Simultaneous formation of both novel bis(#mu#-sulfur)- and bis(#mu#-oxo)-bridged copper(II) dimers by reaction of N-benzoyl-N',N'-dimethylthiourea (HL) with CuCl_(2 centre dot) Syntheses, crystal structures and magnetic properties of [{CuL(HL)(Cl}_2]

摘要

Reaction of N-benzoyl-N',N'-dimethylthiourea (HL) with copper(II) chloride yielded simultaneously two novel dimers: a pale green bis(#mu#-sulfur) bridged copper(II) dimer 1, [{CuL(HL)Cl}_2], and a dark green bis(#mu#-oxo) bridged copper(II) dimer 2, [{CuL_2)_2], instead of the mononuclear copper(II) complexes, [CuL_2], usually formed from other dialkyl-substituted benzoylthiourea ligands. The molecular structures of 1 and 2 have been established by singlecrystal X-ray analyses. In dimer 1 the central copper(II) ion has a distorted tetrahedral co-ordination environment with one chloride and three sulfur atoms derived from one terminal and two bridging ligands. The two sulfur atoms of both bridging ligands with two copper(II) ions form a strictly planar Cu_2S_2 bridging core, including two short [2.330(2) A] and two longer [2.549(2) A] Cu-S distances. The dimer 2 may be considered as comprising two mononuclear [CuL_2] complexes bridged by one of the acyl oxygen atoms of each to the copper atom of the other, resulting in a distorted tetragonal pyramidal geometry at each copper(II) center, and forming a planar four-membered Cu_2O_2 bridging unit which consists of two short [1.944(3) A] and two longer Cu-O distances [2.668(3) A], bridging bond angle Cu-O-Cu~* [97.9(1) deg]. Magnetic measurements for both dimers showed weak antiferromagnetic coupling between the copper(II) centers through bis-sulfur or bis-oxo bridges. The best fitting of the experimental magnetic susceptibility data gave g = 2.110, J = -33 cm~(-1) for dimer 1 and g = 2.107, J = -4.5 cm~(-1) for 2.