8-(Dimethylamino)naphthylcopper(I), a novel stable organocopper compound with unusual structural features. Its synthesis, crystal structure (X-ray), and reactivity

Abstract

The synthesis and isolation of a hydrocarbon- and ether-insoluble organocopper compound containing the rigid 8-(dimethylamino)naphthyl group is described. An X-ray determination of its structure revealed a tetranuclear copper aggregate, in which the Cu atoms are arranged in a parallelogram (Cu…Cu 2.407(2) and 2.430(2) Å) and are three-center, two-electron bridged by C( ipso) (Cu-C 2.025(6) Å mean) of the naphthyl group. The amine ligands coordinate pairwise to opposite copper atoms. The copper aggregate thus contains two distinct types of Cu atoms, involving two nucleophilic two-coordinate and two electrophilic four-coordinate sites, pointing to a strong cuprate character. Reaction of the organocopper compound with several copper(I) salts resulted either in the formation of binaphthyl and dimethylaminonaphthalene or a stable mixed copper cluster, depending on the anion in the copper salt. With dimethyl acetylenedicarboxylate the copper compound, without added lithium or magnesium salts, gave the ( syn) addition product 8-Me 2NnaphthylC(CO 2Me)=C(CO 2Me)Cu. These reactions are discussed in relation to the structural features of the tetranuclear organocopper compound.