rac-2,2'-Bipiperidine-1,1'-diium dibromide.

In the title compound, C(10)H(22)N(2) (2+)·2Br(-), a precursor in the synthesis of organocatalysts, the bipiperidinium ion is located on a twofold rotation axis which passes through the mid-point of the central C-C bond. The piperidinium ring adopts a chair conformation. In the crystal, the cations are linked together by Br(-) ions through N-H⋯Br hydrogen bonds, forming layers parallel to the ab plane.

Related literature

For the synthesis, see: Krumholz (1953 ▶); Herrmann et al. (2006 ▶). For the application of N-substituted enanti­opure derivatives of the title compound in organocatalysis, see: Laars et al. (2008 ▶). For details of the CuII–catalysed Henry reaction, see: Noole et al. (2010 ▶). For related structures, see: Sato et al. (1982 ▶); Baran et al. (1992a ▶,b ▶); Intini et al. (2008 ▶).

Experimental

Crystal data

C10H22N2 2+·2Br−

M = 330.12

Monoclinic,

a = 11.789 (2) Å

b = 10.6403 (18) Å

c = 11.6632 (17) Å

β = 107.687 (5)°

V = 1393.9 (4) Å3

Z = 4

Mo Kα radiation

μ = 5.79 mm−1

T = 300 K

0.40 × 0.30 × 0.20 mm

Data collection

Bruker SMART X2S diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T min = 0.151, T max = 0.391

4225 measured reflections

1225 independent reflections

1012 reflections with I > 2σ(I)

R int = 0.068

Refinement

R[F 2 > 2σ(F 2)] = 0.038

wR(F 2) = 0.093

S = 1.08

1224 reflections

70 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.47 e Å−3

Δρmin = −0.94 e Å−3

Data collection: GIS (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97.

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811016084/is2700sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811016084/is2700Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811016084/is2700Isup3.cml

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

C10H22N22+·2Br−	F(000) = 664
Mr = 330.12	Dx = 1.573 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1621 reflections
a = 11.789 (2) Å	θ = 2.6–24.9°
b = 10.6403 (18) Å	µ = 5.79 mm−1
c = 11.6632 (17) Å	T = 300 K
β = 107.687 (5)°	Prism, colourless
V = 1393.9 (4) Å3	0.40 × 0.30 × 0.20 mm
Z = 4

Bruker SMART X2S diffractometer	1225 independent reflections
Radiation source: XOS X-beam microfocus source	1012 reflections with I > 2σ(I)
doubly curved silicon crystal	Rint = 0.068
ω scans	θmax = 25.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −13→14
Tmin = 0.151, Tmax = 0.391	k = −12→12
4225 measured reflections	l = −13→13

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.093	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ2(Fo2) + (0.P)2 + 0.0285P] where P = (Fo2 + 2Fc2)/3
1224 reflections	(Δ/σ)max < 0.001
70 parameters	Δρmax = 0.47 e Å−3
0 restraints	Δρmin = −0.94 e Å−3

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 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 > σ(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.

	x	y	z	Uiso*/Ueq
Br1	0.19514 (3)	0.07309 (4)	0.77393 (4)	0.0429 (2)
N1	0.1066 (3)	0.1990 (3)	0.1590 (3)	0.0319 (7)
H1NA	0.156 (3)	0.271 (4)	0.183 (3)	0.038*
H1NB	0.146 (3)	0.132 (4)	0.202 (4)	0.038*
C1	−0.0106 (3)	0.2219 (3)	0.1814 (3)	0.0287 (8)
H1	−0.0630	0.1510	0.1473	0.034*
C2	−0.0661 (3)	0.3394 (4)	0.1136 (3)	0.0385 (9)
H2A	−0.1423	0.3553	0.1265	0.046*
H2B	−0.0148	0.4111	0.1438	0.046*
C3	−0.0836 (4)	0.3232 (5)	−0.0213 (4)	0.0524 (11)
H3A	−0.1393	0.2553	−0.0526	0.063*
H3B	−0.1169	0.3997	−0.0635	0.063*
C4	0.0349 (4)	0.2940 (4)	−0.0433 (3)	0.0489 (11)
H4A	0.0213	0.2782	−0.1284	0.059*
H4B	0.0872	0.3662	−0.0208	0.059*
C5	0.0944 (4)	0.1811 (4)	0.0280 (4)	0.0442 (10)
H5A	0.0474	0.1064	−0.0017	0.053*
H5B	0.1725	0.1694	0.0182	0.053*

