N-Methyl­ethyl­enedi­ammonium tetra­iodo­cadmium(II)

The title compound, (C₃H₁₂N₂)[CdI₄] [abbreviated (MEDA)CdI₄], contains isolated N-methyl­ethyl­enedi­ammonium cations and tetrahedral tetraiodidecadmate(II) anions, forming segregated layers. Hydro­gen bonding between cations and anions provides three-dimensional stability to the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 83 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.019
• wR factor = 0.045
• Data-to-parameter ratio = 26.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1B    ...          ?
PLAT732_ALERT_1_C Angle   Calc   113.02(3), Rep   113.02(1) ......       2.31 su-Rat
              I4   -CD   -I2      1.555   1.555   1.555
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C3 H12 N2

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

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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
   1 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

The (MEDA)CdI₄ structure, (I), is composed of isolated tetrahedral CdI₄ monomers and individual N-methylethylenediammonium (MEDA) cations, as displayed in Fig. 1. There does not appear to be any unusual distortion in the metal–halide structure due to the presence of the MEDA cation. The cadmium coordination contains Cd—I bond distances of 2.7958 (8), 2.7857 (7), 2.7736 (7), and 2.7683 (7) Å, with bond angles ranging between 104.82 (3) and 113.023 (13)°. The average Cd—I distance for isolated CdI₄ anions from the Cambridge Structural Database (Version 5.24 of November 2002; Allen, 2002) is 2.778 (8)° [Cd—I range 2.728–2.813 Å and I—Cd—I bond angle range 101.98–118.46°].

Both the CdI₄ anions and the MEDA cations form individual layers that run parallel to the ab plane (Fig. 2). Three-dimensional stability is achieved through hydrogen bonding between these layers by the NH₃⁺ groups on one side and the NH₂⁺ groups on the other side of each cation layer (Fig. 2). Table 1 lists the various hydrogen-bond contacts.

The secondary ammonium group of the MEDA cation has one normal and one bifurcated hydrogen bond, resulting in asymmetrical H···I contacts. The primary ammonium group has two bifurcated hydrogen bonds (see Table 1). This unique arrangement of hydrogen bonding forces the trans,gauche conformation of the MEDA cations (Fig. 2).

S2. Experimental

Crystals were prepared by the slow evaporation of a solution containing (MEDA)I₂ (0.655 g, 2 mmol) and CdI₂ (1.465 g, 4 mmol) dissolved in 20 ml of deionized water and acidified by 10 drops of 1 M HI. The resulting crystals were fragile colourless parallelpipeds.

S3. Refinement

H atoms were positioned geometrically and refined using a riding model, with U_iso for the secondary C—H and N—H groups constrained to be 1.2U_eq of the carrier atom, while those of the primary C—H and N—H protons were set at 1.5U_eq. There is a residual of 0.727 e Å ⁻³ ca 0.703 Å from Cd1.

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. Illustration of the Cd^II ion coordination. Ellipsoids are drawn at the 50% probability level.
	Fig. 2. Illustration of the MEDA cation and the CdI4 anion layers parallel to the ab axis. The dotted lines represent hydrogen bonding. Only the two-center cations (labeled A) show all of the H···I interactions.

Methylethylenediamine tetraiodocadmium(II)

Crystal data

(C3H12N2)[CdI4]	F(000) = 1216
Mr = 696.15	Dx = 3.368 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7493 reflections
a = 8.4114 (17) Å	θ = 2.5–30.0°
b = 10.891 (2) Å	µ = 10.54 mm^−1
c = 15.245 (3) Å	T = 83 K
β = 100.55 (3)°	Parallelepiped, colourless
V = 1372.9 (5) Å^3	0.20 × 0.10 × 0.10 mm
Z = 4

Data collection

Bruker/Siemens SMART APEX diffractometer	2418 independent reflections
Radiation source: normal-focus sealed tube	2320 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 8.3 pixels mm^-1	θmax = 25.0°, θmin = 2.3°
ω scans	h = −10→10
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −12→12
Tmin = 0.189, Tmax = 0.349	l = −18→18
17982 measured reflections

