Synthesis and crystal structure of di-μ-chlorido-bis­[bis(2,6-di­methyl­pyrazine)­copper(I)] and di-μ-bromido-bis[bis(2,6-di­methyl­pyrazine)copper(I)]

Näther, C.

doi:10.1107/S2056989026004330

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Volume 82| Part 6| June 2026|

https://doi.org/10.1107/S2056989026004330

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Synthesis and crystal structure of di-μ-chlorido-bis[bis(2,6-dimethylpyrazine)copper(I)] and di-μ-bromido-bis[bis(2,6-dimethylpyrazine)copper(I)]

Christian Näther ^a ^*

^aInstitut für Anorganische Chemie, Universität Kiel, Max-Eyth.-Str. 2, 24118 Kiel, Germany
^*Correspondence e-mail: [email protected]

Edited by B. Therrien, University of Neuchâtel, Switzerland (Received 13 April 2026; accepted 24 April 2026; online 7 May 2026)

Crystals of [Cu₂Cl₂(C₆H₈N₂)₄] (1) and of [Cu₂Br₂(C₆H₈N₂)₄] (2), C₆H₈N₂ = 2,6-dimethylpyrazine, were obtained from the reaction of CuCl or CuBr with 2,6-dimethylpyrazine in acetonitrile under solvothermal conditions. Both compounds are isotypic. The asymmetric unit of each compound consists of one Cu cation, one halide anion and one 2,6-dimethylpyrazine ligand in general positions. The copper cations are tetrahedrally coordinated by two μ-1,1 bridging halide anions and two terminal 2,6-dimethylpyrazine ligands. Two copper cations are linked by the two halide anions via common edges into discrete dinuclear complexes that are located on centers of inversion. The discrete complexes are linked by intermolecular C—H⋯X (X = Cl, Br) hydrogen bonding into chains that propagate along the a-axis direction. Between these chains, additional C–H⋯X interactions are observed, which might be stronger for compound 1.

Keywords: dinuclear complex; coordination compounds; copper(I) chloride; copper(I) bromide; 2,6-dimethylpyrazine; crystal structure.

CCDC references: 2549116; 2549115

1. Chemical context

Monovalent copper halide and pseudohalide coordination compounds have been investigated for several years. First of all, they are of interest from a structural point of view, because they show an extremely large structural variability (Kromp & Sheldrick, 1999 ; Li et al., 2005 ; Peng et al., 2010 ), but also because of their luminescence properties (Chesnut et al., 1999 ; Lemos et al., 2001 ; Näther et al., 2003 ; Starosta et al., 2012 ; Nitsch et al., 2015 ). Two main reasons are responsible for the structural variability. Firstly, the metal cations can be linked by bridging halide anions, which leads to the formation of different CuX substructures such as, for example, mononuclear and dinuclear complexes as well as chains and layers of different topology (Kromp & Sheldrick, 1999; Näther et al., 2013 ). Secondly, for a given copper halide or pseudohalide and a given neutral ligand, compounds with a different ratio between CuX and the organic ligand can be obtained (Näther et al., 2001 , 2002 ; Näther & Jess, 2001 ). The structural variety can be further enhanced if bridging organic ligands such as pyrazine and its derivatives are used in the synthesis.

In this context, we have reported on a compound with the composition CuNCS(C₆H₈N₂) (C₆H₈N₂ = 2,6-dimethylpyrazine) in which the metal cations are fourfold coordinated by one N- and two S-bonded thiocyanate anions and one 2,6-dimethylpyrazine ligand, which coordinate with the N atom that is not adjacent to the two methyl groups to the metal centers (Näther, 2026 ). The copper cations are linked by μ-1,1,3(S,S,N)-bridging thiocyanate anions into corrugated layers and shows a complicated CuX substructure. It is noted that some compounds with copper pseudohalides and 2,6-dimethylpyrazine are already reported and they are listed in the Database survey section (see below).

Only two compounds are known with copper halides and 2,6-dimethylpyrazine. In (CuCl)₂(2,6-dimethylpyrazine), the copper cations are tetrahedrally coordinated and linked into double chains by μ-1,1,1-bridging chloride anions that condense into layers by bridging 2,6-dimethylpyrazine ligands (CSD refcode YEFPOR; Fan et al., 2015a ). The same double chains are also observed in CuI(2,6-dimethylpyrazine) but the 2,6-dimethylpyrazine ligand is only terminally coordinated (TONQOE and TONQOE01; Kitada & Ishida, 2014 and Zhang et al., 2014 ). The observation that despite the different ratio between CuX and organic ligand the same CuX substructure is observed in both compounds can be traced back to the fact that 2,6-dimethylpyrazine can act as both a terminal and as a ligand because the metal coordination to the N atom that is adjacent to the two methyl groups is sterically hindered. This means that with CuCl, a compound with the composition CuCl(2,6-dimethylpyrazine) might exist, in which the 2,6-dimethylpyrazine ligand is only terminally coordinated, as is the case in CuI(2,6-dimethylpyrazine). If the coligand acts as a bridging ligand, the structure might consists of CuCl single chains that are linked into layers by the coligand as observed in CuCl(pyrazine) [ZOLXED (Moreno et al., 1995 ) and ZOLXED01 (Kuhlman et al., 1999 )]. However, as mentioned above, such compounds show an extremely versatile structural behavior, which make structural predictions more difficult.

