Bis[N-(3-aminopropyl)propane-1,3-diamine-κ3 N,N′,N′′]cadmium nitrate perchlorate

The title complex, [Cd(C6H17N3)2](ClO4)(NO3), was synthesized by the reaction of Cd(NO3)2·4H2O, bis(3-aminopropyl)amine and sodium perchlorate in methanol. The asymmetric unit of the title complex consists of one Cd2+ cation, two tridentate bis(3-aminopropyl)amine ligands, one nitrate anion and one perchlorate anion. The Cd2+ cation is coordinated by six N atoms of the bis(3-aminopropyl)amine ligands in a slightly distorted octahedral coordination geometry. In the crystal, molecules are held together by an intricate network of N—H⋯O interactions. One of the two amine ligands was found to be disordered over two sets of sites, with a ratio of 0.802 (3):0.198 (3), similarly to the nitrate anion, with a ratio of 0.762 (10):0.238 (10).

The title complex, [Cd(C 6 H 17 N 3 ) 2 ](ClO 4 )(NO 3 ), was synthesized by the reaction of Cd(NO 3 ) 2 Á4H 2 O, bis(3-aminopropyl)amine and sodium perchlorate in methanol. The asymmetric unit of the title complex consists of one Cd 2+ cation, two tridentate bis(3-aminopropyl)amine ligands, one nitrate anion and one perchlorate anion. The Cd 2+ cation is coordinated by six N atoms of the bis(3-aminopropyl)amine ligands in a slightly distorted octahedral coordination geometry. In the crystal, molecules are held together by an intricate network of N-HÁ Á ÁO interactions. One of the two amine ligands was found to be disordered over two sets of sites, with a ratio of 0.802 (3): 0.198 (3), similarly to the nitrate anion, with a ratio of 0.762 (10):0.238 (10).

Experimental
Crystal data [Cd(C 6
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: JANA2006 (Petříček et al., 2006); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010). In the crystal structure of the title complex, see Fig. 1, the Cd 2+ cation is bonded to six nitrogen atoms of two tridentate bis(3-aminopropyl)amine ligands in a slightly distorted octahedral coordination. One of the ligands was found to be disordered, assuming two differently occupied orientations (Fig. 2). Because the low occupation of one of these orientations does not allow its free refinement, its precise geometry remains unsure (for further details, see experimental section) and therefore will not be included in the following discussion.
The angles around the metals atoms range from 81.40 (5)° to 103.19 (7)° and from 159.83 (5)° to 175.31 (7)°. Both the perchlorate and nitrate anions are linked to the complex cations through an intricate network of N-H···O hydrogen bonds. The hydrogen bonds involving the nitrate anion connect the molecules of the complex to slabs parallel to (100).
The hydrogen bonds involving the perchlorate anion eventually connect the slabs into three-dimensional network ( Table   2, Fig. 3).

Experimental
The title complex was prepared by the branch tube method: bis(3-aminopropyl)amine (0.282 ml, 2 mmol) was placed in one arm of a branched tube and Cd(NO 3 ) 2 .4H 2 O (0.308 g, 1 mmol) and sodium perchlorate (0.122 g, 1 mmol) in the other. Methanol was then carefully added to fill both arms, the tube sealed and the ligand-containing arm immersed in a bath at 333 K, while the other was left at ambient temperature. After one week, colorless crystals were collected in the cooler arm. Then they were then filtered off, washed with acetone and diethylether, and air dried. M.p.: 583 K, yield: (78%).

Refinement
All hydrogen atoms were discernible in difference Fourier maps and could be refined to reasonable geometries.
According to common practice, H atoms bonded to C were kept in ideal positions with C-H = 0.96 Å while positions of H atoms bonded to N (except N7 and N7′ -see below) were refined with distance restraint N-H= 0.87 Å (NH 1 , NH 2 ). In both cases U iso (H) was set to 1.2U eq (C,N). Disorder of the nitrate anion was treated using a rigid body refinement. Two orientations of the disordered bis(3-aminopropyl)amine ligand (Fig. 2) were refined using split atom positions. While some atoms of both orientations coincide, the C8, N7 and C10 positions were split to C8-C8′, N7-N7′ and C10-C10′, respectively. The sum of occupancies for each split pair was kept equal to the original full occupancy and the occupancies of all atoms belonging to a given conformer were kept equal. Positions C5, C7 and C9 were the same for both orientations but the attached hydrogen atoms positions were split because of a different geometry of neighboring atoms.
These carbon atoms were formally split by placing two atoms to the same position in order to allow the refinement program using two geometry constraints for two different pairs of hydrogen atoms. Thus C5 is bonded to hydrogen atoms H1C5, H2C5, H1C5′ and H2C5′, and similarly for C7 and C9. The positions of the major orientation were refined without restrictions. However, the low occupancy of the minor component, 0.198 (3), did not allow a free refinement of positions C8′, N7′, and C10′. For these atoms we defined following distance restraints: C9-C8′ = 1.517 Å, C8′-N7′ = 1.482 Å, N7′-C5′ = 1.482 Å, C5′-C10′ = 1.517 Å and C10′-C7 = 1.517 Å, with weight 0.001 allowing only very small deviations during the refinement from the defined values. Hydrogen atoms attached to N7 and N7′ were kept in ideal positions, without refinement.
The angles of the minor component of the disordered part were refined to slightly differents values compared with the major part (see Table 2). However, it remained unclear whether the difference could be taken seriously or whether this is caused by an unreliable refinement due to the low occupation. For this reason we created (using the rigid body tool in Jana2006) a structure model where both orientations were described with a common shape of the ligand refining its atomic parameters and a translation vector plus three rotations (followed by inversion, when necessary) allowing transformation of the common ligand to the position of the first and the second orientation, respectively. In this approach, both orientations have exactly the same geometry, differing only in their occupation. While the number of refined parameters decreased from 298 to 295, the R value increased by 0.8% and the occupation of the minor component decreased from 0.198 (3) to 0.109 (4). The increase of R value and decrease of the minor component occupation indicate that the conformers are really slightly different in their shape. Hence this approach was finally neglected.