Di-μ-bromido-bis­[bromido­(4,4′-dihy­droxy-2,2′-bi­pyridine-κ2N,N′)copper(II)]

Rodriguez-Santiago, A.J.; Acosta, C.; Raptis, R.G.

doi:10.1107/S2414314616010294

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 1| Part 7| July 2016| x161029

https://doi.org/10.1107/S2414314616010294

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Di-μ-bromido-bis[bromido(4,4′-dihydroxy-2,2′-bipyridine-κ²N,N′)copper(II)]

Alan J Rodriguez-Santiago,^a ^* Carlos Acosta ^a and Raphael G Raptis ^a

^aFlorida International University, Department of Chemistry and Biochemistry, 11200 SW 8th St., Miami, FL 33199-0001, USA
^*Correspondence e-mail: arodr927@fiu.edu

Edited by M. Weil, Vienna University of Technology, Austria (Received 10 June 2016; accepted 24 June 2016; online 12 July 2016)

The molecules of the title compound, [Cu₂Br₄(C₁₀H₈N₂O₂)₂], are centrosymmetric dimers. The Cu^II atom exhibits a distorted square-pyramidal coordination geometry, with two bridging bromide ligands and the N atoms of the 4,4′-dihydroxy-2,2′-bipyridine chelate in the equatorial plane. π–π stacking and hydrogen-bonding interactions of the O—H⋯Br, C—H⋯·Br and C—H⋯O types consolidate the crystal packing.

Keywords: crystal structure; copper(II); centrosymmetric dimer; dihydroxybipyridine.

CCDC reference: 1487651

Structure description

The synthesis of the title compound is a variation of the one reported by Yang et al. (2014 ), using the corresponding bipyridine derivative. The asymmetric unit contains one half-molecule which dimerizes and is related by an inversion center (Fig. 1). Each Cu^II atom is five-coordinated in a square-pyramidal coordination geometry, with the two N atoms of the 4,4′-dihydroxy-2,2′-bipyridine (DHBP) ligand and two bridging bromide ligands assuming equatorial positions and a terminal bromide ligand in the apical position. The Cu—Br bond involving the apical bromide ligand is considerably longer [2.6462 (12) Å] than the Cu—Br bonds to the bromide ligands in the equatorial positions [2.4458 (10) and 2.4647 (11) Å]. The crystal structure reveals π–π interactions between the pyridine rings of adjacent complex molecules, with a centroid-to-centroid distance of 3.57 Å, as well as hydrogen bonding between the hydroxy groups and the terminal bromide ligands. Additional C—H⋯X interactions (X = O, Br) are also found (Fig. 2 and Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C10—H10⋯Br1ⁱ	0.93	2.81	3.373 (7)	120
C2—H2A⋯O1ⁱⁱ	0.93	2.56	3.390 (9)	149
C4—H4⋯Br1ⁱⁱⁱ	0.93	3.11	3.707 (7)	123
C1—H1A⋯Br1	0.93	2.73	3.340 (7)	124
C7—H7⋯Br2ⁱⁱⁱ	0.93	2.94	3.685 (7)	138
O1—H1⋯Br2^iv	0.82	2.36	3.164 (5)	169
O2—H2⋯Br2ⁱⁱⁱ	0.82	2.44	3.263 (5)	177
Symmetry codes: (i) -x+2, -y+2, -z+1; (ii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) x, y-1, z; (iv) -x+1, -y+1, -z+1.

Figure 1
The structure of [Cu₂(μ-Br)₂(DHBP)₂(Br)₂], showing displacement ellipsoids at the 50% probability level. All non-labeled atoms are generated by the symmetry code (−x + 2, −y + 2, −z + 1).

Figure 2
The crystal packing of [Cu₂(μ-Br)₂(DHBP)₂(Br)₂], showing the O—H⋯Br hydrogen bonding as red lines.

