Coordination chemistry of mononuclear iron carbonyl complexes

This review is devoted to recent advances in mononuclear iron carbonyl coordination chemistry starting from M+[EFe(CO)(4)](-) complexes (E=H, RCO) easily obtained from Fe(CO)(5). E=H. The reaction of K+[HFe(CO)(4)](-) with phosphines, phosphites and phosphinites (abbreviated "P") allows selective syntheses for a large range of (phosphane)iron carbonyl complexes such as Fe(CO)(3)P-2, Fe(CO)(2)P-3, H2Fe(CO)(2)P-2, K+[HFe(CO)(3)P](-) and K+[HFe(CO)(2)P-2](-), In the special case of the new optically active phosphinite-ammonium ligands P-(*)-N+ named "ephosium" and "valphosium", optically active zwitterionic complexes [HFe(CO)(3)P](-) -(*)-N+ have been obtained, the structures of which have been studied both in the solid state and in solution. The above reactions have been shown to involve first a CO substitution, generating [HFe(CO)(3)P](-) species which then react further, the final product depending on both the nature of the solvent (protic or not) and the steric and electronic properties of the phosphane. In contrast, reaction with tri(amino)phosphines proceeds by substitution at the phosphorus atom, affording the Collman dianion [Fe(CO)(4)](2-) and [(R2N)(2)PH]Fe(CO)(4) complexes the reactivities of which with KH have been studied. E=RCO. The reaction of lithium aldimines such as [t-BuN=C(t-Bu)]Li with Fe(CO), generates lithium (alpha-iminoacyl)tetracarbonylferrates, which are imino-protected equivalents of the rare [(CO)(4)Fe-CO-CO-Z](-) sequence. Alkylation with Me3OBF4 yields the corresponding alpha,beta-unsaturated Fischer carbene complexes. The reaction of RCO(Li)Fe(CO)(4) (R = alkyl) with PPh2Cl (or PPhCl2) cleanly proceeds by a tandem acylation-complexation to afford the complexed acylphosphines [RCOPPh2]Fe(CO), (or [RCOPPhCl]Fe(CO)(4)) in goad yield. (C) 1998 Elsevier Science S.A. All rights reserved.