–Pb(2)–N(21) 87.9(2)S(22)–Pb(2)–N(21) 89.6(2)S(21)–Pb(2)–N(22) 85.3(2)S(22)–Pb(2)–N(22) 87.8(2)N(21)–Pb(2)–N(22) 172.8(3)

Table 3 Selected bond distances (Å) and angles (°) for 10

10

Pb(1)–S(1) 2.696(2) Pb(2)–S(3) 2.720(2)Pb(1)–S(2) 2.699(2) Pb(2)–S(4) 2.825(2)Pb(1)S(1) 3.000(2) Pb(2)–S(4) 2.836(2)Pb(1)S(3) 2.993(2) Pb(2)…S(1) 3.422(1)Pb(1)S(4) 3.268(1) Pb(2)S(2) 3.212(2) Pb(2)–N(1) 2.842(5)

S(1)–Pb(1)–S(1) 80.99(5)S(1)–Pb(1)–S(2) 97.85(5) S(3)–Pb(2)–S(4) 89.50(5)S(1)–Pb(1)–S(3) 70.05(5) S(3)–Pb(2)–S(4) 86.30(5)S(1)–Pb(1)–S(4) 73.16(4) S(3)–Pb(2)–S(1) 155.19(4)S(2)–Pb(1)–S(1) 85.85(4) S(3)–Pb(2)–S(2) 103.23(4)S(2)–Pb(1)–S(3) 100.19(4) S(3)–Pb(2)–N(1) 85.7(1)S(2)–Pb(1)–S(4) 170.90(4) S(4)–Pb(2)–S(4) 77.63(5) S(4)–Pb(2)–S(1) 88.61(4) S(4)–Pb(2)–S(2) 156.82(4) S(4)–Pb(2)–N(1) 81.43(1) S(4)–Pb(2)–N(1) 157.62(1)

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3 5 1 8 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0 3 5 1 9

Solution 1H (270 MHz) and 13C{1H} NMR (67.9 MHz) were recorded at 23 °C on a JEOL GMX 270 MHz spectrometer and are calibrated to the residual solvent signal. Elemental analyses were provided by Chemisar Laboratories Inc., Guelph, Ontario.

Preparation of (2,6-Me2C6H3S)2Pb (6)

A solution of 2,6-dimethylbenzenethiol (0.720 g, 5.21 mmol) in ethanol (15 ml) was added dropwise to a solution of Pb(OAc)2·3H2O (1.00 g, 2.64 mmol) in ethanol/water (8 mL/2 mL) at 25 °C to give a bright red/orange colored solution and precipitate. After 1.5 h, the reaction was filtered and the precipitate washed with 95% ethanol (20 mL) and diethyl ether (40 mL) to yield 6 as an orange powder (1.10 g, 2.28 mmol, 87%). Anal. Calcd. for C16H18PbS2: C, 39.90; H, 3.77; N, 0.00. Found: C, 39.67; H, 3.55; N, <0.10%. M.p. 118 °C (dec.). IR (cm−1): 715 w, 764 s, 885 vw, 982 w, 1024 m, 1047 s, 1115 w, 1163 w, 1246 vw, 1581 w, 1915 vw, 2357 vw. NMR data (thf-d8): 1H NMR, d = 2.56 (s, 12H, C6H3Me2), 6.71 (t, 3JH,H = 7 Hz, 2H, p-C6H3Me2), 7.00 (d, 3JH,H = 7 Hz, 4H, m-C6H3Me2); 13C{1H} NMR, 23.3 (C6H3Me2), 124.8 (C6H3Me2), 126.6 (C6H3Me2), 142.3 (C6H3Me2).

