catena-Poly[[manganese(III)-bis{μ-2-[(2-hydroxyethyl)iminomethyl]-6-methoxyphenolato-κ3 O 1,N:O 2;κ3 O 2:N,O 1}] iodide]

In the title one-dimensional coordination polymer, {[Mn(C10H12NO3)2]I}n, the potentially tetradentate (O,O,O,N) 2-[(2-hydroxyethyl)iminomethyl]-6-methoxyphenol (H2 L) ligands are mono-deprotonated (as HL −) and coordinated by the metal ions in a tridentate chelate-bridging fashion [2.0111112]. The MnIII atom possesses a distorted trans-MnO4N2 octahedral coordination environment. The bridging ligands lead to [010]-chain polymeric cations {[Mn(HL)2]+}n in the crystal. The charge-balancing iodide ions are disordered over two sites in a 0.690 (2):0.310 (2) ratio and a weak O—H⋯I hydrogen bond occurs. The crystal studied was found to be a racemic twin.


Experimental
Crystal data [Mn(C 10 H 12   Developing the "direct synthesis" approach (Babich et al., 1996;Vinogradova et al., 2002;Makhankova et al., 2002), our research group are now interested in the preparation of manganese-based heterometallic "salen-type" Schiff bases complexes as promising objects for search and production of new materials with useful properties. Synthesis from metal powders as reagents has been recently demonstrated to be an alternative and efficient way to similar Fe/Co complexes (Nesterov et al., 2012;Chygorin et al., 2012). But in some cases instead of heterometallic compounds we can obtain monometallic ones or a mixture of different compounds as more thermodinamically favorable products in selected conditions. Such a case is observed with the investigated system The total dissolution of metal powders was observed within 6 h resulting into intensive dark brown solution. The block brown crystalls precipitate after 24 h with 45% yield. Interestingly that the stechiometric system Mn 0 -{2(o-vanillin) -2(Hea)} -NH 4 I -CH 3 OH produces the same complex, but the dissolution of metal powders is longer (more than 7 h) and the yield is lower (26%).
The {[Mn(HL) 2 ]} n unit ( Fig.1) demonstrates the [O 4 N 2 ] coordination environment with a distorted octahedral geometry around the central atom. The metal assignment and its oxidation state were confirmed by considering coordination bond lengths, existence of Jahn-Teller elongation and bond valence sum calculation [BVS(Mn) = 3.07 (Brown & Altermatt, 1985)].
The one-dimensional polymeric structure of the crystal (Fig. 2) is realised by means of chelate-bridging function of the ligand, [2.01 1 1 1 1 2 ] by Harris notation (Coxall et al., 2000), which is firstly observed for H 2 L. Experimental 2-Aminoethanol (0.18 g, 3 mmol) and o-vanillin (0.457 g, 3 mmol) were added to 30 ml of methanol and stirred magnetically for 15 min until the colour of the solution turned in yellow. After manganese powder (0.055 g, 1 mmol), iron powder (0.058 g, 1 mmol) and NH 4 I (0.29 g, 2 mmol) were added to the solution, the reaction mixture was stirred at 50°C for ca 6 h. Almost total dissolution of metal powders was observed. Dark brown crystals that precipitated after 1 day were collected by filtration and dried in air; yield 45%. Elemental analysis for C 20 H 24 I 2 MnN 2 O 6 (Mr = 570.26). Calcd:

Refinement
All H atoms were placed in idealized positions (C-H = 0.93 -0.97 Å, O-H = 0.86 Å) and constrained to ride on their parent atoms, with U iso = 1.2Ueq (except U iso = 1.5Ueq for methyl and hydroxyl groups). It should be noted that the mean value of the |E 2 -1| is 0.816 and the structure can be solved in both polar (Pca2 1 ) and centrosymmetric (Pbca) groups, however, the R 1 value in the latter case is consistently higher (ca. 0.24) that in the former (less than 0.10), so the noncentrosymmetric space group is believed to be the correct choice. Flack parameter value (Flack, 1983) of 0.48 (5)  The asymmetric unit of (I) with 30% probability ellipsoids for non-H atoms. C-H hydrogen atoms are ommited for clarity. Iodide ion is disodered in two positions I1A and I1B with occupancy ratio 0.69:0.31, respectively.

Figure 2
Fragment of chain polymeric structure of (I).  Packing of (I) viewed down the (010) direction.

Special details
Experimental. Absorption correction: CrysAlis PRO (Agilent, 2011). Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.