Trifluoromethylphosphine complexes of tricarbonylnitrosylcobalt

Abstract

The reaction of P(CF₃)_nX_3–n(L; n= 1 or 2, X = F, Cl, Br, or I) with [Co(CO)₃(NO)] at room temperature gives [Co(CO)₂(NO)L] as the major product in ail cases except P(CF₃)I₂. The chloro- and fluoro-phosphines can additionally form [Co(CO)(NO)L₂] and the fluorophosphines give intermediates of sufficient thermal stability to allow total substitution of CO under more forcing conditions, giving [Co(NO)L₃]. Exchange reactions between free ligand (L′) and the co-ordinated phosphine (L) in [Co(CO)₂(NO)L] enable the construction of the following displacement series: P(CF₃)F₂∼ P(CF₃)F > P(CF₃)Cl₂∼ P(CF₃)₂Cl > PBr(CF₃)₂ > P(CF₃)H₂ > P(CF₃)₂I > PBr₂(CF₃). The reactivity of the P–X bond in the co-ordinated phosphines is much lower than that in the corres-pondingfree phosphine.