UNUSUAL MIGRATION OF MANGANESE TO AN ARENE VIA PROTONATION OF AN AGOSTIC ETA(3-CH)-CYCLOHEXENYL COMPLEX

Treatment of the agostic compound [Mn(eta(3:CH)-C(6)H(8)Ph)(CO)(3)] la with HBF4 . Et(2)O in CH2Cl2 gave the arene complex [Mn{eta(6)-C6H5(C 6H9)}(CO)(3)][BF4] 2 via migration of the metal from the cyclohexenyl ring to the aryl substituent. Reaction of 2 with the nucleophiles trip henylphosphine and methylmagnesium chloride respectively gave the subs titution product [Mn{eta(6)-C6H5(C6H9)}(CO)(2)(PPh(3))][BF4] 3 and the addition product [Mn{eta(5)-C(6)H(5)Me(C6H9)}(CO)(3)] 4 as a mixture of isomers. The crystal structure of complex 2 has been determined: tr iclinic, space group P ($) over bar 1, a = 9.399(3), b = 10.644(2), c = 8.979(1) Angstrom, alpha = 93.03(1), beta = 116.39(2), gamma = 79.45 (3)degrees, R = 0.057 for 1316 independent reflections.