To prove whether 2,6-dimethylpyrazine-rich compounds are available, CuCl was reacted with different amounts of 2,6-dimethylpyrazine and because no compounds are known with copper bromide, similar reactions were performed with CuBr. Within these investigations, crystals of one chloride and one bromide compound were obtained and these were characterized by single crystal X-ray diffraction.

2. Structural commentary

[(CuCl)₂(C₆H₈N₂)₄] (1) and [(CuBr)₂(C₆H₈N₂)₄] (2) are isotypic. The asymmetric units of both compounds are built up of one crystallographically independent copper cation, one chloride or bromide anion and one 2,6-dimethylpyrazine coligand that occupy general positions.

The copper(I) cations are fourfold coordinated by two μ-1,1 bridging halide anions and two 2,6-dimethylpyrazine ligands that are terminally coordinated by the N atom that is not adjacent to the methyl groups (Figs. 1 and 2). Bond lengths and angles show that the tetrahedra are strongly distorted with the largest values for the N—Cu—N angles, presumably because of steric repulsion between the bulky ligands (Tables 1 and 2). Only minor differences in the bonding angles are observed between the chloride and the bromide compounds. Each two copper(I) cations are connected by two μ-1,1 bridging halide anions via common edges into discrete dinuclear complexes that are located on centers of inversion (Fig. 1).

Table 1
Selected geometric parameters (Å, °) for 1

Cu1—N11	2.0097 (18)	Cu1—Cl1ⁱ	2.4337 (7)
Cu1—N1	2.0222 (17)	Cu1—Cu1ⁱ	2.9295 (7)
Cu1—Cl1	2.3893 (7)

N11—Cu1—N1	126.52 (7)	N11—Cu1—Cl1ⁱ	107.89 (6)
N11—Cu1—Cl1	107.27 (6)	N1—Cu1—Cl1ⁱ	107.07 (6)
N1—Cu1—Cl1	100.98 (6)	Cl1—Cu1—Cl1ⁱ	105.20 (2)
Symmetry code: (i) .

Table 2
Selected geometric parameters (Å, °) for 2

Cu1—N11	2.016 (3)	Cu1—Br1ⁱ	2.5513 (6)
Cu1—N1	2.026 (3)	Cu1—Cu1ⁱ	2.9677 (10)
Cu1—Br1	2.5249 (7)

N11—Cu1—N1	128.12 (13)	N11—Cu1—Br1ⁱ	107.19 (9)
N11—Cu1—Br1	105.01 (9)	N1—Cu1—Br1ⁱ	106.55 (9)
N1—Cu1—Br1	100.22 (9)	Br1—Cu1—Br1ⁱ	108.45 (2)
Symmetry code: (i) .

Figure 1
Crystal structure of compound 1 with the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. Symmetry code: (i) = −x + 1, −y + 1, −z + 1.

Figure 2
Crystal structure of compound 2 with the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. Symmetry code: (i) −x + 1, −y + 1, −z + 1.

It is noted that this structural motif is very common for this class of compounds and more than 70 structures with chloride anions and N-donor coligands are listed in the CSD (Version 5.43, 2026; Groom et al., 2016) using CONQUEST (Bruno et al., 2002 ). If this search is limited to pyrazine derivatives, only one hit is found, viz. [(CuCl)₂]₂(2,3-dimethylpyrazine)₆-2,3-dimethylpyrazine solvate (Jess & Näther, 2006b ), which exhibits a structure very similar to that of the title compound. This compound consists of dinuclear (CuCl)₂(L)₄ units (L = 2,3-dimethylpyrazine), but only three of the neutral coligands ligands are terminally coordinated, whereas the fourth ligand acts as a bridging ligand to bind to a second (CuCl)₂(L)₄ unit. This leads to the formation of tetranuclear complexes.

3. Supramolecular features

In the extended structure, the dinuclear discrete complexes are linked by centrosymmetric pairs of intermolecular C—H⋯X (X = Cl, Br) hydrogen bonding between the halide anions and one of the methyl H atoms (H6A and H16A, respectively, and H6B/H16B) into chains, that propagate along the a-axis direction (Fig. 3). There are only minor differences in the H⋯A and D⋯H distances and the C—H⋯X angles are close to linear, indicating that these are relatively strong interactions (Tables 3 and 4).

Table 3
Hydrogen-bond geometry (Å, °) for 1

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6B⋯Cl1ⁱⁱ	0.98	2.92	3.895 (3)	171
C16—H16B⋯Cl1ⁱⁱ	0.98	2.96	3.912 (3)	163
C5—H5C⋯Cl1ⁱⁱⁱ	0.98	2.78	3.716 (3)	159
C6—H6A⋯Cl1^iv	0.98	2.92	3.820 (2)	153
Symmetry codes: (ii) ; (iii) ; (iv) .

Table 4
Hydrogen-bond geometry (Å, °) for 2

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6A⋯Br1ⁱⁱ	0.98	2.98	3.943 (4)	169
C16—H16A⋯Br1ⁱⁱ	0.98	3.03	3.998 (4)	168
C1—H1⋯Br1ⁱ	0.95	3.07	3.722 (4)	127
C6—H6B⋯Br1ⁱⁱⁱ	0.98	3.08	3.920 (4)	144
C11—H11⋯Br1ⁱ	0.95	3.09	3.739 (4)	127
Symmetry codes: (i) ; (ii) ; (iii) .

