Tris(ethyl­enediamine)nickel(II) tetra­iodo­cadmate(II)

Sohail, M.; Molloy, K.C.; Mazhar, M.; Kociok-Köhn, G.; Khosa, M.K.

doi:10.1107/S1600536806002522

metal-organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 62| Part 2| February 2006| Pages m394-m396

https://doi.org/10.1107/S1600536806002522

Tris(ethylenediamine)nickel(II) tetraiodocadmate(II)

Manzar Sohail,^a Kieran C. Molloy,^b Muhammad Mazhar,^a ^* G. Kociok-Köhn ^b and M. Kaleem Khosa ^a

^aDepartment of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan, and ^bDepartment of Chemistry, University of Bath, Bath BA2 7AY, England
^*Correspondence e-mail: mazhar42pk@yahoo.com

(Received 29 November 2005; accepted 20 January 2006; online 31 January 2006)

The title compound, [Ni(C₆H₂₄N₆)][CdI₄], contains two discrete ions, an [Ni(en)₃]²⁺ (en = ethylenediamine) cation and a [CdI₄]²⁻ anion. The Ni²⁺ ion is coordinated by three chelating ethylenediamine ligands in a distorted octahedral geometry while the Cd²⁺ ion binds four iodide ions in a slightly distorted tetrahedron. Both the Ni and Cd atoms lie on threefold axes of rotation. The structure is disordered at cadmium, with two alternative sites for the metal in a 97:3 ratio; the minor component of the disorder inverts the CdI₄ tetrahedron and reverses the direction of propagation of the aligned [CdI₄]_n²⁻ units.

Comment

There has been considerable interest in the development of chemical routes for the deposition of nickel oxide (NiO) and complex oxides containing nickel, which have a number of important industrial applications. For instance, nickel oxide is a component of electrochromic devices such as automotive mirrors and smart windows, optical or electrical gas sensors. (Ozer & Lampert, 1998 ). Complex (I) (Fig. 1 and Table 1) has been synthesized in a continuation of attempts to obtain suitable precursors for the deposition of complex oxides containing nickel through aerosol-assisted chemical vapour deposition (AACVD) (Sohail et al., 2005 ).

The structure is disordered at cadmium, with two alternative sites for the metal in a 97:3 ratio; the minor component of the disorder inverts the CdI₄ tetrahedron and reverses the direction of propagation of the aligned [CdI₄]_n²⁻ units. Only the major component of the structure is shown in Fig. 1 and discussed here. Complex (I) contains discrete [Ni(en)₃]²⁺ and [CdI₄]²⁻ ions, with each of the Ni and Cd atoms lying on threefold axes of rotation. The Ni^II ion is coordinated by three chelating ethylenediamine ligands, resulting in distorted octahedral geometry. All axial/equatorial N—Ni—N bond angles lie in the range 82.01 (10)–93.47 (12)°, showing a significant distortion, while symmetry dictates that all trans N—Ni—N angles are identical [173.05 (11)°], as are all Ni—N bonds [2.130 (3) Å], the latter being slightly longer than analogous bonds in related compounds (Colacio et al., 2003 ). The Cd^II ion in the [CdI₄]²⁻ anion is coordinated by four I atoms with a distorted tetrahedral geometry.

The range of relevant I—Cd1—I bond angles, 105.377 (14)–113.237 (12)°, indicates that the geometry shows some significant deviation from regular tetrahedral, as is the case in other complexes containing [CdI₄]²⁻ (Bailey & Pennington, 1995 ). The Cd1—I bond lengths are comparable to those of similar compounds (Bengtsson-Kloo et al., 1996 ). The anions align to allow the cadmium centres to become linked to each other through bridging iodine ligands [I2⋯Cd1^e = 4.223 (1) Å] [symmetry code: (e) −x + y, y, z − $[{1\over 2}]$ ]. This interaction is weak, and consistent with a lengthening of the Cd—I2 bond [2.7889 (11)] at the limit of detection in comparison with analogous bonds involving non-bridging halogens [2.7815 (15) Å]. However, a flattening of the tetrahedron, evident from the I1—Cd—I1 angle [113.237 (12)°] is evidence of a meaningful anion–anion interaction. The distortions from octahedral and tetrahedral in both of the ions of the complex (I) may result from packing effects and are observed in other such complexes (Kallel & Bats, 1981 ).

