Structure and reactions of matrix-isolated tetracarbonyliron(0)

Abstract

U.v. photolysis of ¹³CO enriched pentacarbonyliron in SF₆ and Ar matrices at 20 K indicates that tetracarbonyliron has a C_2v structure, with bond angles ca. 145 and 120°, as estimated from i.r. intensities. Photolysis of [Fe(CO)₅] in an N₂ matrix produces [Fe(CO)₄] which can be reacted reversibly with the matrix to form [Fe(CO)₄(N₂)]. Equivalent experiments in CH₄ or Xe matrices produce two [Fe(CO)₄] species; one is [Fe(CO)₄] with the same structure as in other matrices, and there is strong circumstantial evidence for the other being [Fe(CO)₄(CH₄)] or [Fe(CO)₄Xe]. The behaviour of [Os(CO)₅] is similar. The results are compared with those obtained in frozen hydrocarbon glasses at 77 K. In matrices with high concentrations of [Fe(CO)₅](>1 : 1 000 carbonyl compound : matrix), polynuclear iron carbonyls, [Fe₂(CO)₈], [Fe₂(CO)₉], and [Fe₃(CO)₁₂], are formed.