First row transition metal diethyl phosphonoformates

Abstract

During interactions of triethyl phosphonoformate (tepf) with 3d metal perchlorates in triethyl orthoformate solution at 50°C, the corresponding diethyl phosphonoformato (depf; ▪) metal complexes were precipitated, with concomitant elimination of ethyl perchlorate. Most of the new metal complexes (Cr(depf) 2(ClO 4). Fe(depf) 3, M(depf) 2 (M = Fe, Cu, Zn)) involve bidentate bridging depf ligands, coordinating through the two POO oxygens, and appear to be hexa- (for M 3+) or tetra(for M 2+) coordinated linear chain-like polymeric species. Mn(depf) 2, in which part of the depf ligands coordinate also through the CO oxygen, has apparently a pentacoordinated chain-like polymeric structure, with both bi- and tridentate depf bridging ligands. Finally, M(depf) 2 (M = Co, Ni), which unlike all the preceding complexes dissolve in some organic solvents and contain exclusively tridentate depf ligands, binding through the CO and the two POO oxygens, are considered to be either monomeric chelates or low chain-like oligomers. In the cases involving briding tridentate depf (M = Mn 2+ and, possibly, Co 2+ and Ni 2+, the CO and one of the POO oxygens would form a chelate ring with one metal ion, while the second POO oxygen of the same depf ligand would coordinate to an adjacent metal ion in the linear polymeric chain.