Tris(μ2-methanolato)-μ3-oxido-tris{[(E)-4-chloro-2-({[2-(pyridin-2-yl)ethyl]imino}methyl)phenolato]manganese(III)} perchlorate–dichloromethane–diethyl ether (1/1.1/0.9)

The structure of a trinuclear manganese Schiff base complex with an Mn3O core is reported with the stoichiometry, C45H42Cl3Mn3N6O7, ClO4, C4H10O, CH2Cl2.


Chemical context
Single-molecule magnets (SMMs) have attracted extensive attention because they are nanoscale magnetic particles of a well-defined size (Gatteschi & Sessoli 2003;Tasiopoulos et al., 2004) and, in particular, manganese polynuclear manganese units have been investigated extensively in this respect. Employing salicylaldoxime ligands in manganese chemistry has proved to be extremely successful in the synthesis of new polynuclear complexes, including some SMMs (Milios et al., 2004) and single-chain magnets (SCMs) (Feng et al., 2009), suggesting that such ligands are excellent candidates for the preparation of polynuclear Mn complexes with interesting magnetic properties. A common motif in this chemistry is the formation of an Mn 3 O central core and a search of the Cambridge Structural Database (CSD; Groom et al., 2016) for this moiety with each Mn atom surrounded by an additional N 2 O coordination environment gave over 500 hits. Most surprisingly in view of ubiquity of this type of ligand in transition metal coordination chemistry, there was not a single example in this list where the N 2 O coordination environment was supplied by a Schiff base ligand based on substituted salicylaldehyde derivatives. This paper reports the first example of such a structural type.

Structural commentary
In the title compound, [Mn 3 (C 14 H 11 ClN 2 O) 3 (CH 3 O) 3 O]ClO 4 Á-1.1CH 2 Cl 2 Á0.9C 4 H 10 O, the cation consists of a central Mn 3 O core with 2 -methanolate bridging between adjacent Mn III atoms, thus giving each Mn III atom a mer-O 3 coordination environment (Fig. 1). Six-coordination for each Mn III atom is provided by the deprotonated Schiff base ligand (E)-4-chloro- ISSN 2056-9890 2-({[2-(pyridin-2-yl)ethyl]imino}methyl)phenolate, also coordinating in a mer-N 2 O fashion to each Mn III atom. Thus the best description of the central Mn 3 O 4 core, made up of the three Mn III atoms, the central O and the bridging methanolate O atoms, is as a pseudo-cubane, missing one vertex. This can be seen by considering the Mn-O-Mn angles of 103.12 (6), 102.75 (6) and 101.75 (6) .
Since each Mn III atom is in the +3 oxidation state and thus a high-spin d 4 ion, they are expected to exhibit Jahn-Teller distortion (Jahn & Teller, 1937). The most common type of Jahn-Teller distortion is a tetragonal distortion with the bond lengths along one trans axis being longer than expected. For each Mn III atom, this is provided by the methanolate O and pyridine N atoms. Thus the Mn-O bond lengths involving the methanolate O atom are very asymmetric with one long (for the O atom involved in the Jahn-Teller distortion) and one short bond [2.1973 (14)

Supramolecular features
As seen in Fig. 2, there are extensive C-HÁ Á ÁO and C-HÁ Á ÁCl interactions (Table 1), which link the cation anion and solvent molecules into a three-dimensional array. Diagram of the cation showing the atom labeling. Anions and solvent molecules have been omitted for clarity. Atomic displacement parameters are drawn at the 30% probability level.

Figure 2
Packing diagram, viewed along the b axis, showing the extensive C-HÁ Á ÁO and C-HÁ Á ÁCl interactions linking the cation, anion, and solvent molecules into a three-dimensional array. For the disordered moieties, only the major disorder component is shown.

Database survey
A survey of the Cambridge Structural Database for Mn 3 O fragments where the Mn atoms are also coordinated by Schiff base ligands gave no hits. However, there were many instances of such units with salicylaldoxime ligands as this is a fertile field of research in the search for single molecule magnets.

Synthesis and crystallization
A solution of the ligand C 14 H 13 ClNO (2.4793 g,9.5 mmol) and an equivalent amount of triethylamine (C 6 H 15 N; 1.3 ml, 9.5 mmol) both in methanol, was mixed with a methanol solution of Mn(ClO 4 ) 2 (1.7276 g, 4.8 mmol) in a 150 ml reaction flask. The mixture was refluxed for four h before it was cooled to room temperature. The solvent was reduced by rotary evaporation and the precipitate that formed was filtered by suction, washed with diethylether and dried in a desiccator. Crystals suitable for X-ray diffraction were obtained by dissolving the compound in a mixture of methanol and dichloromethane and layering the solution with diethyl ether. The yield was 2.60 g (62%

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The H atoms were positioned geometrically and allowed to ride on their parent atoms, with C-H = ranging from 0.93 to 0.98 Å and U iso (H) = xU eq (C), where x = 1.5 for methyl H atoms and 1.2 for all other C-bound H atoms. The dichloromethane and diethyl ether solvate molecules were disordered. One of the dichloromethane solvate molecules was disordered over three orientations with occupancies of 0.529 (3), 0.344 (3), and 0.127 (2) and was refined through the use of SAME and SIMU commands. The diethyl ether molecule was disordered over two conformations and in addition there was a dichloromethane molecule in the same vicinity. The diethyl ether molecule was treated as being disordered and was refined with restraints to have similar metrical parameters using the SAME command. The occupancies of the two diethyl ether conformers [0.725 (3), 0.179 (3)], and the adjacent dicholormethane molecule [0.0962 (18)] was summed to 1 through the use of the SUMP command. The displacement parameters of similar disordered species were restrained through the use of SIMU commands. Computer programs: CrysAlis PRO (Agilent 2012), SHELXS97 and SHELXTL (Sheldrick, 2008) and SHELXL2016 (Sheldrick, 2015). Table 1 Hydrogen-bond geometry (Å , ).   (Sheldrick, 2008); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.74 e Å −3 Δρ min = −0.78 e Å −3 Extinction correction: SHELXL2016 (Sheldrick, 2015), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.00127 (15) 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.