Figure 1
The structure of (I)

, showing the atom-numbering scheme and displacement ellipsoids drawn at the 30% probability level. Only the major disorder component is shown. H atoms have been omitted.[Symmetry codes: (a) −y + 1, x − y, z; (b) −x + y + 1, −x + 1, z; (c) −x + y, −x + 1, z; (d) −y + 1, x − y + 1, z; (e) −x + y, y, z − $[{1\over 2}]$ .]

Experimental

Tris(ethylenediammine)nickel(II) bromide, [Ni(en)₃]Br₂ (3.199 g, 6.8 mmol), and potassium tetraiodocadmate(II), K₂[CdI₄] (3.62 g, 6.8 mmol), were dissolved in water (30 ml), resulting in the formation of a precipitate of complex (I). This was washed several times with distilled water and recrystallized from ethylene glycol over a two-month period at room temperature.

Crystal data

[Ni(C₆H₂₄N₆)][CdI₄]
M_r = 859.02
Trigonal, P 3c 1
a = 9.023 (5) Å
c = 14.203 (5) Å
V = 1001.4 (9) Å³
Z = 2
D_x = 2.849 Mg m⁻³
Mo Kα radiation
Cell parameters from 15955 reflections
θ = 2.9–30.0°
μ = 8.16 mm⁻¹
T = 150 (2) K
Block, colourless
0.25 × 0.20 × 0.20 mm

Data collection

Nonius KappaCCD diffractometer
ω scans
Absorption correction: multi-scan(SORTAV; Blessing, 1995 )T_min = 0.120, T_max = 0.195
21288 measured reflections
1944 independent reflections
1937 reflections with I > 2σ(I)
R_int = 0.056
θ_max = 30.0°
h = −11 → 12
k = −12 → 12
l = −19 → 19

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.018
wR(F²) = 0.039
S = 1.17
1944 reflections
72 parameters
H atoms treated by a mixture of independent and constrained refinement
w = 1/[σ²(F_o²) + (0.0075P)² + 1.6741P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max = 0.001
Δρ_max = 0.99 e Å⁻³
Δρ_min = −0.61 e Å⁻³
Absolute structure: Flack (1983 ), 968 Friedel pairs
Flack parameter: 0.00 (3)

Table 1
Selected geometric parameters (Å, °)

Cd1—I1ⁱ	2.7815 (15)
Cd1—I2	2.7889 (11)
Cd1A—I1ⁱ	2.771 (4)
Cd1A—I2ⁱⁱ	2.879 (15)
Ni—N2ⁱⁱⁱ	2.130 (3)

I1ⁱ—Cd1—I1^iv	113.237 (12)
I1ⁱ—Cd1—I2	105.377 (14)
I1ⁱ—Cd1A—I1^iv	113.90 (2)
I1ⁱ—Cd1A—I2ⁱⁱ	104.60 (3)
N2ⁱⁱⁱ—Ni—N2^v	92.83 (12)
N2ⁱⁱⁱ—Ni—N1ⁱⁱⁱ	82.01 (10)
N2—Ni—N1ⁱⁱⁱ	173.05 (11)
N1ⁱⁱⁱ—Ni—N1	93.47 (12)
Symmetry codes: (i) -x+y, -x+1, z; (ii) $[-x+y, y, z-{\script{1\over 2}}]$ ; (iii) -x+y+1, -x+1, z; (iv) -y+1, x-y+1, z; (v) -y+1, x-y, z.

