Di­chlorido­(pyridine-κN)[2,3,5,6-tetra­kis­(pyridin-2-yl)pyrazine-κ³ N ²,N ¹,N ⁶]nickel(II)

The central Ni^II ion has an N₄Cl₂ octa­hedral coordination sphere defined by three N atoms of the tridentate 2,3,5,6-tetra-2-pyridyl­pyrazine ligand, one N atom of the pyridine ligand and two Cl⁻ anions.

Abstract

In the title complex, [NiCl₂(C₅H₅N)(C₂₄H₁₆N₆)], the Ni^II ion is six-coordinated in a distorted octa­hedral coordination environment defined by three N atoms of the tridentate 2,3,5,6-tetra-2-pyridyl­pyrazine ligand, one N atom of the pyridine ligand and two Cl⁻ anions, with the latter being mutually trans. The complex is disposed about a twofold rotation axis along the a axis. The complex molecules are connected in the crystal via C—H⋯Cl, C—H⋯N and π–π [closest inter-centroid separation = 3.7446 (14) Å between pyridyl rings].

Structure description

With reference to the title compound, [NiCl₂(py)(tppz)] (py = pyridine, tppz = 2,3,5,6-tetra-2-pyridyl­pyrazine), the crystal structures of a related tetra­nuclear Ni^II complex, [Ni₄Cl₆(tppz)₂(CH₃OH)₄]Cl₂·CH₃OH (Winpenny et al., 2005 ▸), and of a dinuclear Mn^II complex, [Mn₂Cl₄(tppz)₂] (Ha, 2011 ▸), have been determined previously.

In the title complex, the central Ni^II cation is six-coordinated in a considerably distorted octa­hedral coordination environment defined by three N atoms of the tridentate tppz ligand, one N atom of the pyridine ligand and two Cl⁻ anions (Fig. 1 ▸). The complex is disposed about a twofold rotation axis along the a axis; thus the asymmetric unit contains one half of the complex. The main contribution to the distortion is the tight N—Ni—N chelating angle [<N1—Ni1—N3 = 77.97 (5)°], which results in a non-linear trans arrangement of the N3—Ni1—N3ⁱ bonds [<N3—Ni1—N3ⁱ = 155.95 (11)°; symmetry code: (i) x − y, −y, −z], whereas the Cl1—Ni1—Cl1ⁱ bonds are almost linear [<Cl1—Ni1—Cl1ⁱ = 175.77 (4)°]. The Ni—N[pyrazine­(N1) or pyrid­yl(N3, N5)] bond lengths are roughly equivalent, with distances of 2.008 (3) – 2.1026 (19) Å. The pyrazine ring (N1—C1ⁱ) slightly deviates from planarity, with a maximum deviation of 0.057 (2) Å for the C2 atom from the least-squares plane of the ring. The dihedral angles between the nearly planar pyridyl rings and the least-squares plane of their carrier pyrazine ring are 14.90 (4)° for the coordinating pyridyl ring (N3—C7) and 54.42 (9)° for the non-coord­inating pyridyl ring (N4—C12), respectively. The dihedral angle between the pyrazine ring and the pyridine ligand (N5—C13ⁱ) is 57.8 (1)°.

Figure 1.

The mol­ecular structure of the title compound showing the atom labelling and displacement ellipsoids drawn at the 50% probability level for all non-H atoms. [Symmetry code: (i) x − y, −y, −z.]

In the crystal, the complex displays numerous inter- and intra­molecular π–π inter­actions between adjacent six-membered rings. The most significant inter­action of this kind is that between Cg1 (the centroid of the ring N3/C3–C7) and Cg1ⁱⁱ [symmetry code: (ii) x, x − y, −z +  ], with a centroid-to-centroid distance of 3.7446 (14) Å and a dihedral angle between the ring planes of 22.24 (12)°. In addition, the complex exhibits inter- and intra­molecular C—H⋯N and C—H⋯Cl hydrogen bonds (Table 1 ▸) that consolidate the three-dimensional packing (Fig. 2 ▸).

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯Cl1i	0.94	2.78	3.513 (3)	136
C10—H10⋯N4ii	0.94	2.46	3.360 (3)	161
C12—H12⋯Cl1iii	0.94	2.71	3.602 (3)	160
C13—H13⋯Cl1iv	0.94	2.68	3.261 (3)	121

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .

