THE NATURE OF THE BRIDGING NITRIDO LIGAND - SYNTHESIS AND REACTIVITY OF HETEROBIMETALLIC NITRIDO-BRIDGED COMPOUNDS

Heterobimetallic nitrido-bridged compounds (R(3)SIO)(3)V=N-M(CO)(PPh(3 ))(2) (R = Me or Et and M = Ir or Rh) and (Me(3)SiO)(3)V=N-Rh(PPh(3))( 3) have been synthesized. by condensation reactions between vanadium s ilylimido compounds, V(NSiR(3))(OSiR(3))(3), and group VIII metal fluo rides, MF(L)(PPh(3))(2). Oxidative addition of small molecules (MeI, O -2, H-2) to the iridium(I) of (R(3)SiO)(3)V=N-Ir(CO)(PPh(3))(2) occurs , producing iridium(III) compounds in which the V=N-Ir interaction is retained. In contrast, however, the nitrido linkages in (Me(3)SiO)(3)V =N-M(L)(PPh(3))(2) are readily cleaved by silylating reagents (C1SiMe( 3), ClSiEt(3), HSiEt(3)), producing V(NSIR(3))(OSiMe(3))(3) and a grou p VIII metal chloride or hydride product. Comparison of the reactivity and spectroscopic data among the nitrido-bridged compounds and with r elated iridium(I) and rhodium(I) complexes suggests that the nitrido-b ridged compounds are best viewed as adducts in which anionic [(R(3)SIO )(3)V=N:](-) acts as a simple two-electron donor to the 14-electron ca tionic [M(L)(PPh)(2)](+) fragment.