metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

Di-μ-chlorido-bis­­[(2-amino-4-methyl­pyridine-κN)­chloridomercury(II)]

aDepartment of Chemistry, Iran University of Science and Technology, Tehran 16846-13114, Iran, and bDepartment of Chemistry, Shahid Beheshti University, G. C., Evin, Tehran 1983963113, Iran
*Correspondence e-mail: tajarodi@iust.ac.ir

(Received 20 August 2012; accepted 19 September 2012; online 26 September 2012)

In the centrosymmetric dinuclear title compound, [Hg2Cl4(C6H8N2)2], the HgII ion is four-coordinated by one pyridine N atom from a 2-amino-4-methyl­pyridine ligand, one terminal Cl atom and two bridging Cl atoms. A distorted tetra­hedral geometry is formed around each HgII ion. The crystal packing is stabilized by intra- and inter­molecular N—H⋯Cl hydrogen bonding. There are also ππ stacking inter­actions in the structure, with centroid-to-centroid distances of 3.594 (6) Å.

Related literature

For a coordination compound of 2-amino-4-methyl­pyridine, see: Arab Ahmadi et al. (2011[Arab Ahmadi, R., Safari, N., Khavasi, H. R. & Amani, S. (2011). J. Coord. Chem. 64, 2056-2065.]). For proton-transfer compounds of 2-amino-4-methyl­pyridine, see: Gharbia et al. (2008[Gharbia, I. B., Kefi, R., Nasr, C. B. & Durif, A. (2008). Rev. Roum. Chim. 53, 169-175.]); Choudhury et al. (2009[Choudhury, S. R., Dey, B., Das, S., Robertazzi, A., Jana, A. D., Chen, C. Y., Lee, H. M., Gameze, P. & Mukhopadhyay, S. (2009). Dalton Trans. pp. 7617-7624.]); Das et al. (2010[Das, A., Choudhury, S. R., Dey, B., Yalamanchili, S. K., Helliwell, M., Gamez, P., Mukhopadhyay, S., Estarellas, C. & Frontera, A. (2010). J. Phys. Chem. B, 114, 4998-5009.]); Hemamalini & Fun (2010[Hemamalini, M. & Fun, H.-K. (2010). Acta Cryst. E66, o2151-o2152.]); Aghabozorg et al. (2011[Aghabozorg, H., Mofidi Rouchi, A., Mirzaei, M. & Notash, B. (2011). Acta Cryst. E67, o54.]); Eshtiagh-Hosseini et al. (2010[Eshtiagh-Hosseini, H., Aghabozorg, H., Mirzaei, M., Amini, M. M., Chen, Y. G., Shokrollahi, A. & Aghaei, R. (2010). J. Mol. Struct. 973, 180-189.]). For mixed-ligand complexes of 2-amino-4-methyl­pyridine, see: Zhang et al. (2008[Zhang, L., You, Z. & Jiao, Q. (2008). Transition Met. Chem. 33, 573-577.]); Castillo et al. (2001[Castillo, O., Luque, A., Julve, M., Lloret, F. & Roman, P. (2001). Inorg. Chim. Acta, 315, 9-17.]); Yenikaya et al. (2011[Yenikaya, C., Büyükkidany, N., Sariz, M., Keşli, R., Ilkimeny, H., Bülbüly, M. & Büyükgüngor, O. (2011). J. Coord. Chem. 64, 3353-3365.]). For similar structures, see: Baul et al. (2004[Baul, T. S. B., Lycka, A., Butcher, R. & Smith, E. F. (2004). Polyhedron, 23, 2323-2329.]).

