Diazidobis(propane-1,3-diamine)copper(II)

In the title complex, [Cu(N3)2(C3H10N2)2], the CuII ion resides on a centre of symmetry and is in a Jahn–Teller distorted octahedral coordination environment comprising two N atoms from azide anions in axial positions and four N atoms from propane-1,3-diamine (tn) ligands in equatorial positions. Intermolecular N—H⋯N hydrogen bonds produce R 2 1(6), R 2 2(8), R 2 2(12) and R 4 2(8) rings, generating a two-dimensional layer.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999 (Mondal & Mukherjee, 2008;Gu et al., 2007). The azide anion has rich coordination modes (Shen et al., 2000), and many metal-azide complexes have been reported (Monfort et al., 2000). In most of the compounds reported to date, the co-ligands are neutral organic ligands, while charged ligands are very scarce (Escuer et al., 1997). The 1,3-diaminopropane (tn) ligand behaves as a strong chelatator in its metal complexes due to the formation of a stable six-membered ring. At the same time, it is a good H-bond donor due to the existence of amino groups (Sundberg et al., 2001). Previously, the polymorphic dinuclear compound featuring both bridging and terminal azido groups was reported (Luo et al., 2004;Triki et al., 2005). Herein, we report the synthesis and structure of the mononuclear complex with only terminal azido ligands.
The molecular structure and atom-labelling scheme are shown in Fig. 1. The Cu II atom is located on a center of symmetry and is coordinated by four N atoms from two tn ligands and two N atoms from two azide anions. The geometry around the Cu II ion ( Table 1) is that of a distorted octahedron, the equatorial plane of which (N1/N2/N1 i /N2 i ) is formed by four amino N atoms [symmetry code: (i) 2-x, -y, -z]. The axial positions in the octahedron are occupied by two N atoms (N4 and N4 i ). The Cu1-N4 distance is longer than the corresponding distances in related structures (Luo et al., 2004;Triki et al., 2005). This elongation can be attributed to the static Jahn-Teller effect. The tn ligand shows chelating coordination behavior and displays a chair conformation in the equatorial direction. This kind of coordination mode was also found in the similar complexes (Sundberg et al., 2001;Sundberg & Sillanpaa, 1993;Sundberg & Uggla, 1997). The Cu1-N1 and Cu1-N2 bond lengths are very similar to those in the previously reported Bis(4-aminobenzenesulfonato-κO)bis(propane-1,3-diamine-κ 2 N,\ N')copper(II) dihydrate (Zhang et al., 2009).
Amino atom N2 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H3, to atom N3 ii so forming a C(6) (Bernstein et al., 1995) chain running parallel to the [110] direction. Amino atom N2 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H4, to atom N3 iii so forming a C(6) chain running parallel to the [-100] direction. Similarly, amino atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H1, to atom N3 i so forming a C(6) chain running parallel to the [100] direction. Amino atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via H2, to atom N4 ii so forming a C(4) chain running parallel to the [110] direction. The combination of C(4) and C(6) chains produce R 2 1 (6), R 2 2 (8), R 2 2 (12) and R 4 2 (8) rings (Fig. 2).

Experimental
Copper(II) sulphate (0.16 g, 1.0 mmol) was dissolved in methanol (20 ml). Sodium azide (0.134 g, 2.0 mmol) and 1,3diaminopropane(0.148 g, 2.0 mmol) were added and the mixture refluxed for 3 hours. A blue solution formed, which was filtered. After a few days, blue blocks were obtained from the methanol filtrate.
supplementary materials sup-2 Refinement All H atoms bound to C atoms were refined using a riding model, with C-H = 0.97Å and U iso (H) = 1.2U eq (C) for methylene C atoms. Amino H atoms were located in difference maps and refined subject to a DFIX restraint of N-H = 0.87 (2) Å.  Table 2).