Crystal structure of an HgII coordination polymer with an unsymmetrical dipyridyl ligand: catena-poly[[[di-chlorido-mercury(II)]-μ-N-(pyridin-4-ylmeth-yl)pyridin-3-amine-κ2N:N'] chloro-form hemisolvate].

The asymmetric unit of the title compound, {[HgLCl2]·0.5CHCl3} n (L = N-(pyridin-4-ylmeth-yl)pyridin-3-amine, C11H11N3), contains one HgII ion, one bridging L ligand, two chloride ligands and a chloro-form solvent mol-ecule with half-occupancy that is disordered about a crystallographic twofold rotation axis. Each HgII ion is coordinated by two pyridine N atoms from two symmetry-related L ligands and two chloride anions in a highly distorted tetra-hedral geometry with bond angles falling in the range 99.05 (17)-142.96 (7)°. Each L ligand bridges two HgII ions, forming polymeric zigzag chains propagating in [010]. In the crystal, the chains are linked by inter-molecular N/C-H⋯Cl hydrogen bonds together with weak C-H⋯π inter-actions, resulting in the formation of a three-dimensional supra-molecular network, which is further stabilized by C-Cl⋯π inter-actions between the solvent chloro-form mol-ecules and the pyridine rings of L [chloride-to-centroid distances = 3.442 (11) and 3.626 (13) Å]. In addition, weak Cl⋯Cl contacts [3.320 (5) Å] between the chloro-form solvent mol-ecules and the coordinating chloride anions are also observed.

Chemical context

A variety of coordination polymers have been explored extensively over the last two decades because of their fascinating architectures and their useful applications in materials chemistry (Silva et al., 2015 ▸; Furukawa et al., 2014 ▸; Robson, 2008 ▸; Leong & Vittal, 2011 ▸). In this area of research, symmetrical dipyridyl ligands composed of two terminal n class="Chemical">pyridines with same substituted nitro­gen positions have been used mainly for the design and construction of the coordination polymers. By contrast, investigations based on unsymmetrical dipyridyl ligands, with the nitro­gen atoms in different positions on each of the two terminal pyridines, are still rare (Uemura et al., 2008 ▸; Khlobystov et al., 2003 ▸). Recently, our group and that of Gao have already reported AgI coordination polymers with some unsymmetrical dipyridyl ligands such as N-(pyridine-3-ylmeth­yl)pyridine-2-amine (Lee et al., 2013 ▸; Zhang et al., 2013 ▸), N-(pyridine-2-ylmeth­yl)pyridine-3-amine (Ju et al., 2014 ▸; Moon & Park, 2014 ▸; Moon et al., 2014 ▸; Zhang et al., 2013 ▸) and N-(pyridine-4-ylmeth­yl)pyridine-3-amine (Lee et al., 2015 ▸; Moon et al., 2015 ▸; Zhang et al., 2013 ▸). As a part of our ongoing efforts to construct coordination polymers with such unsymmetrical dipyridyl ligands, we prepared the title compound obtained by the reaction of mercury(II) chloride with an unsymmetrical dipyridyl ligand, namely N-(pyridine-4-ylmeth­yl)pyridine-3-amine, synthesized according to a literature procedure (Lee et al., 2013 ▸). Herein, we report the crystal structure of the title compound.

Structural commentary

The asymmetric unit of the title compound, {[HgLCl2]·0.5CHCl3}, L = N-(n class="Chemical">pyridine-4-ylmeth­yl)pyridine-3-amine, C11H11N3, comprises one HgII ion, one L ligand, two chloride anions and one half-mol­ecule of chloro­form. The solvent mol­ecule is disordered over two orientations of equal occupancy about the crystallographic twofold rotation axis. As shown in Fig. 1 ▸, the coordination geometry of each HgII ion is highly distorted tetra­hedral with two coordination sites being occupied by two pyridine N atoms from two symmetry-related L ligands. The geometry of the HgII ion is completed by the coordination of two chloride ions. The tetra­hedral angles around the HgII ion fall in the range of 99.05 (17)–142.96 (7)° (Table 1 ▸).

Figure 1

A view of the mol­ecular structure of the title compound, showing the atom-numbering scheme [symmetry code: (i) −x + , y + , −z + ]. Displacement ellipsoids are drawn at the 30% probability level. Only one component of the disordered chloro­form mol­ecule is shown. The dashed line represents the inter­molecular C—Cl⋯π inter­action [Cl4⋯Cg2 = 3.442 (11) Å; Cg2 is the centroid of the N2/C7–C11 ring].

