76157-16-9Relevant academic research and scientific papers
Substitution and S-alkylation reactions of thiocarbonyl-bridged Cp2Fe2(CO)3CS
Quick, Michael H.,Angelici, Robert J.
, p. 1123 - 1130 (1981)
In refluxing CH3CN, Cp2Fe2(CO)3CS reacts with PEt3, PMe2Ph, PMePh2, and P(OMe)3 to give the monosubstituted derivatives Cp2Fe2(CO)2(PR3)CS, in which the CS group remains in the bridging position, as it does in all of the complexes described in this report. The reaction of MeNC with Cp2Fe2(CO)3CS in refluxing THF or cyclohexane gives Cp2Fe2-(CO)2(MeNC)CS which exists predominantly as an isomer in which the MeNC is terminal. There is, however, spectroscopic evidence for a less abundant isomer in which the MeNC is bridging. The bissubstituted complex Cp2Fe2(CO)(MeNC)2CS may be obtained by refluxing Cp2Fe2(CO)3CS and MeNC in acetonitrile. This complex has been partially separated chromatographically into a major isomer, in which one MeNC is bridging and the other is terminal, and a minor bis-terminal MeNC isomer. The bridging thiocarbonyl sulfur atom of CpFe2(CO)3CS may be alkylated at room temperature by reaction with alkyl iodides, benzyl bromide, allyl bromide, MeOSO2F, and Et3O+ to give the Cp2Fe2(CO)3CSR+ complexes. The methyl derivative Cp2Fe2(CO)3CSMe+ reacts readily with ligands PEt3, PMe2Ph, PMePh2, P(OMe)3, and MeNC to give the CO-substituted products Cp2Fe2(CO)2(L)CSMe+. Both alkylation and substitution occur when Cp2Fe2(CO)3CS is refluxed in acetonitrile with MeI and NaI to give Cp2Fe2(CO)2(I)(CSMe). Only the CS-alkylated product Cp2Fe2-(CO)2(MeNC)CSMe+ is obtained from the reaction of Cp2Fe2(CO)2(MeNC)CS with MeOSO2F or MeI. The bissubstituted complex Cp2Fe2(CO)(MeNC)2CS reacts with MeI to yield the CS-alkylated compound Cp2Fe2(CO)(MeNC)2CSMe+ in which both of the MeNC groups are terminal. With the stronger alkylating MeOSO2F, this complex gives the dimethylated product Cp2Fe2(CO)(MeNC)(Me2NC)CSMe2+, in which both alkylated groups are bridging. All of the complexes are characterized by their IR and 1H and 13C NMR spectra, which give evidence of isomers in which the Cp rings are cis or trans to each other across the Fe-Fe bond. Mechanisms for the interconversion of several of the isomers are discussed.