[Scheme 1]

Experimental

Crystal data
  • [Hg2Cl4(C6H8N2)2]

  • Mr = 759.27

  • Monoclinic, P 2/n

  • a = 7.1777 (14) Å

  • b = 9.1672 (18) Å

  • c = 14.546 (3) Å

  • β = 101.92 (3)°

  • V = 936.5 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 16.94 mm−1

  • T = 120 K

  • 0.25 × 0.25 × 0.20 mm

Data collection
  • Stoe IPDS 2T diffractometer

  • Absorption correction: numerical (shape of crystal determined optically; X-RED and X-SHAPE, Stoe & Cie, 2005[Stoe & Cie (2005). X-AREA, X-RED and X-SHAPE. Stoe & Cie, Darmstadt, Germany.]) Tmin = 0.101, Tmax = 0.133

  • 6495 measured reflections

  • 2507 independent reflections

  • 2019 reflections with I > 2σ(I)

  • Rint = 0.090

Refinement
  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.111

  • S = 1.00

  • 2507 reflections

  • 109 parameters

  • 2 restraints

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 2.35 e Å−3

  • Δρmin = −2.80 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H2B⋯Cl2i 0.87 (2) 2.62 (7) 3.380 (8) 146 (11)
N2—H2A⋯Cl2ii 0.87 (2) 2.68 (11) 3.379 (9) 139 (13)
Symmetry codes: (i) -x, -y+1, -z+2; (ii) [x-{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}].

Data collection: X-AREA (Stoe & Cie, 2005[Stoe & Cie (2005). X-AREA, X-RED and X-SHAPE. Stoe & Cie, Darmstadt, Germany.]); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997[Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.]); software used to prepare material for publication: WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]).

Supporting information


Comment top

To the best of our knowledge, coordination chemistry of 2-amino-4-methylpyridine has not been explored sufficiently. It has the potential to coordinate to metals through the N atom of the pyridyl group (Arab Ahmadi et al., 2011).

Contrary to other derivatives of aminopicolines, less work has been done on the synthesis of the complexes merely containing 2-amino-4-methylpyridine and most of the work is focused on its mixed ligand complexes (Zhang et al., 2008; Castillo et al., 2001; Yenikaya et al., 2011) or proton transfer compounds (Gharbia et al., 2008; Choudhury et al., 2009; Das et al., 2010; Hemamalini & Fun, 2010; Aghabozorg et al., 2011; Eshtiagh-Hosseini et al., 2010).

Herein, we report the synthesis and crystal structure of the title compound, [Hg2(C6H8N2)2Cl4], which is a dimeric complex. The centrosymmetric structure is made up of two Hg atoms, each coordinated by a terminal chloride atom and a nitrogen pyridyl ligand and bridged by chloride atoms. A distorted tetrahedral geometry is formed around each metal center (Fig. 1). The asymmetric unit contains one-half of a molecule since the whole molecule lies across a crystallographic inversion center. Bridging chloride atoms along with amino groups take part in intra- and intermolecular N—H··· Cl hydrogen bonds (Fig. 2 and Table 1). There is also ππ stacking in the structure of title compound with centroid–centroid distance of 3.594 (6) Å (Fig. 2).

Related literature top

For a coordination compound of 2-amino-4-methylpyridine, see: Arab Ahmadi et al. (2011). For proton-transfer compounds of 2-amino-4-methylpyridine, see: Gharbia et al. (2008); Choudhury et al. (2009); Das et al. (2010); Hemamalini & Fun (2010); Aghabozorg et al. (2011); Eshtiagh-Hosseini et al. (2010). For mixed-ligand complexes of 2-amino-4-methylpyridine, see: Zhang et al. (2008); Castillo et al. (2001); Yenikaya et al. (2011). For similar structures, see: Baul et al. (2004).

Experimental top

A solution of 2-amino-4-methylpyridine (1 mmol) in methanol was added to a methanolic solution of HgCl2 (1 mmol) and stirred for 20 min at 50°C. Slow evaporation of the resulting solution gave colorless crystals suitable for X-ray analysis.

Refinement top

H atoms attached to N atoms were found in difference Fourier map. They were refined with distance restraints of N—H 0.87 (2). H atoms attached to C atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 Å (CH), with C—H = 0.96 Å (CH3), and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(Cmethyl).

