STRUCTURAL DETERMINATION AND ACIDOLYSIS REACTIONS OF ORTHO-METALATED RHENIUM TETRAHYDRIDE COMPOUNDS PREPARED FROM REACTIONS OF REH7(PPH3)(2) WITH BENZYLIC IMINES

Reactions between ReH7(PPh3)(2) and a series of benzylic imines, PhCHN R (R = Me, Ph, or Bn), produce the compounds ReH4[eta(2)-(1,2-C6H4)CHN R](PPh3)(2). One such compound, ReH4[eta(2)-(1,2-C6H4)CHNPh] (PPh3)(2) , was characterized by X-ray diffraction analysis. The compound ReH4[e ta(2)-(1,2-C6H4)CHNPh](PPh3)(2) crystallizes in the P-(1 over bar) spa ce group with the following unit cell dimensions: a = 12.422(3) Angstr om, b = 12.696(3) Angstrom, c = 13.604(5) Angstrom, alpha = 93.26(2)de grees, beta = 90.66(2)degrees, gamma = 107.03(2)degrees, V = 2047.2 An gstrom(3), and Z = 2. The structure was refined to R(F-o) = 0.029 (R-w (F-o) = 0.034) for 5352 data with I > 3.0 sigma(I). The structure dete rmination indicates that orthometalation of the imine reactant occurs during the reaction of ReH7(PPh3)(2) With PhCHNPh, The observation of four v(Re-H) absorptions in the infrared spectrum of each ReH4[eta(2)- (1,2-C6H4)CHNR](PPh3)(2) compound indicates that the rhenium-bound hyd rogen atoms, in these compounds, are better regarded as classical hydr ide ligands rather than as elongated dihydrogen ligands. Acidolysis re actions of the compounds ReH4[eta(2)-(1,2-C6H4)CHNR]-(PPh3)(2), with H BF4. Et2O in acetonitrile, result in loss of the ortho-metalated imine ligands from the rhenium coordination spheres and in reduction of the imine functional groups to secondary ammonium cations. One hydride li gand is transferred to the imine carbon atom, during the course of eac h acidolysis reaction.