Reductive activation of tripod cobalt compounds: Oxidative addition of H-H, P-H, and Sn-H functions

Treatment of the tripod compounds tripodCoCl(2) (1), and tripod-CoCl (2), [ tripod = CH3C(CH2,PPh2)(3)] in THF solution under argon atmosphere with str ong reducing agents such as KC8 leads to the generation of reactive species . While the dinitrogen compound tripodCo(N-2)Cotripod (3), which is formed under N-2 atmosphere, is rather unreactive, the species formed under argon atmosphere undergo selective reactions with compounds containing P-H or Sn- H functions. With PhPH2, as the reagent, the diphosphone compound tripodCo( eta (2)-PhP=PPh) (8), is formed in a yield (44%) similar to that achieved i n the preparation of 8 from 2 and PhPHNa (60%). With Ph3SnH as the reagent, tripodCoSnPh(3) (9), is obtained (yield 61%), while reaction with Bu3SnH p roduces tripodCo(H)(2)SnBu3 (10a, 50%). The Co-I species 9 undergoes oxidat ive addition of dihydrogen to produce the Co-III compound tripodCo(H)(2)SnP h3 (10b), which is an analogue of 10a. The properties of these new compound s are characterized by the usual analytical techniques, including NMR spect roscopy, cyclic voltammetry, and X-ray analysis.