Structure description top

To the best of our knowledge, coordination chemistry of 2-amino-4-methylpyridine has not been explored sufficiently. It has the potential to coordinate to metals through the N atom of the pyridyl group (Arab Ahmadi et al., 2011).

Contrary to other derivatives of aminopicolines, less work has been done on the synthesis of the complexes merely containing 2-amino-4-methylpyridine and most of the work is focused on its mixed ligand complexes (Zhang et al., 2008; Castillo et al., 2001; Yenikaya et al., 2011) or proton transfer compounds (Gharbia et al., 2008; Choudhury et al., 2009; Das et al., 2010; Hemamalini & Fun, 2010; Aghabozorg et al., 2011; Eshtiagh-Hosseini et al., 2010).

Herein, we report the synthesis and crystal structure of the title compound, [Hg2(C6H8N2)2Cl4], which is a dimeric complex. The centrosymmetric structure is made up of two Hg atoms, each coordinated by a terminal chloride atom and a nitrogen pyridyl ligand and bridged by chloride atoms. A distorted tetrahedral geometry is formed around each metal center (Fig. 1). The asymmetric unit contains one-half of a molecule since the whole molecule lies across a crystallographic inversion center. Bridging chloride atoms along with amino groups take part in intra- and intermolecular N—H··· Cl hydrogen bonds (Fig. 2 and Table 1). There is also ππ stacking in the structure of title compound with centroid–centroid distance of 3.594 (6) Å (Fig. 2).