Figure 3
Crystal structure of compound 1 in a view along [01 $[\overline{1}]$ ]. Intermolecular C—H⋯N hydrogen bonding is shown as dashed lines. A similar packing arrangement is observed in 2.

Additional C—H⋯X interactions are observed between these chains, but for the chloride compound 1 the H⋯A and D⋯H distances are significantly shorter and the C—H⋯X angles are close to linear, which is not the case for the bromide compound 2 (Fig. 4 and Tables 3 and 4). This suggests that the interactions between neighbouring chains are stronger in compound 1.

Figure 4
Crystal structure of compound 1 in a view along the crystallographic a-axis direction. Intermolecular C—H⋯N hydrogen bonding is shown as dashed lines. A similar packing arrangement is observed in 2.

4. Database survey

As mentioned in the Chemical context section, some compounds with copper(I) halides or pseudohalides and 2,6-dimethylpyrazine are reported in the CSD (Version 5.43, 2025; Groom et al., 2016 ) using CONQUEST (Bruno et al., 2002). These include (CuCl)₂(2,6-dimethylpyrazine) (CSD refcode YEFPOR; Fan et al., 2015a) and CuI(2,6-dimethylpyrazine) (TONQOE and TONQOE01; Kitada & Ishida, 2014 and Zhang et al., 2014), already mentioned above, as well as CuNCS(2,6-dimethylpyrazine), which forms CuNCS layers (Näther, 2026). Two isomers of Cu₂(CN)₂(2,6-dimethylpyrazine) with copper cyanide show complicated layered CuCN substructures (Fan et al., 2015b ). Finally, there is a mixed copper(I/II) pseudohalide compound with the composition [Cu₈^ICu₂^II(CN)₄(NCS)₈(2,6-dimethylpyrazine)₇], which also shows a two-dimensional coordination network (Jess & Näther, 2006a ).

5. Synthesis and crystallization

General

Copper(I) chloride, copper(I) bromide and 2,6-dimethylpyrazine were purchased from Sigma-Aldrich.

Synthesis

In a closed ampoule, 1 mmol of copper(I) halide (CuCl, 99.0 mg; CuBr, 143.5 mg) and 2 mmol of 2,6-dimethylpyrazine (216.3 mg) were heated in 2 ml of acetonitrile at 413 K for 2 d. After cooling, yellow blocks of compounds 1 and 2 were obtained, which decompose in air.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 5. C—H hydrogen atoms were positioned with idealized geometry (methyl H atoms allowed to rotate but not to tip) and were refined isotropically with U_iso(H) = 1.2U_eq(C) (1.5 for methyl H atoms).

Table 5
Experimental details

	1	2
Crystal data
Chemical formula	[Cu₂Cl₂(C₆H₈N₂)₄]	[Cu₂Br₂(C₆H₈N₂)₄]
M_r	630.55	719.47
Crystal system, space group	Triclinic, P $[\overline{1}]$	Triclinic, P $[\overline{1}]$
Temperature (K)	170	170
a, b, c (Å)	7.9342 (9), 8.0095 (10), 11.5556 (14)	7.9999 (6), 7.9947 (8), 11.8737 (10)
α, β, γ (°)	95.882 (15), 98.755 (14), 106.416 (14)	97.590 (11), 98.361 (10), 106.618 (10)
V (Å³)	687.96 (15)	707.77 (12)
Z	1	1
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	1.77	4.35
Crystal size (mm)	0.2 × 0.2 × 0.1	0.15 × 0.12 × 0.11

Data collection
Diffractometer	Stoe IPDS-I	Stoe IPDS-I
Absorption correction	Numerical (X-RED and X-SHAPE; Stoe & Cie, 2002 )	Numerical (X-RED and X-SHAPE; Stoe & Cie, 2002)
T_min, T_max	0.714, 0.851	0.551, 0.623
No. of measured, independent and observed [I > 2σ(I)] reflections	5429, 3171, 2559	7272, 3193, 2332
R_int	0.034	0.040
(sin θ/λ)_max (Å⁻¹)	0.661	0.660

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.085, 1.01	0.036, 0.087, 0.96
No. of reflections	3171	3193
No. of parameters	168	164
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.35, −0.58	0.59, −0.62
Computer programs: X-AREA (Stoe & Cie, 2002), SHELXT (Sheldrick, 2015a ), SHELXL (Sheldrick, 2015b ), DIAMOND (Brandenburg, 1999 ), XP in SHELXTL-PC (Sheldrick, 2008 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 2549116; 2549115

Crystal structure: contains datablocks 1, 2. DOI: https://doi.org/10.1107/S2056989026004330/tx2109sup1.cif

Structure factors: contains datablock 1. DOI: https://doi.org/10.1107/S2056989026004330/tx21091sup2.hkl

