REACTIVITY OF PYRAZOLYLBORATE COMPLEXES OF SAMARIUM WITH TRANSITION-METAL CARBONYLS

The reaction of [Sm(Tp(Me,Me))(2)] with [M(eta-C(5)H(4)R)(CO)(3)](2) ( M = Cr, R = H; M = Mo, R = Me, (t)Bu; M = W, R = H) gives good yields of [Sm(Tp(Me,Me))(2)(mu-OC) M{(eta-C(5)H(4)R)(CO)(2)}]. The crystal st ructure of the complex for which M = Mo and R = Me has been determined (triclinic, <P(1)over bar>, a=10.4106(6), b=14.1022(8), c=18.6974(11) Angstrom, alpha=71.579(2), beta=88.751(2), gamma=85.095(2)degrees and V=2594.8(3)Angstrom) confirms the seven coordinate samarium centre wi th the expected bridging isocarbonyl. In contrast, the reaction of[Sm( Tp(Me,Me))(2)] with [Co-2(CO)(8)] gives the salt [Sm(Tp(Me,Me))(2)][Co (CO)(4)] together with [Co-4(CO)(12)].