Synthesis, molecular structure and theoretical considerations on Mo(PhCCCOOEt)3(PMe3)
摘要:
The reaction of trans-Mo(C2H4)(2)(PMe3)(4) with PhC equivalent to CCOOEt affords (PhC equivalent to CCOOEt)(3)(PMe3) (1). The molecular structure of 1 has been determined by means of X-ray analysis. NMR studies have shown that 1 undergoes a dynamic process in solution due to the alkyne rotation. The related energy barrier is experimentally determined to be 15.1 kcal mol(-1). The well established EHMO theoretical arguments, which uniquely explain the chemical bonding in these complexes, are extended to interpret the nature of the barrier and its dependence on the pi-donor or pi-acceptor capability of the axial ligand. The conceptual continuity between the chemical bonding of d(6) metal species coordinated by at least two alkyne molecules (e.g. M(alkyne)(2)L-4, M(alkyne)(2)L-2 and M(alkyne)(3)L) is highlighted. (C) 1998 Elsevier Science S.A. All rights reserved.