For a coordination compound of 2-amino-4-methylpyridine, see: Arab Ahmadi et al. (2011). For proton-transfer compounds of 2-amino-4-methylpyridine, see: Gharbia et al. (2008); Choudhury et al. (2009); Das et al. (2010); Hemamalini & Fun (2010); Aghabozorg et al. (2011); Eshtiagh-Hosseini et al. (2010). For mixed-ligand complexes of 2-amino-4-methylpyridine, see: Zhang et al. (2008); Castillo et al. (2001); Yenikaya et al. (2011). For similar structures, see: Baul et al. (2004).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of [Hg2(C6H8N2)2Cl4] with displacement ellipsoids drawn at 30% probability level.
[Figure 2] Fig. 2. The packing diagram of the title compound showing hydrogen bonding as blue dashed lines and ππ stacking.
Di-µ-chlorido-bis[(2-amino-4-methylpyridine)chloridomercury(II)] top
Crystal data top
C12H16Cl4Hg2N4F(000) = 688
Mr = 759.27Dx = 2.693 Mg m3
Monoclinic, P2/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yacCell parameters from 2507 reflections
a = 7.1777 (14) Åθ = 2.6–29.1°
b = 9.1672 (18) ŵ = 16.94 mm1
c = 14.546 (3) ÅT = 120 K
β = 101.92 (3)°Block, colorless
V = 936.5 (3) Å30.25 × 0.25 × 0.20 mm
Z = 2
Data collection top
Stoe IPDS 2T
diffractometer
2507 independent reflections
Radiation source: fine-focus sealed tube2019 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.090
Detector resolution: 0.15 mm pixels mm-1θmax = 29.1°, θmin = 2.6°
rotation method scansh = 99
Absorption correction: numerical
shape of crystal determined optically
k = 1210
Tmin = 0.101, Tmax = 0.133l = 1919
6495 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.046Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.111H atoms treated by a mixture of independent and constrained refinement
S = 1.00 w = 1/[σ2(Fo2) + (0.0604P)2]
where P = (Fo2 + 2Fc2)/3
2507 reflections(Δ/σ)max < 0.001
109 parametersΔρmax = 2.35 e Å3
2 restraintsΔρmin = 2.80 e Å3
Crystal data top
C12H16Cl4Hg2N4V = 936.5 (3) Å3
Mr = 759.27Z = 2
Monoclinic, P2/nMo Kα radiation
a = 7.1777 (14) ŵ = 16.94 mm1
b = 9.1672 (18) ÅT = 120 K
c = 14.546 (3) Å0.25 × 0.25 × 0.20 mm
β = 101.92 (3)°
Data collection top
Stoe IPDS 2T
diffractometer
2507 independent reflections
Absorption correction: numerical
shape of crystal determined optically
2019 reflections with I > 2σ(I)
Tmin = 0.101, Tmax = 0.133Rint = 0.090
6495 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0462 restraints
wR(F2) = 0.111H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 2.35 e Å3
2507 reflectionsΔρmin = 2.80 e Å3
109 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
xyzUiso*/Ueq
Hg10.21238 (5)0.47797 (4)0.94011 (2)0.02164 (12)
Cl10.3952 (3)0.6882 (3)0.98493 (15)0.0237 (4)
Cl20.1382 (3)0.3856 (2)1.10331 (13)0.0205 (4)
N10.1135 (11)0.2841 (9)0.8633 (5)0.0210 (15)
N20.0000 (13)0.4145 (10)0.7272 (5)0.0278 (18)
C10.0312 (12)0.2842 (11)0.7714 (6)0.0221 (18)
C20.0152 (13)0.1524 (12)0.7224 (6)0.025 (2)
H20.07090.15410.65720.030*
C30.0199 (16)0.0208 (12)0.7685 (7)0.031 (2)
C40.022 (2)0.1198 (14)0.7162 (8)0.046 (3)
H4A0.12420.10480.66100.068*
H4B0.06120.19310.75730.068*
H4C0.09300.15360.69590.068*
C50.0993 (15)0.0221 (12)0.8661 (7)0.028 (2)
H50.12060.06620.90090.034*
C60.1444 (14)0.1542 (11)0.9089 (6)0.0241 (18)
H60.20030.15500.97410.029*
H2A0.080 (14)0.429 (19)0.675 (5)0.06 (4)*
H2B0.028 (19)0.495 (7)0.753 (9)0.03 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg10.02222 (18)0.0215 (2)0.01994 (17)0.00052 (14)0.00134 (11)0.00125 (13)
Cl10.0237 (10)0.0218 (12)0.0245 (10)0.0020 (8)0.0025 (8)0.0015 (8)
Cl20.0194 (9)0.0248 (11)0.0177 (8)0.0030 (8)0.0047 (7)0.0008 (7)
N10.021 (4)0.020 (4)0.022 (3)0.003 (3)0.005 (3)0.001 (3)
N20.040 (5)0.026 (5)0.016 (3)0.010 (4)0.001 (3)0.001 (3)
C10.010 (4)0.033 (5)0.024 (4)0.001 (3)0.005 (3)0.003 (3)
C20.020 (4)0.038 (6)0.017 (4)0.004 (4)0.006 (3)0.010 (4)
C30.038 (6)0.033 (6)0.026 (4)0.015 (4)0.017 (4)0.012 (4)
C40.073 (9)0.036 (7)0.033 (5)0.030 (6)0.023 (6)0.022 (5)
C50.033 (5)0.023 (5)0.031 (5)0.003 (4)0.014 (4)0.002 (4)
C60.025 (5)0.026 (5)0.019 (4)0.001 (4)0.002 (3)0.002 (3)
Geometric parameters (Å, º) top
Hg1—N12.141 (8)C2—C31.377 (16)
Hg1—Cl12.347 (2)C2—H20.9500
Hg1—Cl22.6755 (19)C3—C51.417 (16)
Hg1—Cl2i2.763 (2)C3—C41.496 (14)
Cl2—Hg1i2.763 (2)C4—H4A0.9800
N1—C11.345 (12)C4—H4B0.9800
N1—C61.359 (13)C4—H4C0.9800
N2—C11.353 (13)C5—C61.369 (15)
N2—H2A0.87 (2)C5—H50.9500
N2—H2B0.87 (2)C6—H60.9500
C1—C21.407 (14)
N1—Hg1—Cl1158.87 (19)C3—C2—H2119.8
N1—Hg1—Cl295.45 (19)C1—C2—H2119.8
Cl1—Hg1—Cl2102.46 (7)C2—C3—C5118.4 (9)
N1—Hg1—Cl2i93.9 (2)C2—C3—C4120.6 (10)
Cl1—Hg1—Cl2i97.04 (8)C5—C3—C4120.9 (11)
Cl2—Hg1—Cl2i90.41 (7)C3—C4—H4A109.5
Hg1—Cl2—Hg1i89.59 (7)C3—C4—H4B109.5
C1—N1—C6118.7 (9)H4A—C4—H4B109.5
C1—N1—Hg1123.2 (7)C3—C4—H4C109.5
C6—N1—Hg1118.0 (6)H4A—C4—H4C109.5
C1—N2—H2A125 (10)H4B—C4—H4C109.5
C1—N2—H2B125 (9)C6—C5—C3118.1 (10)
H2A—N2—H2B94 (10)C6—C5—H5121.0
N1—C1—N2117.9 (9)C3—C5—H5121.0
N1—C1—C2120.8 (9)N1—C6—C5123.6 (9)
N2—C1—C2121.3 (8)N1—C6—H6118.2
C3—C2—C1120.3 (8)C5—C6—H6118.2
N1—Hg1—Cl2—Hg1i94.0 (2)C6—N1—C1—C22.5 (12)
Cl1—Hg1—Cl2—Hg1i97.30 (8)Hg1—N1—C1—C2174.1 (6)
Cl2i—Hg1—Cl2—Hg1i0.0N1—C1—C2—C31.2 (12)
Cl1—Hg1—N1—C164.4 (10)N2—C1—C2—C3179.2 (9)
Cl2—Hg1—N1—C1147.6 (6)C1—C2—C3—C51.4 (14)
Cl2i—Hg1—N1—C156.8 (6)C1—C2—C3—C4177.6 (9)
Cl1—Hg1—N1—C6112.2 (7)C2—C3—C5—C62.6 (15)
Cl2—Hg1—N1—C635.8 (6)C4—C3—C5—C6176.3 (9)
Cl2i—Hg1—N1—C6126.6 (6)C1—N1—C6—C51.2 (13)
C6—N1—C1—N2179.4 (8)Hg1—N1—C6—C5175.6 (7)
Hg1—N1—C1—N24.0 (11)C3—C5—C6—N11.4 (15)
Symmetry code: (i) x, y+1, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···Cl2i0.87 (2)2.62 (7)3.380 (8)146 (11)
N2—H2A···Cl2ii0.87 (2)2.68 (11)3.379 (9)139 (13)
Symmetry codes: (i) x, y+1, z+2; (ii) x1/2, y+1, z1/2.

