Poly[[bis{μ3-tris[2-(1H-tetrazol-1-yl)ethyl]amine}copper(II)] bis(perchlorate)]

In the title compound, {[Cu(C9H15N13)2](ClO4)2}n, the Cu2+ cation lies on an inversion center and is coordinated by the tetrazole N4 atoms of six symmetry-equivalent tris[2-(1H-tetrazol-1-yl)ethyl]amine ligands (t 3 z) in the form of a Jahn–Teller-distorted octahedron with Cu—N bond distances of 2.0210 (8), 2.0259 (8) and 2.4098 (8) Å. The tertiary amine N atom is stereochemically inactive. The cationic part of the structure, viz. [Cu(t 3 z)2]2+, forms an infinite two-dimensional network parallel to (100), in pockets of which the perchlorate anions reside. The individual networks are partially interlocked and held together by C—H⋯O interactions to the perchlorate anions and C—H⋯N interactions to tetrazole N atoms.

In the title compound, {[Cu (C 9 H 15 N 13 ) 2 ](ClO 4 ) 2 } n , the Cu 2+ cation lies on an inversion center and is coordinated by the tetrazole N 4 atoms of six symmetry-equivalent tris[2-(1Htetrazol-1-yl)ethyl]amine ligands (t 3 z) in the form of a Jahn-Teller-distorted octahedron with Cu-N bond distances of 2.0210 (8), 2.0259 (8) and 2.4098 (8) Å . The tertiary amine N atom is stereochemically inactive. The cationic part of the structure, viz. [Cu(t 3 z) 2 ] 2+ , forms an infinite two-dimensional network parallel to (100), in pockets of which the perchlorate anions reside. The individual networks are partially interlocked and held together by C-HÁ Á ÁO interactions to the perchlorate anions and C-HÁ Á ÁN interactions to tetrazole N atoms.
The title compound crystallizes in the triclinic space group P1 with one formula unit, [Cu(C 9 H 15 N 13 ) 2 ](ClO 4 ) 2 , per unit cell. Copper lies on an inversion center (we selected x,y,z = 1/2, 1/2, 1/2 for Cu) and is coordinated by six symmetry = 170.74 (7)°, N9-C8-C9-N13 = 66.24 (10)°). It is obvious that the ligand is not chelating a copper atom but forms exclusively bridging links between each three of them. This is not unexpected because 1-alkyl-1H-tetrazoles coordinate transition metals generally via their N4 atoms (i.e. N4, N8 and N12 in the title compound) and the spacer length of four carbon plus one nitrogen atoms between two rigid tetrazole rings is too short to permit a reasonable chelation of a single metal centre. With this in mind it is clear that the structure of the title compound should be a coordination polymer. Instead of an expected three-dimensional network, the cationic part of the structure is an infinite two-dimensional coordination polymer extending parallel to (100), as shown in Figs. 3 and 4. The ClO 4 anions are residing in pockets of this coordination polymer and are anchored via intra-as well as inter-layer C-H···O interactions ( Table 1). Two of these interactions are depicted in Fig. 2.
Interestingly, the title compound turned out to be isostructural with [Cu(t 3 z) 2 ](NO 3 ) 2 recently described by Hartdegen et al. (2009). This compound crystallizes similar to (I) in the triclinic space group P1 with a = 8.5850 (5)  Experimental CAUTION! Tetrazoles and perchlorates are energetic compounds sensitive towards heat and impact. Proper precautions and care should be applied. The ligand tris(2-(1H-tetrazol-1-yl)ethyl)-amine, t 3 z, was prepared according to the supplementary materials sup-2 general procedure of Kamiya & Saito (1973). A solution of 2.0 g tris(2-aminoethyl)-amine (13.7 mmol, Aldrich, 96%), 3.07 g sodium azide (47.2 mmol, Wako, min. 98.0%) and 9.12 g triethyl orthoformate (61.5 mmol, Sigma-Aldrich, 98%) in 120 ml glacial acetic acid (Kanto Chemical, 99.5%), was stirred for 3 h at a temperature of 343 -353 K. After cooling to rt overnight the solvent was removed under reduced pressure. The solid residue was dissolved in 20 ml H 2 O, the solution was made alkaline (pH>11) by adding 100 ml of aqueous 4 N NaOH, and was then extracted with ethyl acetate. The combined organic layers were dried with sodium sulphate and the solvent was distilled off. The raw product was recrystallised from

Refinement
All H atoms were placed in calculated positions and thereafter treated as riding. U iso (H) = 1.2U eq (C) was used. Fig. 1. The coordination octahedron of Cu in (I) with incomplete t 3 z ligands. Displacement ellipsoids for the non-hydrogen atoms drawn at the 50% probability level. Symmetry codes for the t 3 z fragments are given in italics.

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.