Preparation of [(2,6-Me2C6H3S)2Pb(py)2] (7)

(2,6-Me2C6H3S)2Pb 6 (0.100 g, 0.208 mmol) was added to pyridine (1 ml) to give a yellow saturated solution, which was centrifuged and decanted. After 7 days at 4 °C, the precipitate was washed with diethyl ether (1 mL), yielding 7 as a pale yellow crystalline solid (0.132 g, 0.206 mmol, 99%). Anal. Calcd. for C26H28N2PbS2: C, 48.80; H, 4.42; N, 4.38. Found: C, 48.90; H, 4.52; N, 4.37%. M.p. 88 °C. IR (cm−1): 615 w, 669 vw, 702 s, 750 s, 764 m, 879 w, 906 vw, 997 m, 1030 m, 1051 s, 1215 m, 1444 vs, 1589 s, 1617 w, 1826 vw, 2341 m, 2360 s. NMR data (thf-d8): 1H NMR, d = 2.46 (s, 12H, C6H3Me2), 6.70 (t, 3JH,H = 7 Hz, 2H, p-C6H3Me2), 6.97 (d, 3JH,H = 7 Hz, 4H, m-C6H3Me2), 7.32 (m, 4H, NC5H5), 7.75 (tt, 3JH,H = 7 Hz, 4JH,H = 2 Hz, 2H, NC5H5), 8.62 (m, 4H, NC5H5).

Preparation of [(2,6-Me2C6H3S)2Pb(l2-bipy)]∞ (8)

A solution of 4,4-bipyridyl (0.26 g, 1.66 mmol) in thf (2 mL) was added dropwise to a solution of 6 (0.200 g, 0.415 mmol) in thf (8 mL) to give a cloudy yellow solution. After stirring for 15 min, the yellow reaction mixture was centrifuged, decanted and allowed to stand at 4 °C. After 2 days, the precipitate was collected to yield 8 as a yellow crystalline solid (0.012 g, 0.016 mmol, 5%). Anal. Calcd. for C26H26N2S2Pb: C, 48.95; H, 4.12; N, 4.39. Found: C, 48.79; H, 4.46; N, 4.32%. M.p. 118 °C (dec.). IR (cm−1): 617 vs, 712 m, 766 s, 812 m, 997 m, 1065 s, 1160 w, 1213 m, 1407 m, 1529 w, 1593 vs. NMR data (thf-d8): 1H NMR, d = 2.58 (s, 12H, C6H3Me2), 6.73 (t, 3JH,H = 7 Hz, 2H, p-C6H3Me2), 7.01 (d, 3JH,H = 7 Hz, 4H, m-C6H3Me2), 7.66 (d, 4H, 3JH,H = 6 Hz, N2C10H8), 8.67 (d, 3JH,H = 6 Hz, 4H, N2C10H8).

Preparation of [(2,6-Me2C6H3S)2Pb(l2-pyr)]∞ (9)

A solution of pyrazine (0.133 g, 1.66 mmol) in thf (3 mL) was added dropwise to a solution of 6 (0.200 g, 0.451 mmol) in thf (6 mL) at room temperature. After stirring for 10 min, the cloudy yellow solution was centrifuged and decanted, and allowed to evaporate slowly at 25 °C. After 4 days, the solid precipitate was collected and washed with thf (1 mL) and hexane (1 mL), giving 9 as a yellow crystalline solid (0.061 g, 0.109 mmol, 24%). Anal. Calcd. for C20H22N2S2Pb: C, 42.76; H, 3.95; N, 4.99. Found: C, 42.19; H, 3.68; N, 4.37%. M.p. 170 °C (dec.). IR (cm−1): 762 s, 877 w, 920 w, 1047 s, 1120 m, 1161 w, 1581 s, 1604 vs, 2318 vw, 2359 vw, 3161 vw, 3259 w, 3332 vw. NMR data (thf-d8): 1H NMR, d = 2.55 (s, 12H, C6H3Me2), 6.70 (t, 3JH,H = 7 Hz, 2H, p-C6H3Me2), 7.01 (d, 3JH,H = 7 Hz, 4H, m-C6H3Me2), 8.53 (s, 4H, N2C4H4).