Structure factors: contains datablock 2. DOI: https://doi.org/10.1107/S2056989026004330/tx21092sup3.hkl

checkCIF report

Computing details top

Di-µ-chlorido-bis[bis(2,6-dimethylpyrazine)copper(I)] (1) top

Crystal data top

[Cu₂Cl₂(C₆H₈N₂)₄]	Z = 1
M_r = 630.55	F(000) = 324
Triclinic, P1	D_x = 1.522 Mg m⁻³
a = 7.9342 (9) Å	Mo Kα radiation, λ = 0.71073 Å
b = 8.0095 (10) Å	Cell parameters from 5965 reflections
c = 11.5556 (14) Å	θ = 2.8–28.0°
α = 95.882 (15)°	µ = 1.77 mm⁻¹
β = 98.755 (14)°	T = 170 K
γ = 106.416 (14)°	Block, yellow
V = 687.96 (15) Å³	0.2 × 0.2 × 0.1 mm

Data collection top

Stoe IPDS-I diffractometer	2559 reflections with I > 2σ(I)
Phi scans	R_int = 0.034
Absorption correction: numerical (X-Red and X-Shape; Stoe & Cie, 2002)	θ_max = 28.0°, θ_min = 2.7°
T_min = 0.714, T_max = 0.851	h = −10→10
5429 measured reflections	k = −10→10
3171 independent reflections	l = −15→14

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.033	w = 1/[σ²(F_o²) + (0.0539P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.085	(Δ/σ)_max < 0.001
S = 1.01	Δρ_max = 0.35 e Å⁻³
3171 reflections	Δρ_min = −0.58 e Å⁻³
168 parameters	Extinction correction: SHELXL-2016/6 (Sheldrick 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.030 (4)

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
Cu1	0.65195 (4)	0.58730 (3)	0.44740 (2)	0.02227 (12)
Cl1	0.64043 (7)	0.36585 (7)	0.57225 (5)	0.02170 (13)
N1	0.8283 (2)	0.7997 (2)	0.55504 (15)	0.0185 (4)
C1	0.7716 (3)	0.9041 (3)	0.62846 (19)	0.0197 (4)
H1	0.647296	0.891650	0.618220	0.024*
C2	0.8897 (3)	1.0304 (3)	0.71942 (18)	0.0191 (4)
N2	1.0668 (2)	1.0556 (2)	0.73508 (15)	0.0193 (4)
C3	1.1249 (3)	0.9534 (3)	0.66057 (19)	0.0179 (4)
C4	1.0056 (3)	0.8253 (3)	0.57177 (18)	0.0183 (4)
H4	1.050947	0.754131	0.521620	0.022*
C5	0.8231 (3)	1.1410 (3)	0.8041 (2)	0.0287 (5)
H5A	0.924917	1.220955	0.861577	0.043*
H5B	0.741903	1.064207	0.846063	0.043*
H5C	0.759116	1.209900	0.759905	0.043*
C6	1.3226 (3)	0.9814 (3)	0.6766 (2)	0.0258 (5)
H6A	1.383392	1.102579	0.667025	0.039*
H6B	1.346472	0.899086	0.617104	0.039*
H6C	1.367048	0.960824	0.756053	0.039*
N11	0.6766 (2)	0.4839 (2)	0.28719 (16)	0.0198 (4)
C11	0.5341 (3)	0.4087 (3)	0.20026 (19)	0.0236 (5)
H11	0.420381	0.417133	0.211264	0.028*
C12	0.5480 (3)	0.3180 (3)	0.0938 (2)	0.0261 (5)
N12	0.7052 (3)	0.3025 (3)	0.07479 (16)	0.0251 (4)
C13	0.8491 (3)	0.3779 (3)	0.16187 (19)	0.0206 (4)
C14	0.8341 (3)	0.4689 (3)	0.26692 (19)	0.0206 (4)
H14	0.938372	0.522019	0.326098	0.025*
C15	0.3877 (4)	0.2328 (5)	−0.0039 (2)	0.0435 (7)
H15A	0.420999	0.253686	−0.080588	0.065*
H15B	0.291496	0.283431	0.007702	0.065*
H15C	0.346398	0.105722	−0.002240	0.065*
C16	1.0260 (3)	0.3585 (3)	0.1424 (2)	0.0287 (5)
H16A	1.012735	0.233860	0.118206	0.043*
H16B	1.114498	0.403305	0.216083	0.043*
H16C	1.066046	0.425684	0.080123	0.043*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.01979 (16)	0.02445 (16)	0.01745 (15)	0.00281 (11)	0.00182 (10)	−0.00620 (10)
Cl1	0.0167 (2)	0.0256 (3)	0.0219 (3)	0.0066 (2)	0.00183 (19)	0.00174 (19)
N1	0.0153 (8)	0.0194 (8)	0.0170 (8)	0.0021 (7)	0.0006 (6)	−0.0023 (7)
C1	0.0133 (10)	0.0242 (10)	0.0194 (10)	0.0052 (8)	0.0019 (8)	−0.0035 (8)
C2	0.0186 (10)	0.0208 (9)	0.0169 (10)	0.0062 (8)	0.0015 (8)	0.0001 (8)
N2	0.0166 (8)	0.0213 (8)	0.0165 (8)	0.0038 (7)	−0.0009 (7)	−0.0007 (7)
C3	0.0139 (10)	0.0203 (9)	0.0183 (10)	0.0040 (8)	0.0024 (7)	0.0016 (8)
C4	0.0156 (10)	0.0189 (9)	0.0193 (10)	0.0044 (8)	0.0037 (8)	−0.0006 (7)
C5	0.0285 (12)	0.0332 (12)	0.0232 (11)	0.0124 (10)	0.0029 (9)	−0.0071 (9)
C6	0.0136 (10)	0.0306 (11)	0.0294 (12)	0.0044 (9)	0.0007 (8)	−0.0013 (9)
N11	0.0183 (9)	0.0235 (9)	0.0156 (8)	0.0056 (7)	0.0019 (7)	−0.0015 (7)
C11	0.0168 (10)	0.0335 (12)	0.0186 (10)	0.0081 (9)	0.0017 (8)	−0.0032 (9)
C12	0.0206 (11)	0.0368 (12)	0.0190 (11)	0.0107 (10)	−0.0007 (8)	−0.0038 (9)
N12	0.0242 (10)	0.0346 (10)	0.0164 (9)	0.0128 (8)	0.0017 (7)	−0.0039 (8)
C13	0.0186 (10)	0.0250 (10)	0.0188 (10)	0.0082 (8)	0.0043 (8)	0.0009 (8)
C14	0.0170 (10)	0.0252 (10)	0.0178 (10)	0.0058 (8)	0.0022 (8)	−0.0013 (8)
C15	0.0259 (13)	0.069 (2)	0.0280 (13)	0.0157 (13)	−0.0059 (10)	−0.0163 (13)
C16	0.0233 (12)	0.0405 (13)	0.0247 (12)	0.0146 (10)	0.0067 (9)	−0.0015 (10)