Experimental details

Crystal data
Chemical formulaC12H16Cl4Hg2N4
Mr759.27
Crystal system, space groupMonoclinic, P2/n
Temperature (K)120
a, b, c (Å)7.1777 (14), 9.1672 (18), 14.546 (3)
β (°) 101.92 (3)
V3)936.5 (3)
Z2
Radiation typeMo Kα
µ (mm1)16.94
Crystal size (mm)0.25 × 0.25 × 0.20
Data collection
DiffractometerStoe IPDS 2T
Absorption correctionNumerical
shape of crystal determined optically
Tmin, Tmax0.101, 0.133
No. of measured, independent and
observed [I > 2σ(I)] reflections
6495, 2507, 2019
Rint0.090
(sin θ/λ)max1)0.685
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.111, 1.00
No. of reflections2507
No. of parameters109
No. of restraints2
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)2.35, 2.80

Computer programs: X-AREA (Stoe & Cie, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2B···Cl2i0.87 (2)2.62 (7)3.380 (8)146 (11)
N2—H2A···Cl2ii0.87 (2)2.68 (11)3.379 (9)139 (13)
Symmetry codes: (i) x, y+1, z+2; (ii) x1/2, y+1, z1/2.
 

Acknowledgements

The authors acknowledge the Iran University of Science and Technology (IUST) for financial support.

References

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