Reactions of diiron m-aminocarbyne complexes containing nitrile ligands

Abstract

The acetonitrile ligand in the mu-aminocarbyne complexes [Fe2{mu-CN(Me)R}(mu-CO)(CO)(NCMe)(Cp)2][SO 3CF3] (R = Me, 2a, CH2Ph, 2b, Xyl, 2c) (Xyl = 2,6-Me2C6H3) is readily displaced by halides and cyanide anions affording the corresponding neutral species [Fe2{mu-CN(Me)R}(mu-CO)(CO)(X)(Cp)2 ] (X = Br, I, CN). Complexes 2 undergo deprotonation and rearrangement of the coordinated MeCN upon treatment with organolithium reagents. Trimethylacetonitrile, that does not contain acidic alpha hydrogens has been used in place of MeCN to form the complexes [Fe2{mu-CN(Me)R}(mu-CO)(CO)(NCCMe3 )(Cp)2][SO3CF3] (7a-c). Attempts to replace the nitrile ligand in 3 with carbon nucleophiles (by reaction with RLi) failed, resulting in decomposition products. However the reaction of 7c with LiCºCTol (Tol = C6H4Me), followed by treatment with HSO3CF3, yielded the imino complex [Fe2{mu-CN(Me)Xyl}(mu-CO)(CO) {N(H)C(CºCC6H4Me-4)CMe3}(Cp) 2][SO3CF3 ] (8), obtained via acetilyde addition at the coordinated NCCMe3.

Keywords

• acetonitrile
• nitrile activation
• carbyne complexes
• dinuclear complexes
• C-C bond formation