Crystal structure of bis(1,3-bis{[(1H-pyrrol-2-yl)methylidene]amino-κN}propan-2-olato-κO)manganese(III) nitrate methanol monosolvate

The MnIII ion in the title compound shows a slightly distorted octahedral coordination geometry with two O and four N atoms of the pyrrolyl derivative ligand. In the crystal, intermolecular N—H⋯O hydrogen bonds between the pyrrole group of the ligand and the uncoordinated nitrate ion give a chain structure along [10].

The asymmetric unit of the title compound, [Mn(C 13 H 15 N 4 O) 2 ]NO 3 ÁCH 3 OH, contains two independent complex cations, in each of which the Mn III ion is located on an inversion centre. The Mn III ion is coordinated by four N and two O atoms from two 1,3-bis{[(1H-pyrrol-2-yl)methylidene]amino}propan-2-olate ligands, resulting in a distorted octahedral geometry. The average Mn-ligand bond lengths in the two complex molecules are 2.074 and 2.079 Å . In the crystal, intermolecular N-HÁ Á ÁO hydrogen bonds between the pyrrole group of the ligand and the non-coordinating nitrate ion give rise to a chain structure along [101]. The methanol solvent molecule and the nitrate ion are connected by an O-HÁ Á ÁO hydrogen bond.

Chemical context
Pyrrolyl derivatives ligands have attracted considerable attention in chemistry and materials science because they can easily be used for the preparation of multifunctional metal complexes with various transition metal ions. These complexes have potential applications in catalysis, and as luminescent materials (Goff & Cosnier, 2011). For example, a Cr I,III complex with a 2,5-dimethylpyrrole ligand has been investigated as a potential ethylene trimerization catalyst (Yang et al., 2014). Furthermore, zinc complexes containing various pyrrolyl substituents exhibit excellent luminescence properties due to the n-* transitions in the electronic spectra of the pyrrolyl ligand precursors (Gomes et al., 2009). Here, we report the synthesis and the crystal structure of an Mn III complex with the metal octahedrally coordinated by two anions of 1,3-bis{[(1H-pyrrol-2-yl)methylidene]amino}propan-2-ol (Hbpmap), the title compound [Mn(bpmap) 2 ]-NO 3 ÁCH 3 OH.

Structural commentary
The title compound crystallizes with two crystallographically independent complex molecules in the asymmetric unit ( Fig. 1). Each Mn III ion is located on an inversion centre and is six-coordinated in a distorted octahedral geometry. Two bpmap ligands are coordinated to the Mn III ion in a tridentate and fac-type manner (Berends et al., 2012). That is, one O atom and one imine N of each bpmap ligand occupy in the equatorial plane and the other imine N atom is in the axial position. The pyrrole groups of both ligands are noncoordinating. Interestingly, the geometry of pyrrole groups, which results from different bpmap ligands, displays a trans conformation in the axial positions (Jeong et al., 2014). The average equatorial bond lengths, Mn1-L eq and Mn2-L eq , are 1.952 and 1.918 Å , respectively. The axial bond lengths, Mn1-N2 and Mn2-N6, are 2.318 (3) and 2.345 (3) Å , respectively. The axial bond lengths are much longer than the equatorial bond lengths, which can be attributed to a rather large Jahn-Teller distortion of the Mn III ion (Halcrow, 2013). The bite distance (O1Á Á ÁN2) and the bite angle (N2-Mn1-O1) of the five-membered chelate ring are 2.590 (4) Å and 83.07 (10) , respectively, while O2Á Á ÁN6 and O2-Mn2-N6 are 2.715 (3) Å and 79.26 (9) . There are intramolecular N-HÁ Á ÁO hydrogen bonds between the pyrrole groups and the O atoms of the bpmap ligands ( Fig. 1 and Table 1).

Supramolecular features
The packing in the structure involves N-HÁ Á ÁO hydrogen bonds between the pyrrole groups and the non-coordinating nitrate anions (Table 1), giving chains along [101]. The hydroxy group of methanol and the nitrate ion are also connected by an O-HÁ Á ÁO hydrogen bond (Fig. 2).

Database survey
A search of the Cambridge Structural Database (Version 5.35, November 2013 with 3 updates; Allen, 2002) indicates that only one Cu II complex with the bpmap ligand has been reported (Borer & Sinn, 1998). This paper elucidates the synthesis of various pyrrole, imidazole, and salicylaldehyde derivatives and investigates the magnetic properties and chelating effects of Cu complexes.

Figure 2
A view of the crystal packing structure of the title compound, with N-HÁ Á ÁO hydrogen bonds drawn as red (intramolecular)

Refinement
Crystal data, data collection and structure refinement details are summarized in