Reduction–oxidation properties of organotransition-metal complexes. Part 13. Cationic iron(II) carbonyls via the radical coupling, and substitution reactions of [Fe(CO)3(PPh3)2]+ : synthetic and electron spin resonance spectroscopic studies

Abstract

The radical cation [Fe(CO)₃(PPh₃)₂]⁺(1) undergoes oxidative-substitution reactions with the diamagnetic ligands S₂CPPh₃ and [S₂CNMe₂]^– to give cis,trans-[Fe(CO)₂(PPh₃)₂(S₂CR)]^Z(R = PPh₃, Z= 2; R = NMe₂, Z= 1); the dithiocarbamato-complex is also prepared from Me₂NC(S)SSC(S)NMe₂. Radical–radical coupling occurs between (1) and NO or NO₂ to give [Fe(CO)₂(NO)(PPh₃)₂]⁺ and mer,trans-[Fe(NO₂)(CO)₃(PPh₃)₂]⁺ respectively. On thermolysis, the nitro-complex yields CO₂ and the nitrosyl derivative via cis,trans-[[graphic omitted]O}-(CO)₂(PPh₃)₂]⁺. The spin trapping of [Fe(CO)₃(PPh₃)₂]+ with Bu^tNO, and the formation of paramagnetic complexes with 1,2-diketones, have been studied by e.s.r. spectroscopy; cis,trans-[Fe(CO)₂(PPh₃)₂(O₂C₆Cl₄)]⁺, from 3,4,5,6-tetrachloro-p-benzoquinone, has been isolated and fully characterised.