Coordination of LiH Molecules to Mo≡Mo Bonds: Experimental and Computational Studies on Mo_2LiH_2, Mo_2Li_2H_4, and Mo_6Li_9H_(18) Clusters

摘要

The reactions of LiAlH_4 as the source of LiH with complexes that contain (H)MoiMo and (H)Mo≡Mo(H) cores stabilized by the coordination of bulky Ad~(Dipp2) ligands result in the respective coordination of one and two molecules of (thf)LiH, with the generation of complexes exhibiting one and two HLi(thf)H ligands extending across the MoiMo bond (Ad~(Dipp2) = HC(NDipp)_2; Dipp = 2,6-~iPr_2C_6H_3; thf = tetrahydrofuran, C_4H_8O). A theoretical study reveals the formation of Mo-H-Li three-center-two-electron bonds, supplemented by the coordination of the Mo≡Mo bond to the Li ion. Attempts to construct a [Mo_2{HLi(thf)H}_3(Ad~(Dipp2))] molecular architecture led to spontaneous trimerization and the formation of a chiral, hydride-rich Mo_6Li_9H_(18) supramolecular organization that is robust enough to withstand the substitution of lithium-solvating molecules of tetrahydrofuran by pyridine or 4-dimethylaminopyridine.