Mononuclear and dinuclear bromide-nitrite cadmium(II) complexes with related 1,4-diaza­bicyclo­[2.2.2]octane ligands

The title compounds, di-[mu]-bromido-bis­[bromido(1-carb­oxy­methyl-4-aza-1-azoniabicyclo­[2.2.2]octane-[kappa]N⁴)(nitrito-[kappa]²O,O')cadmium(II)] dihydrate, [Cd₂Br₄(C₈H₁₅N₂O₂)₂(NO₂)₂]·2H₂O, (I), and aqua­bromido(1-cyano­methyl-4-aza-1-azoniabi­cy­clo­[2.2.2]octane-[kappa]N⁴)bis­(nitrito-[kappa]²O,O')cadmium(II) monohydrate, [CdBr(C₈H₁₄N₃)(NO₂)₂(H₂O)]·H₂O, (II), are two-dimensional hydrogen-bonded metal-organic hybrid com­plexes. In (I), the complex is situated on a centre of inversion so that each symmetry-related Cd^II atom is coordinated by two bridging Br atoms, one monodentate Br atom, one chelating nitrite ligand and one organic ligand, yielding a significantly distorted octa­hedral geometry. The combination of O-H...O and O-H...Br hydrogen bonds produces centrosymmetric R₆⁶(16) ring motifs, resulting in two-dimensional layers parallel to the ab plane. In contrast, the complex mol­ecule in (II) is mononuclear, with the Cd^II atom seven-coordinated by two bidentate nitrite groups, one N atom from the organic ligand, one monodentate Br atom and a water O atom in a distorted penta­gonal-bipyramidal environment. The combination of O-H...O and O-H...Br hydrogen bonds produces R₅⁴(14) and R₃³(8) rings which lead to two-dimensional layers parallel to the ac plane.

S1. Comment

Certain metal–organic hybrid materials are of interest for their electric properties, such as ferroelectricity, piezoelectricity and dielectricity (Planta & Unruh, 1993; Fu et al., 2008; Ye et al., 2009; Zhang et al., 2010). A large variety of multifunctional ligands, such as 1,2,4-triazine, carboxylates and bipyridyl, have been used in order to prepare new metal–organic hybrid materials. Extended structures of cadmium(II) nitrate–organic ligand materials have been reported (Marlin et al., 2006; Sharma & Clearfield, 2000; Lu et al., 2005), but cadmium(II) nitrite–organic ligand materials are very rare. Additionally, previous studies have reported that 1,4-diaza-bicyclo[2.2.2]octane (DABCO) derivatives can go through phase transitions (Zhang et al., 2009; Ye et al., 2010). As part of an exploration of new metal–organic hybrid materials, we produced a new DABCO derivative, namely 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide, and then obtained novel cadmium(II) complexes with this ligand and the related 1-carboxymethyl-4-aza-1-azoniabicyclo[2.2.2]octane ligand, together with nitrite and bromide.

Cadmium(II) complexes have rich coordination numbers and geometries because of the d¹⁰ configuration of the Cd^II ions. The structural diversity observed includes monomers (Choudhury et al., 2003), dimers (Fuhr & Fenske, 1999) and coordination polymers (Thorn et al., 2005). The title compounds are a cadmium(II) dimer with bromide bridges, di-µ-bromido-bis[bromido(1-carboxymethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κN⁴)(nitrito-κ²O,O')cadmium(II)] dihydrate, (I), and a cadmium(II) monomer, aquabromido(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane-κN⁴)bis(nitrito-κ²O,O')cadmium(II) monohydrate, (II), both of which are the first structurally examined cadmium complexes with these organic ligands.

