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The μ-(amino)alkylidyne complex [Fe2Cp2(CO)2(μ-CO){μ-CNMe(CH2CHCH2)}]CF3SO3, [1]CF3SO3, reacted with NBu4CN in dichloromethane affording the μ-(cyano)(amino)alkylidene [Fe2Cp2(CO)2(μ-CO){μ-C(CN)N(Me)(CH2CHCH2)}], 2, in 91% yield. Decarbonylation of 2 by using Me3NO in acetone at room temperature yielded [Fe2Cp2(CO)(μ-CO){μ-κ3C-C(CN)N(Me)(CH2CHCH2)}], 3, containing a multidentate alkylidene-alkene ligand occupying both a bridging site and a terminal site, in admixture with the μ-(amino)alkylidyne cyanide product [Fe2Cp2(CN)(CO)(μ-CO){μ-CN(Me)(CH2CHCH2)}], 4. The reaction of the μ-(amino)alkylidyne imine complex [Fe2Cp2(CO)(μ-CO)(NHCPh2){μ-CN(Me)(CH2CHCH2)}]CF3SO3, [7]CF3SO3, with NBu4CN gave 3 with an optimized yield of 75% via imine elimination. According to DFT calculations, 3 is less stable than its geometric isomer 4 by 13.4 kcal mol-1 and quantitative conversion to 4 was achieved by refluxing a THF solution of 3 for 2 hours. No replacement of alkene coordination occurred upon treating 3 with CO or PPh3. The previously unknown compounds 2, 3, 4 and [7]CF3SO3 were fully characterized by analytical and spectroscopic techniques and the structure of 3 was elucidated by single crystal X-ray diffraction.

The reactivity of MoCl5 with α-amino acids was investigated for the first time by choosing CH2Cl2 as the reaction medium. The interaction of MoCl5 with l-proline proceeded with Cl/O interchange and led to the formation of [NH2(CH2)3CHC(O)Cl][MoOCl4], 1, in 63% yield. The reactions of MoCl5 with l-phenylalanine, sarcosine, N,N-dimethylglycine and N,N-dimethyl-l-phenylalanine afforded the α-amino-acylchloride complexes MoOCl3[O[double bond, length as m-dash]C(Cl)CH(R)N(R')(R'')] (R = CH2Ph, R' = R'' = H, 2a; R = R' = H, R'' = Me, 2b; R = H, R' = R'' = Me, 2c R = CH2Ph, R' = R'' = Me, 2d), in ca. 70% yields. According to DFT studies, 2a,d are mononuclear Mo(v) octahedral complexes bearing a N,O-coordinated α-amino-acylchloride ligand. The presumed species formed during the first stages of the MoCl5/l-phenylalanine interaction were DFT-elucidated, thus the calculated Gibbs free energy profile for the multi-step reaction of MoCl5 with l-phenylalanine was traced. [NH3CH(CH2Ph)C(O)Cl][MoOCl4], 3, acting as an intermediate in the course of the formation of 2a, was isolated by combination of [NH3CH(CH2Ph)C(O)Cl][Cl] with MoOCl3.