Geometric parameters (Å, º) top

Cu1—N11	2.0097 (18)	C6—H6B	0.9800
Cu1—N1	2.0222 (17)	C6—H6C	0.9800
Cu1—Cl1	2.3893 (7)	N11—C11	1.340 (3)
Cu1—Cl1ⁱ	2.4337 (7)	N11—C14	1.341 (3)
Cu1—Cu1ⁱ	2.9295 (7)	C11—C12	1.399 (3)
N1—C4	1.343 (3)	C11—H11	0.9500
N1—C1	1.344 (3)	C12—N12	1.336 (3)
C1—C2	1.398 (3)	C12—C15	1.507 (3)
C1—H1	0.9500	N12—C13	1.348 (3)
C2—N2	1.343 (3)	C13—C14	1.389 (3)
C2—C5	1.506 (3)	C13—C16	1.502 (3)
N2—C3	1.346 (3)	C14—H14	0.9500
C3—C4	1.393 (3)	C15—H15A	0.9800
C3—C6	1.500 (3)	C15—H15B	0.9800
C4—H4	0.9500	C15—H15C	0.9800
C5—H5A	0.9800	C16—H16A	0.9800
C5—H5B	0.9800	C16—H16B	0.9800
C5—H5C	0.9800	C16—H16C	0.9800
C6—H6A	0.9800

N11—Cu1—N1	126.52 (7)	C3—C6—H6B	109.5
N11—Cu1—Cl1	107.27 (6)	H6A—C6—H6B	109.5
N1—Cu1—Cl1	100.98 (6)	C3—C6—H6C	109.5
N11—Cu1—Cl1ⁱ	107.89 (6)	H6A—C6—H6C	109.5
N1—Cu1—Cl1ⁱ	107.07 (6)	H6B—C6—H6C	109.5
Cl1—Cu1—Cl1ⁱ	105.20 (2)	C11—N11—C14	116.68 (18)
N11—Cu1—Cu1ⁱ	119.83 (5)	C11—N11—Cu1	121.77 (15)
N1—Cu1—Cu1ⁱ	113.52 (5)	C14—N11—Cu1	121.12 (14)
Cl1—Cu1—Cu1ⁱ	53.291 (18)	N11—C11—C12	121.9 (2)
Cl1ⁱ—Cu1—Cu1ⁱ	51.912 (17)	N11—C11—H11	119.1
Cu1—Cl1—Cu1ⁱ	74.80 (2)	C12—C11—H11	119.1
C4—N1—C1	116.54 (17)	N12—C12—C11	121.0 (2)
C4—N1—Cu1	121.87 (14)	N12—C12—C15	117.0 (2)
C1—N1—Cu1	120.60 (14)	C11—C12—C15	121.9 (2)
N1—C1—C2	122.02 (19)	C12—N12—C13	117.40 (19)
N1—C1—H1	119.0	N12—C13—C14	121.1 (2)
C2—C1—H1	119.0	N12—C13—C16	117.87 (19)
N2—C2—C1	120.97 (19)	C14—C13—C16	121.0 (2)
N2—C2—C5	117.70 (18)	N11—C14—C13	121.9 (2)
C1—C2—C5	121.3 (2)	N11—C14—H14	119.1
C2—N2—C3	117.29 (17)	C13—C14—H14	119.1
N2—C3—C4	121.26 (19)	C12—C15—H15A	109.5
N2—C3—C6	117.78 (18)	C12—C15—H15B	109.5
C4—C3—C6	120.95 (19)	H15A—C15—H15B	109.5
N1—C4—C3	121.89 (19)	C12—C15—H15C	109.5
N1—C4—H4	119.1	H15A—C15—H15C	109.5
C3—C4—H4	119.1	H15B—C15—H15C	109.5
C2—C5—H5A	109.5	C13—C16—H16A	109.5
C2—C5—H5B	109.5	C13—C16—H16B	109.5
H5A—C5—H5B	109.5	H16A—C16—H16B	109.5
C2—C5—H5C	109.5	C13—C16—H16C	109.5
H5A—C5—H5C	109.5	H16A—C16—H16C	109.5
H5B—C5—H5C	109.5	H16B—C16—H16C	109.5
C3—C6—H6A	109.5

