Heterocyclic thioamides of copper(I): Synthesis and crystal structures of copper complexes with 1,3-imidazoline-2-thiones in the presence of triphenyl phosphine

Reaction of copper(l) chloride with 1,3-imidazoline-2-thione (imzSH) in the presence of Ph3P in 1:2:2 or 1:1:2 (M:L:PPh3) molar ratios yielded a compound of unusual composition, [Cu-2(imzSH)(PPh3)(4)Cl-2] center dot CH3OH (1), whose X-ray crystallography has shown that its crystals consist of four coordinated [CuCl(1 kappa S-imzSH)(PPh3)(2)] (1a), and three coordinated [Cu(PPh3)(2)Cl] (1b) independent molecules in the same unit cell. In contrast, crystals of complexes of copper(I) bromide/iodide are formed by single molecules of [CuBr(1 kappa S-imzSH)(PPh3)(2)] center dot H2O (2) and [CuI(1 kappa S-imzSH)(PPh3)(2)] (3), respectively, similar to molecule 1a. The related ligand, 1,3-benzimidazoline-2-thione (bzimSH) formed a complex [CuBr(1 kappa S-bzimSH)(PPh3)(2)] center dot CH3COCH3 (4), similar to 2. The formation of 1a and 1b has been also revealed by NMR spectroscopy. The NMR spectra of 2-4 also showed weak signals indicating formation of compounds similar to 1b. It reveals that the lability of the Cu-S bond varies in the order: Cl >> Br similar to I. Weak interactions {e.g. C-H center dot center dot center dot pi electrons of ringy, -NH center dot center dot center dot halogens/oxygen, C-H center dot center dot center dot halogens/oxygen, pi center dot center dot center dot pi (between rings)} have played an important role in building 2D chains of complexes 1-4. (c) 2007 Elsevier Ltd. All rights reserved.