Tricarbonylchromium complexes acetonitrile

Nucleophilic attack by the lithium anion of acetonitrile has been extended to Cr complexes of ring A aromatic steroids, thereby allowing access to more elaborate derivatives. For example, the diastereomeric tricarbonylchromium complexes of 17/ -(tert-butyldimethylsily-loxy)-3-methoxyestra-l,3,5-triene 60a give the corresponding ipso 3-cyanomethyl complexes 60b after displacement of the methoxide group. The free arene was obtained in 46 % yield after h oxidation (Scheme 29) [47]. 

Tricarbonylchromium,221 -molybdenum,221 -tungsten,221 and-ruthenium222 complexes of 1H-azepine-l-carboxylatcs have been prepared by treating the azepines with tris(acetonitrile)tricar-bonylchromium(O), tricarbonyldiglymemolybdenum(O), tris(acetonitrile)tricarbonyltung-sten(O), and dodecacarbonylruthcnium(O), respectively. 

Whether [6]radialenes have a potential as novel ligands for metal complexes remains to be seen. A first example of a successful complexation is provided by 150, which reacts with tris(acetonitrile)tricarbonylchromium in dioxane at room temperature to give the ortho-xylylene chromium complex 175 in excellent yield (83%) (equation 23)105. 

The hydrocarbons 52a-52e and 52g contain four G=C double bonds. In addition to the conjugated diene unit, two isolated bonds are present. The exocyclic one is parallel and the endocyclic one is perpendicular to the local plane of symmetry of the diene portion. When the hydrocarbons 52a-52e and 52g are recoordinated to chromium by the reaction with tris(acetonitrile)-tricarbonylchromium(0) (55) [Eq. (32)], the complexes 46 are not obtained... 

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