Synthesis and reactions of [Co(RCN){PPh(OEt)2}3{η2-C6H5PO(OEt)2}]BPh4 derivatives:: Strong evidence for η2-coordination of the phenyl ring of the C6H5PO(OEt)2 ligand

Cobalt(I) complexes [Co(RCN)P-3{eta(2)-C6H5PO(OEt)(2)}]BPh4 (1; R = Me, Ph; P = PPh(OEt)(2)) were prepared by allowing [CoClP4]BPh4 compound to react with zinc dust in a cosolvent mixture of nitrile and ethanol. eta(2)-Coordination of the arena ring of the C6H5PO(OEt)(2) ligand was confirmed by H-1 and C-13 NMR spectra and decoupling experiments. Substitution reactions with CO Or isocyanide gave free C6H5PO(OEt)(2), RCN, and [Co(CO)(2)P-3](+) or [Co(RNC)(2)P-3](+) cations. Treatment of 1 with H-2 (1 atm), in either the presence or absence of a heterogeneous catalyst, gave the unstable cobalt(III) dihydride derivative [CoH2P3{eta(2)-C6H5PO(OEt)(2)}](+).