The coordinates of H atoms attached to N atoms were found in difference maps and allowed to refine freely with fixed isotropic displacement parameters. H atoms bound to C atoms were refined using a riding model, with C—H = 0.99 Å and U_iso(H) = 1.2U_eq(C). PLATON (Spek, 2003 ) reveals metrical relationships among atoms consistent with a higher symmetry space group. The highly symmetric ions also suggest the higher symmetry space group $[P\overline{6}c]$ 2. However, checking the R_int values, the structure is unequivocally trigonal ( $[\overline{3}]$ m1 or $[\overline{3}]$ symmetry; R_int < 0.057). R_int for any hexagonal 6/m or 6/mmm symmetry (or trigonal $[\overline{3}]$ 1m) symmetry is > 0.187. Disorder in the occupation of the anions has been resolved and refined, the principal disorder component having an occupancy of 0.972 (8). Analysis of the model considering long-range hydrogen bonds between the cation and the anion favours the 97% position of the anion.

Data collection: COLLECT (Nonius, 2000 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SIR (Altomare et al., 1999 ); program(s) used to refine structure: SHELX97 (Sheldrick, 1997 ); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536806002522/sj6176sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536806002522/sj6176Isup2.hkl

Computing details top

Data collection: COLLECT (Nonius, 2000); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR (Altomare et al., 1999); program(s) used to refine structure: SHELX97 (Sheldrick, 1997); molecular graphics: ORTEP 3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Tris(ethylenediamine)nickel(II) tetraiodocadmate(II) top

Crystal data top

[Ni(C₆H₂₄N₆)][CdI₄]	D_x = 2.849 Mg m⁻³
M_r = 859.02	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3c1	Cell parameters from 15955 reflections
Hall symbol: P 3 -2 " c	θ = 2.9–30.0°
a = 9.023 (5) Å	µ = 8.16 mm⁻¹
c = 14.203 (5) Å	T = 150 K
V = 1001.4 (9) Å³	Block, colourless
Z = 2	0.25 × 0.20 × 0.20 mm
F(000) = 780

Data collection top

Nonius KappaCCD diffractometer	1944 independent reflections
Radiation source: fine-focus sealed tube	1937 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.056
188 2.0° images with ω scans	θ_max = 30.0°, θ_min = 3.9°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −11→12
T_min = 0.120, T_max = 0.195	k = −12→12
21288 measured reflections	l = −19→19

Refinement top

Refinement on F²	H atoms treated by a mixture of independent and constrained refinement
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0075P)² + 1.6741P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.018	(Δ/σ)_max = 0.001
wR(F²) = 0.039	Δρ_max = 0.99 e Å⁻³
S = 1.17	Δρ_min = −0.61 e Å⁻³
1944 reflections	Absolute structure: Flack (1983), 968 Friedel pairs
72 parameters	Absolute structure parameter: 0.00 (3)
1 restraint

