Bis(2,6-dimethyl­pyridinium) tetra­bromido­cobaltate(II)

Ali, B.F.; Al-Far, R.H.; Haddad, S.F.

doi:10.1107/S160053680800439X

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 3| March 2008| Pages m485-m486

doi:10.1107/S160053680800439X

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Bis(2,6-dimethylpyridinium) tetrabromidocobaltate(II)

Basem Fares Ali,^a Rawhi H. Al-Far ^b ^* and Salim F. Haddad ^c

^aDepartment of Chemistry, Al al-Bayt University, Mafraq 25113, Jordan, ^bFaculty of Information Technology and Science, Al-Balqa'a Applied University, Salt, Jordan, and ^cDepartment of Chemistry, The University of Jordan, Amman, Jordan
^*Correspondence e-mail: rohi@bau.edu.jo

(Received 9 February 2008; accepted 13 February 2008; online 20 February 2008)

In the crystal structure of the title compound, (C₇H₁₀N)₂[CoBr₄], the [CoBr₄]²⁻ anion is connected to two cations through N—H⋯Br and H₂C—H⋯Br hydrogen bonds to form two-dimensional cation–anion–cation layers normal to the crystallographic b axis. Interactions of the π–π type are absent between cations in the stacks [centroid–centroid separation = 5.01 (5) Å]. Significant intermolecular Br–aryl interactions are present in the structure, especially an unusually short Br–ring centroid interaction of 3.78 (1) Å. The coordination geometry of the anion is approximately tetrahedral and a twofold rotation axis passes through the Co atom.

Related literature

For general background, see: Al-Far & Ali (2007a ,b ); Ali & Al-Far (2007 ); Allen et al. (1997 ); Desiraju & Steiner (1999 ); Dolling et al. (2001 ); Hunter (1994 ); Panunto et al. (1987 ); Robinson et al. (2000 ). For related literature, see: Al-Far & Ali (2008 ); Ali & Al-Far (2008 ); Allen et al. (1987 ); Desiraju (1997 ); Zhang et al. (2005 ).

Experimental

Crystal data

(C₇H₁₀N)₂[CoBr₄]
M_r = 594.89
Orthorhombic, P b c n
a = 17.234 (2) Å
b = 9.0691 (10) Å
c = 13.729 (2) Å
V = 2145.7 (5) Å³
Z = 4
Mo Kα radiation
μ = 8.24 mm⁻¹
T = 293 (2) K
0.40 × 0.30 × 0.20 mm

Data collection

Bruker P4 diffractometer
Absorption correction: ψ scan;(North et al., 1968 ) T_min = 0.064, T_max = 0.192
2534 measured reflections
1930 independent reflections
885 reflections with I > 2σ(I)
R_int = 0.072

Refinement

R[F² > 2σ(F²)] = 0.055
wR(F²) = 0.117
S = 0.97
1930 reflections
97 parameters
H-atom parameters constrained
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.40 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Br1—Co1	2.4002 (13)
Co1—Br2	2.4044 (15)

Br1—Co1—Br1ⁱ	115.28 (9)
Br1—Co1—Br2	108.06 (3)
Br1—Co1—Br2ⁱ	108.37 (4)
Br2—Co1—Br2ⁱ	108.54 (9)
Symmetry code: (i) $[-x+1, y, -z+{\script{1\over 2}}]$ .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Br2	0.86	2.51	3.366 (7)	176
C7—H7A⋯Br2	0.96	2.97	3.856 (10)	153

Data collection: XSCANS (Siemens, 1996 ); cell refinement: XSCANS; data reduction: SHELXTL (Sheldrick, 2008 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680800439X/at2543sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053680800439X/at2543Isup2.hkl

checkCIF report

Comment top

Noncovalent interactions play an important role in organizing structural units in both natural and artificial systems (Desiraju, 1997). They exercise important effects on the organization and properties of many materials in areas such as biology (Hunter 1994; Desiraju & Steiner 1999), crystal engineering (see for example: Allen et al.,1997; Dolling et al., 2001) and material science (Panunto et al., 1987; Robinson et al., 2000). The interactions governing the crystal organization are expected to affect the packing and then the specific properties of solids. In connection with ongoing studies (Ali & Al-Far, 2008; Al-Far & Ali, 2008; Ali & Al-Far, 2007; Al-Far & Ali, 2007a,b) of the structural aspects of halo-metal anion salts, we herein report the crystal structure of the title compound (I) along with its crystal supramolecularity.