Figure 2.

The packing in the crystal of the title compound, viewed approximately along the a axis. Hydrogen-bonding inter­actions are drawn as dashed lines. Colour codes are as in Fig. 1 ▸.

Synthesis and crystallization

To a solution of NiCl₂·6H₂O (0.3779 g, 1.590 mmol) in ethanol (20 ml) was added 2,3,5,6-tetra-2-pyridyl­pyrazine (0.6220 g, 1.601 mmol), followed by stirring for 24 h at rooom temperature. The formed precipitate was separated by filtration, washed with ethanol and acetone, and dried at 323 K, to give a brown powder (0.5045 g). Brown crystals suitable for X-ray analysis were obtained by slow evaporation from its pyridine/N,N-di­methyl­formamide (DMF) solution at 333 K.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. The maximum and minimum remaining electron density peaks in the difference Fourier map are located 0.34 and 0.74 Å, respectively, from atoms C9 and Ni1.

Table 2. Experimental details.

Crystal data
Chemical formula	[NiCl2(C5H5N)(C24H16N6)]
M r	597.14
Crystal system, space group	Hexagonal, P6122
Temperature (K)	223
a, c (Å)	13.8244 (4), 23.8935 (8)
V (Å3)	3954.6 (3)
Z	6
Radiation type	Mo Kα
μ (mm−1)	0.97
Crystal size (mm)	0.15 × 0.10 × 0.07
Data collection
Diffractometer	PHOTON 100 CMOS detector
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 ▸)
T min, T max	0.700, 0.744
No. of measured, independent and observed [I > 2σ(I)] reflections	125055, 2614, 2412
R int	0.106
(sin θ/λ)max (Å−1)	0.618
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.024, 0.054, 1.08
No. of reflections	2614
No. of parameters	179
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.22, −0.14
Absolute structure	Flack x determined using 894 quotients [(I +)−(I −)]/[(I +)+(I −)] (Parsons et al., 2013 ▸).
Absolute structure parameter	−0.002 (5)

Computer programs: APEX2 and SAINT (Bruker, 2016 ▸), SHELXT (Sheldrick, 2015a ▸), SHELXL (Sheldrick, 2015b ▸) and ORTEP-3 for Windows (Farrugia, 2012 ▸).

Supplementary Material

CCDC reference: 2058988

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

full crystallographic data

Crystal data

[NiCl2(C5H5N)(C24H16N6)]	Dx = 1.504 Mg m−3
Mr = 597.14	Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P6122	Cell parameters from 9199 reflections
a = 13.8244 (4) Å	θ = 2.4–26.0°
c = 23.8935 (8) Å	µ = 0.97 mm−1
V = 3954.6 (3) Å3	T = 223 K
Z = 6	Block, brown
F(000) = 1836	0.15 × 0.10 × 0.07 mm

Data collection

PHOTON 100 CMOS detector diffractometer	2412 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.106
φ and ω scans	θmax = 26.1°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −17→17
Tmin = 0.700, Tmax = 0.744	k = −17→17
125055 measured reflections	l = −29→29
2614 independent reflections