Table 1

Selected geometric parameters (Å, °)

Hg1—N1	2.367 (5)	Hg1—Cl1	2.3759 (18)
Hg1—Cl2	2.3718 (19)	Hg1—N2i	2.385 (5)
N1—Hg1—Cl2	103.82 (14)	N1—Hg1—N2i	99.05 (17)
N1—Hg1—Cl1	102.31 (14)	Cl2—Hg1—N2i	101.20 (14)
Cl2—Hg1—Cl1	142.96 (7)	Cl1—Hg1—N2i	100.11 (13)

Symmetry code: (i) .

Each L ligand bridges two HgII ions into an infinite zigzag chain propagating along the b axis (Fig. 2 ▸). The separation between the HgII ions through a L ligand in the chain is 8.1033 (6) Å. In the L ligand, the Cpy—N—C—Cpy torsion angle is −70.9 (7)° while the dihedral angle between two terminal n class="Chemical">pyridine ring planes is 85.0 (2)°. The conformation of the L ligand, along with the the Npy—Hg—Npy coordination angle [99.05 (17)°], may induce the zigzag topology of the chain.

Figure 2

The layer formed through inter­molecular N—H⋯Cl hydrogen bonds (black dashed lines) and weak C—H⋯π inter­actions (red dashed lines). Disordered chloro­form mol­ecules and inter­molecular C—Cl⋯π inter­actions are shown as two-colored dashed lines and yellow dashed lines, respectively. H atoms not involved in inter­molecular inter­actions have been omitted for clarity.

Supra­molecular features

In the crystal, adjacent zigzag chains are linked by inter­molecular N—H⋯Cl n class="Chemical">hydrogen bonds and weak inter­molecular C—H⋯π inter­actions (Table 2 ▸), forming a layer extending parallel to the bc plane (Figs. 2 ▸ and 3 ▸). Furthermore, neighboring layers are packed by C—H⋯Cl hydrogen bonds (Table 2 ▸), resulting in the formation of a three-dimensional supra­molecular network (Fig. 3 ▸). This three-dimensional network is further stabilized by C—Cl⋯π inter­actions (Chifotides & Dunbar, 2013 ▸; Matter et al., 2009 ▸) between the solvent chloro­form mol­ecules and the pyridine rings of L with Cl4⋯Cg2 = 3.442 (11) Å, C12—Cl4⋯Cg2 = 170.7 (8)°, Cl5⋯Cg2iv = 3.626 (13) Å and C12—Cl5⋯Cg2iv 144.1 (8)° [yellow dashed lines in Figs. 1 ▸, 2 ▸ and 3 ▸; Cg2 is the centroid of the N2/C7–C11 ring; symmetry code: (iv) −x, y, −z + ]. In addition, weak inter­molecular Cl⋯Cl contacts between the solvent chloro­form mol­ecule and the coordinating chloride anion [Cl1⋯Cl3v = 3.320 (5) Å, Hg1—Cl1⋯Cl3v = 126.70 (14) and Cl1⋯Cl3v—C12v = 169.2 (8)°; symmetry code: (v) x + , y + , z] are observed.

Table 2

Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the N1/C1–C5 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H3⋯Cl2ii	0.86	2.78	3.467 (5)	138
C8—H8⋯Cl1iii	0.93	2.80	3.654 (6)	153
C6—H6B⋯Cg1ii	0.97	2.71	3.465 (7)	135

Symmetry codes: (ii) ; (iii) .

Figure 3

The three-dimensional supra­molecular network constructed through inter­molecular C—H⋯Cl hydrogen bonds (light-blue dashed lines) and C—Cl⋯π inter­actions (yellow dashed lines) between the layers formed through N—H⋯Cl (black dashed lines) and C—H⋯π (red dashed lines) inter­actions. Disordered chloro­form mol­ecules are shown as two-colored dashed lines. H atoms not involved in inter­molecular inter­actions have been omitted for clarity.

Synthesis and crystallization

The L ligand was synthesized according to a literature method (Lee et al., 2013 ▸). X-ray-quality single crystals of the title compound were obtained by slow diffusion of a methanol solution of HgCl2 into a chloro­form solution of the L ligand.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3 ▸. A reflection affected by the beamstop was omitted from the final refinement. The chloro­form mol­ecule is n class="Disease">disordered over two sets of sites about a twofold rotation axis with equal occupancy. The C—Cl bond lengths were restrained using the DFIX instructions in SHELXL2014/7 (Sheldrick, 2015 ▸). All H atoms were positioned geometrically with d(C—H) = 0.93 Å for Csp 2—H, 0.97 Å for methyl­ene C—H, 0.98 Å for methine C—H, and 0.86 Å for amine N—H, and were refined as riding with U iso(H) = 1.2U eq(C,N).