Compound (I) consists of discrete neutral [Cd₂(1-carboxymethyl-4-aza-1-azoniabicyclo[2.2.2]octane)₂(µ₂-Br)₂Br₂(NO₂)₂] molecules and interstitial water molecules (Fig. 1). The dinuclear complex is distributed across a centre of inversion so that the asymmetric unit consists of one Cd^II cation, two bromide anions, one nitrite anion, one organic ligand and one lattice water molecule. Each Cd^II ion takes a sixfold coordination of two O atoms from a bidentate nitrite ion, one N atom from the organic ligand and three bromide ions, which can be regarded as a somewhat distorted octahedral coordination geometry. One of the three bromide ligands is monodentate, while the other two are bridging, thus producing a tetranuclear [Cd₂Br₂] dimeric unit. The two terminal bromide ligands are trans oriented with respect to the four-membered bridge ring, and the two bridging bromide ligands and two Cd^II ions form a rectangular plane whose centre is located on a crystallographic centre of inversion. The Cd₂Br₂ rings in reported cadmium(II) dimers (Pickardt & Staub, 1999) are almost square because the Cd^II atom only has one kind of ligand other than Br, while in (I) the Cd₂Br₂ ring is rectangular since there are two quite different ligands besides Br, resulting in asymmetry of the Cd—Br bonds (Table 1). A similar [Cd₂Br₂] unit with a terminal Br on each Cd has been observed previously in the compound di-µ-bromo-bis[bromo(di-2-pyridylmethanediol)cadmium(II)] trihydrate (Zhu et al., 2000). The Cd—O bond distances within the nitrite ligand are slightly shorter than the Cd—N distance, which is the opposite of what is observed in the related complex [Cd(pyterpy)(H₂O)(NO₃)₂] [pyterpy is 4'-(4-pyridyl)-2,2':6',2''-terpyridine; Granifo et al., 2004]. The two Br ligands and bidentate nitrite at the equatorial positions are almost coplanar, with a dihedral angle between the Cd1/Br1/Br2 and Cd1/O1/O2 planes of 7.33 (34)°. The apical N1—Cd1—Br1ⁱ angle [symmetry code: (i) -x, -y + 1, -z + 1] deviates only modestly from 180°.

Molecules are linked into two-dimensional sheets parallel to the crystallographic ab plane through O—H···Br and O—H···O interactions which also form centrosymmetric R₆⁶(16) rings (Fig. 2). Carboxyl atom O5 of the organic ligand forms one donor hydrogen bond with a monodentate Br ligand from an adjacent dimer and also one acceptor hydrogen bond with a water molecule from another adjacent dimer. The intermolecular O—H···Br hydrogen bonds (Table 2) serve to link the complexes into zigzag chains, some of which run along [110] and others along [110] depending on which layer one is in. Meanwhile, water molecules act as hydrogen-bond donors to O2 atoms of the coordinated nitrite. The hydrogen bonds produced by the water molecules extend the zigzag chains into two-dimensional hydrogen-bonded layers which then stack along [001], with no obvious interactions.

Although compound (II) has similar ligands, the structure of (II) is a Cd^II monomer with quite different coordination geometry. The Cd^II ion in (II) is seven-coordinate and the distorted pentagonal–bipyramidal coordination environment consists of one monodentate Br atom, one N atom of the organic ligand, four O atoms from two bidentate nitrite groups and one coordinated water molecule (Fig. 3). The asymmetric unit also includes one non-coordinated water molecule. The two coordinated nitrite groups at the equatorial positions are not coplanar, with a dihedral angle between the Cd1/O1/O2 and Cd1/O3/O4 planes of 12.70 (33)°, which is different from what is found in a related complex containing two nitrite ligands (Marandi et al., 2005), though the ligands at the apical positions in the two complexes are quite different.

While the molecular structures of the Cd complexes in (I) and (II) are dissimilar, they do have similar intermolecular interactions. For both complexes, the uncoordinated water molecule is decisive for the crystal packing. In (II), intermolecular O—H···Br hydrogen bonds link discrete neutral molecules into chains along the c axis (Fig. 4). The free water atom (O6) acts as a hydrogen-bond donor, via atoms H6WA and H6WB, respectively, to atoms O2ⁱⁱⁱ and Br1, and also as a hydrogen-bond acceptor with O5ⁱⁱ via atom H5WB [symmetry codes: (ii) x + 1, -y - 3/2, z + 1/2; (iii) x + 1, y, z]. The combination of the O—H···O and O—H···Br hydrogen bonds generates alternating R₅⁴(14) and R₃³(8) rings, resulting in two-dimensional layers parallel to ac plane.

Dielectric measurements of both compounds show no dielectric anomaly from 93 to 363 K, indicating no structural phase transitions in the measured temperature range.

Related literature

For related literature, see: Fu et al. (2008); Fuhr & Fenske (1999); Granifo et al. (2004); Lu et al. (2005); Marandi et al. (2005); Marlin et al. (2006); Planta & Unruh (1993); Sharma & Clearfield (2000); Thorn et al. (2005); Ye et al. (2010); Zhang et al. (2009, 2010); Zhu et al. (2000).

S2. Experimental

Bromoacetonitrile (0.1 mol, 12.00 g) was added to a CH₃CN solution of 1,4-diazabicyclo[2.2.2]octane (DABCO) (0.05 mol, 5.6 g) with stirring for 1 h at room temperature. 1-Cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide which quickly formed as a white solid was filtered off, washed with acetonitrile and dried (yield: 80%). The compounds (I) and (II) were prepared from aqueous solutions containing 1-carboxymethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide [for (I)], or 1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide [for (II)] (0.01 mol, 2.32 g), CdSO₄ (0.01 mol, 2.08 g), Ba(NO₂)₂ (0.01 mol, 2.29 g) and, additionally, imidazole (0.01 mol, 0.68 g) for (I). After removal of the precipitated BaSO₄, the resulting solution was allowed to evaporate for 18 d [for (I)] or 6 d [for (II)] at room temperature, and colourless crystals suitable for X-ray analysis were obtained.

