Poly[[μ-N,N′-bis­(2-hy­droxy­eth­yl)-N,N,N′,N′-tetra­methyl­propane-1,3-diaminium-κ2 O:O′]tetra-μ-bromido-dibromidodimanganese(II)]

Heikki Rinta; Anssi Peuronen; Manu Lahtinen

doi:10.1107/S1600536812044765

. 2012 Nov 3;68(Pt 12):m1453–m1454. doi: 10.1107/S1600536812044765

Poly[[μ-N,N′-bis(2-hydroxyethyl)-N,N,N′,N′-tetramethylpropane-1,3-diaminium-κ² O:O′]tetra-μ-bromido-dibromidodimanganese(II)]

Heikki Rinta ^a, Anssi Peuronen ^a, Manu Lahtinen ^a,^*

PMCID: PMC3588717 PMID: 23468682

Abstract

The asymmetric unit of the title three-dimensional coordination polymer, [Mn₂Br₆(C₁₁H₂₈N₂O₂)]_n, consists of one Mn^II cation, half of a dicationic N,N′-bis(2-hydroxyethyl)-N,N,N′,N′-tetramethylpropane-1,3-diaminium ligand (L) (the other half being generated by a twofold rotation axis), and three bromide ions. The Mn^II cation is coordinated by a single L ligand via the hydroxy O atom and by five bromide ions, resulting in a distorted octahedral MnBr₅O coordination geometry. Four of the bromide ions are bridging to two adjacent Mn^II atoms, thereby forming polymeric chains along the a and b axes. The L units act as links between neighbouring Mn—(μ-Br)₂—Mn chains, also forming a polymeric continuum along the c axis, which completes the formation of a three-dimensional network. Classical O—H⋯Br hydrogen bonds are present. The distance between adjacent Mn^II atoms is 4.022 (1) Å.

Related literature

For related structures of M ^II transition metal halide one-dimensional coordination polymers, see: Han et al. (2012 ▶); Englert & Schiffers (2006 ▶). For two-dimensional networks, see: Hu & Englert (2006 ▶); Turgunov et al. (2011 ▶). For properties of metal halides, see: Hitchcock et al. (2003 ▶); Wang et al. (2011 ▶). For ligand conformations, see: Kärnä et al. (2010 ▶).

Experimental

Crystal data

[Mn₂Br₆(C₁₁H₂₈N₂O₂)]
M _r = 809.69
Tetragonal,
a = 8.0163 (4) Å
c = 35.3103 (18) Å
V = 2269.1 (2) Å³
Z = 4
Mo Kα radiation
μ = 11.69 mm⁻¹
T = 123 K
0.25 × 0.25 × 0.20 mm

Data collection

Bruker–NoniusKappa APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a ▶) T _min = 0.440, T _max = 0.746
5076 measured reflections
1966 independent reflections
1856 reflections with I > 2σ(I)
R _int = 0.032

Refinement

R[F ² > 2σ(F ²)] = 0.021
wR(F ²) = 0.047
S = 1.02
1966 reflections
111 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.41 e Å⁻³
Absolute structure: Flack (1983 ▶), 690 Friedel pairs
Flack parameter: 0.048 (14)

Data collection: COLLECT (Bruker, 2008 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b ▶); molecular graphics: Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Click here for additional data file.^{(21.1KB, cif)}

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812044765/fj2604sup1.cif

e-68-m1453-sup1.cif^{(21.1KB, cif)}

Click here for additional data file.^{(94.9KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812044765/fj2604Isup2.hkl

e-68-m1453-Isup2.hkl^{(94.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯Br3ⁱ	0.75 (2)	2.49 (2)	3.232 (3)	175 (5)

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Symmetry code: (i) Inline graphic .

Acknowledgments

The financial support of University of Jyväskylä is gratefully acknowledged.

supplementary crystallographic information

Comment

Solid state chemistry of metal halides has been widely studied in order to improve various magnetic and non-linear optical applications. In the crystal structure of the type MX₄L₂, the bridging qualities of the halide anions and the coordination properties of the organic ligands result in various polymeric structures. For example, one-dimensional M-(µ-X)₂—M bridged chains with low-dimensional arrangement have more suitable magnetic properties than classic structures of layered metal halide salts (Han et al. 2012; Wang et al. 2011 and Hitchcock et al. 2003).

The title compound, [Mn^II(µ-Br)₂µ-(C₁₁H₂₈N₂O₂)Br]_n, crystallizes in a tetragonal P4₃2₁2 crystal system showing one Mn^II cation, half of a dicationic [C₁₁H₂₈N₂O₂]²⁺ ligand (L) and three bromide anions in an asymmetric unit (Fig. 1). In this three-dimensional polymer each Mn^II cation is coordinated by four bridging bromo anions in the equatorial plane. A single terminal bromo anion and a ligand are located in the axial positions of the distorted octahedron showing axial Br3—Mn1—O1 angle of 174.03 (8)°. The three-dimensional network structure comprises two alternating crossed Mn-(µ-Br)₂—Mn chains (a- and b-axes) and an undulated L—Mn-(µ-Br)₂—Mn—L chain (c-axis). Distances between parallel Mn-(µ-Br)₂—Mn chains (planes through Mn -centres) are about 17.656 Å and between anti-parallel chains 8.7825 Å. This allows a formation of a structure model having alternating organic cation and a metal halide layers along c-axis (Figures 2 & 3).

In Mn^II cation coordination environment, the terminal Br^- anion fulfills the coordination of the Mn^II cation to octahedral MnBr₅O. The metal–metal distance along the resulting chain of octahedra is 4.022 (1) Å. All the equatorial Mn—Br bridge bond distances are almost identical but still somewhat longer than the axial Mn1—Br3 bond. The bridging bromides and the adjacent Mn -centers form folded square-planar geometry, showing nearly orthogonal contact angle of 94.05 (2)° via Mn4—Br2- Mn4 atoms, and torsion angle of 12.82 (2)° through Mn4—Br2—Mn4—Br1 atoms.

In the structure, the ligands are in S-shaped conformation between the anti-parallel Mn-(µ-Br)₂—Mn chains (Fig. 4). It seems that S-conformation is an ideal conformation for this type of relatively flexible ditopic ligand (Kärnä et al. 2010). The torsion angle C2—N4—N4—C2 is 156.70°. Similar cation conformations are found in ion pair structures [Zn^IIBr₄(C₁₁H₂₈N₂O₂)] and (C₁₁H₂₈N₂O₂) Br₂ H₂O.

Classical Br3···H–O1 hydrogen bonds are present in the Mn^II cation coordination environment between the terminal Br^- anions of Mn^II cation and the hydroxyl group of the neighboring metal center (Fig. 5). Hence, it seems likely that in the parent complex the hydrogen bonding steers the oxygen's coordination to the Mn^II cation. Weak interactions between O1 and halide bridge on the other side of Br1 and Br2 leads to distortions of chains torsion angle. The angle between the Mn1—Br1—Br2 and Mn1—Br1—Br2 planes is 162.6°. For this reason, Mn-(µ-Br)₂—Mn chains zigzag-conformation (Fig. 6).

Experimental

The single crystals of the title compound were obtained in the following two steps: First, dicationic bromide salt, as the precursor, was synthesized in 30 ml of acetone by reacting 2.20 ml (13.15 mmol) of TMPDA, C₇H₁₈N₂, and 2.16 ml (28.93 mmol) of 2-bromo-1-ethanol, C₂H₅BrO, for 48 h at 60 °C in a sealed flask. After removing the solvent, the white precipitation was washed by acetone and dried in vacuo (yield 71.6%; 3.58 g).

¹H-NMR (DMSO, 250 MHz, p.p.m.): 2.08–2.32 (2H, m, CH₂—CH₂-CH₂), 3.16 (12H, s, N—CH₃), 3.31 (2H, s, H₂O), 3.37–3.43 (4H, t, HO—CH₂—CH₂-N), 3.48–3.52 (4H, t, N—CH₂-CH₂—CH₂-N), 3.84 (4H, s, CH₂-OH), 5.29–5.33 (2H, t, OH)

Second, the precursor salt and the dried MnBr₂ 4H₂O (molar ratio ~1:1.5) were dissolved separately in minimum volume of warm methanol before combining the solutions. The title compound was synthesized in an open flask by metathesis reaction of the two aforementioned salts. The combined solution was stirred for about 1 h at 40 °C after which it was slowly cooled to RT and methanol was allowed to evaporate slowly. After several days, purple crystals suitable for X-ray analysis were formed.