Dibromido(dimethyl sulfoxide-κO)(1,10-phenanthroline-κ²N,N′)copper(II)

The solvent effect on the mol­ecular structures of copper(II) complexes produced from the reaction between CuBr₂ and 1,10-phenanthroline is evident. The momomeric title compound, [CuBr₂(C₁₂H₈N₂)(C₂H₆OS)], which consists of discrete units, is produced from this reaction in dimethyl sulfoxide (DMSO), whereas a polymeric copper(II) compound is known to be produced from the same reaction in the poor coordinating solvent ethanol. The geometry around the copper(II) ion in the title compound is best described as trigonal–bipyramidal distorted square-based pyramidal, with a τ value of 0.37. The two phenanthroline N atoms, the DMSO O atom and one of the Br atoms occupy the four basal positions, while the second Br atom occupies the axial position. The magnetic susceptibility data also indicate that the title compound is monomeric, but there is still a weak antiferromagnetic inter­action between paramagnetic copper(II) centers via the inter­molecular `Cu—Br...Br—Cu' contact pathway.

S1. Comment

The polymeric [Cu(phen)Br₂]_∞ (phen is 1,10-phenanthroline) is produced when anhydrous CuBr₂ reacts with an equimolar amount of 1,10-phenanthroline in ethanol. This polymer consists of chains linked by Cu—Br bonds, in which the Cu atom displays tetragonally elongated (4 + 2)-coordination (Garland et al., 1988). However, the same reaction proceeded in dimethylsulfoxide (DMSO), a coordinating solvent, produces the monomeric and five-coordinate title Cu^II complex, [Cu(phen)Br₂(DMSO)], (I). In this work, we report the preparation of (I) and the determination of its single-crystal structure. Selected bond distances and angles for (I) are listed in Table 1.

The coordination geometry around the Cu atom is best described as trigonal–bipyramidal distorted square-based pyramidal, with a τ value of 0.37 (Addison et al., 1984; Harrison et al., 1981; Nagle et al., 1990); two N atoms of the 1,10-phenanthroline molecule, one Br atom and one O atom of DMSO occupy the four basal positions, while the other Br atom occupies the axial position. The basal bond distance Cu—Br2 is considerably shorter than the axial bond distance Cu—Br1, but both distances are longer than the terminal Cu—Br distances observed in the polymeric [Cu(phen)Br₂]_∞ compound. The unequal Cu—N bond distances (Table 1) and distortion of the normally symmetric 1,10-phenanthroline ligand in (I) is attributable to the coordination of the large DMSO molecule to the Cu atom. The Cu—O_DMSO (Cu—O15) distance in (I) is similar to those in [Cu(DMSO)₄](ClO₄)₂ [1.934 (6)–1.954 (6) Å; Blake et al., 1996], but is significantly shorter than those in [Cu(C₉H₅N₂O₃)(DMSO)₂] [2.336 (5) or 2.418 (7) Å; Popović et al., 2007] or the Zn—O_DMSO distances in a similar Zn–DMSO complex [2.045 (5) and 2.066 (5) Å; Che et al., 2006]. The intermolecular distance between the two parallel aromatic rings N1/C2–C5/C14 and C5ⁱ–C8ⁱ/C13ⁱ/C14ⁱ [symmetry code: (i) -x + 1, -y + 2, -z] of the coordinated 1,10-phenanthroline ligands in the packing structure [3.4 (s.u. value available?) Å] is much shorter than 4.11 Å, indicating the existence of significant π–π interactions between them (Fig. 2).

Magnetic data of (I) were collected as a function of temperature (2–300 K). Fig. 3 shows a plot of magnetic susceptibility versus temperature. The room-temperature magnetic moment of (I), estimated from u_eff = 2.828(χ_M)^1/2, is 1.9 B·M. [define units] and the Neel temperature T_N is observed at 4.0 K, indicating the presence of a very weak antiferromagnetic interaction between paramagnetic Cu^II centers. The distance between the two nearest Cu atoms in the packing structure is 7.228 (s.u. value?) Å, which is too long for a pair of Cu^II centers to interact magnetically. In view of the magnetic exchange mechanism of the monomeric copper(II)–bromide system, the `bromide–bromide contact' or Cu—Br···Br—Cu contact is known to be an important pathway for antiferromagnetic interaction (Dyrek et al., 1987; Bond et al., 1995). The Br···Br intermolecular contact distance in (I) is 5.180 (s.u.?) Å. This contact distance is considerably longer than the sum of the van der Walls radii of two Br atoms (3.90 Å), but is in the range of the typical Br···Br contact distances (3.90–5.61 Å) observed for many di- and tetrabromocuprate compounds that exhibit the antiferromagnetisn at low temperature (Kang et al., 2004; Van der Bilt et al., 1981). The observed weak antiferromagnetism of the title compound in the crystalline state is most probably due to magnetic exchange via the `Cu—Br···Br—Cu contact' pathway.