S3. Refinement

For (I), the carbon-bound H atoms were positioned with idealized geometry and treated as riding atoms, with C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C). The H atoms for water and carboxyl were found in the difference Fourier maps; however, they were placed at idealized positions with O—H = 0.85 Å and U_iso(H) = 1.5U_eq(O) and refined using a rotating model with restraints for O(water)—H distances of 0.850 (1) Å. Carboxyl atoms O4 and O5 showed significantly larger anisotropic displacement parameters than C8 that were elongated perpendicular to the carboxyl plane suggesting possible disorder of the carboxylic acid group. Our attempt to model such disorder with two orientations did not afford reasonable results. Considering that the carboxylic acid is a terminal group in the structure, this can be understood as dynamical disorder in a single potential well corresponding to the rotation of the carboxyl group around C7—C8 bond. In the end, we used a SIMU command with an s.u. of 0.005 and a DELU command with an s.u. of 0.01 to maintain reasonable geometry and displacement parameters.

For (II), positional parameters of all the carbon-bound H atoms were calculated geometrically and the atoms were allowed to ride with C—H = 0.97 Å and U_iso(H) = 1.2U_eq(C). All the water H atoms were found in the difference Fourier maps; however, they were placed at ideal positions with O—H = 0.85 Å and U_iso(H) = 1.5U_eq(O) and refined using a rotating model with restraints for the O5—H5WA and O5—H5WB distances of 0.850 (1) Å. The O atoms in the nitrito groups showed large anisotropic displacement parameters that were elongated along the N—O bonds. The origin of this phenomenon is unknown; however, we do not believe it was caused by disorder because trying to model such disorder with two orientations did not afford an acceptable result. To maintain reasonable geometries as observed in similar known nitrito compounds, the N—O bonds were constrained to be 1.25 (1) by using DFIX and the atoms were restrained to have the same U^ij components and the components of U^ij in the direction of the bond by using SIMU with an s.u. of 0.01 and DELU with an s.u. of 0.003 (0.002 for O2—N4).

Computing details

For both compounds, data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are shown at the 30% probability level and dashed lines indicate O—H···O hydrogen bonds. [Symmetry code: (i) -x, -y + 1, -z + 1.]
	Fig. 2. A packing diagram for (I), showing the formation of R6^6(16) rings. Dashed lines represent O—H···O and O—H···Br interactions. The DABCO fragments are shown as sticks for clarity.
	Fig. 3. The molecular structure of (II), showing the atom-numbering scheme. Displacement ellipsoids are shown at the 30% probability level. The dashed line indicates a O—H···Br hydrogen bond. [Please provide symmetry code "A"]
	Fig. 4. A packing diagram for (II), showing the formation of R3^3(8) and R5^4(14) rings. Dashed lines represent O—H···O and O—H···Br interactions. The organic ligand fragments not involved in these interactions have been omitted for clarity.

(I) di-µ-bromido-bis[bromido(1-carboxymethyl-4-aza-1-azoniabicyclo[2.2.2]octane- κN⁴)(nitrito-κ²O,O')cadmium(II)] dihydrate

Crystal data

[Cd2Br4(C8H15N2O2)2(NO2)2]·2H2O	F(000) = 976
Mr = 507.47	Dx = 2.238 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 3824 reflections
a = 8.7790 (18) Å	θ = 2.5–27.5°
b = 13.374 (3) Å	µ = 6.77 mm^−1
c = 13.113 (3) Å	T = 293 K
β = 101.99 (3)°	Block, colourless
V = 1505.9 (5) Å^3	0.2 × 0.2 × 0.2 mm
Z = 4

