Unfolding of the [Cu2(1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane)2]2+ helicate. Coupling of the chlorocarbon dehalogenation to the unfolding process

A new helical dimeric copper(I) complex [Cu2(mphenpr)2](ClO4)2 where mphenpr is 1,3-bis(9-methyl-1,10-phenanthrolin-2-yl)propane has been prepared and characterized by X-ray crystallography and NMR. In the solid state, the metal centers are 6.42 Å apart, and the electronic structure has been investigated with use of density functional theory (DFT) calculations. In solution the dimer equilibrates with a monomeric form [Cu(mphenpr)](ClO4), and the mechanism of unfolding of the dimer into monomer has been studied. In the presence of CCl4, formation of the monomer is coupled to the reductive dehalogenation of the halocarbon. The mechanism of this process has been probed by the study of short-lived potential reaction intermediates using fast kinetic pulse radiolysis techniques and comparisons with DFT calculations. The copper(II) product [Cu(mphenpr)Cl](ClO4) and an analogue [Cu(mphenpr)](ClO4)2 have been isolated and characterized by X-ray crystallography.