Related literature

For related literature, see: Addison et al. (1984); Blake et al. (1996); Bond et al. (1995); Che et al. (2006); Garland et al. (1988); Harrison et al. (1981); Kang et al. (2004); Nagle et al. (1990); Popović et al. (2007); Van der Bilt, Joung, Carlin & De Jongh (1981).

S2. Experimental

Dibromo(1,10-phenanthroline)copper(II), [Cu(phen)Br₂], was prepared according to the methods described by Garland et al. (1988). The chocolate-colored precipitates (0.5 mmol) were dissolved in DMSO. Green single crystals were obtained by slow evaporation in DMSO solution for 3 d. Analysis calculated for C₁₄H₁₄Br₂CuN₂OS: C 34.91, H 2.93, N 5.82%; found C 34.79, H 2.61, N 5.81%.

S3. Refinement

H atoms were positioned geometrically and constrained to ride on their attached atoms. Their U_iso(H) values were fixed at 1.2 or 1.5 times U_eq of their parent atoms.

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); 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

	Fig. 1. An ORTEP-3 (Farrugia, 1997) diagram of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids.
	Fig. 2. π–π stacking interaction between two 1,10-phenanthroline ligands of (I). Views parallel (a) and perpendicular (b) to the π–π stacking interaction are shown. [a = N1···C7^i = 3.411 (7) Å, b = C3···C9^i = 3.414 (8) Å and c = C5···C13^i = 3.466 (7) Å; symmetry code: (i) -x + 1, -y + 2, -z)].
	Fig. 3. A plot of magnetic susceptibilities versus temperature in the temperature region 2–300 K for (I).

Dibromido(dimethyl sulfoxide-κO)(1,10-phenanthroline-κ²N,N')copper(II)

Crystal data

[CuBr2(C12H8N2)(C2H6OS)]	F(000) = 940
Mr = 481.69	Dx = 1.947 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2276 reflections
a = 8.3984 (2) Å	θ = 2.9–23.4°
b = 14.0857 (3) Å	µ = 6.32 mm^−1
c = 14.5004 (3) Å	T = 295 K
β = 106.667 (2)°	Block, green
V = 1643.29 (6) Å^3	0.15 × 0.09 × 0.06 mm
Z = 4

Data collection

Bruker SMART CCD area-detector diffractometer	3778 independent reflections
Radiation source: fine-focus sealed tube	2381 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.074
ϕ and ω scans	θmax = 27.5°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −10→10
Tmin = 0.511, Tmax = 0.685	k = −18→18
22691 measured reflections	l = −18→18

