Organolanthanide and Organoyttrium Hydride Chemistry. 6. Direct Synthesis and 1H NMR Spectral Analysis of the Trimetallic Yttrium and Yttrium-Zirconium Tetrahydride Complexes, 3H> and 2H>

Article abstract of DOI:10.1021/ja00328a027

Improved syntheses for the trimetallic tetrahydride complexes <<(C5H5)2LnH>3H> were investigated by studying the reactions of <(C5H5)2YH(THF)>2 with LiH, CH3Li, and t-C4H9Li.The t-C4H9Li reaction generates the trimer, <<(C5H5)2YH>3H>, in 75percent yield with (C5H5)2Y(t-C4H9)(THF) and (C5H5)3Y(THF) as byproducts.The reaction of <(C5H5)2YD(THF)>2 with t-C4H9Li forms the perdeuterio trimer, <<(C5H5)2YD>3D>.The latter synthesis indicates that the tert-butyl group does not provide an H^- ion for the trimer.A mechanism for formation of the trimer by in situ generation of a (C5H5)2YH2^- intermediate which reacts with the dimeric hydride starting material to give the trimer is described.This mechanism was tested by reacting <(CH3C5H4)2ZrH2>2 with <(CH3C5H4)2YH(THF)>2 to form the heterometallic tetrahydride <<(CH3C5H4)2YH>2<(CH3C5H4)2ZrH>H>.The 1H NMR spectra of <<(C5H5)2YH>3H> and <<(CH3C5H4)2YH>2<(CH3C5H4)2ZrH>H> are presented and the HH, YH, and YY coupling constants are discussed on the basis of computer simulation of the spectra.