Pyridine-2-selenolate and -2-tellurolate as ligands: A multinuclear(Se-77, Sn-119, Te-125) magnetic resonance study of some tin(IV) complexes, and X-ray structural analyses of Sn(SPh)(2)(2-Se-C5H4N-N,Se)(2) and Sn(SPh)(1.85)(2-Se-C5H4N)(2.15)

Reactions between Sn(E'Ph)(n) (E' = S or Se; n = 2 or 4) and the bis(pyridine) dichalcogenides 2,2'-(C(5)H(4)NE)(2) (E = Se or Te), abbreviated py(2)E(2), have been studied using multinuclear (Se-77, Sn-119, Te-125) magnetic resonance. In this way the occurrence of the pyridine-2-chalcogenate complexes Sn(E'Ph)(4-x)(Epy)(x) (E' = S or Se; E = Se, x = 1-4; E = Te, x = 1 or 2) has been demonstrated. The pattern of Sn-119 NMR chemical shifts for Sn(E'Ph)(4-x)(Sepy)(x) (E' = S or Se, x = 0-4) is consistent with bidentate bonding for the pySe(-) ligand when x = 1 and 2. The pyTe(-) ligand is probably bidentate also in all four complexes containing this ligand. As part of the NMR analysis, Se-77 and (or) Te-125 NMR data were obtained for py(2)Te(2) and for the new mixed dichalcogenides PhE'ER (E' = S, Se, or Te; E not equal E' = Se or Te; R = 2-py or Ph), which were produced in the systems Ph(2)E'(2):R(2)E(2). The complex Sn(SPh)(2)(Sepy)(2) (1) was isolated pure and its structure determined by the single crystal X-diffraction technique. The compound crystallizes in the monoclinic space group P2(1)/n, with unit cell dimensions a = 9.7929(9) Angstrom, b = 22.340(2) Angstrom, c = 11.368(1) Angstrom, beta = 108.803(7)degrees, V = 2354.3(4) Angstrom(3), d(calc) = 1.837 g cm(-3), and Z = 4. Refinement by full-matrix least squares on F-2 gave agreement factors R1 = 0.0425 and wR2 = 0.0882 for 2823 independent reflections with F-0 greater than or equal to 4 sigma (F-0) and 258 variables. The structure confirms that the PySe(-) ligand behaves in a chelating manner. The molecule Sn(SPh)(2)(2-Se-C5H4N-N,Se)(2) has a distorted octahedral structure with the PhS(-) ligands in cis positions and the two Se donor atoms in trans positions. The Sn-Se, Sn-S, and Sn-N distances are 2.6291(8) and 2.6358(8) Angstrom, 2.475(2) and 2.464(2) Angstrom, and 2.325(5) and 2.333(5) Angstrom. The bite angles N-Sn-Se of the chelating ligands are 65.9(1)degrees and 65.8(1)degrees. En route to 1, the yellow crystalline compound Sn(SPh)(1.85)(2-Se-C5H4N)(2.15) (2) was isolated. This was shown by Sn-119 NMR spectroscopy to contain both Sn(2-Se-C5H4N)(2)(SPh)(2) and Sn(2-Se-C5H4N)(3)(SPh). The crystal and molecular structure of 2 was determined by single crystal X-ray diffraction techniques. Crystal data: monoclinic, space group P2(1)/n, a = 9.795(2) Angstrom, b = 22.355(4) Angstrom, c = 11.362(2) Angstrom, beta = 108.87(3)degrees, V = 2354.2(8) Angstrom(3), d(calc) = 1.837 g cm(-3), d(obs) = 1.87(5) g cm(-3), Z = 4) R1 = 0.0306, wR2 = 0.0651 for 2756 data (F-0 greater than or equal to 4 sigma(F-0)) and 258 parameters. Crystallographic evidence for the presence of co-crystallized Sn(2-Se-C5H4N)(3)(SPh) occurs only in a minor lengthening of one of the two Sn-S bonds, Sn-S(1) (compared with expectation for 1), and an excess of electron density at S(1) when the data are modelled as Sn(2-Se-C5H4N)(2)(SPh)(2). These effects are attributed to a crystallographic disorder of SPh and eta'-{2-Se-C5H4N} at the S(1)Ph site, involving isostructural Sn(eta(2)-{2-Se-C5H4N})(2)({eta(1)-{2-Se-C5H4N})(SPh) and Sn(eta(2)-{2-Se-C5H4N})(2)(SPh)(2).