Copper(II)-mediated oxime–nitrile coupling in non-aqueous solutions: Synthetic, structural and magnetic studies of the copper(II)–salicylaldehyde oxime reaction system

The reactions of salicylaldehyde oxime (H2salox) with CuII precursors yielded the known complexes [Cu(Hsalox)2] (1) and [Cu(Hsalox)2]n (2), as well as complexes [Cu3(salox)(L1)(L2)]·MeCN (3·MeCN), [CuCl(L1)] (4) and [Cu2Na(O2CMe)5(HO2CMe)]n (5), where L1− = o-O–C6H4–CHNO–C(CH3)NH and L23− = o-O–C6H4–CHNO–C(o-O–C6H4)N. L1− was formed in situ via the nucleophilic addition of the oximato O-atom of salox2− to the unsaturated nitrile group of the MeCN reaction solvent. L23− is also formed in situ probably through the nucleophilic attack of the oximato O-atom to the unsaturated nitrile group of salicylnitrile; the latter, although not directly added to the reaction mixture, can be produced via the dehydration of salox2−. Compounds 1 and 2 contain Hsalox− bound to the metal center in two different coordination modes; they both contain the same mononuclear unit, however a 2D network is generated in 2 due to a relatively long Cu–Ooximato bond. Compound 3 contains three different ligands, i.e. salox2−, L1− and L23−, which act as μ3-κ2O:κO′:κN, κO:κN:κN′ and μ3-κ2O:κ2N:κO′:κN′, respectively, whereas 4 consists of a square planar CuII atom bound to a κO:κN:κN′ L1− and a chloride ion. Compound 5 consists of dinuclear [Cu2(O2CMe)5(HO2CMe)]− units and Na+ ions assembled into an overall 3D network structure. Magnetic susceptibility measurements from polycrystalline samples of 2 and 5 gave best-fit parameters J = +0.36 cm−1 (H = −JŜiŜj) and J = −360 cm−1, zj = +20 cm−1 (H = −JŜiŜj − zJ〈Sz〉Ŝz), respectively.