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.127	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0607P)^2 + 0.0896P] where P = (Fo^2 + 2Fc^2)/3
3778 reflections	(Δ/σ)max = 0.001
190 parameters	Δρmax = 0.53 e Å^−3
0 restraints	Δρmin = −0.48 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cu	0.78965 (8)	0.93879 (4)	0.23195 (4)	0.04082 (19)
Br1	1.02804 (7)	0.81705 (4)	0.28156 (4)	0.0614 (2)
Br2	0.63347 (8)	0.93850 (5)	0.35260 (4)	0.0573 (2)
N1	0.7946 (5)	0.9958 (3)	0.1011 (3)	0.0397 (10)
C2	0.8745 (7)	1.0708 (4)	0.0821 (4)	0.0492 (13)
H2	0.9389	1.1069	0.1329	0.059*
C3	0.8648 (8)	1.0976 (4)	−0.0131 (5)	0.0613 (17)
H3	0.9232	1.1504	−0.0240	0.074*
C4	0.7693 (8)	1.0461 (5)	−0.0900 (5)	0.0607 (17)
H4	0.7642	1.0630	−0.1528	0.073*
C5	0.6809 (7)	0.9685 (4)	−0.0720 (4)	0.0497 (14)
C6	0.5693 (8)	0.9093 (5)	−0.1449 (4)	0.0589 (17)
H6	0.5557	0.9227	−0.2096	0.071*
C7	0.4857 (8)	0.8363 (5)	−0.1220 (4)	0.0580 (16)
H7	0.4135	0.8017	−0.1711	0.070*
C8	0.5045 (6)	0.8101 (4)	−0.0240 (4)	0.0466 (13)
C9	0.4236 (7)	0.7341 (4)	0.0054 (4)	0.0546 (15)
H9	0.3530	0.6953	−0.0404	0.066*
C10	0.4476 (7)	0.7169 (4)	0.0995 (4)	0.0543 (14)
H10	0.3951	0.6660	0.1193	0.065*
C11	0.5528 (7)	0.7766 (4)	0.1674 (4)	0.0512 (14)
H11	0.5676	0.7646	0.2324	0.061*
N12	0.6320 (5)	0.8493 (3)	0.1435 (3)	0.0389 (9)
C13	0.6098 (6)	0.8655 (4)	0.0488 (3)	0.0387 (11)
C14	0.6983 (6)	0.9451 (4)	0.0248 (3)	0.0384 (11)
O15	0.9210 (5)	1.0472 (3)	0.2908 (3)	0.0587 (11)
S16	1.04181 (17)	1.04119 (10)	0.39217 (9)	0.0432 (3)
C17	1.2383 (9)	1.0542 (5)	0.3729 (5)	0.082 (2)
H17A	1.2663	0.9969	0.3452	0.122*
H17B	1.3202	1.0663	0.4332	0.122*
H17C	1.2354	1.1063	0.3298	0.122*
C18	1.0206 (9)	1.1531 (4)	0.4417 (4)	0.0690 (18)
H18A	0.9162	1.1560	0.4563	0.103*
H18B	1.0243	1.2019	0.3961	0.103*
H18C	1.1097	1.1623	0.4996	0.103*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0456 (4)	0.0384 (4)	0.0355 (3)	−0.0042 (3)	0.0069 (3)	0.0016 (3)
Br1	0.0580 (4)	0.0518 (4)	0.0641 (4)	0.0151 (3)	0.0012 (3)	−0.0045 (3)
Br2	0.0572 (4)	0.0750 (5)	0.0423 (3)	0.0086 (3)	0.0184 (3)	0.0036 (3)
N1	0.041 (2)	0.037 (2)	0.044 (2)	0.0076 (19)	0.0168 (19)	0.0066 (19)
C2	0.045 (3)	0.041 (3)	0.065 (3)	0.008 (3)	0.021 (3)	0.012 (3)
C3	0.065 (4)	0.049 (4)	0.083 (4)	0.019 (3)	0.043 (4)	0.027 (3)
C4	0.073 (4)	0.065 (4)	0.057 (4)	0.029 (3)	0.039 (3)	0.021 (3)
C5	0.053 (3)	0.059 (4)	0.044 (3)	0.027 (3)	0.024 (3)	0.015 (3)
C6	0.064 (4)	0.082 (5)	0.029 (3)	0.027 (4)	0.010 (3)	0.002 (3)
C7	0.056 (4)	0.074 (5)	0.039 (3)	0.017 (3)	0.007 (3)	−0.015 (3)
C8	0.040 (3)	0.058 (4)	0.040 (3)	0.017 (3)	0.007 (2)	−0.008 (2)
C9	0.045 (3)	0.049 (4)	0.064 (4)	0.003 (3)	0.005 (3)	−0.014 (3)
C10	0.051 (3)	0.043 (3)	0.063 (4)	−0.001 (3)	0.006 (3)	0.000 (3)
C11	0.055 (3)	0.050 (3)	0.044 (3)	−0.001 (3)	0.007 (2)	0.010 (3)
N12	0.044 (2)	0.036 (2)	0.035 (2)	0.0004 (19)	0.0083 (18)	0.0042 (18)
C13	0.038 (3)	0.043 (3)	0.034 (2)	0.013 (2)	0.007 (2)	0.005 (2)
C14	0.036 (3)	0.044 (3)	0.038 (2)	0.017 (2)	0.015 (2)	0.004 (2)
O15	0.072 (3)	0.044 (2)	0.048 (2)	−0.017 (2)	−0.0035 (19)	0.0030 (17)
S16	0.0482 (8)	0.0414 (8)	0.0399 (6)	−0.0051 (6)	0.0124 (5)	0.0001 (5)
C17	0.066 (4)	0.117 (7)	0.068 (4)	−0.024 (4)	0.028 (4)	−0.019 (4)
C18	0.090 (5)	0.053 (4)	0.056 (4)	0.015 (3)	0.010 (3)	−0.003 (3)

Geometric parameters (Å, º)