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)] = 0.024	H-atom parameters constrained
wR(F2) = 0.054	w = 1/[σ2(Fo2) + (0.0277P)2 + 0.9047P] where P = (Fo2 + 2Fc2)/3
S = 1.08	(Δ/σ)max < 0.001
2614 reflections	Δρmax = 0.22 e Å−3
179 parameters	Δρmin = −0.14 e Å−3
0 restraints	Absolute structure: Flack x determined using 894 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013).
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.002 (5)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ni1	0.41510 (3)	0.0000	0.0000	0.01866 (12)
Cl1	0.44000 (6)	0.03687 (5)	−0.09968 (3)	0.03369 (17)
N1	0.56034 (18)	0.0000	0.0000	0.0181 (6)
N2	0.75658 (19)	0.0000	0.0000	0.0204 (6)
N3	0.53182 (16)	0.17007 (16)	0.01208 (8)	0.0196 (4)
N4	0.86393 (17)	0.24353 (17)	0.07265 (9)	0.0265 (5)
N5	0.2636 (2)	0.0000	0.0000	0.0303 (7)
C1	0.65538 (19)	0.09724 (18)	0.00453 (10)	0.0177 (5)
C2	0.75545 (19)	0.09505 (19)	0.00914 (9)	0.0194 (5)
C3	0.6391 (2)	0.19584 (19)	0.00471 (10)	0.0187 (5)
C4	0.7236 (2)	0.30472 (19)	−0.00359 (11)	0.0242 (5)
H4	0.7967	0.3205	−0.0114	0.029*
C5	0.6992 (2)	0.3896 (2)	−0.00019 (12)	0.0290 (6)
H5	0.7557	0.4642	−0.0056	0.035*
C6	0.5912 (2)	0.3645 (2)	0.01124 (10)	0.0279 (6)
H6	0.5734	0.4213	0.0157	0.033*
C7	0.5104 (2)	0.2537 (2)	0.01591 (10)	0.0236 (6)
H7	0.4362	0.2361	0.0221	0.028*
C8	0.8647 (2)	0.1935 (2)	0.02484 (10)	0.0199 (5)
C9	0.9581 (2)	0.2297 (2)	−0.00795 (12)	0.0299 (6)
H9	0.9555	0.1912	−0.0408	0.036*
C10	1.0561 (2)	0.3239 (2)	0.00830 (12)	0.0385 (7)
H10	1.1210	0.3514	−0.0137	0.046*
C11	1.0565 (2)	0.3761 (2)	0.05722 (11)	0.0323 (6)
H11	1.1217	0.4403	0.0694	0.039*
C12	0.9594 (2)	0.3327 (2)	0.08824 (11)	0.0309 (6)
H12	0.9608	0.3679	0.1221	0.037*
C13	0.1829 (2)	−0.0605 (2)	0.03686 (14)	0.0414 (7)
H13	0.1959	−0.1024	0.0638	0.050*
C14	0.0811 (3)	−0.0642 (3)	0.03700 (18)	0.0579 (10)
H14	0.0250	−0.1105	0.0624	0.070*
C15	0.0629 (3)	0.0000	0.0000	0.0639 (15)
H15	−0.0051	0.0000	0.0000	0.077*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Ni1	0.01813 (17)	0.0145 (2)	0.0222 (2)	0.00723 (11)	0.00093 (9)	0.00185 (17)
Cl1	0.0480 (4)	0.0269 (3)	0.0215 (3)	0.0152 (3)	−0.0012 (3)	0.0025 (2)
N1	0.0175 (10)	0.0147 (13)	0.0210 (14)	0.0073 (7)	−0.0002 (6)	−0.0003 (12)
N2	0.0200 (11)	0.0174 (14)	0.0231 (15)	0.0087 (7)	−0.0006 (6)	−0.0012 (13)
N3	0.0212 (10)	0.0172 (10)	0.0196 (10)	0.0091 (9)	0.0005 (8)	0.0004 (8)
N4	0.0234 (11)	0.0264 (11)	0.0231 (11)	0.0074 (9)	0.0023 (9)	−0.0022 (9)
N5	0.0247 (12)	0.0244 (16)	0.0417 (19)	0.0122 (8)	0.0024 (8)	0.0048 (15)
C1	0.0189 (11)	0.0155 (11)	0.0171 (12)	0.0073 (9)	0.0013 (10)	−0.0007 (9)
C2	0.0195 (12)	0.0165 (12)	0.0194 (12)	0.0069 (10)	0.0017 (10)	0.0010 (10)
C3	0.0220 (12)	0.0163 (11)	0.0176 (11)	0.0095 (10)	−0.0010 (10)	−0.0016 (10)
C4	0.0192 (13)	0.0189 (12)	0.0329 (14)	0.0082 (10)	0.0026 (11)	0.0010 (11)
C5	0.0285 (14)	0.0168 (12)	0.0393 (16)	0.0094 (11)	0.0007 (13)	0.0016 (12)
C6	0.0345 (14)	0.0184 (12)	0.0351 (14)	0.0166 (12)	0.0002 (12)	−0.0012 (11)
C7	0.0257 (13)	0.0237 (13)	0.0254 (14)	0.0153 (11)	0.0025 (10)	0.0015 (10)
C8	0.0186 (12)	0.0160 (12)	0.0241 (13)	0.0080 (10)	−0.0010 (10)	−0.0004 (10)
C9	0.0228 (13)	0.0280 (14)	0.0321 (15)	0.0075 (11)	0.0047 (12)	−0.0085 (12)
C10	0.0206 (14)	0.0381 (16)	0.0406 (18)	0.0025 (12)	0.0078 (12)	−0.0054 (14)
C11	0.0227 (14)	0.0252 (15)	0.0332 (16)	0.0003 (12)	−0.0021 (12)	−0.0018 (12)
C12	0.0319 (14)	0.0260 (14)	0.0232 (13)	0.0057 (12)	−0.0020 (12)	−0.0053 (11)
C13	0.0311 (16)	0.0357 (17)	0.0571 (19)	0.0166 (15)	0.0107 (15)	0.0109 (15)
C14	0.0347 (18)	0.057 (2)	0.082 (3)	0.0222 (17)	0.0195 (18)	0.013 (2)
C15	0.0362 (19)	0.067 (4)	0.098 (5)	0.0336 (18)	0.0005 (18)	0.001 (4)