Data collection

Rigaku Mercury CCD diffractometer	3461 independent reflections
Radiation source: fine-focus sealed tube	2877 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.049
Detector resolution: 28.3714 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ω scans	h = −11→11
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −17→17
Tmin = 0.631, Tmax = 1.000	l = −17→17
15299 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.049	H-atom parameters constrained
wR(F^2) = 0.118	w = 1/[σ^2(Fo^2) + (0.0391P)^2 + 10.3781P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
3461 reflections	Δρmax = 1.30 e Å^−3
172 parameters	Δρmin = −1.10 e Å^−3
15 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0055 (11)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.4707 (8)	0.3433 (5)	0.6601 (6)	0.0376 (15)
H1A	0.4338	0.3653	0.7212	0.045*
H1B	0.4906	0.4023	0.6219	0.045*
C2	0.6221 (7)	0.2850 (5)	0.6946 (5)	0.0333 (14)
H2A	0.7087	0.3237	0.6803	0.040*
H2B	0.6406	0.2725	0.7690	0.040*
C3	0.3348 (7)	0.1867 (5)	0.6485 (6)	0.0357 (15)
H3A	0.2506	0.1479	0.6073	0.043*
H3B	0.3079	0.2010	0.7151	0.043*
C4	0.4832 (8)	0.1250 (5)	0.6668 (6)	0.0350 (14)
H4A	0.5128	0.1063	0.7397	0.042*
H4B	0.4665	0.0644	0.6253	0.042*
C5	0.4028 (8)	0.2576 (6)	0.4961 (5)	0.0386 (16)
H5A	0.4042	0.3179	0.4551	0.046*
H5B	0.3301	0.2111	0.4551	0.046*
C6	0.5645 (8)	0.2114 (6)	0.5200 (5)	0.0392 (16)
H6A	0.6391	0.2579	0.5014	0.047*
H6B	0.5653	0.1510	0.4792	0.047*
C7	0.7660 (7)	0.1368 (5)	0.6647 (6)	0.0361 (15)
H7B	0.7908	0.1267	0.7396	0.043*
H7C	0.8438	0.1815	0.6475	0.043*
C8	0.7781 (11)	0.0379 (7)	0.6126 (8)	0.064 (2)
N1	0.3496 (6)	0.2826 (4)	0.5939 (4)	0.0270 (11)
N2	0.6105 (5)	0.1866 (4)	0.6362 (4)	0.0241 (10)
N3	0.1119 (8)	0.3897 (5)	0.7770 (5)	0.0488 (17)
O1	0.1730 (7)	0.4519 (4)	0.7289 (5)	0.0544 (14)
O2	0.0559 (7)	0.3195 (4)	0.7278 (4)	0.0541 (14)
O3	0.0808 (7)	0.1201 (5)	0.8226 (5)	0.0656 (17)
H3D	0.1004	0.1787	0.8036	0.098*
H3C	0.0712	0.0745	0.7766	0.098*
O4	0.6879 (10)	−0.0053 (6)	0.5509 (7)	0.099 (2)
O5	0.9314 (11)	0.0053 (7)	0.6358 (8)	0.109 (3)
H5C	0.9382	−0.0507	0.6064	0.163*
Br1	0.19513 (9)	0.51062 (6)	0.44617 (6)	0.0458 (2)
Br2	−0.04630 (9)	0.23381 (6)	0.44286 (6)	0.0447 (2)
Cd1	0.10110 (6)	0.37215 (4)	0.56215 (4)	0.03276 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.038 (4)	0.027 (3)	0.047 (4)	0.000 (3)	0.006 (3)	−0.006 (3)
C2	0.032 (3)	0.024 (3)	0.042 (4)	−0.003 (3)	0.002 (3)	−0.009 (3)
C3	0.031 (3)	0.031 (3)	0.046 (4)	−0.005 (3)	0.012 (3)	0.014 (3)
C4	0.036 (3)	0.026 (3)	0.043 (4)	−0.008 (3)	0.008 (3)	0.010 (3)
C5	0.044 (4)	0.046 (4)	0.027 (3)	0.009 (3)	0.008 (3)	0.004 (3)
C6	0.041 (4)	0.054 (5)	0.025 (3)	0.004 (3)	0.011 (3)	0.005 (3)
C7	0.027 (3)	0.032 (3)	0.047 (4)	0.003 (3)	0.002 (3)	0.000 (3)
C8	0.058 (4)	0.051 (5)	0.074 (5)	0.010 (4)	−0.006 (4)	−0.013 (4)
N1	0.029 (3)	0.027 (3)	0.026 (2)	0.001 (2)	0.008 (2)	0.005 (2)
N2	0.025 (2)	0.020 (2)	0.026 (2)	−0.0005 (19)	0.0021 (19)	0.000 (2)
N3	0.058 (4)	0.048 (4)	0.045 (4)	0.023 (3)	0.023 (3)	0.008 (3)
O1	0.056 (3)	0.048 (3)	0.059 (4)	0.008 (3)	0.010 (3)	−0.011 (3)
O2	0.069 (4)	0.045 (3)	0.049 (3)	0.007 (3)	0.014 (3)	0.010 (3)
O3	0.061 (4)	0.059 (4)	0.073 (4)	0.004 (3)	0.008 (3)	0.005 (3)
O4	0.094 (5)	0.083 (5)	0.114 (6)	−0.005 (4)	0.012 (5)	−0.043 (5)
O5	0.109 (5)	0.087 (5)	0.123 (6)	0.031 (5)	0.010 (5)	−0.005 (5)
Br1	0.0407 (4)	0.0409 (4)	0.0579 (5)	0.0031 (3)	0.0154 (3)	0.0171 (3)
Br2	0.0401 (4)	0.0490 (5)	0.0446 (4)	−0.0023 (3)	0.0078 (3)	−0.0109 (3)
Cd1	0.0361 (3)	0.0299 (3)	0.0313 (2)	−0.0018 (2)	0.00475 (19)	0.0037 (2)

