Twenty-five complexes of the type SnX4B2, where X = C1, Br, or I, B = &PO (R = C Z H~, C4H9, C&), (C6H6)3As0, (CH3)zS0, (CeH5)3As, RIP (R = C4H9, CeH6, CSHl?), or COHS(CH~)ZP, and BZ = O-[(COH~)ZP]CSH~, U -( C H~)~N ( C~H~) P -(C&)Z, or [u-(CH3)~N(C6H4)]2P(C6H5), fifteen of them previously unreported, have been synthesized and studied by llgmSnMossbauer and far-infrared techniques. Cis and trans isomers have been distinguished by the number of v(Sn-X) and G(Sn-X) bands they exhibit; those assigned trans on this basis are found t o exhibit Mossbauer quadrupole splittings of ca. 1 mm/sec. The point-charge model predicts that the QS for cis isomers should be half that for the trans, and the QS for these isomers is barely resolvable as expected. In one case, S~C L .~P ( C !~H S )~, the infrared and Mossbauer evidence leads to opposite stereochemical assignments. In general, the oxygen donor ligands give cis complexes while all the fifthgroup donor ligands but triphenylarsine give the trans isomers except when bidentate These differences are rationalized on steric arguments.Dithiocarboxylates (L = CeH6-CSS-= dtb-, P-CH3-CeHa-CSS-= dtt-, CHa-CSS-= dta-, ceH&H~-cSs-= dtpa-) react with both VOz+ ion and V(II1) to give stable VL4 complexes. Magnetic measurements, infrared spectra, and molecular weight measurements in solution are consistent with eight-coordinated V(1V). Epr and preliminary X-ray results demonstrate an approximate Dzd geometry for the VSS chromophores. Electronic spectra are discussed.
