1,1,4,4-Tetra­methyl­piperazinium tetra­iodidocadmate(II)

The title compound, (C₈H₂₀N₂)[CdI₄], contains isolated 1,1,4,4-tetra­methyl­piperazinium cations and tetra­hedral tetra­iodidocadmate(II) anions, both of which lie on crystallographic twofold rotation axes. The cations and anions lie in layers parallel to the (101) planes.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.033
• wR factor = 0.083
• Data-to-parameter ratio = 29.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT128_ALERT_4_C Non-standard setting of Space group P2/c    ....    P2/n
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.25 Ratio

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cd1         (2)       2.34

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

---

S1. Comment

The title compound (Me₄pip)[CdI₄] (where pip denotes piperazine) is composed of isolated tetrahedral [CdI₄]^2- anions and 1,1,4,4-tetra-methylpiperazinium (Me₄pip)²⁺ cations (Fig. 1), both of which lie on crystallographic twofold rotation axes. There does not appear to be any unusual distortion of the metal-halide distances due to the presence of the (Me₄pip)²⁺ cations: the coordination environment of Cd^II involves Cd—I bond distances of 2.7664 (10) and 2.7721 (11) A%, with I—Cd—I bond angles ranging between 106.30 (5) and 114.69 (2)°. The cations and anions lie in layers parallel to the (101) planes (Fig. 2), with C—H···I contacts formed between them.

Related literature

For the structures of the related compounds, (C₈H₂₀N₂)[FeCl₅] and (C₄H₁₂N₂)[CdI₄], see James et al. (1995) and Ishihara et al. (2002), respectively.

S2. Experimental

Crystals of the title compound were prepared by slow evaporation of a solution containing (Me₄pip)I₂ (0.796 g, 2 mmol) and CdI₂ (1.465 g, 4 mmol) in deionized water (20 ml), acidified by 10 drops of 1M HI. The resulting yellow crystals were obtained in approximately 68% yield (based on Cd).

S3. Refinement

H atoms were positioned geometrically, with C—H = 0.97 or 0.96 Å and were refined as riding with U_iso(H)= 1.2U_eq(C) or 1.5U_eq(methyl C). The methyl groups were allowed to rotate about their local threefold axes.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1994); data reduction: SAINT (Siemens, 1994); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Siemens, 1994) and DIAMOND (Brandenburg, 2004); software used to prepare material for publication: SHELXTL (Siemens, 1994).

Figures

	Fig. 1. The molecular structure of the title compound showing displacement ellipsoids at the 35% probability level for non-H atoms.
	Fig. 2. Packing diagram for the title compound. The dashed lines denote intermolecular C—H···I contacts.

1,1,4,4-Tetramethylpiperazinium tetraiodidocadmium(II)

Crystal data

(C8H20N2)[CdI4]	F(000) = 684
Mr = 764.26	Dx = 2.758 Mg m^−3
Monoclinic, P2/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yac	Cell parameters from 5559 reflections
a = 9.777 (4) Å	θ = 2.5–28.3°
b = 7.772 (4) Å	µ = 7.88 mm^−1
c = 12.184 (6) Å	T = 298 K
β = 96.326 (6)°	Block, yellow
V = 920.2 (8) Å^3	0.28 × 0.14 × 0.08 mm
Z = 2

Data collection

Siemens SMART CCD diffractometer	2118 independent reflections
Radiation source: fine-focus sealed tube	1869 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
φ and ω scans	θmax = 28.3°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→12
Tmin = 0.277, Tmax = 0.533	k = −6→10
5322 measured reflections	l = −13→15

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.083	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0397P)^2 + 1.5636P] where P = (Fo^2 + 2Fc^2)/3
2118 reflections	(Δ/σ)max = 0.001
71 parameters	Δρmax = 1.30 e Å^−3
0 restraints	Δρmin = −1.51 e Å^−3