	U11	U22	U33	U12	U13	U23
Br1	0.0502 (3)	0.0283 (3)	0.0495 (4)	−0.01100 (16)	0.0142 (3)	−0.00332 (18)
N1	0.0415 (17)	0.0201 (16)	0.0361 (19)	0.0024 (14)	0.0146 (16)	0.0033 (15)
C1	0.0344 (18)	0.0208 (18)	0.031 (2)	−0.0017 (15)	0.0101 (16)	−0.0031 (17)
C2	0.042 (2)	0.034 (2)	0.037 (2)	0.0072 (18)	0.0088 (19)	0.0033 (19)
C3	0.069 (3)	0.053 (3)	0.029 (2)	0.006 (2)	0.005 (2)	0.004 (2)
C4	0.075 (3)	0.044 (3)	0.031 (2)	−0.004 (2)	0.020 (2)	0.000 (2)
C5	0.068 (3)	0.033 (2)	0.040 (2)	−0.006 (2)	0.030 (2)	−0.012 (2)

N1—C1	1.501 (4)	C2—H2A	0.9700
N1—C5	1.503 (5)	C3—C4	1.528 (5)
N1—H1NB	0.92 (4)	C3—H3A	0.9700
N1—H1NA	0.95 (4)	C3—H3B	0.9700
C1—C2	1.517 (5)	C4—C5	1.508 (6)
C1—C1i	1.542 (6)	C4—H4A	0.9700
C1—H1	0.9800	C4—H4B	0.9700
C2—C3	1.533 (5)	C5—H5A	0.9700
C2—H2B	0.9700	C5—H5B	0.9700
C1—N1—C5	112.9 (3)	C4—C3—C2	110.5 (3)
C1—N1—H1NB	112 (2)	C4—C3—H3A	109.5
C5—N1—H1NB	110 (2)	C2—C3—H3A	109.5
C1—N1—H1NA	109 (2)	C4—C3—H3B	109.5
C5—N1—H1NA	106 (2)	C2—C3—H3B	109.5
H1NB—N1—H1NA	107 (3)	H3A—C3—H3B	108.1
N1—C1—C2	108.5 (3)	C5—C4—C3	111.4 (3)
N1—C1—C1i	108.3 (3)	C5—C4—H4A	109.3
C2—C1—C1i	116.7 (2)	C3—C4—H4A	109.3
N1—C1—H1	107.7	C5—C4—H4B	109.3
C2—C1—H1	107.7	C3—C4—H4B	109.3
C1i—C1—H1	107.7	H4A—C4—H4B	108.0
C1—C2—C3	110.2 (3)	N1—C5—C4	110.2 (3)
C1—C2—H2B	109.6	N1—C5—H5A	109.6
C3—C2—H2B	109.6	C4—C5—H5A	109.6
C1—C2—H2A	109.6	N1—C5—H5B	109.6
C3—C2—H2A	109.6	C4—C5—H5B	109.6
H2B—C2—H2A	108.1	H5A—C5—H5B	108.1

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1NA···Br1ii	0.95 (4)	2.36 (4)	3.293 (3)	168 (3)
N1—H1NB···Br1iii	0.92 (4)	2.34 (4)	3.228 (3)	162 (3)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1NA⋯Br1i	0.95 (4)	2.36 (4)	3.293 (3)	168 (3)
N1—H1NB⋯Br1ii	0.92 (4)	2.34 (4)	3.228 (3)	162 (3)

Symmetry codes: (i) ; (ii) .