Table 3

Experimental details

Crystal data
Chemical formula	[HgCl2(C11H11N3)]·0.5CHCl3
M r	516.40
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	298
a, b, c (Å)	16.6906 (14), 9.1942 (8), 21.0159 (17)
β (°)	95.501 (2)
V (Å3)	3210.2 (5)
Z	8
Radiation type	Mo Kα
μ (mm−1)	10.16
Crystal size (mm)	0.4 × 0.3 × 0.3
Data collection
Diffractometer	Bruker APEXII CCD area detector
Absorption correction	Multi-scan (SADABS; Bruker, 2014 ▸)
T min, T max	0.521, 0.928
No. of measured, independent and observed [I > 2σ(I)] reflections	8852, 3151, 2189
R int	0.044
(sin θ/λ)max (Å−1)	0.617
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.033, 0.074, 0.99
No. of reflections	3151
No. of parameters	190
No. of restraints	3
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.58, −0.83

Computer programs: APEX2 and SAINT (Bruker, 2014 ▸), SHELXS97 and SHELXTL (Sheldrick, 2008 ▸), SHELXL2014 (Sheldrick, 2015 ▸) and DIAMOND (Brandenburg, 2010 ▸).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989016015310/sj5509sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016015310/sj5509Isup2.hkl

CCDC reference: 1507232

Additional supporting information: crystallographic information; 3D view; checkCIF report

[HgCl2(C11H11N3)]·0.5CHCl3	F(000) = 1928
Mr = 516.40	Dx = 2.137 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 16.6906 (14) Å	Cell parameters from 3870 reflections
b = 9.1942 (8) Å	θ = 2.0–28.3°
c = 21.0159 (17) Å	µ = 10.16 mm−1
β = 95.501 (2)°	T = 298 K
V = 3210.2 (5) Å3	Block, colorless
Z = 8	0.4 × 0.3 × 0.3 mm

Bruker APEXII CCD area detector diffractometer	2189 reflections with I > 2σ(I)
phi and ω scans	Rint = 0.044
Absorption correction: multi-scan (SADABS; Bruker, 2014)	θmax = 26.0°, θmin = 2.5°
Tmin = 0.521, Tmax = 0.928	h = −12→20
8852 measured reflections	k = −11→10
3151 independent reflections	l = −24→25

Refinement on F2	3 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.033	H-atom parameters constrained
wR(F2) = 0.074	w = 1/[σ2(Fo2) + (0.034P)2] where P = (Fo2 + 2Fc2)/3
S = 0.99	(Δ/σ)max = 0.001
3151 reflections	Δρmax = 0.58 e Å−3
190 parameters	Δρmin = −0.83 e Å−3

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

	x	y	z	Uiso*/Ueq	Occ. (<1)
Hg1	0.32126 (2)	0.66479 (3)	0.10699 (2)	0.06180 (11)
Cl1	0.44104 (11)	0.8055 (2)	0.11123 (9)	0.0766 (5)
Cl2	0.18389 (11)	0.6629 (2)	0.06581 (9)	0.0839 (6)
N1	0.3676 (3)	0.4300 (6)	0.0825 (2)	0.0548 (13)
N2	0.1898 (3)	0.1323 (5)	0.2816 (2)	0.0568 (13)
N3	0.2853 (4)	0.0648 (6)	0.0611 (2)	0.0641 (15)
H3	0.3015	−0.0182	0.0486	0.077*
C1	0.3176 (4)	0.3179 (7)	0.0811 (3)	0.0522 (15)
H1	0.2663	0.3330	0.0938	0.063*
C2	0.4398 (4)	0.4134 (8)	0.0648 (3)	0.0693 (18)
H2	0.4749	0.4922	0.0662	0.083*
C3	0.4649 (5)	0.2790 (10)	0.0439 (4)	0.080 (2)
H3A	0.5163	0.2687	0.0310	0.096*
C4	0.4152 (5)	0.1641 (8)	0.0423 (3)	0.075 (2)
H4	0.4322	0.0742	0.0284	0.090*
C5	0.3372 (4)	0.1798 (7)	0.0618 (3)	0.0562 (16)
C6	0.2052 (4)	0.0749 (7)	0.0800 (3)	0.0615 (17)
H6A	0.1761	−0.0130	0.0667	0.074*
H6B	0.1780	0.1559	0.0576	0.074*
C7	0.2007 (4)	0.0955 (7)	0.1513 (2)	0.0499 (15)
C8	0.1386 (4)	0.1686 (7)	0.1738 (3)	0.0636 (17)
H8	0.0986	0.2093	0.1454	0.076*
C9	0.1348 (4)	0.1821 (7)	0.2375 (3)	0.0664 (18)
H9	0.0904	0.2298	0.2512	0.080*
C10	0.2502 (4)	0.0629 (7)	0.2600 (3)	0.0677 (19)
H10	0.2895	0.0249	0.2897	0.081*
C11	0.2594 (4)	0.0424 (7)	0.1953 (3)	0.0618 (18)
H11	0.3040	−0.0060	0.1825	0.074*
C12	0.0095 (13)	−0.2965 (16)	0.2726 (7)	0.128 (8)	0.5
H12	0.0355	−0.3356	0.3128	0.153*	0.5
Cl3	−0.0016 (4)	−0.4392 (6)	0.2177 (3)	0.1288 (19)	0.5
Cl4	0.0705 (7)	−0.1706 (11)	0.2464 (6)	0.201 (5)	0.5
Cl5	−0.0803 (8)	−0.2208 (14)	0.2885 (6)	0.230 (7)	0.5

