Tetrakis(pyridine)tetrachloro(μ-chloro)(μ-hydrido)ditungsten(W-W) and its 4-ethylpyridine homologue. Compounds derived from a quadruply bonded dimer by ligand exchange and oxidative addition of hydrogen chloride

Reaction of W{sub 2}(mhp){sub 4} (mhp = anion of 6-methyl-2-hydroxypyridine) with (CH{sub 3}){sub 3}SiCl and pyridine in the presence of methanol provides the light brown compound W{sub 2}HCl{sub 5}(NC{sub 5}H{sub 5}){sub 4}. The 4-ethylpyridine adduct W{sub 2}HCl{sub 5}(NC{sub 5}H{sub 4}C{sub 2}H{sub 5}){sub 4} is obtained by ligand exchange at 100{degree}C. Brown crystals of the latter are monoclinic, space group C2/c, with a = 11.883 (3) {angstrom}, b = 13.213 (3) {angstrom}, c = 21.727 (4) {angstrom}, {beta} = 96.39 (3){degree}, and Z = 4. Structure refinement revealed an edge-shared bioctahedral arrangement with one H atom and one Cl atom in bridging positions between the metal atoms. The Cl atoms all occupy positions in the equatorial plane, and the 4-ethylpyridine ligands occupy the axial positions of the dimer. The short W-W distance, 2.516 (2) {angstrom}, is consistent with a W-W multiple bond. Comparison of the infrared spectra of the hydride and deuteride derivatives confirms the presence of a bridging H atom and indicates an isostructural arrangement for the pyridine and 4-ethylpyridine derivatives, as do electronic reflectance spectra. 33 refs., 4 figs., 4 tabs.