Geometric parameters (Å, º)

Ni1—N1	2.008 (3)	C4—H4	0.9400
Ni1—N5	2.094 (3)	C5—C6	1.380 (4)
Ni1—N3i	2.1026 (19)	C5—H5	0.9400
Ni1—N3	2.1026 (19)	C6—C7	1.377 (4)
Ni1—Cl1i	2.4238 (6)	C6—H6	0.9400
Ni1—Cl1	2.4238 (6)	C7—H7	0.9400
N1—C1	1.334 (3)	C8—C9	1.373 (3)
N1—C1i	1.334 (3)	C9—C10	1.385 (4)
N2—C2i	1.340 (3)	C9—H9	0.9400
N2—C2	1.340 (3)	C10—C11	1.373 (4)
N3—C7	1.332 (3)	C10—H10	0.9400
N3—C3	1.353 (3)	C11—C12	1.380 (4)
N4—C12	1.332 (3)	C11—H11	0.9400
N4—C8	1.338 (3)	C12—H12	0.9400
N5—C13i	1.337 (3)	C13—C14	1.382 (4)
N5—C13	1.337 (3)	C13—H13	0.9400
C1—C2	1.403 (3)	C14—C15	1.362 (4)
C1—C3	1.488 (3)	C14—H14	0.9400
C2—C8	1.489 (3)	C15—C14i	1.362 (4)
C3—C4	1.382 (3)	C15—H15	0.9400
C4—C5	1.377 (4)
N1—Ni1—N5	180.0	C5—C4—H4	120.5
N1—Ni1—N3i	77.97 (5)	C3—C4—H4	120.5
N5—Ni1—N3i	102.03 (5)	C4—C5—C6	119.5 (2)
N1—Ni1—N3	77.97 (5)	C4—C5—H5	120.3
N5—Ni1—N3	102.03 (5)	C6—C5—H5	120.3
N3i—Ni1—N3	155.95 (11)	C7—C6—C5	118.0 (2)
N1—Ni1—Cl1i	87.89 (2)	C7—C6—H6	121.0
N5—Ni1—Cl1i	92.11 (2)	C5—C6—H6	121.0
N3i—Ni1—Cl1i	87.19 (5)	N3—C7—C6	123.4 (2)
N3—Ni1—Cl1i	91.94 (5)	N3—C7—H7	118.3
N1—Ni1—Cl1	87.89 (2)	C6—C7—H7	118.3
N5—Ni1—Cl1	92.11 (2)	N4—C8—C9	123.2 (2)
N3i—Ni1—Cl1	91.93 (5)	N4—C8—C2	114.9 (2)
N3—Ni1—Cl1	87.18 (5)	C9—C8—C2	121.9 (2)
Cl1i—Ni1—Cl1	175.77 (4)	C8—C9—C10	118.8 (2)
C1—N1—C1i	122.5 (3)	C8—C9—H9	120.6
C1—N1—Ni1	118.76 (13)	C10—C9—H9	120.6
C1i—N1—Ni1	118.76 (13)	C11—C10—C9	118.6 (2)
C2i—N2—C2	119.7 (3)	C11—C10—H10	120.7
C7—N3—C3	118.1 (2)	C9—C10—H10	120.7
C7—N3—Ni1	126.90 (16)	C10—C11—C12	118.7 (2)
C3—N3—Ni1	113.83 (15)	C10—C11—H11	120.6
C12—N4—C8	117.2 (2)	C12—C11—H11	120.6
C13i—N5—C13	117.1 (4)	N4—C12—C11	123.4 (3)
C13i—N5—Ni1	121.44 (18)	N4—C12—H12	118.3
C13—N5—Ni1	121.44 (18)	C11—C12—H12	118.3