Geometric parameters (Å, º)

C1—N1	1.471 (8)	C6—H6B	0.9700
C1—C2	1.527 (9)	C7—N2	1.495 (8)
C1—H1A	0.9700	C7—C8	1.503 (11)
C1—H1B	0.9700	C7—H7B	0.9700
C2—N2	1.515 (8)	C7—H7C	0.9700
C2—H2A	0.9700	C8—O4	1.161 (11)
C2—H2B	0.9700	C8—O5	1.387 (12)
C3—N1	1.487 (8)	N1—Cd1	2.447 (5)
C3—C4	1.519 (9)	N3—O2	1.185 (9)
C3—H3A	0.9700	N3—O1	1.233 (9)
C3—H3B	0.9700	O1—Cd1	2.397 (6)
C4—N2	1.509 (8)	O2—Cd1	2.393 (6)
C4—H4A	0.9700	O3—H3D	0.8500
C4—H4B	0.9700	O3—H3C	0.8501
C5—N1	1.491 (8)	O5—H5C	0.8500
C5—C6	1.520 (10)	Br1—Cd1	2.6354 (9)
C5—H5A	0.9700	Br1—Cd1^i	3.0191 (10)
C5—H5B	0.9700	Br2—Cd1	2.5890 (10)
C6—N2	1.529 (8)	Cd1—Br1^i	3.0191 (10)
C6—H6A	0.9700
N1—C1—C2	111.7 (5)	N2—C7—H7C	108.6
N1—C1—H1A	109.3	C8—C7—H7C	108.6
C2—C1—H1A	109.3	H7B—C7—H7C	107.5
N1—C1—H1B	109.3	O4—C8—O5	118.4 (12)
C2—C1—H1B	109.3	O4—C8—C7	132.0 (12)
H1A—C1—H1B	107.9	O5—C8—C7	109.0 (10)
N2—C2—C1	109.3 (5)	C1—N1—C3	108.4 (5)
N2—C2—H2A	109.8	C1—N1—C5	108.5 (5)
C1—C2—H2A	109.8	C3—N1—C5	107.1 (5)
N2—C2—H2B	109.8	C1—N1—Cd1	109.9 (4)
C1—C2—H2B	109.8	C3—N1—Cd1	109.8 (4)
H2A—C2—H2B	108.3	C5—N1—Cd1	113.0 (4)
N1—C3—C4	112.8 (5)	C7—N2—C4	112.3 (5)
N1—C3—H3A	109.0	C7—N2—C2	107.3 (5)
C4—C3—H3A	109.0	C4—N2—C2	108.5 (5)
N1—C3—H3B	109.0	C7—N2—C6	112.5 (5)
C4—C3—H3B	109.0	C4—N2—C6	109.1 (5)
H3A—C3—H3B	107.8	C2—N2—C6	106.9 (5)
N2—C4—C3	108.6 (5)	O2—N3—O1	115.6 (7)
N2—C4—H4A	110.0	N3—O1—Cd1	96.0 (5)
C3—C4—H4A	110.0	N3—O2—Cd1	97.7 (5)
N2—C4—H4B	110.0	H3D—O3—H3C	116.7
C3—C4—H4B	110.0	C8—O5—H5C	109.4
H4A—C4—H4B	108.3	Cd1—Br1—Cd1^i	90.87 (3)
N1—C5—C6	111.0 (5)	O2—Cd1—O1	50.5 (2)
N1—C5—H5A	109.4	O2—Cd1—N1	90.73 (19)
C6—C5—H5A	109.4	O1—Cd1—N1	90.37 (19)
N1—C5—H5B	109.4	O2—Cd1—Br2	100.51 (16)
C6—C5—H5B	109.4	O1—Cd1—Br2	150.81 (16)
H5A—C5—H5B	108.0	N1—Cd1—Br2	93.99 (13)
C5—C6—N2	109.6 (5)	O2—Cd1—Br1	149.41 (16)
C5—C6—H6A	109.7	O1—Cd1—Br1	99.16 (16)
N2—C6—H6A	109.7	N1—Cd1—Br1	93.80 (12)
C5—C6—H6B	109.7	Br2—Cd1—Br1	109.31 (3)
N2—C6—H6B	109.7	O2—Cd1—Br1^i	83.17 (15)
H6A—C6—H6B	108.2	O1—Cd1—Br1^i	82.11 (14)
N2—C7—C8	114.8 (7)	N1—Cd1—Br1^i	172.29 (12)
N2—C7—H7B	108.6	Br2—Cd1—Br1^i	91.75 (3)
C8—C7—H7B	108.6	Br1—Cd1—Br1^i	89.13 (3)

