Versatile coordination patterns in the reaction system of N-benzoyl-N′-(2-pyridyl)thiourea with CuCl2. Their reaction conditions, systematic isolation and crystal structures

Abstract

A versatile reaction system; N-benzoyl-N′-(2-pyridyl)thiourea (L) with CuCl₂, has been studied under conditions of control of the relative concentration of the components (L or CuCl₂). Therefore, both converse approaches were employed: one is dropwise addition of L to CuCl₂ in ethanol solution, from which a dark-brown needle-like crystal, _∞¹{[CuClL′][Cl]} 1, was obtained, which is a chloride-bridged one-dimensional Cu(II) polynuclear complex coordinated by the oxidative cyclization product L′ generated from L (L′ = 2-benzoylimino-[1,2,4]thiadiazolo-[2,3-a]pyridine), and the second approach is conversely dropping CuCl₂ into L in acetone solution; at first, a pale-yellow reduced copper(I) mononuclear complex, [CuL₂Cl] 2, was formed, which exhibits a planar molecular configuration with a regular three coordination geometry, and then a red bis-sulfur-bridged copper(II) dinuclear complex, {[CuLCl₂]₂} 3, appeared subsequently. The crystal structures of these three products have been determined by X-ray diffraction. From the presented results the coordination and redox reaction pathways in the L–CuCl₂ system have been clearly revealed.