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

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 ButNO, 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.