Regioselective reactions of electrophilic iron dicarbonyl cations, [(η5-C5R5)(CO)2Fe]+ (R = H, CH3) with heterofunctional amine ligands

Abstract

The reactions of the ether salts [(η5-C5R5)(CO)2Fe(E)]BF4, (R = H, E = Et2O; R = CH3, E = THF) with various ligands possessing two different coordination sites have been investigated. It was established that [(Cp(CO)2Fe(OEt2)]BF4 (Cp = η5-C5H5), 1, and [Cp*(CO)2Fe(THF)]BF4 (Cp* = η5-C5(CH3)5), 2, react with 1-aminopropanol, 4-methoxybenzylamine and 3-aminopropyltriethoxysilane to give only mononuclear complexes of the type [(η5-C5R5)(CO)2Fe(L)]+, irrespective of the reactant ratios. On the other hand, the reaction of 1 with one equivalent of 4-aminobenzonitrile (ABN) furnished both mononuclear and dinuclear complexes, [Cp(CO)2Fe(ABN)]+ and [{Cp(CO)2Fe}2(μ-ABN)]2+ isolated as tetrafluoroborate salts, with the mononuclear complex being the major product. The reaction of [(η5-C5R5)(CO)2Fe(E)]BF4 with 1,4-phenylenedimethanamine (PDA) afforded only the dinuclear complex [{(η5-C5R5)(CO)2Fe}2(μ-PDA)]2+ regardless of the reactant ratios. The reaction of 2 with one equivalent of the compound [Cp(CO)2Fe(ABN)]BF4 gave the mixed ligand salt [Cp(CO)2Fe(ABN)Fe(CO)2Cp*](BF4)2. The reactions of dipropylamine with [Cp(CO)2Fe(OEt2)]BF4 gave the dipropylamine salt [Cp(CO)2Fe{NH(CH2CH2CH3)2}]BF4. All these compounds are reported for the first time and have been fully characterized by 1H NMR, 13C NMR, IR spectroscopy and elemental analysis. Molecular structures of [Cp(CO)2Fe{NH(CH2CH2CH3)2}]BF4, [Cp*(CO)2Fe{NH2(CH2)2CH2OH}]BF4 and [Cp*(CO)2Fe(NH2C6H4OCH3)]BF4 have been confirmed by single crystal X-ray crystallography.