The asymmetric unit in (I), contains half an anion and one cation (Fig. 1). The geometry of CoBr₄^2- anions is nearly tetrahedral (T_d) about Co metal (Table 1). Co—Br distances are similar, but Co—Br that are engaged in Co—Br···H—N,C hydrogen bonding, Co—Br2 and Co—Br2 [1 - x, y, 1/2 - z], are slightly longer than the others (Table 1). The bond distances and angles fall in the range of those reported previously for compounds containing Co—Br anions (Ali & Al-Far 2008; Al-Far & Ali 2008; Zhang et al., 2005). In the cation, the bond lengths and angles are within normal range (Allen et al., 1987).

The packing of the structure (Fig. 2) can be regarded as alternating stacks of anions and stacks of cations. The anion stacks are parallel to the cation stacks, with Co···Co distance of 9.0691 (10) Å (b axis), with no significant inter- and intra-stack halogen···halogen interactions (shortest Br···Br interactions being 4.4236 (20) Å). The anions and cations are interacting significantly through extensive N—H···Br and C—H···Br hydrogen bonding involving Br^- anions and N—H and CH₃ groups (Table 2; Fig. 3). These interactions link anions and cations into two-dimensional cation···anion···cation layers approximately normal to the crystallographic b axis (Fig. 3).

There is no π···π stacking of cations, the inter-stack centroid separations X1A···X1A [1 - x, y, 1/2 - z] and X1A···X1A [3/2 - x, 1/2 + y, z] being 5.01 (5) Å. This correlates well with the significant intermolecular Br···aryl interactions present in the structure. These are represented by the unusually short Br2···X1A [1 - x, -y, 1 - z] contact (3.78 (1) Å) and Br1···X1A [1 - x, y, 1/2 - z] (4.17 (3) Å) interaction.

Related literature top

For general background, see: Al-Far & Ali (2007a,b); Ali & Al-Far (2007); Allen et al. (1997); Desiraju & Steiner (1999); Dolling et al. (2001); Hunter (1994); Panunto et al. (1987); Robinson et al. (2000). For related literature, see: Al-Far & Ali (2008); Ali & Al-Far (2008); Allen et al. (1987); Desiraju (1997); Zhang et al. (2005). N.B. the cystal description in the CIF is currently `Shunk'; should this be changed to `chunk' or `block'?

Experimental top

Boiling CoCl₂(1.0 mmol), dissolved in absolute ethanol (10 ml) was added to a stirred absolute ethanol solution (10 ml) of 2,6-lutidine (1 mmol) and 48% HBr (3 ml). The mixture was then treated with liquid Br₂ (2 ml). After refluxing for ca 1 h, the mixture was filtered off and allowed to evaporate undisturbed at room temperature. The salt crystallized out over 1 d as blue crystals.

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: SHELXTL (Sheldrick, 2008); 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 (Sheldrick, 2008).

Figures top

	Fig. 1. A view of the asymmetric unit of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry operation: (A) -x + 1, y, -z + 1/2].
	Fig. 2. A packing diagram of (I), shows alternating stacks of anions and cations. Hydrogen atoms have been omitted for clarity.
	Fig. 3. Anion···cation intermolecular interactions. C,N—H···Br—Co intermolecular interactions are shown as dashed lines. Hydrogen atoms not involved in hydrogen bonding omitted for clarity. [Symmetry operation: (i) -x + 1, y, -z + 1/2]

Bis(2,6-dimethylpyridinium) tetrabromidocobaltate(II) top

Crystal data top

(C₇H₁₀N)₂[CoBr₄]	F(000) = 1140
M_r = 594.89	D_x = 1.842 Mg m⁻³
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 36 reflections
a = 17.234 (2) Å	θ = 2.4–16.8°
b = 9.0691 (10) Å	µ = 8.24 mm⁻¹
c = 13.729 (2) Å	T = 293 K
V = 2145.7 (5) Å³	Chunk, blue
Z = 4	0.40 × 0.30 × 0.20 mm

Data collection top

Bruker P4 diffractometer	1930 independent reflections
Radiation source: fine-focus sealed tube	885 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.072
Detector resolution: 3 pixels mm^-1	θ_max = 25.2°, θ_min = 2.4°
ω Scans scans	h = −1→20
Absorption correction: ψ scan (North et al., 1968)	k = −1→10
T_min = 0.064, T_max = 0.192	l = −16→1
2534 measured reflections

