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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.

A series of pentacoordinate d8 PtII complexes, of the type [PtCl2(η2-CH2=CH2)(Men∩NN)], where Men∩NN = bis-nitrogen ligand, with a variable number of Me groups (i.e., 2,2′-bipyridyl; 1,10-phenanthroline; 6-methyl-2,2′-bipyridyl; 2,9-dimethyl-1,10-phenanthroline; 2,9-dimethyl-1,10-phenanthroline; N,N′-trimethyl-ethylenediamine; N,N,N′,N′-tetramethyl-ethylenediamine; N,N,N′,N′-tetramethyl-1,2-diaminocyclohexane) was studied. The compounds are characterized by variable steric hindrance, due to the variable number (n) of Me substituents, on or ortho to the N-donors of aliphatic diamines or aromatic diimines, respectively. This approach was developed to investigate the interaction of substituents with the metal coordination sphere. With this aim, we analyzed the NMR properties of the considered complexes, with respect to modulation of the metal electron density (195Pt NMR signal frequency) by alkyl groups close to the N-donors. 1H and 13C NMR analysis of the η2-olefin signals has revealed, for each kind of bis-nitrogen ligand, a positive or negative chemical shift variation that is proportional to the number of Me groups geminal or vicinal to the N-donors. Interestingly, the 1JPt,C values increase by approximately 45 Hz for each additional Me on the series of diamine or diimine bis-nitrogen ligands. A rationale for the stability changes observed in such pentacoordinate complexes is suggested, based on the NMR spectroscopic data analysis.