Reactions of a terminal phosphido-group in an organoiron complex. Part II. New routes to derivatives of the tricarbonyl(η-cyclopentadienyl)iron cation

Abstract

Two new routes for the preparation of derivatives of [(cp)Fe(CO)₃]⁺(cp =η-cyclopentadienyl) are reported. Reaction of [(cp)Fe(CO)₂{P(CF₃)₂}], (I), with excess of X₂(X =Cl, Br, or I) gives[(cp)Fe(CO)₂{P(CF₃)₂X}][X₃], (II), in quantitative yields. The tri-iodide salt is stable at room temperature but tribromide and trichloride decompose to [(cp)Fe(CO)₂X] and (F₃C)₂PX. with ICl, (II; X = Cl) is formed. A second method for the preparation of cationic phosphine complexes is protonation of (I) to give [(cp)Fe(CO)₂{(CF₃)₂PH}]⁺, (IV), and of [(cp)Fe(CO)₂{P(E)(CF₂)₂}], (III), to give [(cp)Fe(CO)₂{P(CF₃)₂(EH)}]⁺(V; E = O, S, or Se).