Coordination\nof LiH Molecules to Mo≣Mo Bonds:\nExperimental and Computational Studies on Mo₂LiH₂, Mo₂Li₂H₄, and Mo₆Li₉H₁₈ Clusters

Abstract

The reactions of LiAlH₄ as the source of LiH with complexes\nthat contain (H)­Mo≣Mo and (H)­Mo≣Mo­(H) cores stabilized\nby the coordination of bulky Ad^Dipp2 ligands result in\nthe respective coordination of one and two molecules of (thf)­LiH,\nwith the generation of complexes exhibiting one and two HLi­(thf)­H\nligands extending across the Mo≣Mo bond (Ad^Dipp2 = HC­(NDipp)₂; Dipp = 2,6-<i>ⁱ</i>Pr₂C₆H₃; thf = tetrahydrofuran,\nC₄H₈O). A theoretical study reveals the formation\nof Mo–H–Li three-center–two-electron bonds, supplemented\nby the coordination of the Mo≣Mo bond to the Li ion. Attempts\nto construct a [Mo₂{HLi­(thf)­H}₃(Ad^Dipp2)] molecular architecture led to spontaneous trimerization and the\nformation of a chiral, hydride-rich Mo₆Li₉H₁₈ supramolecular organization that is robust enough to withstand\nthe substitution of lithium-solvating molecules of tetrahydrofuran\nby pyridine or 4-dimethyl­aminopyridine.