Dibromidobis(N,N,N′,N′-tetra­methyl­thio­urea-κS)cadmium(II)

Abstract

In the title compound, [CdBr₂(C₅H₁₂N₂S)₂], the Cd^II atom lies on a twofold rotation axis. It exhibits a distorted tetra­hedral coordination environment defined by two S atoms of two tetra­methyl­thio­urea (tmtu) ligands and two bromide ions. The crystal structure is consolidated by C—H⋯N and C—H⋯S hydrogen bonds.

Related literature

For crystallographic and spectroscopic studies of thio­urea complexes, see: Al-Arfaj et al. (1998 ▶); Ali et al. (2009 ▶); Isab et al. (2009 ▶); Lobana et al. (2008 ▶); Marcos et al. (1998 ▶); Moloto et al. (2003 ▶). The structure of the title compound is isotypic with [Cd(tmtu)₂I₂] (Nawaz et al., 2010a ▶) and [Hg(tmtu)₂Cl₂] (Nawaz et al., 2010b ▶).

Experimental

Crystal data

• [CdBr₂(C₅H₁₂N₂S)₂]

• M _r = 536.67

• Monoclinic,

• a = 18.6133 (17) Å

• b = 10.0690 (9) Å

• c = 13.4600 (12) Å

• β = 130.834 (1)°

• V = 1908.6 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 5.54 mm⁻¹

• T = 292 K

• 0.24 × 0.23 × 0.20 mm

Data collection

• Bruker SMART APEX area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.350, T _max = 0.404

• 12678 measured reflections

• 2379 independent reflections

• 2114 reflections with I > 2σ(I)

• R _int = 0.028

Refinement

• R[F ² > 2σ(F ²)] = 0.021

• wR(F ²) = 0.052

• S = 1.05

• 2379 reflections

• 92 parameters

• H-atom parameters constrained

• Δρ_max = 0.44 e Å⁻³

• Δρ_min = −0.45 e Å⁻³

Data collection: SMART (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

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

Table 1. Selected bond lengths (Å).

Cd1—S1	2.5580 (6)
Cd1—Br1	2.5735 (3)

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2A⋯N2	0.96	2.53	2.855 (4)	100
C5—H5A⋯S1	0.96	2.65	3.026 (3)	104

supplementary crystallographic information

Comment

The coordination chemistry of thioureas with metal ions has been the subject of several recent investigations because of their variable binding modes and because of the relevance of their binding sites to those in living systems. Crystallographic reports about d¹⁰ metal complexes of thioureas established that these ligands are coordinated via the sulfur atom (Al-Arfaj et al., 1998; Moloto et al., 2003). Spectroscopic data is also consistent with this finding (Isab et al., 2009; Ali et al., 2009). Herein, we report the crystal structure of a cadmium bromide complex with tetramethylthiourea (tmtu), [Cd(C₅H₁₂N₂S₂)₂Br₂], (I).

The crystal structure of (I) consists of discrete molecular species in which the cadmium atom is located on a twofold rotation axis (Fig. 1). It exhibits a distorted tetrahedral coordination environment defined by two tetramethylthiourea (tmtu) ligands and two bromide ions. The tmtu ligand is terminally bound to the Cd^II atom via coordination of the S1 atom. The Cd—S and Cd—Br bond lengths are 2.5580 (6) and 2.5735 (3) Å, respectively. These values are in agreement with those reported for related compounds, e.g. (Al-Arfaj et al., 1998; Lobana et al. 2008; Marcos et al., 1998; Moloto et al., 2003). The bond angles around Cd are indicative of a slight tetrahedral distortion, with the S—Cd—S angle showing the largest deviation (117.70 (3)°) from the ideal value. The SCN₂— moiety of the tmtu ligand is essentially planar, the maximum deviation from the mean plane being 0.007 (2) Å for the carbon atom. The fragments N1—C1—C2—C3 and N2—C1—C4—C5 are also close to planarity. The maximum deviations from the mean planes are 0.072 (2) Å and 0.065 (2) Å for N1 and N2, respectively. These values are consistent with a significant C—N double bond character and electron delocalization in the SCN₂— moiety. The steric effect of the two adjacent 1,3-methyl groups imposes a dihedral angle of 47.4 (2) ° for the two mean planes and therefore a tilted conformation. The latter is likely stabilized by non-classical intramolecular hydrogen bonding interactions involving methyl H atoms with sulfur and nitrogen atoms (C2—H2A ···N2 and C5—H5A···S1). The molecules pack to form columns approximately parallel to [110] direction (Fig. 2).

