Nitrato(5,10,15,20-tetraphenylporphinato)manganese(III)–benzene–n-hexane (2/1/1)

The central manganese(III) atom has a distorted square-pyramidal coordination environment, defined by the porphyrin N atoms in the basal plane and a nitrate O atom in the apical site.

The crystal structure of solvated [Mn(TPP)(NO 3 )] (TPP = 5,10,15,C 44 H 28 N 4 ), [Mn(C 44 H 28 N 4 O 3 )(NO 3 )]Á0.5C 6 H 14 Á0.5C 6 H 6 , has been determined in the space group Pccn. The Mn III atom has a distorted square-pyramidal environment, being coordinated by four pyrrole N atoms of the porphyrin ligand in the basal plane and an O atom of the nitrato ligand in the apical site. The Mn III atom is displaced out of the porphyrin plane by 0.22 (4) Å with the average Mn-Np distance being 2.011 (6) Å (where Np is a porphyrin N atom). The Mn-O bond length is 2.1246 (18) Å . Two kinds of intermolecular C-HÁ Á ÁO hydrogen bonds exist in the crystal structure, with the apical nitrato ligands interacting with solvent molecules and adjacent molecules, respectively.
In the crystal structure of the title five-coordinate manganese(III) nitrate complex (Fig. 1), the asymmetric unit contains one porphyrin molecule, half of a benzene solvate molecule, and half of an n-hexane solvate molecule. The Mn1 III atom has a distorted square-pyramidal environment, defined by the four pyrrole N atoms of the porphyrin ligand in the basal plane and an O atom of the nitrato ligand in the apical site. Additional quantitative information about the structure is given in Fig. 2, which includes the displacement of each porphyrin core atom (in units of 0.01 Å ) from the 24atom mean plane. Averaged values of the chemically unique bond lengths (in Å ) and angles (in ) are also shown. The Table 1 Selected structural parameters (Å ) for related metalloporphyrin nitrato complexes. Á 4 is the displacement of the metal atom from the mean plane of the four pyrrole nitrogen atoms and Á 24 is the displacement of the metal atom from the 24-atom mean plane.
[   The molecular structure of the title compound, drawn with displacement ellipsoids at the 50% probability level. Only one of the two orientations of the disordered benzene solvate molecules is shown. [Symmetry code: (i) Àx + 1 2 , Ày + 1 2 , z.] mean absolute core-atom displacements of C a , C b , C m and C av are 0.11 (2), 0.28 (3), 0.04 (2) and 0.16 (10) Å , respectively, and the monodentate nitrato ligand forms a dihedral angle of 43.69 (13) with the plane defined by the Mn1, N3 and O1 atoms.
The porphyrin core shows a characteristic saddle-shaped distortion and the Mn1 III atom is displaced by 0.22 (4) Å from the 24-atom porphyrin plane in the direction of the nitrato ligand. This value is smaller than the displacement of the iron atom (0.63 Å ) in [Fe(TPP)(NO) 3 ] reported by Wyllie et al. (2007). This difference is explained by the high-spin configuration of 3d 5 Fe III where the occupied d (x2-y2) orbital 'pushes' the metal out of the porphyrin plane, and the empty d (x2-y2) orbital of 3d 4 Mn III allows a more in-plane conformation (Suslick & Watson, 1991).
In the title compound, C-HÁ Á ÁO hydrogen-bonding interactions are found between the disordered benzene solvent molecule (C4S) and the apical nitrato ligand (O3), as illustrated in Fig. 3 and detailed in Table 2. Similar hydrogen bonds are also found between the apical ligand and phenyl rings of adjacent porphyrin molecules (Fig. 4, Table 2). All these structural parameters are consistent with literature data where C-HÁ Á ÁO bonds range from 3.00-4.00 Å (Desiraju, 1996), with angles of 120-180 (Steiner & Desiraju, 1998). The molecular packing of the title compound is shown in Fig. 5.

Synthesis and crystallization
General information. All experimental manipulations were performed under a purified nitrogen atmosphere using Schlenk techniques. Except for the solvent used in column chromatography, all solvents used in the experimental process were treated under dry conditions and exclusion of oxygen. Benzene and n-hexane were distilled under argon protection, and then refluxed over sodium/benzophenone and potassiumsodium alloy, respectively. All solvents used in the anhydrous and anaerobic operation (Schlenk system) were treated with the pump-freeze-thaw method three times before use.
The title compound was obtained serendipitously in an unsuccessful attempt to isolate the five-coordinate manganese(II) nitrosyl species [Mn(TPP)(NO)]. [Mn(TPP)OH] was prepared according to a reported method (He et al., 2016). The purple [Mn(TPP)OH] powder (10 mg, 0.0015 mmol) was reduced by ethyl mercaptan for 48 h with benzene as solvent, then the solution was evaporated to dryness. NO gas was then bubbled slowly in a solution of the residue in degassed benzene for 5 minutes under an argon atmosphere. There was a dramatic color change from greenish yellow to red. The red solution was finally layered with hexanes. Black, block-shaped crystals were obtained several weeks later. C-HÁ Á ÁO hydrogen-bonding interactions between adjacent porphyrin molecules (dashed lines).

Figure 5
A view of the molecular packing of the title compound in the crystal structure, as seen in a projection along [100]. H atoms have been omitted for clarity. Table 2 Hydrogen-bond geometry (Å , ).

Figure 3
The C-HÁ Á ÁO interactions between the apical nitrato ligand and the benzene solvent molecule.  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.