3,6-Diaza-octane-1,8-diaminium diiodide.

The asymmetric unit of the title salt, C(6)H(20)N(4) (2+)·2I(-), comprises half a 3,6-diaza-octane-1,8-diaminium dication plus an I(-) anion. The dications are symmetrical and lie across crystallographic centres of inversion. In the crystal, the ions form a network involving mainly weak N-H⋯I inter-molecular inter-actions: two H atoms of the ammonium group form inter-actions with two I(-) anions and the H atom of the secondary amine forms a weak inter-action with a third I(-) cation. The third ammonium H atom is hydrogen bonded to a secondary amine of an adjacent cation. The backbone of the cation does not form a uniformly trans chain, but is 'kinked' [C-N-C-C torsion angle = 71.5 (2)°], probably to accommodate the direct hydrogen bond between the ammonium group and the secondary amine in an adjacent cation.

Related literature

For the structure of a dihydrate of the title compound, together with its isostructural Cl− and Br− analogues, see Ilioudis et al. (2000 ▶).

Experimental

Crystal data

C6H20N4 2+·2I−

M = 402.06

Orthorhombic,

a = 8.1253 (2) Å

b = 8.6138 (2) Å

c = 18.9368 (4) Å

V = 1325.38 (5) Å3

Z = 4

Mo Kα radiation

μ = 4.71 mm−1

T = 180 K

0.14 × 0.10 × 0.07 mm

Data collection

Nonius KappaCCD diffractometer

Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T min = 0.688, T max = 0.820

13267 measured reflections

2635 independent reflections

1905 reflections with I > 2σ(I)

R int = 0.042

Refinement

R[F 2 > 2σ(F 2)] = 0.023

wR(F 2) = 0.053

S = 0.97

2635 reflections

67 parameters

1 restraint

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.55 e Å−3

Δρmin = −1.05 e Å−3

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶), SCALEPACK and SORTAV (Blessing, 1995 ▶); program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶), POV-RAY (Cason, 2004 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536812030127/jj2132sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812030127/jj2132Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536812030127/jj2132Isup3.cml

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

C6H20N42+·2I−	F(000) = 760
Mr = 402.06	Dx = 2.015 Mg m−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 8314 reflections
a = 8.1253 (2) Å	θ = 1.0–33.7°
b = 8.6138 (2) Å	µ = 4.71 mm−1
c = 18.9368 (4) Å	T = 180 K
V = 1325.38 (5) Å3	Block, colourless
Z = 4	0.14 × 0.10 × 0.07 mm

Nonius KappaCCD diffractometer	2635 independent reflections
Radiation source: fine-focus sealed tube	1905 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
Thin slice ω and φ scans	θmax = 33.7°, θmin = 3.6°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −12→12
Tmin = 0.688, Tmax = 0.820	k = −13→13
13267 measured reflections	l = −29→29

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)] = 0.023	Hydrogen site location: difference Fourier map
wR(F2) = 0.053	H atoms treated by a mixture of independent and constrained refinement
S = 0.97	w = 1/[σ2(Fo2) + (0.0251P)2] where P = (Fo2 + 2Fc2)/3
2635 reflections	(Δ/σ)max = 0.002
67 parameters	Δρmax = 0.55 e Å−3
1 restraint	Δρmin = −1.05 e Å−3
0 constraints

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
I1	0.151716 (14)	0.140690 (14)	0.149443 (6)	0.03028 (5)
N1	0.07593 (17)	0.28497 (19)	0.32351 (8)	0.0259 (3)
H1A	0.063 (2)	0.258 (2)	0.2810 (11)	0.031*
H1B	−0.012 (3)	0.349 (2)	0.3373 (10)	0.031*
H1C	0.093 (3)	0.175 (3)	0.3520 (9)	0.031*
C2	0.2280 (2)	0.37794 (18)	0.32818 (10)	0.0273 (4)
H2A	0.2138	0.4755	0.3012	0.033*
H2B	0.3201	0.3194	0.3067	0.033*
C3	0.2694 (2)	0.4159 (2)	0.40401 (8)	0.0282 (3)
H3A	0.1759	0.4707	0.4264	0.034*
H3B	0.2901	0.3190	0.4307	0.034*
N4	0.41655 (16)	0.51470 (17)	0.40564 (7)	0.0241 (3)
H4	0.4916 (18)	0.465 (2)	0.3862 (10)	0.029*
C5	0.4643 (2)	0.5645 (2)	0.47735 (8)	0.0277 (3)
H5A	0.3663	0.6076	0.5014	0.033*
H5B	0.5467	0.6488	0.4734	0.033*