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
Cd1	0.2500	0.00204 (7)	0.7500	0.03049 (14)
I1	0.02271 (3)	−0.21007 (5)	0.71028 (3)	0.04278 (13)
I2	0.20422 (4)	0.21594 (5)	0.92431 (3)	0.04632 (14)
N1	0.2645 (4)	0.7067 (5)	0.1294 (3)	0.0285 (8)
C1	0.2223 (5)	0.8634 (6)	0.1897 (4)	0.0314 (10)
H1A	0.1227	0.8692	0.1834	0.038*
H1B	0.2551	0.9653	0.1548	0.038*
C2	0.2221 (5)	0.5506 (6)	0.1900 (4)	0.0330 (10)
H2A	0.2543	0.4484	0.1550	0.040*
H2B	0.1224	0.5456	0.1841	0.040*
C3	0.4172 (5)	0.7061 (8)	0.1194 (5)	0.0440 (14)
H3A	0.4671	0.7024	0.1918	0.066*
H3B	0.4414	0.8085	0.0820	0.066*
H3C	0.4400	0.6069	0.0781	0.066*
C4	0.1892 (6)	0.7085 (8)	0.0150 (4)	0.0413 (12)
H4A	0.0918	0.7050	0.0195	0.062*
H4B	0.2158	0.6100	−0.0252	0.062*
H4C	0.2119	0.8116	−0.0225	0.062*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0308 (2)	0.0302 (3)	0.0304 (3)	0.000	0.00283 (18)	0.000
I1	0.0360 (2)	0.0388 (2)	0.0531 (2)	−0.00967 (14)	0.00302 (16)	−0.00510 (15)
I2	0.0492 (2)	0.0452 (3)	0.0447 (2)	0.00182 (15)	0.00580 (16)	−0.01700 (16)
N1	0.0324 (19)	0.028 (2)	0.026 (2)	−0.0005 (16)	0.0062 (16)	0.0007 (16)
C1	0.039 (2)	0.022 (2)	0.034 (3)	0.0015 (19)	0.0040 (19)	0.001 (2)
C2	0.040 (2)	0.024 (2)	0.035 (3)	−0.0044 (19)	0.008 (2)	−0.002 (2)
C3	0.032 (3)	0.059 (4)	0.044 (3)	−0.001 (2)	0.013 (2)	−0.004 (3)
C4	0.049 (3)	0.047 (3)	0.028 (3)	0.000 (2)	0.001 (2)	0.002 (2)

Geometric parameters (Å, º)

Cd1—I1	2.7664 (10)	C1—H1B	0.970
Cd1—I1^i	2.7664 (10)	C2—C2^ii	1.504 (10)
Cd1—I2	2.7721 (11)	C2—H2A	0.970
Cd1—I2^i	2.7721 (11)	C2—H2B	0.970
N1—C2	1.502 (6)	C3—H3A	0.960
N1—C1	1.503 (6)	C3—H3B	0.960
N1—C4	1.504 (6)	C3—H3C	0.960
N1—C3	1.511 (6)	C4—H4A	0.960
C1—C1^ii	1.509 (9)	C4—H4B	0.960
C1—H1A	0.970	C4—H4C	0.960
I1—Cd1—I1^i	106.84 (4)	N1—C2—C2^ii	112.8 (3)
I1—Cd1—I2	107.28 (2)	N1—C2—H2A	109.0
I1^i—Cd1—I2	114.69 (2)	C2^ii—C2—H2A	109.0
I1—Cd1—I2^i	114.69 (2)	N1—C2—H2B	109.0
I1^i—Cd1—I2^i	107.28 (2)	C2^ii—C2—H2B	109.0
I2—Cd1—I2^i	106.30 (5)	H2A—C2—H2B	107.8
C2—N1—C1	108.0 (4)	N1—C3—H3A	109.5
C2—N1—C4	109.2 (4)	N1—C3—H3B	109.5
C1—N1—C4	108.3 (4)	H3A—C3—H3B	109.5
C2—N1—C3	111.5 (4)	N1—C3—H3C	109.5
C1—N1—C3	111.6 (4)	H3A—C3—H3C	109.5
C4—N1—C3	108.2 (4)	H3B—C3—H3C	109.5
N1—C1—C1^ii	112.8 (3)	N1—C4—H4A	109.5
N1—C1—H1A	109.0	N1—C4—H4B	109.5
C1^ii—C1—H1A	109.0	H4A—C4—H4B	109.5
N1—C1—H1B	109.0	N1—C4—H4C	109.5
C1^ii—C1—H1B	109.0	H4A—C4—H4C	109.5
H1A—C1—H1B	107.8	H4B—C4—H4C	109.5
C2—N1—C1—C1^ii	54.5 (6)	C1—N1—C2—C2^ii	−54.8 (6)
C4—N1—C1—C1^ii	172.6 (5)	C4—N1—C2—C2^ii	−172.3 (5)
C3—N1—C1—C1^ii	−68.4 (6)	C3—N1—C2—C2^ii	68.2 (6)

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