A Cobaloxime Substituted Terminal Alkene Which Rapidly Isomerizes to a Cobaloxime Substituted Internal Alkene Complex

Substituted Internal Alkene Complex Kerry A. Pickin, Cynthia S. Day, Marcus W. Wright, and Mark E. Welker* Department of Chemistry, Wake Forest University, P.O. Box 7486, Winston-Salem, NC 27109 An unusual cobaloxime substituted terminal alkene has been isolated and characterized by X-ray crystallography. The double bond in the alkene readily isomerizes but the title compound could be isolated and structurally characterized at low temperature. Comment We have been interested in the preparation of cobaloxime complexes (cobaloxime = (pyridine)(dimethylglyoxime)2cobalt) which contain cobalt-sp 2 carbon bonds and the use of these complexes in cycloaddition chemistry (Welker, 2001). In 2000, we reported a new method for the preparation of cobalt-sp 2 carbon bonds which involved a zinc mediated coupling of alkenyl halides and triflates (II) to (pyr)2(dmg)2Co (Pickin and Welker, 2000). One of the coupling products prepared, a 2-cobaloxime substituted 1hexene (III) isomerized readily to (E)-2-cobaloxime-2-hexene (IV). The 2-cobaloxime 1hexenyl complex (III) has now been crystallized at low temperature and its structure is reported here.