	U11	U22	U33	U12	U13	U23
I1	0.02627 (7)	0.02885 (7)	0.03570 (8)	−0.00126 (4)	0.00130 (4)	0.00008 (4)
N1	0.0236 (7)	0.0278 (8)	0.0264 (7)	−0.0015 (6)	−0.0020 (6)	0.0004 (6)
C2	0.0240 (8)	0.0330 (10)	0.0249 (8)	−0.0035 (7)	−0.0018 (6)	0.0000 (6)
C3	0.0270 (8)	0.0331 (9)	0.0245 (8)	−0.0044 (7)	−0.0020 (6)	0.0020 (6)
N4	0.0219 (6)	0.0265 (7)	0.0238 (6)	−0.0007 (5)	−0.0013 (5)	−0.0011 (5)
C5	0.0305 (8)	0.0253 (9)	0.0271 (8)	0.0005 (7)	−0.0045 (7)	−0.0004 (6)

N1—C2	1.475 (2)	C3—H3A	0.9900
N1—H1A	0.846 (19)	C3—H3B	0.9900
N1—H1B	0.94 (2)	N4—C5	1.476 (2)
N1—H1C	1.10 (2)	N4—H4	0.833 (14)
C2—C3	1.511 (2)	C5—C5i	1.519 (3)
C2—H2A	0.9900	C5—H5A	0.9900
C2—H2B	0.9900	C5—H5B	0.9900
C3—N4	1.467 (2)
C2—N1—H1A	108.2 (13)	C2—C3—H3A	109.9
C2—N1—H1B	107.8 (12)	N4—C3—H3B	109.9
H1A—N1—H1B	109.4 (17)	C2—C3—H3B	109.9
C2—N1—H1C	109.6 (13)	H3A—C3—H3B	108.3
H1A—N1—H1C	104.0 (16)	C3—N4—C5	113.71 (12)
H1B—N1—H1C	117.5 (16)	C3—N4—H4	106.6 (13)
N1—C2—C3	111.17 (15)	C5—N4—H4	111.4 (13)
N1—C2—H2A	109.4	N4—C5—C5i	114.02 (18)
C3—C2—H2A	109.4	N4—C5—H5A	108.7
N1—C2—H2B	109.4	C5i—C5—H5A	108.7
C3—C2—H2B	109.4	N4—C5—H5B	108.7
H2A—C2—H2B	108.0	C5i—C5—H5B	108.7
N4—C3—C2	109.09 (13)	H5A—C5—H5B	107.6
N4—C3—H3A	109.9
N1—C2—C3—N4	−177.22 (14)	C3—N4—C5—C5i	71.5 (2)
C2—C3—N4—C5	177.58 (13)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1C···N4ii	1.10 (2)	1.71 (2)	2.800 (2)	168.3 (19)
N1—H1A···I1	0.846 (19)	2.78 (2)	3.5761 (16)	157.2 (16)
N1—H1B···I1iii	0.94 (2)	2.77 (2)	3.6156 (16)	150.1 (16)
N4—H4···I1iv	0.83 (1)	3.15 (2)	3.8882 (14)	149 (2)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1C⋯N4i	1.10 (2)	1.71 (2)	2.800 (2)	168.3 (19)
N1—H1A⋯I1	0.846 (19)	2.78 (2)	3.5761 (16)	157.2 (16)
N1—H1B⋯I1ii	0.94 (2)	2.77 (2)	3.6156 (16)	150.1 (16)
N4—H4⋯I1iii	0.83 (1)	3.15 (2)	3.8882 (14)	149 (2)

Symmetry codes: (i) ; (ii) ; (iii) .