Reactions of methyltris(triarylphosphine)cobalt : II. Rearrangement of triarylphosphine and oxidative additions of aryl halides

Solutions of [(C₆H₅)₃P]₃CoCH₃ (I) in C₆H₅Cl yield biphenyl, triphenylphosphine, methyldiphenylphosphine and diphenylphosphine. In 4-ClC₆H₄CH₃, 4-methylbiphenyl and 4,4′-bitolyl form as well. Solutions of I in C₆H₆, C₆D₆, C₆H₅CH₃, C₆H₅Br yield only triphenylphosphine and biphenyl, while in 4-FC₆H₄I 4,4′-difluorobiphenyl is formed but no biphenyl. The cobalt compound is recovered as (Ph₃P)_nCoX or as CoX₂ (XCl, Br, I, n = 3 or 2) from reactions with arylhalides. The results are rationalized in terms of the very strong tendency for I to undergo oxidative addition reactions.