83828-75-5Relevant academic research and scientific papers
Multinuclear NMR studies of molybdenum and tungsten carbonyl isocyanide complexes
Minell, Martin,Maley, Walter J.
, p. 2954 - 2958 (2008/10/08)
M(CO)6-n(CNR)n (n = 0-6) complexes (M = Mo, W; R = 2,6-dimethylphenyl, tert-butyl, cyclohexyl, isopropyl) have been synthesized. Depending on the R group of the isocyanide ligand, four or six carbonyl groups in M(CO)6 can be replaced. The NMR properties of the atoms in these complexes have been studied. The metal centers, observed by 95Mo or 183W NMR, show increased deshielding with the substitution of carbonyl ligands by isocyanide ligands. 95Mo NMR serves as an excellent tool for the identification of mixtures of these compounds and was useful to monitor the reactions. The nitrogen in the isocyanide ligand, observed by 14N NMR spectroscopy, gets more deshielded when the isocyanide is coordinated to the metal center, but with further substitution, the nitrogen becomes more shielded again. The 14N chemical shift of an isocyanide ligand trans to a carbonyl ligand differs slightly from the chemical shift of an isocyanide ligand trans to another isocyanide ligand in the tetrasubstituted complex. The 13C NMR signal of the CNR carbon becomes more deshielded with an increasing number of isocyanides present in the complex. CNR carbons trans to carbonyl groups are more shielded than CNR carbons trans to isocyanides. With the successive substitution of carbonyl groups by isocyanides, the electronic absorption bands in the UV-vis region shift toward longer wavelengths; i.e., the color of the compounds changes from white to orange-red.
