Reaction of Fe2(SH)2(CO)6 and HCHO, which gives Fe2[(SCH2)2NH](CO)6 in the presence of NH3, affords the possible intermediate Fe 2(SCH2OH)2(CO)6, which has been characterized crystallographically as its axial-equatorial isomer. Fe 2(SCH2OH)2(CO)6 was shown to react with ammonia and amines to give Fe2[(SCH2) 2NR](CO)6 (R = H, alkyl). Related hemithioacetal intermediates were generated by treatment of Fe2(SH) 2(CO)6 with RC(O)C(O)R (R = H, Ph, 4-F-C6H 4) to give cycloadducts. The benzil derivative Fe2[S 2C2(OH)2Ph2](CO)6, a C2-symmetric species, was also characterized crystallographically. The acylated azadithiolate Fe2[(SCH2)2NAc](CO) 6 was prepared by reaction of Li2Fe2S 2(CO)6 with (ClCH2)2NC(O)Me. DNMR experiments show that the free energies of activation for rotation of the amide bond are the same for Fe2[(SCH2)2NAc](CO) 6 and Fe2[(SCH2)2NAc](CO) 4(PMe3)2, which implies that the ligands on the iron centers do not strongly affect the basicity of the nitrogen. As a control, we showed that the thioamide Fe2[(SCH2) 2NC(S)Me](CO)6 does exhibit a significantly higher barrier to rotation, attributable to the increased double-bond character of the N-C(S) bond.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry