supporting information

Acta Cryst. (2013). E69, o1711    [ doi:10.1107/S1600536813028754 ]

(2R,2'S)-2,2'-Bi­piperidine-1,1'-diium dibromide

G. Yang, B. C. Noll and E. V. Rybak-Akimova

CCDC reference: 967455

Abstract top

The title compound, C10H22N22+·2Br-, was synthesized via reduction of 2,2'-dipyridyl with Ni-Al alloy/KOH, followed by separation of diastereoisomers (meso and rac) by recrystallization from ethanol. Although the two bridging C atoms are optically active, these two chiral centers adopt an (S,R) configuration; thus, the title compound contains an achiral meso form of 2,2'-bi­piperidine. Both of the piperidinium rings adopt chair conformations, and the two N atoms are trans to each other; an inversion center is located in the mid-point of the central C-C bond. The conformation of the organic moiety resembles that of 1,1'-bi(cyclo­hexa­ne). The organic di­ammonium cations are linked to each other through hydrogen bonding with bromide counter-ions, each of which forms two hydrogen bonds (N-H...Br) with two adjacent organic cations, thus linking the latter together in sheets parallel to (100).

Comment top

N-substituted 2-picolyl derivatives of the title compound, and related tetradentate aminopyridine ligands (Mikhalyova et al., 2012; Lyakin et al., 2012), in the form of Fe(II) and Mn(II) complexes, are good catalysts for selective olefin epoxidation, as well as aromatic or aliphatic hydroxylation reactions, with peroxides or peracids as oxidants. Rigid cyclic diamine scaffolds increase thermodynamic and kinetic stability of the catalysts and orient picolyl groups in the pseudo-octahedral complexes which also contain two labile solvent-occupied sites essential for hydrogen peroxide activation (Mikhalyova et al., 2012). Understanding the molecular structure of these diamine scaffolds is important for catalyst design.

The title compound, which consists of organic diammonium cations and bromide counteranions (Figure 1), crystallizes in the monoclinic space group C2/c. The structure of the organic moiety resembles that of 1,1'-bi(cyclohexane), with both piperidinium rings adopting chair conformations. Two nitrogen atoms are trans to each other. The least square planes passing through the heavy (non-hydrogen) atoms of the two piperidinium rings in the centrosymmetric molecule are coplanar. This conformation differs from the twisted orientation of the piperidinium rings in the racemic isomer of the title compound (the angle between their least-square planes was found to be 77 °) (Laars et al., 2011). Two stereocenters (bridging carbon atoms, C1 and C1') adopt different configurations (R and S, respectively) and are symmetry-related. The centrosymmetric meso form of C10H22N2Br2 described herein is achiral.

The organic diammonium cations are linked to each other through hydrogen bonding with bromide counter ions, each of which forms two hydrogen bonds (N—H···Br) with two adjacent organic cations, thus linking the latter together in sheets parallel to the (100) plane (Figure 2).

Related literature top

For more details about synthetic and characterization methods, see: Denmark et al. (2006); Herrmann et al. (2006). For the chemistry of related complexes, see: Mikhalyova et al. (2012); Lyakin et al. (2012). For a related structure (the racemic isomer of the title compound), see: Laars et al. (2011).

Experimental top

The synthesis of the title compound followed the procedure published by Herrmann et al. (2006). 2,2'-Dipyridyl (8.25g, 0.053mol, in 100ml methanol) was mixed with 3M aqueous solution of KOH (16.8g, 0.3mol); Raney type Ni/Al alloy (1:1, v/v, 30g) was then added in portions and this mixture was stirred and refluxed for 4 days. The solution was separated from nickel mud, concentrated and extracted with 15ml dichloromethane (DCM) 3 times. The combined DCM extracts were evaporated to a faint yellow oil, which was then dissolved in 20ml ethanol. 9 ml of concentrated hydrobromic acid were added dropwise into the ethanolic solution; clear colorless hexagonal plate crystals of meso-C10H22N2Br2 were formed upon slow evaporation of the solution (one of these crystals was selected for X-Ray diffraction analysis).

Further evaporation (no less than 5ml) of the solvent liberated additional amount of meso-C10H22N2Br2. Yield: 6.2g (35%). More meso-C10H22N2Br2 was obtained by separation of meso- and rac-diastereomers of C10H22N2Br2 (from the remaining ethanolic solution) according to W.A. Herrmann et al. (2006) in 55% recovery. 1H NMR (500 MHz, D2O): δ 1.64 (m, 6, CH2), 1.96 (d, J = 14.5 Hz, 2, CH2), 2.02 (d, J = 10.5 Hz, 2, CH2), 2.14 (d, J = 11.5Hz, 2, CH2), 3.11 (t, J = 13.0 Hz, 2, CH2), 3.45 (d, J = 8.5 Hz, 2, CH), 3.56 (d, J = 12.5 Hz, 2, CH2). 13C NMR (500 MHz, D2O): δ 21.26, 21.49, 24.99, 46.02, 58.12. IR νmax /cm-1: 2907, 2714, 2390, 1573, 1413, 1358, 1307, 1010, 901, 605.

Refinement top

Except where noted, hydrogen atoms were placed at calculated geometries and allowed to ride on the position of the parent atom. C–H distances were constrained to 1.00 Å for tertiary CH groups and to 0.99 Å for methylene groups (CH2). Isotropic thermal parameters were set to 1.2× the equivalent isotropic thermal parameter of the parent atom. Hydrogens H1A and H1B, bound to N1, were located in difference density Fourier synthesis maps. The positions of these two H atoms were freely refined. Isotropic thermal parameters for H1A and H1B were set to 1.2× the equivalent isotropic U of N1.

Computing details top

Data collection: APEX2 and Bruker Instrument Service (Bruker, 2013); cell refinement: SAINT (Bruker, 2011); data reduction: SAINT (Bruker, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures top
[Figure 1] Fig. 1. A view of the title compound, with displacement ellipsoids shown at the 50% probability level. Symmetry transformations used to generate equivalent atoms: (i) -x + 1/2, -y + 3/2, -z + 1.
[Figure 2] Fig. 2. A fragment of the packing diagram of the title compound, with displacement ellipsoids shown at the 50% probability level (H atoms, except H atoms attached to N1 atom, are omitted for clarity). Symmetry transformations used to generate equivalent atoms: (i) -x + 1, -y + 1, -z; (ii) x, -y + 1, z + 1/2; (iii) -x + 1/2, y, -z + 1/2.
(2R,2'S)-2,2'-Bipiperidine-1,1'-diium dibromide top
Crystal data top
C10H22N22+·2BrF(000) = 664
Mr = 330.11Dx = 1.698 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 17.9719 (9) ÅCell parameters from 8775 reflections
b = 9.7654 (5) Åθ = 2.3–31.5°
c = 7.3637 (3) ŵ = 6.25 mm1
β = 92.134 (1)°T = 100 K
V = 1291.45 (11) Å3Plate, clear colorless
Z = 40.55 × 0.23 × 0.10 mm
Data collection top
2155 independent reflections
Radiation source: sealed tube, Siemens KFFMO2K-901955 reflections with I > 2σ(I)
Curved graphite monochromatorRint = 0.021
ϕ and ω scansθmax = 31.5°, θmin = 2.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2012)
h = 2626
Tmin = 0.13, Tmax = 0.57k = 1412
12426 measured reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.018Hydrogen site location: mixed
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.11 w = 1/[σ2(Fo2) + (0.0237P)2 + 0.7137P]
where P = (Fo2 + 2Fc2)/3
2155 reflections(Δ/σ)max = 0.001
70 parametersΔρmax = 0.88 e Å3
0 restraintsΔρmin = 0.24 e Å3
Crystal data top
C10H22N22+·2BrV = 1291.45 (11) Å3
Mr = 330.11Z = 4
Monoclinic, C2/cMo Kα radiation
a = 17.9719 (9) ŵ = 6.25 mm1
b = 9.7654 (5) ÅT = 100 K
c = 7.3637 (3) Å0.55 × 0.23 × 0.10 mm
β = 92.134 (1)°
Data collection top
2155 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2012)
1955 reflections with I > 2σ(I)
Tmin = 0.13, Tmax = 0.57Rint = 0.021
12426 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0180 restraints
wR(F2) = 0.045H atoms treated by a mixture of independent and constrained refinement
S = 1.11Δρmax = 0.88 e Å3
2155 reflectionsΔρmin = 0.24 e Å3
70 parameters
Special details top

