Bis(acetylacetonato-κ2 O,O′)(pyridine-κN)(thiocyanato-κN)manganese(III): a redetermination using data from a single crystal

In the crystal structure of the title compound, [Mn(C5H7O2)2(NCS)(C5H5N)], the Mn3+ cation is coordinated by two acetylacetonate anions, one terminal thiocyanate anion and one pyridine ligand within a slightly distorted octahedron. The asymmetric unit consists of half a complex molecule with the Mn3+ cation, the thiocyanate anion and the pyridine ligand located on a mirror plane. The acetylacetonate anion is in a general position. The title compound was previously described [Stults et al. (1975 ▶). Inorg. Chem. 14, 722–730] but could only be obtained as a powder. Suitable crystals have now been obtained for a high-precision single-crystal structure determination.

In the crystal structure of the title compound, [Mn(C 5 H 7 O 2 ) 2 (NCS)(C 5 H 5 N)], the Mn 3+ cation is coordinated by two acetylacetonate anions, one terminal thiocyanate anion and one pyridine ligand within a slightly distorted octahedron. The asymmetric unit consists of half a complex molecule with the Mn 3+ cation, the thiocyanate anion and the pyridine ligand located on a mirror plane. The acetylacetonate anion is in a general position. The title compound was previously described [Stults et al. (1975). Inorg. Chem. 14, 722-730] but could only be obtained as a powder. Suitable crystals have now been obtained for a high-precision single-crystal structure determination.

Related literature
For the preparation of the title compound in the form of a powder, see: Stults et al. (1975).

Experimental
Crystal data [Mn(C 5 H 7 O 2 ) 2 (NCS) (C 5  Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010). Crystals of the title compound were prepared within a project on the synthesis of Manganese(III) coordination polymers containing thiocyanato anions and neutral N-donor co-ligands. Within this project manganese(III) acetylacetonate was reacted with potassium thiocyanate and pyridine in a mixture of ethanol and sulfuric acid leading to the formation of crystals of the title compound. The title compound was already described by Stults et al. (1975) but could only be obtained as a microcrystaline powder. We now have been able to get suitable crystals for a single crystal structure determination.
In the crystal structure the manganese(III) cations are coordinated by four oxygen atoms of two symmetry related acetylacetone anions and two nitrogen atoms of an N-terminal coordinated thiocyanato anion and one pyridine ligand into discrete complexes that are located on a mirror plane (Fig. 1). The coordination polyhedron of the Mn cation can be described as a slightly distorted octahedron.
Pyridine was purchased from Riedel-de Haen. The title compound was prepared by the reaction of 70.5 mg Mn(III) 2,4pentadionate (0.20 mmol) 58.3 mg potassium thiocyanate (0.6 mmol) and 32.3 µl pyridine (0.4 mmol) in a mixture of 1.0 mL ethanol and 10.68 µl sulfuric acid at RT in a closed 3 ml snap cap vial. After three days brown crystals of the title compound, mostly in the form of plates, were obtained by slow evaporation of the solvent.

Refinement
H atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropically with U eq (H) = 1.2 U eq (C) for aromatic H atoms (1.5 for methyl H atoms) using a riding model with C-H = 0.95 Å (aromatic) and with C-H = 0.98 Å (methyl).

Bis(acetylacetonato-κ 2 O,O′)(pyridine-κN)(thiocyanato-κN)manganese(III)
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.22 e Å −3 Δρ min = −0.18 e Å −3 Absolute structure: Flack (1983), 1086 Friedel pairs Absolute structure parameter: 0.015 (19) Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 > 2sigma(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.