catena-Poly[[diazidomanganese(II)]bis[μ-1-(4-pyridylmethyl)-1H-benzimidazole]]

In the title polymeric compound, [Mn(N3)2(C13H11N3)2]n, each MnII centre is six-coordinated in an octahedral geometry by six N atoms from four 1-(4-pyridylmethyl)-1H-benzimidazole (L) ligands and two azide anions (N3 −). Each of the MnII ions lies on an inversion centre. The L ligands and N3 − anions bridge adjacent MnII centres, generating a polymeric chain running along the [110] direction. Adjacent polymeric chains are arranged in a two-dimensional network parallel to the (001) plane, linked by C—H⋯N hydrogen bonds.

In the title polymeric compound, [Mn(N 3 ) 2 (C 13 H 11 N 3 ) 2 ] n , each Mn II centre is six-coordinated in an octahedral geometry by six N atoms from four 1-(4-pyridylmethyl)-1H-benzimidazole (L) ligands and two azide anions (N 3 À ). Each of the Mn II ions lies on an inversion centre. The L ligands and N 3 À anions bridge adjacent Mn II centres, generating a polymeric chain running along the [110] direction. Adjacent polymeric chains are arranged in a two-dimensional network parallel to the (001) plane, linked by C-HÁ Á ÁN hydrogen bonds.

catena-Poly[[diazidomanganese(II)]bis[µ-1-(4-pyridylmethyl)-1Hbenzimidazole]]
Chun-Sen Liu, Jun-Jie Wang and Li-Fen Yan S1. Comment N-containing heterocyclic aromatic compounds are extensively used as bridging ligands in coordination and metallosupramolecular chemistry (Steel, 2005). The most frequently used neutral bridging ligands are 4,4′-bipyridine and its derivatives (Kitagawa et al., 2004). In recent years, however, the benzimidazole groups also were used to link different alkyl or aromatic groups to form a series of bi-and multi-dentate flexible ligands, which can adopt different conformations according to the different geometric requirements of metal centers when forming metal complexes (Li et al., 2007). Many complexes with these ligands show unique structural topologies and interesting properties , such as three-dimensional and two-dimensional networks (Chang et al., 2005;Fan et al., 2006;Su et al., 2001) and one-dimensional helical chains . Recently, we found that Liu and co-workers synthesized a flexible bridging ligand 1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazole (L) as well as its chiral one-dimensional double helix polymer, [Ag(L)(NO 3 )] n (Huang et al., 2006). As such, we also used L as a µ 2 -bridging ligand to react with Mn II salt, meanwhile together with azido anion as a co-ligand, to obtain a one-dimensional manganese coordination polymer [Mn(C 13 H 11 N 3 ) 2 (N 3 ) 2 ] n (I). We report here the crystal structure of (I).
The title compound (I) consists of linear polymeric coordination chains containing only one kind of Mn II coordination environment (Fig. 1). The asymmetric unit of (I) is composed of one Mn II ion which lies on an inversion centre, one L ligand and one N 3anion (L is 1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazole). The geometry around each Mn II ion can be best described as a ideal octahedron (Fig. 1). The Mn II center is six-coordinated by six N atoms from four different L ligands and two N 3anions, respectively (Table 1). In the crystal structure of (I), L adopts µ 2 -bridging 4,4′-bipyridine-like coordination mode and N 3serves as a mono-terminal coordination mode [Mn1-N4: 2.2049 (13) Å], which together link the adjacent Mn II ions into a linear chain along the [1 1 0] direction, with the shortest intrachain non-bonding Mn···Mn separation being 9.725 (2) Å (Fig. 2).
In the crystal structure of (I), the adjacent one-dimensional chains [Mn(C 13 H 11 N 3 ) 2 (N 3 ) 2 ] n are arranged into a twodimensional network parallel to the (0 0 1) plane by interchain C-H···N hydrogen bonding interactions between the coordinated L ligands and N atoms of azido anions (see Fig. 3 and Table 2) (Desiraju et al., 1999).

S2. Experimental
The ligand 1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazole (L) was synthesized according to a method reported in the literature (Li et al., 2007). The reaction of L (58 mg, 0.2 mmol), NaN 3 (13 mg, 0.2 mmol) with Mn(ClO 4 ) 2 (25 mg, 0.1 mmol) in a mixed solution of methanol and aqua (v/v = 1:1, 10 ml) for a few minutes afforded a yellow solid, which was then filtered. The resulting solution was kept at room temperature. Yellow single crystals of compound (I) suitable for Xray analysis were obtained by slow evaporation of the solvent after several days (yield: 40%

S3. Refinement
H atoms were included in calculated positions and treated in the subsequent refinement as riding atoms, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C).

catena-Poly[[diazidomanganese(II)]bis[µ-1-(4-pyridylmethyl)-1H-benzimidazole]]
Crystal data 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.