Structural characterization of some 2-(dimethylamino)methyl-substituted phenylcopper compounds R 4Cu 4

Abstract

2-[(Dimethylamino)methyl] phenylcopper and its 5-methyl and 5-methoxy analogues are tetrameric in benzene. 5-Methyl-2-[(dimethylamino)methyl]phenylcopper is tetrameric in the solid state (X-ray structure determination). The bonding in this tetranuclear cluster (CuCu 2.38 Å, multicenter bonded aryl groups) is discussed. NMR spectroscopy provides indications that CuN coordination observed in the solid is weak in solution. Mass spectra of 2-[(dimethylamino)methyl]phenylcopper (R 4Cu 4) and its 5-methyl analogue (5-MeR) 4Cu 4 reveal that the Cu 4 cluster in both compounds has considerable stability. Although the R 4Cu 4 + ions in both spectra are very abundant, the R 3Cu 4 + (even electron species) forms the base peak in the R nCu n part of the mass spectra. The occurrence in solution of an intercluster exchange between R 4Cu 4 and (5-MeR) 4Cu 4 with formation of the three possible mixed species R(5-MeR) 3Cu 4, R 2(5-MeR) 2Cu 4 and R 3(5-MeR)Cu 4 was confirmed by the mass spectra, which show five patterns in the parent peak region separated by 14 mass units.