Asymmetric dinuclear copper(i) complexes of bis-(2-(2-pyridyl)ethyl)-2-(N-toluenesulfonylamino)ethylamine with short copper–copper distances

Abstract

Addition of two equivalents of CuCl to deprotonated bis-(2-(2-pyridyl)ethyl)-2-(N-toluenesulfonylamino)ethylamine (PETAEA) and its derivatives yielded new types of dinuclear Cu(I) complexes, Cu(µ-PETAEA)CuCl, Cu(µ-PEMAEA)CuCl, and Cu(µ-PENAEA)CuCl (PEMAEA is the 4-methoxyphenyl derivative of PETAEA and PENAEA is the 4-nitrophenyl derivative), exhibiting a four coordinate N₄Cu center, a two coordinate NCuCl center, and a metal–metal distance within the range of 2.6572(8) to 2.6903(3) Å. Analysis of the covalent radii for four coordinate and two coordinate copper(I), the acute copper–nitrogen–copper angles, and density functional theory (DFT) calculations suggest a weak attraction between the two copper atoms. The complexes apparently formed in a two-step process with the formation of the tetracoordinate mononuclear complex preceding the coordination of a second equivalent of CuCl to the lone pair of the sulfonamidate ligand.