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5C···Br2^ii	0.85	2.75	3.569 (9)	162
O3—H3D···O2	0.85	2.13	2.932 (9)	158
O3—H3C···O5^iii	0.85	2.20	2.957 (12)	149

Symmetry codes: (ii) −x+1, −y, −z+1; (iii) x−1, y, z.

(II) aquabromido(1-cyanomethyl-4-aza-1-azoniabicyclo[2.2.2]octane- κN⁴)bis(nitrito-κ²O,O')cadmium(II) monohydrate

Crystal data

[CdBr(C8H14N3)(NO2)2(H2O)]·H2O	F(000) = 928
Mr = 472.58	Dx = 2.075 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4571 reflections
a = 7.343 (2) Å	θ = 3.0–27.5°
b = 16.254 (5) Å	µ = 4.12 mm^−1
c = 12.850 (4) Å	T = 293 K
β = 99.505 (5)°	Block, colourless
V = 1512.6 (8) Å^3	0.2 × 0.2 × 0.2 mm
Z = 4

Data collection

Rigaku Mercury CCD diffractometer	3458 independent reflections
Radiation source: fine-focus sealed tube	3110 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
Detector resolution: 28.2714 pixels mm^-1	θmax = 27.5°, θmin = 2.0°
ω scans	h = −9→9
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −21→21
Tmin = 0.663, Tmax = 1.000	l = −16→16
16104 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.123	w = 1/[σ^2(Fo^2) + (0.0736P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.13	(Δ/σ)max = 0.001
3458 reflections	Δρmax = 1.47 e Å^−3
190 parameters	Δρmin = −0.86 e Å^−3
34 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0055 (11)