The structure of (I) is isotypic with [Cd(tmtu)₂I₂] (Nawaz et al., 2010a), with an equivalent degree of distortion from the ideal tetrahedral configuration and similar Cd—S and C—N bond lengths. The tmtu bond lengths are also consistent with those found for the likewise isotypic compound [Hg(tmtu)₂Cl₂] (Nawaz et al., 2010b), in which a significantly higher distortion of the metal ion coordination sphere is observed.

Experimental

0.35 g (1.0 mmol) cadmium(II) bromide tetrahydrate dissolved in 10 ml water were added to two equivalents of tetramethylthiourea in methanol. A white precipitate formed and was filtered off. The filtrate was kept for crystallization. As a result, an off-white crystalline product suitable for single crystal X-ray diffraction was obtained.

Refinement

H atoms were placed in calculated positions with a C—H distance of 0.96 Å and U_iso(H) = 1.5 U_eq(C).

Figures

Fig. 1.

The molecular structure of title compound with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H-atoms are omitted for clarity.

Fig. 2.

Packing diagram of the title complex

Crystal data

[CdBr2(C5H12N2S)2]	F(000) = 1048
Mr = 536.67	Dx = 1.868 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 12678 reflections
a = 18.6133 (17) Å	θ = 2.5–28.3°
b = 10.0690 (9) Å	µ = 5.54 mm−1
c = 13.4600 (12) Å	T = 292 K
β = 130.834 (1)°	Block, colorless
V = 1908.6 (3) Å3	0.24 × 0.23 × 0.20 mm
Z = 4

Data collection

Bruker SMART APEX area-detector diffractometer	2379 independent reflections
Radiation source: normal-focus sealed tube	2114 reflections with I > 2σ(I)
graphite	Rint = 0.028
ω scans	θmax = 28.3°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −24→24
Tmin = 0.350, Tmax = 0.404	k = −13→13
12678 measured reflections	l = −17→17

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.021	H-atom parameters constrained
wR(F2) = 0.052	w = 1/[σ2(Fo2) + (0.025P)2 + 1.3001P] where P = (Fo2 + 2Fc2)/3
S = 1.05	(Δ/σ)max = 0.001
2379 reflections	Δρmax = 0.44 e Å−3
92 parameters	Δρmin = −0.45 e Å−3
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0068 (2)