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)] = 0.019	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.045	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo^2) + (0.0117P)^2 + 1.6835P] where P = (Fo^2 + 2Fc^2)/3
2418 reflections	(Δ/σ)max = 0.001
91 parameters	Δρmax = 0.73 e Å^−3
0 restraints	Δρmin = −0.56 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
I1	0.55976 (3)	0.64731 (2)	0.117641 (18)	0.01312 (8)
I2	0.28271 (4)	0.73130 (2)	−0.151147 (18)	0.01452 (8)
I3	0.02767 (3)	0.66525 (2)	0.082419 (18)	0.01467 (8)
I4	0.30761 (3)	1.02492 (2)	0.070747 (18)	0.01433 (8)
Cd	0.29077 (4)	0.77723 (3)	0.02937 (2)	0.01358 (9)
N4	−0.2360 (5)	0.5680 (3)	−0.3291 (2)	0.0141 (8)
H4A	−0.2940	0.5185	−0.3724	0.017*
H4B	−0.2465	0.6474	−0.3500	0.017*
N1	−0.3029 (5)	0.6299 (3)	−0.0949 (2)	0.0159 (8)
H1A	−0.2525	0.6789	−0.0499	0.024*
H1B	−0.2960	0.5502	−0.0765	0.024*
H1C	−0.4088	0.6519	−0.1099	0.024*
C2	−0.2235 (6)	0.6438 (4)	−0.1739 (3)	0.0136 (9)
H2A	−0.1079	0.6209	−0.1580	0.016*
H2B	−0.2306	0.7302	−0.1944	0.016*
C3	−0.3101 (6)	0.5599 (4)	−0.2475 (3)	0.0154 (9)
H3A	−0.3042	0.4740	−0.2257	0.018*
H3B	−0.4256	0.5834	−0.2626	0.018*
C5	−0.0622 (6)	0.5326 (4)	−0.3172 (3)	0.0189 (10)
H5A	−0.0251	0.5407	−0.3742	0.028*
H5B	−0.0493	0.4473	−0.2967	0.028*
H5C	0.0020	0.5865	−0.2728	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.01160 (16)	0.01238 (14)	0.01524 (15)	−0.00037 (10)	0.00213 (12)	0.00101 (10)
I2	0.01612 (17)	0.01312 (14)	0.01352 (15)	0.00043 (10)	0.00056 (12)	−0.00032 (10)
I3	0.01207 (17)	0.01566 (14)	0.01564 (16)	−0.00155 (10)	0.00082 (12)	0.00176 (10)
I4	0.01675 (17)	0.01102 (14)	0.01550 (15)	−0.00067 (10)	0.00373 (12)	−0.00097 (10)
Cd	0.01389 (19)	0.01133 (16)	0.01512 (17)	−0.00033 (11)	0.00163 (14)	0.00025 (11)
N4	0.017 (2)	0.0150 (17)	0.0100 (18)	0.0016 (14)	0.0015 (16)	−0.0036 (14)
N1	0.020 (2)	0.0146 (17)	0.0130 (19)	−0.0014 (15)	0.0034 (17)	−0.0042 (14)
C2	0.015 (2)	0.014 (2)	0.012 (2)	0.0010 (17)	0.0021 (19)	0.0004 (16)
C3	0.016 (3)	0.016 (2)	0.015 (2)	−0.0018 (18)	0.0040 (19)	−0.0024 (17)
C5	0.022 (3)	0.015 (2)	0.022 (2)	−0.0039 (18)	0.009 (2)	−0.0031 (18)

Geometric parameters (Å, º)

I1—Cd	2.7959 (8)	N1—H1B	0.9100
I2—Cd	2.7855 (7)	N1—H1C	0.9100
I3—Cd	2.7739 (7)	C2—C3	1.525 (6)
I4—Cd	2.7681 (7)	C2—H2A	0.9900
N4—C5	1.490 (6)	C2—H2B	0.9900
N4—C3	1.494 (5)	C3—H3A	0.9900
N4—H4A	0.9200	C3—H3B	0.9900
N4—H4B	0.9200	C5—H5A	0.9800
N1—C2	1.488 (5)	C5—H5B	0.9800
N1—H1A	0.9100	C5—H5C	0.9800
I4—Cd—I3	111.857 (17)	N1—C2—C3	108.0 (3)
I4—Cd—I2	113.023 (13)	N1—C2—H2A	110.1
I3—Cd—I2	109.43 (3)	C3—C2—H2A	110.1
I4—Cd—I1	112.36 (2)	N1—C2—H2B	110.1
I3—Cd—I1	104.813 (19)	C3—C2—H2B	110.1
I2—Cd—I1	104.82 (3)	H2A—C2—H2B	108.4
C5—N4—C3	115.6 (3)	N4—C3—C2	111.2 (3)
C5—N4—H4A	108.4	N4—C3—H3A	109.4
C3—N4—H4A	108.4	C2—C3—H3A	109.4
C5—N4—H4B	108.4	N4—C3—H3B	109.4
C3—N4—H4B	108.4	C2—C3—H3B	109.4
H4A—N4—H4B	107.4	H3A—C3—H3B	108.0
C2—N1—H1A	109.5	N4—C5—H5A	109.5
C2—N1—H1B	109.5	N4—C5—H5B	109.5
H1A—N1—H1B	109.5	H5A—C5—H5B	109.5
C2—N1—H1C	109.5	N4—C5—H5C	109.5
H1A—N1—H1C	109.5	H5A—C5—H5C	109.5
H1B—N1—H1C	109.5	H5B—C5—H5C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4A···I4^i	0.92	3.01	3.652 (4)	129
N4—H4A···I2^i	0.92	3.15	3.695 (4)	120
N4—H4B···I1^ii	0.92	2.76	3.565 (4)	147
N1—H1A···I3	0.91	2.81	3.526 (4)	136
N1—H1A···I4^iii	0.91	3.27	3.779 (4)	118
N1—H1B···I1^iv	0.91	3.07	3.691 (4)	127
N1—H1B···I3^iv	0.91	3.27	3.945 (4)	133
N1—H1C···I2^v	0.91	2.70	3.607 (4)	177

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