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

Abstract

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 [CuLCl 2] ( 1) were synthesized and structurally characterized. Similarly, bis( μ-OH)dicopper(II,II) complex [Cu 2L 2(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. [Cu 2L 2(S 2)](PF 6) 2 ( 3) and [Cu 2 L 2 ′ (S 2)](PF 6) 2 ( 4) were both structurally characterized, and both structures have two copper(II) ions bridged by a disulfido ligand in a μ- η 2: η 2-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- η 2: η 2-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.