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	1.0000	0.70441 (2)	0.2500	0.03969 (8)
Br1	1.149352 (17)	0.56647 (3)	0.34643 (3)	0.05549 (9)
S1	1.03619 (4)	0.83583 (7)	0.44089 (5)	0.04794 (14)
N1	0.91758 (14)	0.76405 (19)	0.4771 (2)	0.0474 (4)
N2	0.85096 (13)	0.8900 (2)	0.29223 (18)	0.0471 (4)
C1	0.92634 (14)	0.82923 (19)	0.39910 (19)	0.0366 (4)
C2	0.8527 (2)	0.8077 (3)	0.4968 (3)	0.0672 (7)
H2A	0.8267	0.8928	0.4562	0.101*
H2B	0.8867	0.8145	0.5891	0.101*
H2C	0.8022	0.7444	0.4580	0.101*
C3	0.9861 (2)	0.6637 (3)	0.5706 (3)	0.0724 (8)
H3A	1.0111	0.6189	0.5359	0.109*
H3B	0.9552	0.6004	0.5851	0.109*
H3C	1.0369	0.7056	0.6522	0.109*
C4	0.75337 (18)	0.8418 (3)	0.2186 (3)	0.0694 (8)
H4A	0.7550	0.7542	0.2480	0.104*
H4B	0.7211	0.8394	0.1266	0.104*
H4C	0.7203	0.9005	0.2330	0.104*
C5	0.8609 (2)	0.9921 (3)	0.2254 (3)	0.0697 (8)
H5A	0.9218	1.0340	0.2870	0.105*
H5B	0.8118	1.0573	0.1892	0.105*
H5C	0.8557	0.9524	0.1561	0.105*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cd1	0.04286 (13)	0.04283 (13)	0.04311 (13)	0.000	0.03237 (11)	0.000
Br1	0.05068 (15)	0.05784 (16)	0.05843 (16)	0.01407 (10)	0.03588 (13)	0.00638 (11)
S1	0.0391 (3)	0.0665 (4)	0.0425 (3)	−0.0082 (2)	0.0286 (2)	−0.0132 (2)
N1	0.0572 (11)	0.0471 (10)	0.0559 (11)	0.0041 (9)	0.0448 (10)	0.0036 (8)
N2	0.0448 (10)	0.0540 (11)	0.0427 (10)	0.0038 (8)	0.0287 (9)	−0.0020 (8)
C1	0.0406 (10)	0.0363 (10)	0.0371 (10)	−0.0014 (8)	0.0272 (9)	−0.0061 (8)
C2	0.0799 (19)	0.0800 (19)	0.0815 (19)	−0.0012 (15)	0.0702 (18)	−0.0047 (15)
C3	0.090 (2)	0.0600 (16)	0.082 (2)	0.0174 (15)	0.0627 (19)	0.0238 (15)
C4	0.0393 (13)	0.101 (2)	0.0573 (16)	0.0026 (14)	0.0268 (12)	−0.0123 (15)
C5	0.0804 (19)	0.0721 (18)	0.0571 (15)	0.0165 (15)	0.0451 (15)	0.0201 (14)

Geometric parameters (Å, °)

Cd1—S1	2.5580 (6)	C2—H2B	0.9600
Cd1—S1i	2.5580 (6)	C2—H2C	0.9600
Cd1—Br1i	2.5735 (3)	C3—H3A	0.9600
Cd1—Br1	2.5735 (3)	C3—H3B	0.9600
S1—C1	1.731 (2)	C3—H3C	0.9600
N1—C1	1.335 (3)	C4—H4A	0.9600
N1—C3	1.460 (3)	C4—H4B	0.9600
N1—C2	1.463 (3)	C4—H4C	0.9600
N2—C1	1.331 (3)	C5—H5A	0.9600
N2—C5	1.455 (3)	C5—H5B	0.9600
N2—C4	1.471 (3)	C5—H5C	0.9600
C2—H2A	0.9600
S1—Cd1—S1i	117.70 (3)	H2A—C2—H2C	109.5
S1—Cd1—Br1i	105.899 (14)	H2B—C2—H2C	109.5
S1i—Cd1—Br1i	106.524 (15)	N1—C3—H3A	109.5
S1—Cd1—Br1	106.524 (15)	N1—C3—H3B	109.5
S1i—Cd1—Br1	105.899 (14)	H3A—C3—H3B	109.5
Br1i—Cd1—Br1	114.676 (17)	N1—C3—H3C	109.5
C1—S1—Cd1	100.04 (7)	H3A—C3—H3C	109.5
C1—N1—C3	122.1 (2)	H3B—C3—H3C	109.5
C1—N1—C2	122.3 (2)	N2—C4—H4A	109.5
C3—N1—C2	114.2 (2)	N2—C4—H4B	109.5
C1—N2—C5	121.5 (2)	H4A—C4—H4B	109.5
C1—N2—C4	122.8 (2)	N2—C4—H4C	109.5
C5—N2—C4	114.6 (2)	H4A—C4—H4C	109.5
N2—C1—N1	119.41 (19)	H4B—C4—H4C	109.5
N2—C1—S1	121.32 (16)	N2—C5—H5A	109.5
N1—C1—S1	119.26 (16)	N2—C5—H5B	109.5
N1—C2—H2A	109.5	H5A—C5—H5B	109.5
N1—C2—H2B	109.5	N2—C5—H5C	109.5
H2A—C2—H2B	109.5	H5A—C5—H5C	109.5
N1—C2—H2C	109.5	H5B—C5—H5C	109.5

Symmetry codes: (i) −x+2, y, −z+1/2.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···N2	0.96	2.53	2.855 (4)	100
C5—H5A···S1	0.96	2.65	3.026 (3)	104