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Cd1	0.3333	0.6667	0.29989 (3)	0.01805 (12)	0.972 (2)
Cd1A	0.3333	0.6667	0.1989 (10)	0.013 (4)	0.028 (2)
I1	0.27173 (3)	0.34346 (3)	0.24797 (2)	0.02170 (7)
I2	0.3333	0.6667	0.49626 (2)	0.01908 (9)
Ni	0.6667	0.3333	0.50028 (5)	0.01247 (13)
N1	0.8571 (4)	0.5390 (4)	0.5815 (2)	0.0175 (6)
H10A	0.815 (6)	0.555 (6)	0.633 (3)	0.021*
H10B	0.935 (7)	0.520 (6)	0.598 (4)	0.021*
N2	0.6844 (4)	0.5391 (3)	0.4181 (2)	0.0170 (6)
H20A	0.731 (7)	0.546 (6)	0.367 (3)	0.02*
H20B	0.589 (7)	0.523 (6)	0.407 (3)	0.02*
C1	0.9232 (4)	0.6989 (4)	0.5266 (2)	0.0179 (6)
H1A	1.0109	0.7079	0.4815	0.021*
H1B	0.9773	0.7986	0.5695	0.021*
C2	0.7773 (4)	0.6991 (4)	0.4738 (2)	0.0180 (6)
H2A	0.6979	0.707	0.519	0.022*
H2B	0.8228	0.7994	0.4313	0.022*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cd1	0.01746 (15)	0.01746 (15)	0.0192 (2)	0.00873 (8)	0	0
Cd1A	0.011 (5)	0.011 (5)	0.019 (7)	0.005 (2)	0	0
I1	0.02936 (12)	0.02101 (11)	0.01761 (10)	0.01474 (9)	−0.00047 (8)	−0.00215 (8)
I2	0.01780 (12)	0.01780 (12)	0.02164 (18)	0.00890 (6)	0	0
Ni	0.01157 (18)	0.01157 (18)	0.0143 (3)	0.00578 (9)	0	0
N1	0.0161 (13)	0.0168 (13)	0.0189 (14)	0.0078 (11)	−0.0035 (10)	−0.0007 (10)
N2	0.0179 (13)	0.0171 (13)	0.0176 (14)	0.0100 (11)	−0.0020 (10)	0.0006 (9)
C1	0.0142 (14)	0.0146 (13)	0.0213 (15)	0.0045 (12)	−0.0008 (11)	−0.0007 (11)
C2	0.0187 (14)	0.0135 (13)	0.0228 (15)	0.0089 (12)	−0.0003 (12)	0.0002 (12)

Geometric parameters (Å, º) top

Cd1—Cd1A	1.434 (15)	Ni—N1	2.130 (3)
Cd1—I1ⁱ	2.7815 (15)	Ni—N1^vi	2.130 (3)
Cd1—I1ⁱⁱ	2.7815 (15)	N1—C1	1.477 (4)
Cd1—I1	2.7815 (15)	N1—H10A	0.86 (5)
Cd1—I2	2.7889 (11)	N1—H10B	0.84 (5)
Cd1A—I1ⁱ	2.771 (4)	N2—C2	1.484 (4)
Cd1A—I1ⁱⁱ	2.771 (4)	N2—H20A	0.82 (5)
Cd1A—I1	2.771 (4)	N2—H20B	0.81 (5)
Cd1A—I2ⁱⁱⁱ	2.879 (15)	C1—C2	1.516 (5)
I2—Cd1A^iv	2.879 (15)	C1—H1A	0.99
Ni—N2^v	2.130 (3)	C1—H1B	0.99
Ni—N2^vi	2.130 (3)	C2—H2A	0.99
Ni—N2	2.130 (3)	C2—H2B	0.99
Ni—N1^v	2.130 (3)

