Tris[tris(ethane-1,2-diamine)cobalt(II)] bis[octacyanidomolybdate(V)] dihydrate

In the title compound, [CoII(C2H8N2)3]3[MoV(CN)8]2·2H2O, N—H⋯N and N—H⋯O hydrogen-bonding interactions give rise to a three-dimensional network. In the crystal structure, each Mo polyhedron has a square-antiprismatic shape, while the Co complexes show distorted octahedral geometry with an occupancy of 50%. One of the Co atoms resides on a crystallographic inversion centre.

In the title compound, [Co II (C 2 H 8 N 2 ) 3 ] 3 [Mo V (CN) 8 ] 2 Á2H 2 O, N-HÁ Á ÁN and N-HÁ Á ÁO hydrogen-bonding interactions give rise to a three-dimensional network. In the crystal structure, each Mo polyhedron has a square-antiprismatic shape, while the Co complexes show distorted octahedral geometry with an occupancy of 50%. One of the Co atoms resides on a crystallographic inversion centre.
Among the two independent Co(en) 3 complexes the cobalt atom Co2 resides on a crystallographic inversion centre, resulting in inversion related 50:50 disorder of the chiral Λ and Δ forms. Disorder refinement (Müller et al. 2006) was necessary to present a suitable chiral model of the complex. (Fig. 1).
Several classic intermolecular N-H···N hydrogen bonds (Fig. 2) between the non-disordered Co(en) 3 and the Mo(CN) 8 complexes form a complicated three-dimensional network in the structure. The disordered Co2 unit and the disordered water molecules are not considered for further (possible) hydrogen bonding contacts. An interesting example structure with two crystallographically independent Co(en) 3 complexes, different vanadates and six water molecules shows an impressive number of 23 N-H···O and 13 O-H···O hydrogen bonds in the chiral space group P1 (Aschwanden et al. 1993). It may be thinkable that the title structure belongs also to a non-centrosymmetric space group (P 21), but in that case with a dominating part of centrosymmetry in data.

Experimental
For the preparation of the title compound, all of the following procedures were carried out in the dark to avoid decompos- et al., 1975). Yellow block crystals suitable for X-ray single-crystal structure determination were grown at room temperature by slow diffusion of an aqueous solution of CoCl 2 .6H 2 O (0.3 mmol) and ethane-1,2-amine (en, 0.9 mmol) and an aqueous solution of (Bu 3 NH) 3 [Mo(CN) 8 ].4H 2 O (0.2 mmol) for four weeks. The resulting crystals were collected, washed with H 2 O and dried in air.

Refinement
All non-H atoms were refined anisotropically. The H atoms on nitrogen atoms were located from the difference Fourier maps, and the H atoms of water molecules were placed in calculated positions. The H atoms of the Co complexes were placed in calculated positions with C-H and N-H distances 0.99 Å and 0.92 Å, respectively, with U iso (H) = 1.2U eq (C,N).

supplementary materials sup-2
The calculation of the H atoms for the disordered Co2 complex was possible with many FREE instructions using SHELXL97 (Sheldrick, 2008). For atoms N17 and N20 the four H-atom coordinates from the difference map were fixed with AFIX 3 instructions. These N-H distances range between 0.767 and 0.968 Å. The model refinement of the Co2(en) 3 complex was controlled with the programme PLATON (Spek, 2003), (LATT -1 used for model building at the start), symmetry transformation (2 -x, 1 -y, 1 -z) for some atom coordinates applied, introducing a split position for Co2 to get the complete Λ and Δ forms of the inversion related chiral complexes separated, using the information of disorder refinement from the SHELXL guide book (Müller et al., 2006).    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.