Special details

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 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^ > \s(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.2992 (7)	0.6297 (3)	0.7637 (4)	0.0275 (10)
H1A	0.3909	0.6630	0.8079	0.033*
H1B	0.2320	0.6651	0.7098	0.033*
C2	0.3962 (7)	0.5613 (3)	0.7113 (4)	0.0284 (10)
H2A	0.3997	0.5753	0.6383	0.034*
H2B	0.5220	0.5547	0.7476	0.034*
C3	0.2665 (7)	0.5296 (3)	0.8967 (4)	0.0307 (11)
H3A	0.1902	0.5114	0.9471	0.037*
H3B	0.3802	0.5518	0.9358	0.037*
C4	0.3108 (8)	0.4564 (3)	0.8309 (4)	0.0324 (11)
H4A	0.4363	0.4380	0.8552	0.039*
H4B	0.2277	0.4111	0.8384	0.039*
C5	0.0147 (6)	0.5555 (3)	0.7566 (4)	0.0298 (11)
H5A	−0.0631	0.5977	0.7189	0.036*
H5B	−0.0601	0.5232	0.7970	0.036*
C6	0.0902 (6)	0.4996 (3)	0.6775 (4)	0.0280 (10)
H6A	0.0212	0.4484	0.6692	0.034*
H6B	0.0769	0.5264	0.6092	0.034*
C7	0.3627 (8)	0.4154 (3)	0.6535 (4)	0.0316 (11)
H7A	0.4950	0.4107	0.6759	0.038*
H7B	0.3073	0.3633	0.6678	0.038*
C8	0.3254 (7)	0.4310 (3)	0.5413 (4)	0.0295 (10)
N1	0.1689 (5)	0.5945 (2)	0.8292 (3)	0.0202 (7)
N2	0.2893 (5)	0.4822 (2)	0.7169 (3)	0.0219 (8)
N3	0.2950 (7)	0.4459 (3)	0.4532 (4)	0.0422 (11)
N4	−0.3010 (5)	0.6625 (2)	0.9524 (3)	0.0259 (8)
N5	0.2563 (5)	0.8420 (2)	0.9520 (3)	0.0269 (8)
O1	−0.2233 (6)	0.6158 (3)	0.9155 (4)	0.0497 (10)
O2	−0.2363 (6)	0.7303 (3)	0.9817 (4)	0.0515 (11)
O3	0.3111 (6)	0.7861 (3)	0.9084 (4)	0.0496 (10)
O4	0.1159 (6)	0.8418 (3)	0.9881 (4)	0.0526 (10)
O5	−0.0829 (5)	0.7616 (2)	0.7690 (3)	0.0405 (9)
H5WA	−0.0188	0.7869	0.7298	0.061*
H5WB	−0.1732	0.7296	0.7485	0.061*
O6	0.5766 (6)	0.7698 (3)	1.1547 (3)	0.0488 (10)
H6WA	0.5076	0.7313	1.1706	0.073*
H6WB	0.5543	0.7781	1.0885	0.073*
Br1	0.19401 (7)	0.63980 (3)	1.12733 (4)	0.03482 (17)
Cd1	0.05508 (4)	0.700406 (19)	0.93323 (2)	0.02336 (14)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.028 (2)	0.026 (2)	0.031 (2)	−0.0057 (19)	0.0115 (19)	−0.0026 (19)
C2	0.026 (2)	0.027 (2)	0.034 (2)	−0.0033 (19)	0.0098 (19)	−0.0042 (19)
C3	0.041 (3)	0.029 (2)	0.022 (2)	0.010 (2)	0.006 (2)	0.0023 (19)
C4	0.046 (3)	0.029 (2)	0.022 (2)	0.010 (2)	0.005 (2)	0.0021 (18)
C5	0.019 (2)	0.032 (3)	0.038 (3)	−0.0030 (19)	0.0027 (19)	−0.015 (2)
C6	0.023 (2)	0.031 (2)	0.030 (2)	−0.0008 (19)	0.0022 (18)	−0.0120 (19)
C7	0.042 (3)	0.025 (2)	0.028 (2)	0.010 (2)	0.009 (2)	−0.0008 (19)
C8	0.026 (2)	0.030 (2)	0.033 (3)	0.0023 (19)	0.0078 (19)	−0.011 (2)
N1	0.0180 (17)	0.0213 (18)	0.0214 (18)	−0.0005 (14)	0.0035 (14)	0.0003 (14)
N2	0.0233 (19)	0.0210 (18)	0.0221 (18)	0.0011 (14)	0.0057 (14)	−0.0022 (14)
N3	0.039 (3)	0.057 (3)	0.030 (2)	0.004 (2)	0.0071 (19)	−0.010 (2)
N4	0.0222 (18)	0.0355 (19)	0.0168 (17)	−0.0076 (15)	−0.0058 (13)	0.0073 (14)
N5	0.0254 (18)	0.0256 (18)	0.0257 (19)	0.0004 (15)	−0.0077 (14)	0.0064 (14)
O1	0.041 (2)	0.051 (2)	0.056 (3)	−0.0120 (18)	0.0054 (18)	0.001 (2)
O2	0.041 (2)	0.049 (2)	0.066 (3)	−0.0003 (18)	0.013 (2)	−0.016 (2)
O3	0.042 (2)	0.045 (2)	0.062 (3)	−0.0062 (18)	0.008 (2)	−0.0025 (19)
O4	0.054 (2)	0.039 (2)	0.064 (3)	0.003 (2)	0.009 (2)	−0.012 (2)
O5	0.035 (2)	0.049 (2)	0.036 (2)	−0.0009 (17)	0.0028 (16)	0.0143 (17)
O6	0.038 (2)	0.065 (3)	0.043 (2)	0.003 (2)	0.0035 (18)	−0.006 (2)
Br1	0.0400 (3)	0.0389 (3)	0.0252 (3)	0.0049 (2)	0.0043 (2)	0.00038 (19)
Cd1	0.0233 (2)	0.0231 (2)	0.0240 (2)	−0.00063 (12)	0.00500 (14)	−0.00251 (11)

Geometric parameters (Å, º)

