[(4E,11E)-5,7,12,14-Tetrabenzyl-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene]copper(II) bis(perchlorate)

The complete cation in the title compound, [Cu(C40H48N4)](ClO4)2, is generated by the operation of a crystallographic centre of inversion. The CuII ion exists in a tetragonally distorted trans-N4O2 coordination geometry defined by the four N atoms of the macrocyclic ligand and two weakly bound perchlorate-O atoms from two anions. The N—H atoms form intramolecular N—H⋯O(perchlorate) hydrogen bonds. Disorder was resolved in the –CH2–NH– portion of the macrocycle with the major component having a site-occupancy factor of 0.570 (6).

The complete cation in the title compound, [Cu(C 40 H 48 N 4 )]-(ClO 4 ) 2 , is generated by the operation of a crystallographic centre of inversion. The Cu II ion exists in a tetragonally distorted trans-N 4 O 2 coordination geometry defined by the four N atoms of the macrocyclic ligand and two weakly bound perchlorate-O atoms from two anions. The N-H atoms form intramolecular N-HÁ Á ÁO(perchlorate) hydrogen bonds. Disorder was resolved in the -CH 2 -NH-portion of the macrocycle with the major component having a site-occupancy factor of 0.570 (6).

Related literature
For background to the synthesis, characterization, kinetic studies and biological activities of 14-membered methylsubstituted tetraazamacrocyclic ligands, their N-substituted derivatives and their metal complexes, see: Hazari et al. (2008).

Comment
The title complex, (I), was investigated in continuation of studies of the synthesis, characterization and biological activities of methyl substituted tetraazamacrocyclic ligands and their metal complexes (Hazari et al., 2008).
The structure of (I), Fig. 1 ,7,12,14-tetrabenzyl-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene macrocyclic ligand, and the O-donors are derived from two perchlorate anions. The complex is centrosymmetric. A C-meso, N-meso configuration is found in (I). With reference to the six-membered chelate ring, the benzyl and methyl groups equatorially and axially orientated, respectively. The dihedral angle formed between the benzene rings is 44.22 (16) Å. Each N-H atom of the disordered -CH 2 -NH-residue forms an intramolecular N-H···O hydrogen bond with a perchlorate-O atom, Table   2, i.e. to either side of the CuN 4 plane. The competition between the formation of these alternate hydrogen bonds provides a rationale for the observed disorder.

Experimental
The macrocyclic ligand as its hydroperchloric acid salt (0.783 g, 1.0 mmol) was suspended in methanol (20 ml). Copper(II) perchlorate hexahydrate (0.370 g, 1.0 mmol) was dissolved in methanol (30 ml) and then was mixed with the suspension of the ligand salt. The mixture was refluxed for 3 h and a clear violet solution evolved. The solution was filtered and kept at room temperature. After 24 h, violet crystals of the complex were observed. The crystals were separated by filtration, washed with dry ethanol, followed by diethylether and dried in a vacuum desiccator over silica gel. M.pt. 510-512 K. Yield 45%. Anal. Calc. for [Cu(C 40

Refinement
One portion of the macrocycle, i.e. the -CH 2 -NH-portion, is disordered over two positions, with the major component having a site occupancy factor = 0.570 (6). The pair of Cu-N distances were tightly restrained to within 0.005 Å of each other, as were the C-N and C disordered -C ordered distances. The H-atoms were placed in calculated positions (N-H = 0.88 Å and C-H = 0.95-0.99 Å) and were included in the refinement in the riding model approximation, with U iso (H) set to 1.2-1.5U equiv (N,C). The maximum and minimum residual electron density peaks of 0.64 and 1.08 e Å -3 , respectively, were located 1.00 Å and 0.94 Å from the O4 and Cu atoms, respectively.  Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level. Only the major component of the disordered residue is shown. Unlabelled atoms are generated by the symmetry operation (1-x, 1-y, 1-z).