	U11	U22	U33	U12	U13	U23
Hg1	0.06149 (17)	0.07271 (18)	0.05193 (16)	0.00720 (15)	0.00918 (12)	−0.00275 (14)
Cl1	0.0576 (10)	0.0833 (12)	0.0887 (13)	0.0035 (9)	0.0056 (10)	0.0198 (10)
Cl2	0.0639 (11)	0.1104 (15)	0.0748 (11)	0.0191 (11)	−0.0065 (9)	−0.0262 (11)
N1	0.052 (3)	0.069 (3)	0.044 (3)	0.012 (3)	0.006 (3)	−0.001 (2)
N2	0.053 (3)	0.078 (4)	0.040 (3)	0.007 (3)	0.009 (3)	0.006 (2)
N3	0.096 (4)	0.052 (3)	0.047 (3)	0.018 (3)	0.019 (3)	−0.004 (2)
C1	0.053 (4)	0.063 (4)	0.041 (3)	0.017 (3)	0.007 (3)	−0.001 (3)
C2	0.056 (4)	0.083 (5)	0.070 (4)	0.019 (4)	0.011 (4)	0.008 (4)
C3	0.065 (5)	0.097 (6)	0.083 (6)	0.030 (5)	0.026 (4)	0.020 (5)
C4	0.099 (6)	0.072 (5)	0.057 (4)	0.032 (5)	0.027 (4)	0.010 (4)
C5	0.070 (4)	0.066 (4)	0.034 (3)	0.023 (4)	0.010 (3)	0.007 (3)
C6	0.074 (5)	0.061 (4)	0.047 (4)	0.002 (4)	−0.004 (4)	0.001 (3)
C7	0.061 (4)	0.053 (3)	0.036 (3)	0.000 (3)	0.002 (3)	0.006 (3)
C8	0.052 (4)	0.082 (4)	0.053 (4)	0.017 (4)	−0.011 (3)	0.007 (4)
C9	0.052 (4)	0.089 (5)	0.059 (4)	0.015 (4)	0.005 (3)	−0.002 (4)
C10	0.065 (4)	0.083 (5)	0.055 (4)	0.018 (4)	0.004 (4)	0.017 (3)
C11	0.061 (4)	0.083 (5)	0.042 (3)	0.029 (4)	0.008 (3)	0.003 (3)
C12	0.18 (2)	0.108 (14)	0.098 (18)	0.000 (18)	0.04 (2)	−0.024 (10)
Cl3	0.147 (5)	0.100 (3)	0.135 (4)	−0.006 (4)	−0.011 (5)	−0.026 (3)
Cl4	0.208 (10)	0.167 (7)	0.234 (11)	−0.120 (7)	0.051 (8)	−0.057 (7)
Cl5	0.184 (9)	0.242 (12)	0.281 (15)	−0.077 (9)	0.110 (10)	−0.150 (11)