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.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
N10.15631 (5)0.83374 (10)0.52604 (14)0.00987 (17)
H1A0.1668 (8)0.9229 (17)0.500 (2)0.012*
H1B0.1566 (9)0.8270 (15)0.645 (2)0.012*
C10.21196 (6)0.73540 (11)0.45193 (15)0.00905 (18)
C20.18497 (6)0.58942 (11)0.48165 (17)0.0123 (2)
C30.10648 (6)0.56754 (12)0.40071 (17)0.0136 (2)
C40.05255 (6)0.66795 (12)0.48479 (17)0.0133 (2)
C50.07765 (6)0.81376 (12)0.45314 (16)0.0126 (2)
Br10.14264 (2)0.83601 (2)0.96230 (2)0.01383 (5)
Atomic displacement parameters (Å2) top
N10.0097 (4)0.0102 (4)0.0097 (4)0.0001 (3)0.0005 (3)0.0007 (3)
C10.0087 (4)0.0093 (4)0.0092 (4)0.0003 (4)0.0004 (3)0.0005 (4)
C20.0110 (5)0.0093 (5)0.0165 (5)0.0010 (4)0.0010 (4)0.0000 (4)
C30.0104 (5)0.0128 (5)0.0176 (5)0.0025 (4)0.0005 (4)0.0009 (4)
C40.0095 (5)0.0147 (5)0.0158 (5)0.0018 (4)0.0016 (4)0.0004 (4)
C50.0090 (5)0.0142 (5)0.0144 (5)0.0008 (4)0.0006 (4)0.0002 (4)
Br10.01971 (7)0.01159 (7)0.01027 (6)0.00222 (4)0.00163 (4)0.00018 (4)
Geometric parameters (Å, º) top
N1—C11.5036 (14)C2—H2B0.99
N1—C51.5060 (15)C3—C41.5260 (17)
N1—H1A0.913 (16)C3—H3A0.99
N1—H1B0.880 (18)C3—H3B0.99
C1—C21.5243 (16)C4—C51.5143 (16)
C1—C1i1.543 (2)C4—H4A0.99
C2—C31.5259 (16)C5—H5A0.99
C1—N1—C5114.59 (9)C2—C3—C4110.09 (9)
C1—N1—H1A112.7 (10)C2—C3—H3A109.6
C5—N1—H1A104.3 (10)C4—C3—H3A109.6
C1—N1—H1B109.6 (10)C2—C3—H3B109.6
C5—N1—H1B108.4 (11)C4—C3—H3B109.6
H1A—N1—H1B106.8 (13)H3A—C3—H3B108.2
N1—C1—C2109.01 (9)C5—C4—C3110.15 (9)
N1—C1—C1i107.79 (11)C5—C4—H4A109.6
C2—C1—C1i112.85 (11)C3—C4—H4A109.6
C1—C2—C3111.68 (9)N1—C5—C4110.36 (9)
C5—N1—C1—C254.03 (12)C1—C2—C3—C458.25 (13)
C5—N1—C1—C1i176.84 (11)C2—C3—C4—C558.08 (13)
N1—C1—C2—C354.76 (12)C1—N1—C5—C455.44 (12)
C1i—C1—C2—C3174.49 (11)C3—C4—C5—N155.86 (13)
Symmetry code: (i) x+1/2, y+3/2, z+1.
Hydrogen-bond geometry (Å, º) top
N1—H1A···Br1ii0.913 (16)2.408 (16)3.2670 (10)156.7 (13)
N1—H1B···Br10.880 (18)2.359 (18)3.2311 (10)170.9 (14)
Symmetry code: (ii) x, y+2, z1/2.
Hydrogen-bond geometry (Å, º) top
N1—H1A···Br1i0.913 (16)2.408 (16)3.2670 (10)156.7 (13)
N1—H1B···Br10.880 (18)2.359 (18)3.2311 (10)170.9 (14)
Symmetry code: (i) x, y+2, z1/2.
Acknowledgements top

This material is based upon work supported by the US Department of Energy, Office of Basic Energy Science, grant No. DE–FG02-06ER15799. X-ray diffraction instrumentation was purchased with the help of funding from the National Science Foundation (MRI CHE-1229426).