Refinement top

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)] = 0.055	H-atom parameters constrained
wR(F²) = 0.117	w = 1/[σ²(F_o²) + (0.0321P)²] where P = (F_o² + 2F_c²)/3
S = 0.97	(Δ/σ)_max < 0.001
1930 reflections	Δρ_max = 0.55 e Å⁻³
97 parameters	Δρ_min = −0.40 e Å⁻³
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0060 (4)

Crystal data top

(C₇H₁₀N)₂[CoBr₄]	V = 2145.7 (5) Å³
M_r = 594.89	Z = 4
Orthorhombic, Pbcn	Mo Kα radiation
a = 17.234 (2) Å	µ = 8.24 mm⁻¹
b = 9.0691 (10) Å	T = 293 K
c = 13.729 (2) Å	0.40 × 0.30 × 0.20 mm

Data collection top

Bruker P4 diffractometer	1930 independent reflections
Absorption correction: ψ scan (North et al., 1968)	885 reflections with I > 2σ(I)
T_min = 0.064, T_max = 0.192	R_int = 0.072
2534 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.055	0 restraints
wR(F²) = 0.117	H-atom parameters constrained
S = 0.97	Δρ_max = 0.55 e Å⁻³
1930 reflections	Δρ_min = −0.40 e Å⁻³
97 parameters

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
Br1	0.39353 (5)	−0.42729 (12)	0.18719 (7)	0.0680 (4)
Co1	0.5000	−0.2856 (2)	0.2500	0.0500 (6)
Br2	0.45145 (6)	−0.13081 (14)	0.37845 (7)	0.0845 (5)
N1	0.6230 (4)	−0.1559 (9)	0.4945 (5)	0.056 (2)
H1	0.5806	−0.1498	0.4618	0.067*
C2	0.6211 (6)	−0.2366 (13)	0.5769 (8)	0.071 (3)
C3	0.6900 (8)	−0.2499 (13)	0.6250 (9)	0.097 (4)
H3	0.6928	−0.3052	0.6819	0.116*
C4	0.7556 (7)	−0.1811 (15)	0.5891 (10)	0.099 (4)
H4	0.8025	−0.1918	0.6218	0.119*
C5	0.7527 (6)	−0.0991 (13)	0.5078 (8)	0.085 (4)
H5	0.7973	−0.0526	0.4852	0.102*
C6	0.6850 (6)	−0.0840 (11)	0.4588 (6)	0.061 (3)
C7	0.5478 (6)	−0.3092 (14)	0.6029 (8)	0.116 (5)
H7A	0.5083	−0.2813	0.5572	0.174*
H7B	0.5325	−0.2795	0.6672	0.174*
H7C	0.5546	−0.4142	0.6012	0.174*
C8	0.6727 (5)	0.0072 (13)	0.3689 (7)	0.106 (4)
H8A	0.6197	−0.0011	0.3483	0.159*
H8B	0.7063	−0.0274	0.3180	0.159*
H8C	0.6843	0.1086	0.3829	0.159*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0521 (6)	0.0757 (8)	0.0762 (7)	−0.0135 (6)	−0.0140 (6)	0.0045 (6)
Co1	0.0379 (9)	0.0594 (14)	0.0527 (10)	0.000	−0.0008 (9)	0.000
Br2	0.0537 (6)	0.1130 (11)	0.0867 (8)	0.0146 (7)	−0.0040 (6)	−0.0405 (7)
N1	0.036 (4)	0.069 (6)	0.063 (5)	−0.006 (4)	0.001 (4)	−0.005 (5)
C2	0.056 (7)	0.081 (8)	0.075 (7)	−0.007 (6)	−0.003 (6)	0.018 (7)
C3	0.106 (10)	0.080 (10)	0.103 (9)	0.013 (8)	−0.024 (9)	0.009 (8)
C4	0.065 (8)	0.116 (12)	0.117 (11)	0.032 (9)	−0.045 (8)	−0.020 (9)
C5	0.055 (7)	0.113 (11)	0.087 (8)	0.006 (7)	−0.012 (7)	−0.007 (8)
C6	0.050 (6)	0.068 (7)	0.065 (7)	−0.014 (6)	0.005 (5)	−0.017 (6)
C7	0.104 (10)	0.124 (12)	0.120 (9)	−0.034 (9)	0.006 (8)	0.055 (9)
C8	0.085 (8)	0.150 (13)	0.082 (8)	−0.045 (9)	0.002 (7)	0.040 (9)

