Pentakis(μ3-N,2-dioxidobenzene-1-carboximidato)di-μ2-formato-pentakis(1H-imidazole)methanolpentamanganese(III)manganese(II)–methanol–water (1/3.36/0.65)

The title compound, [Mn6(C7H4NO3)5(CHO2)2(C3H4N2)5(CH3OH)]·3.36CH3OH·0.65H2O, or Mn(II)(O2CH)2[15-MCMn(III)N(shi)-5](Im)5(MeOH)·3.36MeOH·0.65H2O (where MC is metallacrown, shi3− is salicylhydroximate, Im is imidazole and MeOH is methanol), contains five MnIII ions as members of the metallacrown ring and an MnII atom bound in the central cavity. The central MnII atom is seven-coordinate with a geometry best described as between face-capped trigonal–prismatic and face-capped octahedral. Three MnIII ions of the metallacrown ring are six-coordinate with distorted octahedral geometries. Of these six-coordinate MnIII ions, two have mirror-plane configurations, while the other has a Δ absolute stereoconfiguration. The remaining two MnIII ions have a coordination number of five with a distorted square-pyramidal geometry. The five imidazole ligands are bound to five different MnIII ions. Disorder is observed for one of the coordinating imidazole ligands, as the imidazole ligand is disordered over two alternative mutually exclusive positions in a ratio of 0.672 (9) to 0.328 (9). The interstitial voids between the main molecules that constitute the structure are mostly filled with methanol molecules that form hydrogen-bonded chains. Some of the sites of the non-coordinated methanol molecules are not fully occupied, with the remainder of the volume either empty or taken up by ill-defined close to amorphous content. One site was refined as being taken up by either two or one methanol molecules, with an occupancy ratio of 0.628 (5) to 0.343 (5). This disorder might thus be correlated with the disorder of the imidazole ring (an N—H⋯O hydrogen bond between the major moieties of the imidazole and the methanol molecules is observed). On the other side of the disordered imidazole ring the chain of partially occupied methanol molecules originates that extends via O—H⋯O hydrogen bonds to the metal-coordinated methanol molecule. The three partially occupied methanol molecules were refined to be disordered with two water molecules to take two residual electron density peaks into account (the exact nature of these weak residual electron density peaks cannot be deduced from the X-ray diffraction data alone, the assignment as water is tentative). The occupancy rate for the methanol molecules refined to 0.480 (7). The occupancy rate of the two water molecules refined to 0.34 (1) and 0.31 (2) for each site.

The title compound, [Mn 6 (C 7 H 4 NO 3 ) 5 (CHO 2 ) 2 (C 3 H 4 N 2 ) 5 -(CH 3 OH)]Á3.36CH 3 OHÁ0.65H 2 O, or Mn(II)(O 2 CH) 2 [15-MC Mn(III)N(shi) -5](Im) 5 (MeOH)Á3.36MeOHÁ0.65H 2 O (where MC is metallacrown, shi 3À is salicylhydroximate, Im is imidazole and MeOH is methanol), contains five Mn III ions as members of the metallacrown ring and an Mn II atom bound in the central cavity. The central Mn II atom is sevencoordinate with a geometry best described as between facecapped trigonal-prismatic and face-capped octahedral. Three Mn III ions of the metallacrown ring are six-coordinate with distorted octahedral geometries. Of these six-coordinate Mn III ions, two have mirror-plane configurations, while the other has a Á absolute stereoconfiguration. The remaining two Mn III ions have a coordination number of five with a distorted square-pyramidal geometry. The five imidazole ligands are bound to five different Mn III ions. Disorder is observed for one of the coordinating imidazole ligands, as the imidazole ligand is disordered over two alternative mutually exclusive positions in a ratio of 0.672 (9) to 0.328 (9). The interstitial voids between the main molecules that constitute the structure are mostly filled with methanol molecules that form hydrogenbonded chains. Some of the sites of the non-coordinated methanol molecules are not fully occupied, with the remainder of the volume either empty or taken up by ill-defined close to amorphous content. One site was refined as being taken up by either two or one methanol molecules, with an occupancy ratio of 0.628 (5) to 0.343 (5). This disorder might thus be correlated with the disorder of the imidazole ring (an N-HÁ Á ÁO hydrogen bond between the major moieties of the imidazole and the methanol molecules is observed). On the other side of the disordered imidazole ring the chain of partially occupied methanol molecules originates that extends via O-HÁ Á ÁO hydrogen bonds to the metal-coordinated methanol molecule. The three partially occupied methanol molecules were refined to be disordered with two water molecules to take two residual electron density peaks into account (the exact nature of these weak residual electron density peaks cannot be deduced from the X-ray diffraction data alone, the assignment as water is tentative). The occupancy rate for the methanol molecules refined to 0.480 (7). The occupancy rate of the two water molecules refined to 0.34 (1) and 0.31 (2) for each site.
Mn1 is located in the central cavity and is seven-coordinate with a geometry best described as between face-capped trigonal prismatic and face-capped octahedral (Fig. 2). The geometry is significantly distorted when compared to the ideal parameters of either geometry. One parameter that can be used to distinguish these geometries is the azimuthal angle (Φ). In a trigonal prism the ideal angle between the atoms on opposite triangular faces is Φ = 0°, while for an octahedron the ideal value is Φ = 60°. To calculate the Φ angle, the centroids of opposite triangular faces made by the donor oxygen atoms (O1, O13, and O18; O7, O10, and O16) were defined using the program Mercury (Macrae et al., 2006), and then twist angles between atoms on opposite faces through the centroids were calculated. [A similar method was used to calculate the Φ angle in a related 15-MC-5 structure (Tigyer et al., 2011).] The estimated Φ angles of 5.90°, 13.17°, and 20.93° indicate that the geometry approaches that of a face-capped trigonal prism though the angle of 20.93° is significantly large (Fig. 2). Another parameter that can be used to distinguish the two geometries is the s/h ratio (Stiefel and Brown, 1972). In an ideal octahedron the s/h ratio is 1.22, while in an ideal trigonal prism the s/h ratio is 1.00.
Defining the distance between the centroids as h and defining the distances between atoms within a triangular face as s, the estimated average s/h ratio for 1 is 1.15± 0.13. When considered together, the Φ angle and the s/h ratio indicate that the geometry about Mn1 is severely distorted from both face-capped trigonal prismatic and face-capped octahedral geometry. The assignment of a 2+ oxidation state for Mn1 is supported by an average bond distance of 2.24 Å.  (Kessissoglou et al., 1994;Dendrinou-Samara et al., 2001, 2002, 2005Emerich et al., 2010;and Tigyer et al., 2011); however, in 1 these bonds do not exist. The geometry about Mn2, Mn5, and Mn6 is best described as a distorted octahedron (Fig. 3a-c). The coordination about these Mn(III) ions can also be described by their configurations. Mn2 and Mn6 adopt a planar (P) configuration, where two chelate rings of different shi 3ligands are located trans to each other. Mn5 has a propeller configuration with Δ absolute stereochemistry. The geometry about Mn3 and Mn4 is best described as distorted square pyramidal (Fig. d-e). To evaluate the geometry about Mn3 and Mn4 the τ parameter was calculated for both Mn(III) ions (Addison et al., 1984). For an ideal square pyramidal geometry τ = 0, while for an ideal trigonal bipyramidal geometry τ = 1. For Mn3 and Mn4, τ equals 0.38 and 0.15, respectively. In addition, Mn2, Mn3, Mn4, Mn5, and Mn6 bind imidazole ligands, which are directed to the periphery of the molecule.
The imidazole attached to Mn2 is disordered over two alternative mutually exclusive positions in a ratio of 0.672 (9) to 0.328 (9).
Manganese(II) chloride tetrahydrate (3.0 mmol) was dissolved in 30 ml of methanol resulting in a light pink solution.
Sodium methoxide (7.5 mmol) and H 3 shi (2.5 mmol) were mixed in 20 ml of methanol, which resulted in a cloudy white liquid. This mixture was then added to the manganese(II) chloride solution. Initially the solution turned a yellow color, but after stirring for 1 h the solution become a dark brown-black. After 1 h of stirring, separate solutions of sodium formate (3.0 mmol in 20 ml of methanol) and imidazole (10 mmol in 30 ml of methanol) were added to the dark brownblack solution. No color change was observed. This final solution (100 ml total volume) was left for slow evaporation of the solvent at room temperature. Dark brown-black crystals suitable for X-ray diffraction analysis were collected after 1 day. The percent yield was 2.5% based on manganese(II) chloride tetrahydrate.

