Reactions of Diiron μ-Aminocarbyne Complexes Containing Nitrile Ligands

The acetonitrile ligand in the μ-aminocarbyne complexes [Fe 2{μ-CN(Me)R}(μ-CO)(CO)(NCMe)(Cp)2][SO 3CF3] (R = Me, 2a, CH2Ph, 2b, Xyl, 2c) (Xyl = 2,6-Mc2C6H3) is readily displaced by halides and cyanide anions affording the corresponding neutral species [Fe 2{μ-CN(Me)R}(μ-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 α hydrogens has been used in place of MeCN to form the complexes [Fe2{μ-CN(Me)R}(μ-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 LiC≡CTol (Tol = C6H4Me), followed by treatment with HSO3CF3, yielded the imino complex [Fe2{μ- CN(Me)Xyl}(μ-CO)(CO) {N(H)C(C≡CC6H4Me-4)CMe 3}(Cp)2][SO3CF3] (8), obtained via acetilyde addition at the coordinated NCCMe3.