Preparation of (C6H5S)2Pb(py)0.5 (10)

A solution of (C6H5S)2Pb 1 (0.216 g, 0.508 mmol) in pyridine (1 mL) was layered with diethyl ether (1 mL), giving a yellow precipitate. After 1 day, the solid was filtered and washed with diethyl ether (1 mL) to yield 10 as a yellow crystalline solid (0.154 g, 0.166 mmol, 65%). Anal. Calcd. for C29H25NS4Pb2: C, 37.45; H, 2.71; N, 1.51. Found: C, 36.93; H, 2.38; N, 1.29%. M.p. 196 °C. IR (cm−1): 685 vs, 700 s, 887 vw, 995 w, 1024 m, 1065 w, 1113 vw, 1213 vw, 1292 vw, 1433 vs, 1572 m, 1585 m, 1653 vw, 1699 vw, 1745 vw, 1919 vw, 2335 w, 2360 m, 2630 vw, 2679 vw. NMR data (dmso-d8): 1H NMR, d = 6.95 (t, 3JH,H = 7 Hz, 2H, C6H5), 7.15 (m, 4H, C6H5), 7.26 (m, 4H, C6H5), 7.38 (m, 2H, NC5H5), 7.78 (tt, 3JH,H = 7 Hz, 4JH,H = 2 Hz, 1H, NC5H5), 8.57 (m, 2H, NC5H5).

X-ray structural analyses

Crystals of 7, 9 and 10 were isolated from the reaction mixtures as indicated above. 8·0.5CH2Cl2 was prepared from the reac-tion of 6 and bipy (1 : 4) in dichloromethane. Single crystals of 7, 8·0.5CH2Cl2, 9 and 10 were coated with Paratone–N oil, mounted using a glass fibre and frozen in the cold nitrogen stream of the goniometer. A hemisphere of data was collected on a Bruker AXS P4/SMART 1000 diffractometer using x and h scans with a scan width of 0.3° and 10 (7), 20 (8·0.5CH2Cl2), 40 (9) or 30 s (10) exposure times. The detector distances were 5 (7) or 6 cm (8·0.5CH2Cl2, 9 and 10). The data were reduced (SAINT)18 and corrected for absorption (SADABS).19 The structures were solved by direct methods and refined by full-matrix least squares on F 2 (SHELXTL).20 All non-hydrogen atoms were refined anisotropically with the exception of the solvent carbon atom of 8·0.5CH2Cl2, which was refined iso-tropically. Hydrogen atoms were found in Fourier difference maps and refined isotropically (7), or were included in calcu-lated positions and refined using a riding model (8·0.5CH2Cl2, 9 and 10).

CCDC reference numbers 243400–243403.See http://www.rsc.org/suppdata/dt/b4/b410320c/ for crystal-

lographic data in CIF or other electronic format.

AcknowledgementsWe thank Dan Durant for assistance in collecting NMR data. Natural Sciences and Engineering Research Council of Canada, the New Brunswick Innovation Foundation and Mount Allison University are thanked for financial support.

References 1 See for example: (a) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak,

J. Wachter, M. O’Keeffe and O. M. Yaghi, Science, 2002, 295, 469; (b) S. Leininger, B. Olenyuk and P. J. Stang, Chem. Rev., 2000, 100, 853; (c) A. P. Côté and G. K. H. Shimizu, Coord. Chem. Rev., 2003, 245, 49; (d) B. Moulton and M. J. Zawarotko, Chem. Rev., 2001, 101, 1629 and references therein.

2 (a) Encyclopedia of Inorganic Chemistry, ed. R. B. King, Wiley, Chichester, England, 1994 vol. 4, p. 1945; (b) Encyclopedia of Inor-ganic Chemistry, ed. R. B. King, Wiley, Chichester, England, 1994 vol. 4, p. 1961.

3 (a) G. G. Briand and N. Burford, Adv. Inorg. Chem., 2000, 50, 285, and references therein; (b) L. J. Farrugia, F. J. Lawlor and N. C. Norman, J. Chem Soc., Dalton Trans., 1995, 1163; (c) K. M. Anderson, C. J. Baylies, A. H. M. M. Jahan, N. C. Norman, A. G. Orpen and J. Starbuck, Dalton Trans., 2003, 3270.

4 See for example: (a) T. Tsubumura, M. Ito and K. Sakai, Inorg. Chim. Acta, 1999, 284, 149; (b) R. E. Cramer, C. A. Waddling, C. H. Fujimoto, D. W. Smith and K. E. Kim, J. Chem Soc., Dalton Trans., 1997, 1675.