Synthesis and crystallization

CuBr₂ (30 mg, 0.134 mmol) was dissolved in 10 ml of ethanol and the resulting solution added dropwise to a tetrahydrofuran solution (10 ml) containing 50 mg (0.266 mmol) of dihydroxybipyridine at room temperature. The mixture was stirred overnight to give a blue–green solution. Crystals were grown by layering the reaction solution over toluene.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	[Cu₂Br₄(C₁₀H₈N₂O₂)₂]
M_r	823.09
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	300
a, b, c (Å)	8.0636 (7), 8.4278 (7), 17.2516 (14)
β (°)	91.820 (2)
V (Å³)	1171.80 (17)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	8.67
Crystal size (mm)	0.25 × 0.08 × 0.03

Data collection
Diffractometer	Bruker D8 Quest CMOS
Absorption correction	Multi-scan (SADABS; Bruker, 2013 )
T_min, T_max	0.53, 0.79
No. of measured, independent and observed [I > 2σ(I)] reflections	15036, 2414, 1936
R_int	0.047
(sin θ/λ)_max (Å⁻¹)	0.627

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.106, 1.16
No. of reflections	2414
No. of parameters	156
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.98, −0.76
Computer programs: APEX2 andSAINT (Bruker, 2013), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), Mercury (Macrae et al., 2008 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1487651

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: https://doi.org/10.1107/S2414314616010294/wm4018sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616010294/wm4018Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314616010294/wm4018Isup3.cdx

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2013); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Di-µ-bromido-bis[bromido(4,4'-dihydroxy-2,2'-bipyridine-κ²N,N')copper(II)] top

Crystal data top

[Cu₂Br₄(C₁₀H₈N₂O₂)₂]	F(000) = 788
M_r = 823.09	D_x = 2.333 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.0636 (7) Å	Cell parameters from 6190 reflections
b = 8.4278 (7) Å	θ = 3.4–26.3°
c = 17.2516 (14) Å	µ = 8.67 mm⁻¹
β = 91.820 (2)°	T = 300 K
V = 1171.80 (17) Å³	Plate, translucent light green-yellow
Z = 2	0.25 × 0.08 × 0.03 mm

Data collection top

Bruker D8 Quest CMOS diffractometer	2414 independent reflections
Radiation source: fine-focus tube	1936 reflections with I > 2σ(I)
Detector resolution: 10.4167 pixels mm^-1	R_int = 0.047
φ and ω scans	θ_max = 26.5°, θ_min = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2013)	h = −10→10
T_min = 0.53, T_max = 0.79	k = −10→10
15036 measured reflections	l = −21→21

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.047	H-atom parameters constrained
wR(F²) = 0.106	w = 1/[σ²(F_o²) + (0.0229P)² + 10.5467P] where P = (F_o² + 2F_c²)/3
S = 1.16	(Δ/σ)_max = 0.001
2414 reflections	Δρ_max = 0.98 e Å⁻³
156 parameters	Δρ_min = −0.76 e Å⁻³

