{3,14-Dimethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane-κ4 N,N′,N′′,N′′′)bis(nitrato-κO)copper(II)

The CuII atom in the title compound, [Cu(NO3)2(C20H40N4)], is N,N′,N′′,N′′′-chelated by the macrocyclic ligand: the four N atoms form a square, above and below which are located the O atoms of the nitrate ions. The metal atom exists in a tetragonally distorted octahedron, on a special position of site symmetry. One of the amino groups is hydrogen bonded to an O atom of the nitrate ion. The other amino group is hydrogen bonded to O atom of an adjacent molecule, generating a supramolecular dimeric hydrogen-bonded dinuclear aggregate.

The Cu II atom in the title compound, [Cu(NO 3 ) 2 (C 20 H 40 N 4 )], is N,N 0 ,N 00 ,N 000 -chelated by the macrocyclic ligand: the four N atoms form a square, above and below which are located the O atoms of the nitrate ions. The metal atom exists in a tetragonally distorted octahedron, on a special position of 1 site symmetry. One of the amino groups is hydrogen bonded to an O atom of the nitrate ion. The other amino group is hydrogen bonded to O atom of an adjacent molecule, generating a supramolecular dimeric hydrogen-bonded dinuclear aggregate.

Comment
The macrocycle, cyclam (1,4,8,11-tetraazacyclotetradecane), forms a large number of complexes with copper(II) salts in which the macrocle chelates in a tetradentate matter. In same cases, the counterion bonded to the metal atoms and in other cases, the metal atom exists in square-pyramidal geometry as the counterion is far away. The crystal structure of copper nitrate-cyclam has not been reported; the crystal structures of other substituted cyclams have the metal atom in a tetragonally elongated octahedral geometry (Amadei et al., 1999;Choi et al., 2006;Choi et al., 2001;Dong et al., 1999;Liu & Chu, 2010).
The Cu II atom in the title compound (Scheme I) is similarly chelated by the macrocyclic ligand in a tetragonally distorted octahedron ( Fig.1). The atom lies on a special position of -1 site symmetry. One of the amino groups is hydrogen-bonded to an O atom of the nitrate ion. The other amino group is hydrogen-bonded to O atom of an adjacent molecule to generate a hydrogen-bonded dinuclear molecule (Table 1).

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H 0.99 to 1.00 Å, U iso (H) 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation.
The amino H-atoms were located in a difference Fourier map, and were refined with a distance restraint of N-H 0.88±0.01 Å; their temperature factors were refined. Fig. 1. Thermal ellipsoid plot (Barbour, 2001)