5 A. D. Rae, D. C. Craig, I. G. Dance, M. L. Scudder, P. A. W. Dean, M. A. Kmetic, N. C. Payne and J. J. Vittal, Acta Crystallogr., Sect. B: Struct. Sci., 1997, B53, 457.

6 B. Krebs, A. Brömmelhaus, B. Kersting and M. Nienhaus, Eur. J. Solid State Inorg. Chem., 1992, 29, 167.

7 P. A. W. Dean, J. J. Vittal and N. C. Payne, Inorg Chem., 1985, 24, 3594.

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3 5 2 0 D a l t o n T r a n s . , 2 0 0 4 , 3 5 1 5 – 3 5 2 0

8 B. Krebs and A. Brommelhaus, Z. Anorg. Allg. Chem., 1991, 595, 167.

9 M. Veith, P. Hobein and R. Rosler, Z. Naturforsch., 1989, B44, 1067.10 See for example: (a) B. Krebs, A. Brommelhaus, B. Kersting

and M. Nienhaus, Eur. J. Solid State Chem., 1992, 29, 167; (b) D. Labahn, E. Pohl, R. Herbst-Irmer, D. Stalke, H. W. Roesky and G. M. Sheldrick, Chem. Ber., 1991, 124, 1127; (c) B. Krebs and A. Brommelhaus, Angew. Chem., Int. Ed. Engl., 1989, 28, 1682.

11 P. B. Hitchcock, M. F. Lappert, B. J. Samways and E. L. Weinberg, J. Chem Soc., Chem Commun., 1983, 1492.

12 See for example: (a) K. Ruhlandt-Senge and P. P. Power, Inorg. Chem., 1993, 32, 3478; (b) D. A. Atwood, A. H. Cowley, R. D. Hernandez, R. A. Jones, L. L. Rand, S. G. Bott and J. L. Atwood, Inorg. Chem., 1993, 99, 2972; (c) D. M. Barnhart, D. L. Clark and J. G. Watkin, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1994, C50, 702; (d) W. J. Evans, J. H. Hain, Jr. and J. W. Ziller, Chem. Commun., 1989, 1628; (e) B. Cetinkaya, I. Gumrukca, M. F. Lappert, J. L. Atwood, R. D. Rogers and M. J. Zaworotko, J. Am. Chem. Soc., 1980, 102, 2088; (f) M. Bochmann, X. Song, M. B. Hursthouse and A. Karalov, J. Chem. Soc., Dalton Trans., 1995, 1649.

13 R. A. Shaw and M. Woods, J. Chem. Soc. A, 1971, 1569.14 (a) H. Hagihara, N. Yoshida and Y. Watanabe, Acta Crystal-

logr., Sect. B: Struct. Crystallogr. Cryst. Chem., 1969, B25, 1775; (b) J. M. Harrowfield, H. Miyamae, B. W. Skelton, A. A. Soudi and A. H. White, Aust. J. Chem., 1996, 49, 1165; (c) L. Pu, B. Twamley and P. P. Power, Organometallics, 2000, 19, 2874.

15 H. Miyamae, H. Toriyama, T. Abe, G. Hihara and M. Nagata, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1984, C40, 1559.

16 (a) A. Bondi, J. Phys. Chem., 1964, 68, 441; (b) I. D. Brown, Chem. Soc. Rev., 1978, 7, 359.

17 (a) Y.-J. Shi, Y. Xu, Y. Zhong, B. Huang, D.-R. Zhu, C.-M. Jin, Z. Yu, X.-T. Chen and X.-Z. You, Chem. Lett., 2001, 678; (b) Y. Cui, J. Ren, G. Chen, W. Yu and Y. Qian, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 2000, C56, e552.

18 SAINT 6.02, 1997–1999, Bruker AXS, Inc., Madison, Wisconsin, USA.

19 SADABS George Sheldrick, 1999, Bruker AXS, Inc., Madison, Wisconsin, USA.

20 SHELXTL 5.1, George Sheldrick, 1997, Bruker AXS, Inc., Madison, Wisconsin, USA.

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