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
Br1	0.89203 (9)	1.04991 (8)	0.57654 (4)	0.0314 (2)
Br2	0.62406 (10)	0.95551 (9)	0.39730 (5)	0.0355 (2)
Cu1	0.86595 (11)	0.82989 (9)	0.48451 (5)	0.0256 (2)
O2	0.8375 (8)	0.2138 (6)	0.3009 (3)	0.0404 (14)
H2	0.7877	0.1466	0.3255	0.061*
O1	0.4946 (7)	0.3622 (6)	0.6850 (3)	0.0400 (14)
H1	0.4760	0.2804	0.6605	0.060*
N2	0.8753 (7)	0.6318 (6)	0.4220 (3)	0.0242 (12)
N1	0.7524 (7)	0.6839 (6)	0.5573 (3)	0.0235 (12)
C6	0.8010 (8)	0.5057 (7)	0.4538 (4)	0.0199 (13)
C5	0.7311 (8)	0.5351 (8)	0.5306 (4)	0.0216 (14)
C7	0.7873 (9)	0.3626 (8)	0.4157 (4)	0.0261 (15)
H7	0.7376	0.2764	0.4394	0.031*
C3	0.5822 (9)	0.4625 (8)	0.6417 (4)	0.0259 (15)
C9	0.9252 (9)	0.4769 (8)	0.3099 (4)	0.0300 (16)
H9	0.9697	0.4705	0.2609	0.036*
C1	0.6915 (9)	0.7206 (9)	0.6267 (4)	0.0329 (17)
H1A	0.7076	0.8225	0.6461	0.040*
C8	0.8481 (9)	0.3480 (8)	0.3422 (4)	0.0280 (16)
C4	0.6459 (8)	0.4215 (8)	0.5713 (4)	0.0235 (14)
H4	0.6319	0.3196	0.5515	0.028*
C2	0.6074 (10)	0.6141 (9)	0.6694 (4)	0.0334 (17)
H2A	0.5668	0.6434	0.7172	0.040*
C10	0.9346 (10)	0.6144 (9)	0.3518 (4)	0.0332 (17)
H10	0.9860	0.7013	0.3296	0.040*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0407 (4)	0.0218 (3)	0.0324 (4)	−0.0124 (3)	0.0112 (3)	−0.0071 (3)
Br2	0.0416 (4)	0.0233 (4)	0.0411 (5)	−0.0050 (3)	−0.0056 (3)	0.0008 (3)
Cu1	0.0368 (5)	0.0152 (4)	0.0250 (4)	−0.0078 (4)	0.0065 (3)	−0.0020 (3)
O2	0.074 (4)	0.023 (3)	0.025 (3)	−0.011 (3)	0.018 (3)	−0.013 (2)
O1	0.060 (4)	0.031 (3)	0.030 (3)	−0.023 (3)	0.017 (3)	−0.003 (2)
N2	0.033 (3)	0.021 (3)	0.020 (3)	−0.004 (2)	0.007 (2)	−0.002 (2)
N1	0.031 (3)	0.017 (3)	0.023 (3)	−0.003 (2)	0.004 (2)	0.001 (2)
C6	0.018 (3)	0.015 (3)	0.026 (4)	0.001 (2)	0.000 (3)	−0.001 (3)
C5	0.023 (3)	0.019 (3)	0.023 (3)	−0.002 (3)	0.003 (3)	−0.003 (3)
C7	0.032 (4)	0.019 (3)	0.027 (4)	−0.006 (3)	0.003 (3)	−0.001 (3)
C3	0.031 (4)	0.021 (3)	0.026 (4)	−0.007 (3)	0.002 (3)	−0.001 (3)
C9	0.044 (4)	0.025 (4)	0.021 (4)	−0.005 (3)	0.007 (3)	−0.003 (3)
C1	0.038 (4)	0.024 (4)	0.037 (4)	−0.006 (3)	0.012 (3)	−0.010 (3)
C8	0.030 (4)	0.020 (3)	0.035 (4)	0.000 (3)	0.006 (3)	−0.006 (3)
C4	0.029 (4)	0.016 (3)	0.026 (4)	−0.004 (3)	0.002 (3)	−0.002 (3)
C2	0.046 (5)	0.033 (4)	0.021 (4)	−0.012 (3)	0.012 (3)	−0.006 (3)
C10	0.048 (5)	0.027 (4)	0.025 (4)	−0.013 (3)	0.008 (3)	0.003 (3)