Refinement
Crystals of the compound were heavily intergrown. A mostly single piece was extracted from a larger cluster, but due to the dark color and fragility of the material no completely single fragment of sufficient size could be obtained. The crystal chosen for data collection thus consisted of several fragments, two of which were dominant. The orientation matrices for the two major components were identified using the program CELL_NOW ( The data were corrected for absorption using TWINABS, and the structure was solved and refined using direct methods using only the non-overlapping reflections of component 1 with a resolution better than 0.7 Å. Overlapping reflections were ignored. The R int value given is for all reflections and is based on agreement between observed single intensities of component 1 before the cutoff at 0.7 Å [TWINABS (Sheldrick, 2009)].
Disorder is observed for one of the coordinated imidazole ligands and for the solvate methanol and water molecules.
The imidazole ligand is disordered over two alternative, mutually exclusive positions in a ratio of 0.672 (9) to 0.328 (9).
The geometries of the two moieties were restrained to be similar and ADPs of partially overlapping atoms of the two moieties were constrained to be identical. The interstitial voids between the main molecules that constitute the structure are mostly filled with methanol molecules that form hydrogen bonded chains. Some of the sites of the non-coordinated methanol molecules are not fully occupied, with the remainder of the volume either empty or ill-defined. One site was refined as being taken up by either two or one methanol molecules, with an occupancy ratio of 0.628 (5) to 0.343 (5).
This disorder might thus be correlated with the disorder of the imidazole ring (an N-H···O hydrogen bond between the major moieties of the imidazole and the methanol molecules is observed). On the other side of the disordered imidazole ring a chain of partially occupied methanol molecules originates that extends via O-H···O hydrogen bonds to the metal coordinated methanol molecule. The three partially occupied methanol molecules were refined to be disordered with two water molecules to take two residual electron density peaks into account (the exact nature of these weak residual electron density peaks cannot be deduced from the X-ray diffraction data alone, the assignment as water is tentative). The occupancy of the methanol molecules refined to 0.480 (7). The occupancy of the two water molecules refined to 0.34 (1) and 0.31 (2). The ADPs of the water molecules were restrained to be approximately isotropic. Acidic H atoms were set based on hydrogen bonding considerations and were restrained or constrained.       (8)  O13 0.0149 (9) 0.0218 (9) 0.0165 (9) −0.0030 (7) 0.0022 (7) 0.0023 (7)  O14 0.0222 (10) 0.0215 (9) 0.0172 (9) −0.0019 (7) −0.0018 (7) 0.0002 (7)