Conversion of Alkynes and Nitriles into Organo and Organonitrogenated Species at Group VI and VII Dinitrogen-Binding Metal Centers. Synthesis of Some Vinylidene and Alkynyl Complexes of Rhenium

Article abstract of DOI:10.1007/BF00817310

The reactions of phenylacetylene and other alkynes , in the presence of acetonitrile or benzonitrile, with the following complexes have been investigated usually at room temperature: trans (L = PMe2Ph), cis, cis-, trans-, mer- , and <(ν⁵-MeC5H4)Mn(CO)2(NCMe)>.Cyclic trimerization was the main reaction detected for phenylacetylene (except for the Mn complex), although dimers, products of hydrogenation and species derived from alkyne/nitrile coupling were also formed in smaller amounts; for the Mo- or W-systems, the total yields were below ca. 40percent relative to the metal, but the Re-systems exhibited a modest catalytic activity.The other alkynes underwent, also in low yields, mainly dimerization, cyclic or linear trimerization, apart from, to a smaller extent, coupling reactions with the nitriles or hydrogenation.The alkynyl complexes (PPh3)L'2> and ReCl(C*CPh) were prepared by reaction of mer- with PhC*CH, in the absence and in the presence of NCMe, respectively, whereas the benzonitrile/dinitrogen complex was obtained either by reaction of that N2-complex with NCPh or by the reaction of with NCPh in the presence of NaOMe.The vinylidene compound trans- (dppe = Ph2PCH2CH2PPh2) was formed by reaction of trans- with PhC*CH, in the presence of Tl which did not lead to the formation of detectable amounts of any alkyne-derived organic product. - Keywords: Alkynes; Nitriles; Dinitrogen complexes; Alkynyl complexes; Vinylidene complexes; Phosphite complexes; Phosphonate complexes