SPECTROSCOPIC STUDIES OF HYDRIDE ADDITION TO THE TRICARBONYLCYCLOPENTADIENYLIRON CATION

Hydride addition to [CPFe(CO)3]BF4 by NaBH3CN in THF was monitored in the temperature range -60-degrees-C to +40-degrees-C by IR an H-1 NMR spectroscopy. At low temperatures, initial attack occurred both at the carbonyl group, to give the formyls [CpFe(CO)2CHO:BH2CN] and [CpFe(CO)2CHO], and at the metal centre to give [CpFe(CO)3H] (probably best formulated as [(eta3-C5H5)Fe(CO)3H]). At higher temperatures these intermediates decompose to leave [CpFe(CO)2H], which dimerizes to [CpFe(CO)2]2 at +40-degrees-C. In addition [CpFe(CO)2CH2OH], [CpFe(CO)2CH3] and [CpFe(CO)2COOH] are formed. Finally the thermodynamically stable ring adduct [(5-exo-eta4-C5H6)Fe(CO)3] is observed even at low temperatures.