Geometric parameters (Å, º) top

Br1—Co1	2.4002 (13)	C4—C5	1.341 (15)
Co1—Br1ⁱ	2.4002 (13)	C4—H4	0.9300
Co1—Br2	2.4044 (15)	C5—C6	1.354 (12)
Co1—Br2ⁱ	2.4044 (15)	C5—H5	0.9300
N1—C2	1.348 (11)	C6—C8	1.501 (12)
N1—C6	1.345 (10)	C7—H7A	0.9600
N1—H1	0.8600	C7—H7B	0.9600
C2—C3	1.363 (13)	C7—H7C	0.9600
C2—C7	1.468 (12)	C8—H8A	0.9600
C3—C4	1.383 (15)	C8—H8B	0.9600
C3—H3	0.9300	C8—H8C	0.9600

Br1—Co1—Br1ⁱ	115.28 (9)	C4—C5—C6	120.1 (12)
Br1—Co1—Br2	108.06 (3)	C4—C5—H5	119.9
Br1ⁱ—Co1—Br2	108.37 (4)	C6—C5—H5	119.9
Br1—Co1—Br2ⁱ	108.37 (4)	N1—C6—C5	117.0 (10)
Br1ⁱ—Co1—Br2ⁱ	108.06 (3)	N1—C6—C8	117.1 (9)
Br2—Co1—Br2ⁱ	108.54 (9)	C5—C6—C8	125.9 (10)
C2—N1—C6	126.0 (8)	C2—C7—H7A	109.5
C2—N1—H1	117.0	C2—C7—H7B	109.5
C6—N1—H1	117.0	H7A—C7—H7B	109.5
N1—C2—C3	115.7 (10)	C2—C7—H7C	109.5
N1—C2—C7	117.9 (9)	H7A—C7—H7C	109.5
C3—C2—C7	126.3 (11)	H7B—C7—H7C	109.5
C2—C3—C4	120.0 (11)	C6—C8—H8A	109.5
C2—C3—H3	120.0	C6—C8—H8B	109.5
C4—C3—H3	120.0	H8A—C8—H8B	109.5
C5—C4—C3	121.1 (11)	C6—C8—H8C	109.5
C5—C4—H4	119.5	H8A—C8—H8C	109.5
C3—C4—H4	119.5	H8B—C8—H8C	109.5

C6—N1—C2—C3	−2.9 (16)	C3—C4—C5—C6	−1 (2)
C6—N1—C2—C7	−178.9 (10)	C2—N1—C6—C5	3.0 (15)
N1—C2—C3—C4	0.8 (18)	C2—N1—C6—C8	−176.3 (9)
C7—C2—C3—C4	176.5 (12)	C4—C5—C6—N1	−1.0 (16)
C2—C3—C4—C5	1 (2)	C4—C5—C6—C8	178.2 (11)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br2	0.86	2.51	3.366 (7)	176
C7—H7A···Br2	0.96	2.97	3.856 (10)	153

Experimental details

Crystal data
Chemical formula	(C₇H₁₀N)₂[CoBr₄]
M_r	594.89
Crystal system, space group	Orthorhombic, Pbcn
Temperature (K)	293
a, b, c (Å)	17.234 (2), 9.0691 (10), 13.729 (2)
V (Å³)	2145.7 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	8.24
Crystal size (mm)	0.40 × 0.30 × 0.20

Data collection
Diffractometer	Bruker P4 diffractometer
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.064, 0.192
No. of measured, independent and observed [I > 2σ(I)] reflections	2534, 1930, 885
R_int	0.072
(sin θ/λ)_max (Å⁻¹)	0.600

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.055, 0.117, 0.97
No. of reflections	1930
No. of parameters	97
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.55, −0.40

Computer programs: XSCANS (Siemens, 1996), SHELXTL (Sheldrick, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008).

Selected geometric parameters (Å, º) top

Br1—Co1	2.4002 (13)	Co1—Br2	2.4044 (15)

Br1—Co1—Br1ⁱ	115.28 (9)	Br1—Co1—Br2ⁱ	108.37 (4)
Br1—Co1—Br2	108.06 (3)	Br2—Co1—Br2ⁱ	108.54 (9)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br2	0.86	2.51	3.366 (7)	175.6
C7—H7A···Br2	0.96	2.97	3.856 (10)	153.4

Acknowledgements

Financial support from Al al-Bayt University and Al-Balqa'a Applied University is greatly appreciated.

References

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