Tris(2,2'-bipyridine)-nickel(II) hexa-molybdate.

The asymmetric unit of the title compound, [Ni(C10H8N2)3][Mo6O19], consists of one complex [(Ni(C10H8N2)3]2+ cation and one Lindqvist-type [Mo6O19]2− polyanion. The Ni2+ ion is in a distorted octahedral coordination by six N atoms from three chelating 2,2′-bipyridine ligands. The Lindqvist-type anion exhibits the characteristic Mo—O bond-length distribution, with the shortest bonds being the Mo—O(terminal) bonds [mean = 1.679 (2) Å] and the longest being those to the central O atom [mean = 2.318 (7) Å]. A number of C—H⋯O interactions contribute to the crystal packing.

The asymmetric unit of the title compound, [Ni(C 10
tions (Zhang et al., 2009a,b). Here, we describe the synthesis and structural characterization of the title compound, [(Ni(C 10 Figure 1. The nickel(II) ion is in a distorted octahedral coordination by six N atoms from three chelating 2,2'-bipyridine ligands. The Ni-N bond lengths are in the normal range of 2.066 (3)-2.101 (3) Å and are also in agreement with previous studies (Zhang et al., 2009a). The rms deviations of the three bipyridine groups from planarity are 0.0779, 0.0178, and 0.0806 Å, respectively.
The hexamolybdate anion is of the Lindqvist-type (Pope, 1983;Che et al., 1979) and typically consists of six molybdenum atoms arranged octahedrally around a central oxygen atom. Each molybdenum is then bonded peripherally to neighboring molybdenum atoms through oxygen bridges. One terminal oxygen atom is attached to each molybdenum atom. Alternatively, the structure can be visualized as formed from six MoO 6 octahedra that have condensed so that they all share a common vertex.
Multipoint C-H···O interactions between the hydrogen atoms from the organic amines and the terminal oxygen atoms of the anion make a contribution to stabilize the packing of the crystal, as shown in Figure 2 and Table 2.

Refinement
All hydrogen atoms bound to carbon were refined using a riding model with distance C-H = 0.93 Å and U iso (H) = 1.2U eq (C). Fig. 1. The cation and anion of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level; H atoms are given as spheres of arbitrary radius.