Geometric parameters (Å, º) top

Br1—Cu1	2.4458 (10)	C6—C5	1.477 (9)
Br1—Cu1ⁱ	2.4647 (11)	C5—C4	1.382 (9)
Br2—Cu1	2.6462 (12)	C7—C8	1.381 (10)
Cu1—N2	1.990 (5)	C7—H7	0.9300
Cu1—N1	2.001 (5)	C3—C2	1.376 (10)
Cu1—Br1ⁱ	2.4647 (11)	C3—C4	1.379 (9)
O2—C8	1.338 (8)	C9—C10	1.367 (10)
O2—H2	0.8200	C9—C8	1.378 (10)
O1—C3	1.343 (8)	C9—H9	0.9300
O1—H1	0.8200	C1—C2	1.356 (10)
N2—C10	1.324 (9)	C1—H1A	0.9300
N2—C6	1.346 (8)	C4—H4	0.9300
N1—C1	1.344 (9)	C2—H2A	0.9300
N1—C5	1.345 (8)	C10—H10	0.9300
C6—C7	1.376 (9)

Cu1—Br1—Cu1ⁱ	95.00 (4)	C6—C7—C8	119.4 (6)
N2—Cu1—N1	81.4 (2)	C6—C7—H7	120.3
N2—Cu1—Br1	169.65 (17)	C8—C7—H7	120.3
N1—Cu1—Br1	95.19 (16)	O1—C3—C2	117.8 (6)
N2—Cu1—Br1ⁱ	93.97 (16)	O1—C3—C4	123.3 (6)
N1—Cu1—Br1ⁱ	154.89 (17)	C2—C3—C4	118.9 (6)
Br1—Cu1—Br1ⁱ	85.00 (4)	C10—C9—C8	118.2 (6)
N2—Cu1—Br2	93.88 (17)	C10—C9—H9	120.9
N1—Cu1—Br2	105.01 (17)	C8—C9—H9	120.9
Br1—Cu1—Br2	96.45 (4)	N1—C1—C2	122.3 (7)
Br1ⁱ—Cu1—Br2	99.90 (4)	N1—C1—H1A	118.8
C8—O2—H2	109.5	C2—C1—H1A	118.8
C3—O1—H1	109.5	O2—C8—C9	118.3 (6)
C10—N2—C6	117.6 (6)	O2—C8—C7	123.1 (6)
C10—N2—Cu1	127.5 (5)	C9—C8—C7	118.6 (6)
C6—N2—Cu1	114.7 (4)	C3—C4—C5	118.6 (6)
C1—N1—C5	118.2 (6)	C3—C4—H4	120.7
C1—N1—Cu1	127.2 (5)	C5—C4—H4	120.7
C5—N1—Cu1	114.5 (4)	C1—C2—C3	119.8 (7)
N2—C6—C7	121.9 (6)	C1—C2—H2A	120.1
N2—C6—C5	114.8 (5)	C3—C2—H2A	120.1
C7—C6—C5	123.3 (6)	N2—C10—C9	124.2 (7)
N1—C5—C4	122.1 (6)	N2—C10—H10	117.9
N1—C5—C6	114.6 (6)	C9—C10—H10	117.9
C4—C5—C6	123.3 (6)

Symmetry code: (i) −x+2, −y+2, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C10—H10···Br1ⁱ	0.93	2.81	3.373 (7)	120
C2—H2A···O1ⁱⁱ	0.93	2.56	3.390 (9)	149
C4—H4···Br1ⁱⁱⁱ	0.93	3.11	3.707 (7)	123
C1—H1A···Br1	0.93	2.73	3.340 (7)	124
C7—H7···Br2ⁱⁱⁱ	0.93	2.94	3.685 (7)	138
O1—H1···Br2^iv	0.82	2.36	3.164 (5)	169
O2—H2···Br2ⁱⁱⁱ	0.82	2.44	3.263 (5)	177

Symmetry codes: (i) −x+2, −y+2, −z+1; (ii) −x+1, y+1/2, −z+3/2; (iii) x, y−1, z; (iv) −x+1, −y+1, −z+1.

Acknowledgements

ARS was supported by NIH/NIGMS R25 GM061347. CA was supported by the Nuclear Regulatory Commission Scholarship grant NRC-HQ-13-G-38-0017 to FIU.

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