Bis(1,10-phenanthroline-κ2 N,N′)(sulfato-κ2 O,O′)nickel(II) propane-1,2-diol monosolvate

In the title compound, [Ni(SO4)(C12H8N2)2]·C3H8O2, the NiII atom exhibits a distorted octahedral coordination by four N atoms from two chelating 1,10-phenanthroline ligands and two O atoms from an O,O′-bidentate sulfate group. A twofold rotation axis passes through the Ni and S atoms and the mid-point of the hydroxyl C—C bond of the propane-1,2-diol solvent molecule. The dihedral angle between the two chelating N2C2 groups is 85.61 (8)°. The [NiSO4(C10H8N2)2] and propane-1,2-diol units are held together by a pair of symmetry-related intermolecular O—H⋯O hydrogen bonds involving the uncoordinating O atoms of the sulfate ion. Due to symmetry, the solvent molecule is equally disordered over two positions.


Comment
The self-assembly of coordination polymers and the crystal engineering of metal-organic coordination frameworks have recently attracted great interest, owing to their interesting structural topologies and potential application as functional materials (Batten & Robson, 1998;Zhang et al., 2010;Zhong et al., 2011). The neutral bidentate ligand 1,10phenanthroline (phen) as an auxiliary ligand has been widely applied in constructing interesting coordination polymers.
Recently, we have obtained unexpectedly some nickel-phen complexes (Zhong et al., 2009;Ni et al., 2010;Zhong & Ni, 2012) with interesting four-membered chelating rings during attempts to synthesize mixed-ligand coordination polymers with phen as auxiliary ligand via an alcohol-solvothermal reaction. We here report the title compound, [NiSO 4 (C 12 H 8 N 2 ) 2 ]. C 3 H 8 O 2 , which is the part of our systematic investigation of transition metal nickel complexes with bidentate bridging sulfate ligands. It is isostructural to the previously reported cobalt(II) analog (Zhong, 2013).
The single-crystal X-ray diffraction experiment revealed that the crystal structure of the the title compound consists of a neutral monomeric [NiSO 4 (C 10 H 8 N 2 ) 2 ] complex and a solvent propane-1,2-diol molecule. A two-fold rotation axis (symmetry code: -x + 1, y, -z + 1/2) passes through the Ni and S atoms, and the mid-point of the hydroxyl C-C bond of the propane-1,2-diol solvent molecule is likewise located on a the same crystallographic axis. The Ni II metal ion has a distorted NiN 4 O 2 octahedral geometry, with four N atoms from two chelating phenanthroline ligands and two O atoms from an O,O′-bidentate sulfate anion (Fig. 1). The Ni-O bond distance of 2.107 (2) Å, the O-Ni-O bite angle of 67.95 (9)°, the Ni-N bond distances in the range of 2.076 (2)-2.082 (2) Å, the N-Ni-N bite angle of 80.09 (7)° and the dihedral angle of 85.61 (8)° between the two chelating NCCN groups are in good agreement with those observed in the previously reported nickel complexes (Zhong et al., 2009;Ni et al., 2010;Zhong & Ni, 2012) (Table 1).
The solvent molecule is disordered over two positions and was refined with a site-occupancy ratio of 0.50:0.50. The metal complex and the solvent molecules are held together by a pair of intermolecular O-H···O hydrogen bonds, which help to further stabilize the crystal structure ( Fig.1 and Table 2).

Experimental
Green block-shaped crystals of the title compound were obtained by a procedure similar to that described previously (Zhong, 2013), but with NiSO 4 ·7H 2 O in place of CoSO 4 ·7H 2 O.

Refinement
The non-hydrogen atoms were refined anisotropically. The H atoms of phen were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). The H atoms of propane-1,2-diol were placed

Figure 1
The molecular structure showing the atom-numbering scheme and with displacement ellipsoids drawn at the 30% probability level. The light broken lines depict O-H···O interactions. Unlabeled atoms are related to the labelled atoms by the symmetry operator (-x, y, -z + 1/2). 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 R-factors(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.