Cd1A—Cd1—I1ⁱ	74.623 (14)	N1^v—Ni—N1	93.47 (12)
Cd1A—Cd1—I1ⁱⁱ	74.623 (14)	N2^v—Ni—N1^vi	173.05 (11)
I1ⁱ—Cd1—I1ⁱⁱ	113.237 (12)	N2^vi—Ni—N1^vi	82.01 (11)
Cd1A—Cd1—I1	74.623 (14)	N2—Ni—N1^vi	92.08 (12)
I1ⁱ—Cd1—I1	113.237 (12)	N1^v—Ni—N1^vi	93.47 (12)
I1ⁱⁱ—Cd1—I1	113.237 (12)	N1—Ni—N1^vi	93.47 (12)
Cd1A—Cd1—I2	180.00 (2)	C1—N1—Ni	108.7 (2)
I1ⁱ—Cd1—I2	105.377 (14)	C1—N1—H10A	106 (3)
I1ⁱⁱ—Cd1—I2	105.377 (14)	Ni—N1—H10A	112 (3)
I1—Cd1—I2	105.377 (14)	C1—N1—H10B	112 (3)
Cd1—Cd1A—I1ⁱ	75.40 (3)	Ni—N1—H10B	112 (3)
Cd1—Cd1A—I1ⁱⁱ	75.40 (3)	H10A—N1—H10B	107 (5)
I1ⁱ—Cd1A—I1ⁱⁱ	113.90 (2)	C2—N2—Ni	108.4 (2)
Cd1—Cd1A—I1	75.4 (3)	C2—N2—H20A	112 (4)
I1ⁱ—Cd1A—I1	113.9 (2)	Ni—N2—H20A	111 (3)
I1ⁱⁱ—Cd1A—I1	113.9 (2)	C2—N2—H20B	108 (3)
Cd1—Cd1A—I2ⁱⁱⁱ	180	Ni—N2—H20B	110 (3)
I1ⁱ—Cd1A—I2ⁱⁱⁱ	104.60 (3)	H20A—N2—H20B	107 (5)
I1ⁱⁱ—Cd1A—I2ⁱⁱⁱ	104.60 (3)	N1—C1—C2	109.6 (3)
I1—Cd1A—I2ⁱⁱⁱ	104.60 (3)	N1—C1—H1A	109.8
Cd1A—I1—Cd1	29.9 (3)	C2—C1—H1A	109.8
Cd1—I2—Cd1A^iv	180.00 (3)	N1—C1—H1B	109.8
N2^v—Ni—N2^vi	92.83 (12)	C2—C1—H1B	109.8
N2^v—Ni—N2	92.83 (12)	H1A—C1—H1B	108.2
N2^vi—Ni—N2	92.83 (12)	N2—C2—C1	109.3 (3)
N2^v—Ni—N1^v	82.01 (10)	N2—C2—H2A	109.8
N2^vi—Ni—N1^v	92.08 (12)	C1—C2—H2A	109.8
N2—Ni—N1^v	173.05 (11)	N2—C2—H2B	109.8
N2^v—Ni—N1	92.08 (12)	C1—C2—H2B	109.8
N2^vi—Ni—N1	173.05 (11)	H2A—C2—H2B	108.3
N2—Ni—N1	82.01 (11)

I1ⁱⁱ—Cd1—Cd1A—I1ⁱ	−120.000	N2^v—Ni—N1—C1	79.3 (2)
I1—Cd1—Cd1A—I1ⁱ	120.000	N2^vi—Ni—N1—C1	−55.6 (13)
I1ⁱ—Cd1—Cd1A—I1ⁱⁱ	120.000	N2—Ni—N1—C1	−13.2 (2)
I1—Cd1—Cd1A—I1ⁱⁱ	−120.000	N1^v—Ni—N1—C1	161.5 (2)
I1ⁱ—Cd1—Cd1A—I1	−120.00	N1^vi—Ni—N1—C1	−104.8 (3)
I1ⁱⁱ—Cd1—Cd1A—I1	120.00	N2^v—Ni—N2—C2	−106.3 (3)
II1ⁱ—Cd1A—I1—Cd1	−66.50 (4)	N2^vi—Ni—N2—C2	160.7 (2)
I1ⁱⁱ—Cd1A—I1—Cd1	66.50 (4)	N1^v—Ni—N2—C2	−64.3 (12)
I2ⁱⁱⁱ—Cd1A—I1—Cd1	180	N1—Ni—N2—C2	−14.6 (2)
I1ⁱ—Cd1—I1—Cd1A	65.33 (2)	N1^vi—Ni—N2—C2	78.6 (2)
I1ⁱⁱ—Cd1—I1—Cd1A	−65.33 (2)	Ni—N1—C1—C2	38.6 (3)
I2—Cd1—I1—Cd1A	180.000 (2)	Ni—N2—C2—C1	39.6 (3)
Cd1A—Cd1—I2—Cd1A^iv	0 (16)	N1—C1—C2—N2	−52.9 (3)

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

Acknowledgements

The authors thank the Pakistan Science Foundation Islamabad 45320, Pakistan, for funding [contract/grant No. PSF/R&D/C-QU/Chem(218)].

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