Di-μ-thiocyanato-κ4 N:N-bis({5-methoxy-2-[3-(methylamino)propyliminomethyl]phenolato-κ3 O 1,N,N′}copper(II))

The title thiocyanate-bridged dinuclear copper(II) complex, [Cu2(C12H17N2O2)2(NCS)2], possesses crystallographic inversion symmetry. Each CuII atom is five-coordinated by one imine N, one amine N and one phenolate O atom of the Schiff base ligand, and by two N atoms from two bridging thiocyanate ligands, forming a square-pyramidal geometry. Beside the two thiocyanate bridges, there are two intramolecular N—H⋯O hydrogen bonds, which further link the two Cu(C12H17N2O2)(NCS) units. The Cu⋯Cu separation is 3.261 (2) Å. Parts of the methylaminopropylimino segment are disordered over two sites with occupancies of 0.669(9) and 0.331(9).


Comment
An extensive effort has been made to prepare and characterize a variety of coordination complexes in an attempt to model the physical and chemical behaviour of copper-containing enzymes (Reddy et al., 2000). The peculiarity of copper lies in its ability to form complexes with coordination numbers of four, five, and six (Ray et al. 2003;Arnold et al., 2003;Raptopoulou et al., 1998). As a continuation of our own work in this area (Wang & Li, 2005;Wang et al., 2006), the title compound, a new copper(II) complex, is reported here.
The title compound is a thiocyanate-bridged dinuclear copper(II) complex ( Fig. 1), with a Cu···Cu separation of 3.2608 (7) Å. The complex possesses a crystallographic inversion centre symmetry. Each Cu II atom is five-coordinated by one imine N, one amine N, and one phenolate O atom of the Schiff base ligand, and by two N atoms from two thiocyanate ligands, forming a square-pyramidal geometry. The bond lengths and angles (Table 1) are typical and comparable with those in other copper(II) complexes with Schiff bases and thiocyanate ligands (Elmali et al., 2000;You & Zhu, 2005;Liu et al., 2004;Datta et al., 2008;Habibi et al., 2007). Beside the two thiocyanate bridges, there exist two N-H···O hydrogen bonds (Table   2) in the complex, which further link the two [Cu(C 12 H 17 N 2 O 2 )(NCS)] units together (Fig. 2). .9 mg) were dissolved in methanol (20 ml). The mixture was stirred at room temperature for 1 h to give a blue solution. The resulting solution was allowed to stand in air for a few days, and blue block-shaped crystals were formed.

Refinement
Atoms C9, C10 and C11 of the methylaminopropylimino segment are disordered over two sites with occupancies of 0.669 (9) and 0.331 (9). The N-C and also the C-C distances involving the disordered atoms were restrained to be equal. The U ij parameters of the disordered atoms, and atom C12 were restrained to an approximate isotropic behaviour. H atoms were placed in idealized positions and constrained to ride on their parent atoms, with C-H distances in the range 0.93-0.97 Å, N-H distances in the range 0.90-0.91 Å and with U iso (H) = 1.2U eq (C,N) and 1.5U eq (methyl C).
supplementary materials sup-2 Figures Fig. 1. The molecular structure of the title compound, showing 30% displacement ellipsoids (arbitrary spheres for the H atoms). Unlabelled atoms are at the symmetry position (1 -x, -y, -z). Only the major disorder component is shown.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.