η 3-allyl)dicarbonylmolybdenum(II) complexes of the unsymmetrical ditertiary phosphines Ph 2PCH 2CH 2P(C 6H 4X) 2 (X = m-F, p-F or m-CF 3)

Abstract

Complexes of the type [XMo(CO) 2(η 3-C 3H 5)(PP′)] (X  Cl or Br; PP′  R 2PCH 2CH 2PPh 2; R = m-FC 6H 4 ( 1a), p-FC 6H 4 ( 1b), m-CF 3C 6H 4 ( 1c)) have been prepared from the reaction of [XMo(CO) 2 (η 3-C 3H 5)(MeCN) 2] with the relevant ditertiary phosphines in acetone. From their 1H NMR and IR data these complexes have been assigned essentially octahedral structures in which the allyl moiety is trans to be unidentate anion, and the two cis-carbonyl groups and two phosphorus donor atoms of the bidentate ligand are approximately coplanar. CO force constants have been calculated.