C4—N1—C1—C2	−1.4 (3)	C14—N11—C11—C12	0.4 (3)
Cu1—N1—C1—C2	167.41 (16)	Cu1—N11—C11—C12	−172.15 (18)
N1—C1—C2—N2	1.8 (3)	N11—C11—C12—N12	0.2 (4)
N1—C1—C2—C5	−177.4 (2)	N11—C11—C12—C15	179.8 (3)
C1—C2—N2—C3	−0.6 (3)	C11—C12—N12—C13	−0.2 (4)
C5—C2—N2—C3	178.6 (2)	C15—C12—N12—C13	−179.8 (2)
C2—N2—C3—C4	−0.8 (3)	C12—N12—C13—C14	−0.3 (3)
C2—N2—C3—C6	179.5 (2)	C12—N12—C13—C16	178.9 (2)
C1—N1—C4—C3	0.0 (3)	C11—N11—C14—C13	−0.9 (3)
Cu1—N1—C4—C3	−168.65 (16)	Cu1—N11—C14—C13	171.67 (17)
N2—C3—C4—N1	1.1 (3)	N12—C13—C14—N11	0.9 (4)
C6—C3—C4—N1	−179.2 (2)	C16—C13—C14—N11	−178.3 (2)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6B···Cl1ⁱⁱ	0.98	2.92	3.895 (3)	171
C16—H16B···Cl1ⁱⁱ	0.98	2.96	3.912 (3)	163
C5—H5C···Cl1ⁱⁱⁱ	0.98	2.78	3.716 (3)	159
C6—H6A···Cl1^iv	0.98	2.92	3.820 (2)	153

Symmetry codes: (ii) −x+2, −y+1, −z+1; (iii) x, y+1, z; (iv) x+1, y+1, z.

Di-µ-bromido-bis[bis(2,6-dimethylpyrazine)dicopper(I)] (2) top

Crystal data top

[Cu₂Br₂(C₆H₈N₂)₄]	Z = 1
M_r = 719.47	F(000) = 360
Triclinic, P1	D_x = 1.688 Mg m⁻³
a = 7.9999 (6) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.9947 (8) Å	Cell parameters from 6871 reflections
c = 11.8737 (10) Å	θ = 2.7–28.0°
α = 97.590 (11)°	µ = 4.35 mm⁻¹
β = 98.361 (10)°	T = 170 K
γ = 106.618 (10)°	Block, yellow
V = 707.77 (12) Å³	0.15 × 0.12 × 0.11 mm

Data collection top

Stoe IPDS-I diffractometer	2332 reflections with I > 2σ(I)
Phi scans	R_int = 0.040
Absorption correction: numerical (X-Red and X-Shape; Stoe & Cie, 2002)	θ_max = 28.0°, θ_min = 2.7°
T_min = 0.551, T_max = 0.623	h = −9→9
7272 measured reflections	k = −10→10
3193 independent reflections	l = −15→15

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.036	w = 1/[σ²(F_o²) + (0.0504P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.087	(Δ/σ)_max < 0.001
S = 0.96	Δρ_max = 0.59 e Å⁻³
3193 reflections	Δρ_min = −0.62 e Å⁻³
164 parameters	Extinction correction: SHELXL-2016/6 (Sheldrick 2016), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.017 (2)

