Coordination and Ligand Substitution Chemistry of Bis(cyclooctyne)copper(I)

Abstract

Cationic bis(alkyne)copper(I) carbonyl and bis(alkyne)copper(I) isocyanide complexes have been synthesized from the precursor (cyclooctyne)2CuBr. [Cu(cyclooctyne)2(CO)][SbF6] and [Cu(cyclooctyne)2(CNtBu)][SbF6] have trigonal-planar and three-coordinate copper centers. The copper carbonyl complex [Cu(cyclooctyne)2(CO)][SbF6] displays its C–O stretching frequency in the “nonclassical” metal carbonyl region (2171 cm–1), and the analogous copper(I) isocyanide complex [Cu(cyclooctyne)2(CNtBu)][SbF6] also has an unusually high CN stretching band at 2230 cm–1. The reaction of 3,5-Me2C6H3NH2 and 4-tBuC6H4NH2 with [Cu(cyclooctyne)2(CO)][SbF6] led to CO displacement rather than addition to CO. CNtBu reacts with [Cu(cyclooctyne)2(CO)][SbF6] to afford [Cu(cyclooctyne)2(CNtBu)][SbF6]. The syntheses of [Cu(cyclooctyne)(CNtBu)2][SbF6] and [Cu(CNtBu)4][SbF6] from the (cyclooctyne)2CuBr precursor are also reported.