C1—N1	1.489 (5)	C7—C8	1.444 (7)
C1—C2	1.535 (6)	C7—N2	1.510 (6)
C1—H1A	0.9700	C7—H7A	0.9700
C1—H1B	0.9699	C7—H7B	0.9700
C2—N2	1.514 (6)	C8—N3	1.144 (7)
C2—H2A	0.9700	N1—Cd1	2.413 (4)
C2—H2B	0.9700	N4—O1	1.102 (5)
C3—N1	1.474 (6)	N4—O2	1.234 (5)
C3—C4	1.526 (6)	N5—O3	1.172 (5)
C3—H3A	0.9700	N5—O4	1.199 (5)
C3—H3B	0.9701	O1—Cd1	2.443 (4)
C4—N2	1.506 (6)	O2—Cd1	2.376 (4)
C4—H4A	0.9701	O3—Cd1	2.403 (4)
C4—H4B	0.9701	O4—Cd1	2.424 (4)
C5—N1	1.485 (5)	O5—Cd1	2.401 (4)
C5—C6	1.533 (6)	O5—H5WA	0.8500
C5—H5A	0.9700	O5—H5WB	0.8500
C5—H5B	0.9699	O6—H6WA	0.8501
C6—N2	1.493 (6)	O6—H6WB	0.8500
C6—H6A	0.9702	Br1—Cd1	2.7187 (9)
C6—H6B	0.9699
N1—C1—C2	110.9 (4)	C3—N1—C5	108.1 (4)
N1—C1—H1A	109.4	C3—N1—C1	108.2 (4)
C2—C1—H1A	109.4	C5—N1—C1	107.7 (3)
N1—C1—H1B	109.5	C3—N1—Cd1	111.3 (3)
C2—C1—H1B	109.5	C5—N1—Cd1	110.8 (3)
H1A—C1—H1B	108.1	C1—N1—Cd1	110.6 (3)
N2—C2—C1	108.2 (4)	C6—N2—C4	108.8 (4)
N2—C2—H2A	110.0	C6—N2—C7	111.7 (4)
C1—C2—H2A	110.1	C4—N2—C7	109.5 (3)
N2—C2—H2B	110.1	C6—N2—C2	108.0 (4)
C1—C2—H2B	110.1	C4—N2—C2	108.2 (4)
H2A—C2—H2B	108.4	C7—N2—C2	110.5 (4)
N1—C3—C4	111.1 (4)	O1—N4—O2	123.1 (5)
N1—C3—H3A	109.4	O3—N5—O4	124.6 (4)
C4—C3—H3A	109.4	N4—O1—Cd1	93.3 (3)
N1—C3—H3B	109.4	N4—O2—Cd1	93.1 (3)
C4—C3—H3B	109.4	N5—O3—Cd1	92.8 (3)
H3A—C3—H3B	108.0	N5—O4—Cd1	91.1 (3)
N2—C4—C3	108.9 (4)	Cd1—O5—H5WA	121.8
N2—C4—H4A	109.9	Cd1—O5—H5WB	102.3
C3—C4—H4A	109.9	H5WA—O5—H5WB	126.3
N2—C4—H4B	110.0	H6WA—O6—H6WB	109.5
C3—C4—H4B	109.9	O2—Cd1—O5	83.00 (15)
H4A—C4—H4B	108.3	O2—Cd1—O3	132.41 (14)
N1—C5—C6	110.3 (4)	O5—Cd1—O3	82.45 (15)
N1—C5—H5A	109.7	O2—Cd1—N1	134.50 (13)
C6—C5—H5A	109.7	O5—Cd1—N1	86.75 (13)
N1—C5—H5B	109.5	O3—Cd1—N1	89.43 (13)
C6—C5—H5B	109.5	O2—Cd1—O4	81.96 (15)
H5A—C5—H5B	108.1	O5—Cd1—O4	83.89 (16)
N2—C6—C5	109.1 (3)	O3—Cd1—O4	51.57 (14)
N2—C6—H6A	109.8	N1—Cd1—O4	140.72 (14)
C5—C6—H6A	109.9	O2—Cd1—O1	50.46 (15)
N2—C6—H6B	109.8	O5—Cd1—O1	85.77 (14)
C5—C6—H6B	109.8	O3—Cd1—O1	167.12 (16)
H6A—C6—H6B	108.3	N1—Cd1—O1	84.71 (14)
C8—C7—N2	112.7 (4)	O4—Cd1—O1	132.21 (15)
C8—C7—H7A	109.0	O2—Cd1—Br1	92.94 (12)
N2—C7—H7A	109.0	O5—Cd1—Br1	175.22 (10)
C8—C7—H7B	109.1	O3—Cd1—Br1	98.55 (11)
N2—C7—H7B	109.1	N1—Cd1—Br1	97.92 (9)
H7A—C7—H7B	107.8	O4—Cd1—Br1	93.06 (12)
N3—C8—C7	177.9 (5)	O1—Cd1—Br1	93.61 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5WA···Br1^i	0.85	2.50	3.352 (4)	175
O5—H5WB···O6^ii	0.85	2.02	2.731 (6)	140
O6—H6WA···Br1	0.85	2.72	3.486 (5)	151
O6—H6WB···O2^iii	0.85	2.36	2.872 (6)	120

Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) x−1, −y+3/2, z−1/2; (iii) x+1, y, z.