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Cu1	0.65082 (6)	0.59508 (6)	0.44939 (4)	0.02835 (15)
Br1	0.65337 (5)	0.35740 (5)	0.56951 (3)	0.02645 (13)
N1	0.8239 (4)	0.8099 (4)	0.5599 (2)	0.0244 (6)
C1	0.7659 (5)	0.9116 (5)	0.6339 (3)	0.0250 (7)
H1	0.642464	0.898468	0.623456	0.030*
C2	0.8834 (5)	1.0372 (5)	0.7265 (3)	0.0250 (7)
N2	1.0577 (4)	1.0627 (4)	0.7434 (2)	0.0258 (6)
C3	1.1174 (5)	0.9637 (5)	0.6679 (3)	0.0247 (7)
C4	1.0002 (5)	0.8364 (5)	0.5778 (3)	0.0258 (8)
H4	1.046083	0.766012	0.527401	0.031*
C5	0.8129 (6)	1.1438 (6)	0.8114 (3)	0.0356 (9)
H5A	0.683443	1.111408	0.788259	0.053*
H5B	0.843087	1.118499	0.888982	0.053*
H5C	0.866381	1.270626	0.812073	0.053*
C6	1.3145 (5)	0.9938 (6)	0.6861 (3)	0.0337 (9)
H6A	1.340434	0.914057	0.625809	0.051*
H6B	1.375844	1.117285	0.682047	0.051*
H6C	1.355642	0.969628	0.762323	0.051*
N11	0.6723 (4)	0.4889 (4)	0.2905 (2)	0.0257 (6)
C11	0.5296 (5)	0.4163 (5)	0.2047 (3)	0.0307 (8)
H11	0.418492	0.429462	0.215818	0.037*
C12	0.5399 (6)	0.3221 (6)	0.0997 (3)	0.0345 (9)
N12	0.6943 (5)	0.3008 (5)	0.0805 (3)	0.0336 (8)
C13	0.8378 (5)	0.3746 (5)	0.1648 (3)	0.0263 (8)
C14	0.8256 (5)	0.4691 (5)	0.2696 (3)	0.0256 (7)
H14	0.929792	0.520968	0.327670	0.031*
C15	0.3786 (7)	0.2388 (8)	0.0040 (4)	0.0581 (15)
H15A	0.275018	0.263779	0.028525	0.087*
H15B	0.400020	0.288577	−0.065683	0.087*
H15C	0.356006	0.110124	−0.013101	0.087*
C16	1.0097 (6)	0.3491 (6)	0.1434 (3)	0.0358 (9)
H16A	1.103626	0.409358	0.211303	0.054*
H16B	0.996624	0.222055	0.129384	0.054*
H16C	1.041353	0.399368	0.075588	0.054*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0243 (3)	0.0316 (3)	0.0236 (2)	0.0064 (2)	0.00211 (18)	−0.00626 (18)
Br1	0.0199 (2)	0.0311 (2)	0.02680 (19)	0.00841 (14)	0.00289 (13)	0.00052 (14)
N1	0.0198 (17)	0.0263 (15)	0.0229 (13)	0.0045 (12)	0.0026 (11)	−0.0023 (11)
C1	0.0162 (19)	0.0306 (19)	0.0244 (17)	0.0068 (14)	0.0006 (13)	−0.0035 (14)
C2	0.027 (2)	0.0250 (17)	0.0217 (16)	0.0087 (14)	0.0025 (13)	−0.0005 (13)
N2	0.0248 (18)	0.0262 (15)	0.0243 (14)	0.0078 (12)	0.0010 (12)	0.0016 (12)
C3	0.0189 (19)	0.0288 (18)	0.0266 (17)	0.0073 (14)	0.0054 (13)	0.0050 (14)
C4	0.021 (2)	0.0278 (18)	0.0259 (17)	0.0062 (15)	0.0053 (13)	−0.0016 (13)
C5	0.032 (2)	0.046 (2)	0.0289 (18)	0.0186 (18)	0.0032 (15)	−0.0052 (17)
C6	0.019 (2)	0.040 (2)	0.036 (2)	0.0058 (16)	0.0019 (15)	−0.0017 (17)
N11	0.0222 (18)	0.0326 (16)	0.0202 (13)	0.0081 (13)	0.0042 (11)	−0.0017 (11)
C11	0.022 (2)	0.044 (2)	0.0232 (17)	0.0115 (16)	0.0034 (14)	−0.0044 (15)
C12	0.026 (2)	0.048 (2)	0.0235 (17)	0.0113 (18)	0.0005 (14)	−0.0080 (16)
N12	0.030 (2)	0.045 (2)	0.0228 (15)	0.0139 (15)	0.0030 (12)	−0.0044 (13)
C13	0.024 (2)	0.0335 (19)	0.0218 (16)	0.0094 (15)	0.0062 (13)	0.0018 (14)
C14	0.021 (2)	0.0291 (18)	0.0240 (16)	0.0075 (14)	0.0022 (13)	−0.0012 (14)
C15	0.030 (3)	0.097 (4)	0.033 (2)	0.022 (3)	−0.0070 (18)	−0.026 (2)
C16	0.026 (2)	0.048 (2)	0.033 (2)	0.0153 (18)	0.0072 (15)	−0.0029 (17)

Geometric parameters (Å, º) top

Cu1—N11	2.016 (3)	C6—H6B	0.9800
Cu1—N1	2.026 (3)	C6—H6C	0.9800
Cu1—Br1	2.5249 (7)	N11—C14	1.334 (5)
Cu1—Br1ⁱ	2.5513 (6)	N11—C11	1.344 (5)
Cu1—Cu1ⁱ	2.9677 (10)	C11—C12	1.394 (5)
N1—C1	1.340 (5)	C11—H11	0.9500
N1—C4	1.345 (5)	C12—N12	1.342 (6)
C1—C2	1.403 (5)	C12—C15	1.511 (6)
C1—H1	0.9500	N12—C13	1.338 (5)
C2—N2	1.331 (5)	C13—C14	1.400 (5)
C2—C5	1.507 (5)	C13—C16	1.498 (6)
N2—C3	1.346 (5)	C14—H14	0.9500
C3—C4	1.391 (5)	C15—H15A	0.9800
C3—C6	1.504 (6)	C15—H15B	0.9800
C4—H4	0.9500	C15—H15C	0.9800
C5—H5A	0.9800	C16—H16A	0.9800
C5—H5B	0.9800	C16—H16B	0.9800
C5—H5C	0.9800	C16—H16C	0.9800
C6—H6A	0.9800