Hg1—N1	2.367 (5)	C4—C5	1.409 (10)
Hg1—Cl2	2.3718 (19)	C4—H4	0.9300
Hg1—Cl1	2.3759 (18)	C6—C7	1.519 (7)
Hg1—N2i	2.385 (5)	C6—H6A	0.9700
N1—C2	1.303 (8)	C6—H6B	0.9700
N1—C1	1.326 (8)	C7—C8	1.358 (8)
N2—C10	1.310 (8)	C7—C11	1.371 (8)
N2—C9	1.323 (8)	C8—C9	1.352 (9)
N2—Hg1ii	2.386 (5)	C8—H8	0.9300
N3—C5	1.366 (8)	C9—H9	0.9300
N3—C6	1.434 (8)	C10—C11	1.394 (8)
N3—H3	0.8600	C10—H10	0.9300
C1—C5	1.382 (8)	C11—H11	0.9300
C1—H1	0.9300	C12—Cl4	1.670 (15)
C2—C3	1.389 (11)	C12—Cl5	1.713 (17)
C2—H2	0.9300	C12—Cl3	1.746 (13)
C3—C4	1.342 (10)	C12—H12	0.9800
C3—H3A	0.9300
N1—Hg1—Cl2	103.82 (14)	C1—C5—C4	115.5 (7)
N1—Hg1—Cl1	102.31 (14)	N3—C6—C7	114.6 (5)
Cl2—Hg1—Cl1	142.96 (7)	N3—C6—H6A	108.6
N1—Hg1—N2i	99.05 (17)	C7—C6—H6A	108.6
Cl2—Hg1—N2i	101.20 (14)	N3—C6—H6B	108.6
Cl1—Hg1—N2i	100.11 (13)	C7—C6—H6B	108.6
C2—N1—C1	120.0 (6)	H6A—C6—H6B	107.6
C2—N1—Hg1	120.0 (5)	C8—C7—C11	117.5 (5)
C1—N1—Hg1	119.7 (4)	C8—C7—C6	121.0 (5)
C10—N2—C9	115.6 (5)	C11—C7—C6	121.5 (6)
C10—N2—Hg1ii	122.4 (4)	C9—C8—C7	119.9 (6)
C9—N2—Hg1ii	122.0 (4)	C9—C8—H8	120.0
C5—N3—C6	123.7 (5)	C7—C8—H8	120.0
C5—N3—H3	118.2	N2—C9—C8	124.5 (6)
C6—N3—H3	118.2	N2—C9—H9	117.7
N1—C1—C5	123.7 (6)	C8—C9—H9	117.7
N1—C1—H1	118.2	N2—C10—C11	124.3 (6)
C5—C1—H1	118.2	N2—C10—H10	117.8
N1—C2—C3	120.6 (7)	C11—C10—H10	117.8
N1—C2—H2	119.7	C7—C11—C10	118.1 (6)
C3—C2—H2	119.7	C7—C11—H11	120.9
C4—C3—C2	120.3 (7)	C10—C11—H11	120.9
C4—C3—H3A	119.8	Cl4—C12—Cl5	110.8 (10)
C2—C3—H3A	119.8	Cl4—C12—Cl3	109.4 (9)
C3—C4—C5	119.9 (7)	Cl5—C12—Cl3	113.3 (11)
C3—C4—H4	120.1	Cl4—C12—H12	107.7
C5—C4—H4	120.1	Cl5—C12—H12	107.7
N3—C5—C1	123.1 (6)	Cl3—C12—H12	107.7
N3—C5—C4	121.4 (6)
C2—N1—C1—C5	0.3 (9)	N3—C6—C7—C8	150.4 (6)
Hg1—N1—C1—C5	174.1 (4)	N3—C6—C7—C11	−29.1 (9)
C1—N1—C2—C3	0.6 (9)	C11—C7—C8—C9	−2.3 (10)
Hg1—N1—C2—C3	−173.3 (5)	C6—C7—C8—C9	178.2 (6)
N1—C2—C3—C4	−0.8 (11)	C10—N2—C9—C8	−1.6 (10)
C2—C3—C4—C5	0.1 (11)	Hg1ii—N2—C9—C8	179.0 (5)
C6—N3—C5—C1	0.1 (9)	C7—C8—C9—N2	2.3 (11)
C6—N3—C5—C4	−179.6 (5)	C9—N2—C10—C11	1.1 (10)
N1—C1—C5—N3	179.5 (5)	Hg1ii—N2—C10—C11	−179.5 (5)
N1—C1—C5—C4	−0.8 (9)	C8—C7—C11—C10	1.9 (10)
C3—C4—C5—N3	−179.7 (6)	C6—C7—C11—C10	−178.7 (6)
C3—C4—C5—C1	0.6 (9)	N2—C10—C11—C7	−1.4 (11)
C5—N3—C6—C7	−70.9 (7)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···Cl2iii	0.86	2.78	3.467 (5)	138
C8—H8···Cl1iv	0.93	2.80	3.654 (6)	153
C6—H6B···Cg1iii	0.97	2.71	3.465 (7)	135