New examples of μ-η2:η2-disulfido dicopper(II,II) complexes with bis(tetramethylguanidine) ligands

The new ligand N ,N ′- (2-methyl-2-(2-pyridyl)propan-1,3-diyl)bis(tetramethylguanidine) (L) and its four-coordinate, distorted square-planar copper(II) complex [CuLCl2] (1) were synthesized and structurally characterized. Similarly, bis(μ -OH)dicopper(II,II) complex [Cu2L2(OH)2](OTf)2 (2) was synthesized and structurally characterized. The pyridyl group in L does not coordinate in either 1 or 2. New examples of μ -η 2:η 2-disulfido dicopper(II,II) complexes were synthesized by treating a copper(I) complex of either L or L′ [L′ = 2′,2′-(propane-1,3-diyl)bis(1,1,3,3-tetramethylguanidine)] with elemental sulfur. [Cu2L2(S2)](PF6)2 (3) and [Cu2View the MathML sourceL2′(S2)](PF6)2 (4) were both structurally characterized, and both structures have two copper(II) ions bridged by a disulfido ligand in a μ-η2:η2-manner. The ligands L and L′ coordinate in a bidentate fashion (like 1 and 2, the pyridyl ring does not coordinate in 3), and the geometry around the copper ions in 3 and 4 is distorted square planar. The metrical parameters of 3 and 4 were found to be similar to other μ-η2:η2-disulfido dicopper(II,II) complexes, and the Cu–S and Cu···Cu distances are among the shortest reported for this class of copper disulfide dimers.