The use of ferrocene in organometallic synthesis: A two-step preparation of cyclopentadienyliron acetonitrile and phosphine cations via photolysis of cyclopentadienyliron tricarbonyl or arene cations

Abstract

UV photolysis of [CpFe II(CO) 3] + PF6 6 − (I) or [CpFe II(η 6-toluene)] + PF 6 − − (II) in CH 3CN in the presence of 1 mole of a ligand L gives the new air sensitive, red complexes [CpFe II(NCCH 3) 2L] +PF 6 − (III, L = PPh 3; IV; L = CO; VIII, L = cyclohexene; IX, L = dimethylthiophene) and the known air stable complex [CpFe II(PMe 3) 2(NCMe)] + PF 6 − (V). The last product is also obtained by photolysis in the presence of 2 or 3 moles of PMe 3. In the presence of dppe, the known complex [CpFe II (dppe)(NCCH 3)] + (XI) is obtained. Complex III reacts with CO under mild conditions to give the known complex [CpFe(NCCH 3)(PPh 3)CO] + PF 6 − (X). UV photolysis of I in CH 3CN in the presence of 1-phenyl-3,4-dimethylphosphole (P) gives [CpFe IIP 3] + PF 6 − (XII); UV photolysis of II in CH 2Cl 2 in the presence of 3 moles of PMe 3 or I mole of tripod (CH 3C(CH 2Ph 2) 3) provides an easy synthesis of the known complexes [CpFe II(PMe 3) 3] + PF 6 − (VII) or [CpFe IIη 3-tripod] + PF 6 t- (XIII). Since I and II are easily accessible from ferrocene, these photolytic syntheses provide access to a wide range of piano-stool cyclopentadienyliron(II) cations in a 2-step process from ferrocene.