PYRIDINE COORDINATION-COMPLEXES OF THE DIVALENT YTTERBIUM CHALCOGENOLATES YB(EPH)2 (E=S, SE, TE)

Chalcogenolate complexes of ytterbium can be prepared via a number of synthetic approaches. The reaction between Yb metal and PhE-EPh (E = S ,Se,Te) in liquid ammonia results in the formation of divalent ytterbi um chalcogenolates, which can be isolated as the pyridine coordination complexes (pyridine)4Yb(SC6H5)2 (1) (pyridine)4Yb(SeC6H5)2 (2), and ( pyridine)5Yb(TeC6H5)2 (3). Reaction of YbCl3 with 3 equiv of NaTePh re sults in the reduction of the metal and the formation of 3 and dipheny l ditelluride. The thiolate 1 and selenolate 2 can be prepared by redu cing the corresponding dichalcogenide with a ytterbium/mercury amalgam in THF. All three ytterbium complexes have been characterized by elem ental analysis and by NMR, IR, and UV-visible spectroscopy. The visibl e spectra were found to be concentration dependent. All three complexe s have also been characterized by single-crystal X-ray diffraction and shown to be molecular, with trans phenylchacogenolate ligands. Octahe dral 1 crystallizes in the triclinic space group P1BAR, with a = 8.797 (3) angstrom, b = 9.412(4) angstrom, c = 9.947(7) angstrom, alpha = 87 .07(4)degrees, beta = 66.79(4)degrees, gamma = 75.25(3)degrees, V = 73 0.9(7) angstrom3, Z = 1, and rho(calc) = 1.608 g/cm3 (Mo Kalpha radiat ion at -115-degrees-C). Octahedral 2 crystallizes in the space group C 2/c, with a = 25.670angstrom(6) angstrom, b = 9.027(4) angstrom, c = 1 7.680(3) angstrom, beta = 133.62(2)degrees, V = 2966(2) angstrom3, Z = 4, rho(calc) = 1.795 g/cm3 (Mo Kalpha radiation at -120-degrees-C). T he pentagonal bipyramid 3 crystallizes in the space group Pbca, with a = 13.695(9) angstrom, b = 16.422(8) angstrom, c = 31.917(7) angstrom, V = 7178(6) angstrom3, Z = 8, rho(calc) = 1.83 g/cm3 (Mo Kalpha radia tion at -120-degrees-C). The metal-chalcogenide bond lengths in all th ree structures can be predicted with the summation of ionic radii.