N11—Cu1—N1	128.12 (13)	C3—C6—H6B	109.5
N11—Cu1—Br1	105.01 (9)	H6A—C6—H6B	109.5
N1—Cu1—Br1	100.22 (9)	C3—C6—H6C	109.5
N11—Cu1—Br1ⁱ	107.19 (9)	H6A—C6—H6C	109.5
N1—Cu1—Br1ⁱ	106.55 (9)	H6B—C6—H6C	109.5
Br1—Cu1—Br1ⁱ	108.45 (2)	C14—N11—C11	116.6 (3)
N11—Cu1—Cu1ⁱ	118.32 (9)	C14—N11—Cu1	121.3 (2)
N1—Cu1—Cu1ⁱ	113.31 (9)	C11—N11—Cu1	121.7 (3)
Br1—Cu1—Cu1ⁱ	54.639 (19)	N11—C11—C12	121.9 (4)
Br1ⁱ—Cu1—Cu1ⁱ	53.811 (18)	N11—C11—H11	119.1
Cu1—Br1—Cu1ⁱ	71.55 (2)	C12—C11—H11	119.1
C1—N1—C4	116.7 (3)	N12—C12—C11	120.9 (4)
C1—N1—Cu1	120.7 (3)	N12—C12—C15	117.4 (3)
C4—N1—Cu1	121.5 (2)	C11—C12—C15	121.7 (4)
N1—C1—C2	121.4 (3)	C13—N12—C12	117.7 (3)
N1—C1—H1	119.3	N12—C13—C14	120.7 (4)
C2—C1—H1	119.3	N12—C13—C16	117.6 (3)
N2—C2—C1	121.5 (3)	C14—C13—C16	121.7 (3)
N2—C2—C5	118.4 (3)	N11—C14—C13	122.2 (3)
C1—C2—C5	120.1 (4)	N11—C14—H14	118.9
C2—N2—C3	117.4 (3)	C13—C14—H14	118.9
N2—C3—C4	121.0 (3)	C12—C15—H15A	109.5
N2—C3—C6	117.5 (3)	C12—C15—H15B	109.5
C4—C3—C6	121.5 (3)	H15A—C15—H15B	109.5
N1—C4—C3	122.0 (3)	C12—C15—H15C	109.5
N1—C4—H4	119.0	H15A—C15—H15C	109.5
C3—C4—H4	119.0	H15B—C15—H15C	109.5
C2—C5—H5A	109.5	C13—C16—H16A	109.5
C2—C5—H5B	109.5	C13—C16—H16B	109.5
H5A—C5—H5B	109.5	H16A—C16—H16B	109.5
C2—C5—H5C	109.5	C13—C16—H16C	109.5
H5A—C5—H5C	109.5	H16A—C16—H16C	109.5
H5B—C5—H5C	109.5	H16B—C16—H16C	109.5
C3—C6—H6A	109.5

C4—N1—C1—C2	−1.0 (5)	C14—N11—C11—C12	1.2 (6)
Cu1—N1—C1—C2	166.5 (3)	Cu1—N11—C11—C12	−171.4 (3)
N1—C1—C2—N2	1.2 (6)	N11—C11—C12—N12	−0.1 (7)
N1—C1—C2—C5	−177.2 (3)	N11—C11—C12—C15	179.3 (4)
C1—C2—N2—C3	0.2 (5)	C11—C12—N12—C13	−0.8 (6)
C5—C2—N2—C3	178.7 (3)	C15—C12—N12—C13	179.8 (4)
C2—N2—C3—C4	−1.8 (5)	C12—N12—C13—C14	0.6 (6)
C2—N2—C3—C6	179.3 (3)	C12—N12—C13—C16	179.5 (4)
C1—N1—C4—C3	−0.5 (5)	C11—N11—C14—C13	−1.4 (5)
Cu1—N1—C4—C3	−168.0 (3)	Cu1—N11—C14—C13	171.2 (3)
N2—C3—C4—N1	2.0 (6)	N12—C13—C14—N11	0.5 (6)
C6—C3—C4—N1	−179.1 (3)	C16—C13—C14—N11	−178.3 (4)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6A···Br1ⁱⁱ	0.98	2.98	3.943 (4)	169
C16—H16A···Br1ⁱⁱ	0.98	3.03	3.998 (4)	168
C1—H1···Br1ⁱ	0.95	3.07	3.722 (4)	127
C6—H6B···Br1ⁱⁱⁱ	0.98	3.08	3.920 (4)	144
C11—H11···Br1ⁱ	0.95	3.09	3.739 (4)	127

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, −y+1, −z+1; (iii) x+1, y+1, z.

Acknowledgements

Financial support by the State of Schleswig-Holstein is gratefully acknowledged.

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research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Synthesis and crystal structure of di-μ-chlorido-bis­­[bis­(2,6-di­methyl­pyrazine)­copper(I)] and di-μ-bromido-bis­[bis­(2,6-di­methyl­pyrazine)copper(I)]

1. Chemical context

2. Structural commentary

3. Supra­molecular features

4. Database survey

5. Synthesis and crystallization

6. Refinement

Supporting information

Acknowledgements

References

research communications

Synthesis and crystal structure of di-μ-chlorido-bis[bis(2,6-dimethylpyrazine)copper(I)] and di-μ-bromido-bis[bis(2,6-dimethylpyrazine)copper(I)]

3. Supramolecular features