| Abstrakt: |
The reactions of N-silylated and free diphenylphosphino thioformaraides, Ph2PC(S)NRR′ (R = Ph, Me, Et; R′ = Me3Si, H), with CpFe(CO)2l yield, by displacement of one equivalent CO, both red-brown P,S-coordinated chelate complexes 1 a-c and green P-coordinated iodo complexes 2a-c. With thiocarbamoylphosphine sulfides, Ph2P(S)C(S)NHR (R = Ph, Me), the S,S′-coordinated chelate complexes 3a, b are obtained. The corresponding phosphine oxides only form deeply coloured, weak 1/1 adducts 4a, b with CpFe(CO)2l. The course of the nucleophilic substitution of CpFe(CO)2X (X = Cl, Br, I) by N-silyl phosphino thioformamides reveals a significant dependence on the halogen employed. For X = Cl, elimination of RNCS and formation of the cationic diiron complex [CpFe(CO)2]2_ PPh2+Cl-(5 a) takes place, whereas for X = Br no reaction occurs at room temperature. Mechanistic reasons for this unexpected behaviour are discussed. |
