Reductive coupling nitrile metal complexes

Raman spectroscopy metal in water complexes, 309 Rare earth complexes acetylacetone synthesis, 377 guanidinium, 282 hydroxamic acids, 506 Redox properties bipyridyl metal complexes, 90 Reductive coupling nitrile metal complexes, 265 Resorcinol, 2,4-dinitro-metal complexes, 273 Rhenium complexes acetylacetone, 376 synthesis, 375, 378... 

A two metal, two-electron (not two metal, four-electron) reductive coupling of organic nitriles can lead to dimeric methyleneamido complexes (equation 97). 

The dinuclear complex formed from TaCU and CH3CN, of composition Ta2Cl6(CH3CN)4, contains two Ta(V) centers and bridging a ligand formed by reductive coupling of two nitriles no Ta(III) metal-metal-bound species are isolated from these or related reactions . 

An electron transfer-sensitive oln coordination alternative of substituted olefins to metal centers has been demonstrated [81] in the system [(NC)2C=C(CN)2W(CO)5]" (20) where the n complex with n = 0 (olefin coordination) changes reversibly to an ESR detectable a complex (nitrile coordination) after one-electron reduction ( = -1). Even in the absence of a detailed spin population analysis the low symmetry of the anionic complex is evident from at least three distinctly different N coupling constants in the ESR spectrum [81]. 

Likewise when two alkyne molecules coordinate to a transition metal such as Co(I) with subsequent coupling of the C-C bond, oxidative cyclization takes place to give a metallacyclopentadiene. Further reaction of another alkyne molecule with the metallacyclopentadiene followed by reductive elimination liberates benzene derivatives. Thus cyclotrimerization of three alkyne molecules catalyzed by a cobalt complex [40,41] can be performed. If a nitrile is used as the second component, pyridine derivatives are obtained catalytically as shown in Scheme 1.13 [42]. The catalytic cyclotrimerization and cyclodimerization of alkynes and conjugated enynes have found extensive applications in synthesis of complex cyclic compounds such as steroid derivatives [43]. 

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