N1—C1—C2	118.0 (2)	N5—C13—C14	122.7 (3)
N1—C1—C3	113.6 (2)	N5—C13—H13	118.7
C2—C1—C3	128.4 (2)	C14—C13—H13	118.7
N2—C2—C1	120.2 (2)	C15—C14—C13	119.4 (4)
N2—C2—C8	115.7 (2)	C15—C14—H14	120.3
C1—C2—C8	124.0 (2)	C13—C14—H14	120.3
N3—C3—C4	121.6 (2)	C14i—C15—C14	118.6 (5)
N3—C3—C1	114.0 (2)	C14i—C15—H15	120.7
C4—C3—C1	124.4 (2)	C14—C15—H15	120.7
C5—C4—C3	119.1 (2)
C1i—N1—C1—C2	−5.20 (15)	C4—C5—C6—C7	−3.4 (4)
Ni1—N1—C1—C2	174.80 (15)	C3—N3—C7—C6	1.8 (4)
C1i—N1—C1—C3	175.6 (2)	Ni1—N3—C7—C6	−164.88 (19)
Ni1—N1—C1—C3	−4.4 (2)	C5—C6—C7—N3	2.6 (4)
C2i—N2—C2—C1	−5.36 (16)	C12—N4—C8—C9	0.2 (4)
C2i—N2—C2—C8	173.8 (2)	C12—N4—C8—C2	−179.4 (2)
N1—C1—C2—N2	10.7 (3)	N2—C2—C8—N4	−125.1 (2)
C3—C1—C2—N2	−170.2 (2)	C1—C2—C8—N4	54.0 (3)
N1—C1—C2—C8	−168.31 (19)	N2—C2—C8—C9	55.3 (3)
C3—C1—C2—C8	10.8 (4)	C1—C2—C8—C9	−125.6 (3)
C7—N3—C3—C4	−5.6 (4)	N4—C8—C9—C10	−1.4 (4)
Ni1—N3—C3—C4	162.80 (19)	C2—C8—C9—C10	178.1 (3)
C7—N3—C3—C1	176.4 (2)	C8—C9—C10—C11	1.3 (5)
Ni1—N3—C3—C1	−15.3 (3)	C9—C10—C11—C12	0.1 (5)
N1—C1—C3—N3	13.1 (3)	C8—N4—C12—C11	1.3 (4)
C2—C1—C3—N3	−166.0 (2)	C10—C11—C12—N4	−1.4 (5)
N1—C1—C3—C4	−164.9 (2)	C13i—N5—C13—C14	1.5 (3)
C2—C1—C3—C4	16.0 (4)	Ni1—N5—C13—C14	−178.5 (3)
N3—C3—C4—C5	4.8 (4)	N5—C13—C14—C15	−3.1 (5)
C1—C3—C4—C5	−177.3 (2)	C13—C14—C15—C14i	1.5 (3)
C3—C4—C5—C6	−0.2 (4)

Symmetry code: (i) x−y, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···Cl1ii	0.94	2.78	3.513 (3)	136
C10—H10···N4iii	0.94	2.46	3.360 (3)	161
C12—H12···Cl1iv	0.94	2.71	3.602 (3)	160
C13—H13···Cl1i	0.94	2.68	3.261 (3)	121

Symmetry codes: (i) x−y, −y, −z; (ii) x−y, x, z+1/6; (iii) y+1, −x+y+1, z−1/6; (iv) −y+1, x−y, z+1/3.

Funding Statement

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (grant No. 2018R1D1A1B07050550).