Schiff-base complexes of tetracarbonyliron from enneacarbonyldi-iron

Abstract

The reaction between [Fe₂(CO)₉] and Schiff bases of the type PhCHCH–CHN–C₆H₄X (I; X = H, 4-Cl, 4-Br, 3-Br, 4-F, 4-I, 4-Me, and 4-OMe) and R¹R²R³R⁴C₆HCHN–C₆H₄OMe-4 (II; R¹,R²,R³,R⁴= H, Me, or OMe) has been re-examined. The first stage of the reaction leads to the formation of [Fe(CO)₄L] complexes (L = Schiff base)[III; L =(I)] and [IV; L =(II)]. I.r. and n.m.r. evidence suggests that the Fe is bonded to the nitrogen lone-pair electrons of the Schiff base. With ligands (I) the second stage of the reaction gives formation of [Fe(η-PhCHCH–CHN–C₆H₄X)(CO)₃] complexes (V). Ligands (II) having unsubstituted benzene ring ortho positions give complexes of the type [Fe₂(CO)₆L].