Cu—N1	2.071 (4)	C8—C9	1.398 (8)
Cu—N12	2.003 (4)	C8—C13	1.403 (7)
Cu—Br1	2.5769 (8)	C9—C10	1.343 (8)
Cu—Br2	2.4692 (8)	C9—H9	0.9300
Cu—O15	1.933 (4)	C10—C11	1.400 (7)
N1—C2	1.322 (6)	C10—H10	0.9300
N1—C14	1.370 (6)	C11—N12	1.320 (6)
C2—C3	1.411 (8)	C11—H11	0.9300
C2—H2	0.9300	N12—C13	1.351 (6)
C3—C4	1.379 (9)	C13—C14	1.442 (7)
C3—H3	0.9300	O15—S16	1.531 (4)
C4—C5	1.388 (8)	S16—C17	1.760 (7)
C4—H4	0.9300	S16—C18	1.762 (6)
C5—C14	1.408 (7)	C17—H17A	0.9600
C5—C6	1.457 (8)	C17—H17B	0.9600
C6—C7	1.339 (9)	C17—H17C	0.9600
C6—H6	0.9300	C18—H18A	0.9600
C7—C8	1.433 (8)	C18—H18B	0.9600
C7—H7	0.9300	C18—H18C	0.9600
N1—Cu—N12	80.84 (16)	C10—C9—C8	120.2 (5)
N1—Cu—Br1	107.20 (11)	C10—C9—H9	119.9
N1—Cu—Br2	143.48 (11)	C8—C9—H9	119.9
N1—Cu—O15	86.51 (17)	C9—C10—C11	119.1 (6)
N12—Cu—Br1	94.47 (12)	C9—C10—H10	120.4
N12—Cu—Br2	93.71 (12)	C11—C10—H10	120.4
N12—Cu—O15	165.55 (16)	N12—C11—C10	123.1 (5)
Br1—Cu—O15	95.93 (13)	N12—C11—H11	118.5
Br2—Cu—O15	92.31 (13)	C10—C11—H11	118.5
Br2—Cu—Br1	109.22 (3)	C11—N12—C13	117.7 (4)
C2—N1—C14	117.7 (4)	C11—N12—Cu	127.6 (3)
C2—N1—Cu	130.2 (4)	C13—N12—Cu	114.7 (3)
C14—N1—Cu	112.0 (3)	N12—C13—C8	122.9 (5)
N1—C2—C3	121.9 (6)	N12—C13—C14	116.5 (4)
N1—C2—H2	119.1	C8—C13—C14	120.6 (4)
C3—C2—H2	119.1	N1—C14—C5	123.5 (5)
C4—C3—C2	120.5 (6)	N1—C14—C13	115.9 (4)
C4—C3—H3	119.7	C5—C14—C13	120.6 (5)
C2—C3—H3	119.7	S16—O15—Cu	121.2 (2)
C3—C4—C5	118.7 (5)	O15—S16—C17	103.6 (3)
C3—C4—H4	120.7	O15—S16—C18	103.0 (3)
C5—C4—H4	120.7	C17—S16—C18	100.4 (3)
C4—C5—C14	117.7 (6)	S16—C17—H17A	109.5
C4—C5—C6	125.5 (5)	S16—C17—H17B	109.5
C14—C5—C6	116.8 (5)	H17A—C17—H17B	109.5
C7—C6—C5	122.2 (5)	S16—C17—H17C	109.5
C7—C6—H6	118.9	H17A—C17—H17C	109.5
C5—C6—H6	118.9	H17B—C17—H17C	109.5
C6—C7—C8	121.9 (5)	S16—C18—H18A	109.5
C6—C7—H7	119.1	S16—C18—H18B	109.5
C8—C7—H7	119.1	H18A—C18—H18B	109.5
C9—C8—C13	117.0 (5)	S16—C18—H18C	109.5
C9—C8—C7	125.1 (5)	H18A—C18—H18C	109.5
C13—C8—C7	117.9 (5)	H18B—C18—H18C	109.5
O15—Cu—N1—C2	5.2 (4)	N1—Cu—N12—C13	1.8 (3)
N12—Cu—N1—C2	178.2 (5)	Br2—Cu—N12—C13	145.5 (3)
Br2—Cu—N1—C2	94.4 (5)	Br1—Cu—N12—C13	−104.9 (3)
Br1—Cu—N1—C2	−89.9 (4)	C11—N12—C13—C8	1.5 (7)
O15—Cu—N1—C14	−175.0 (3)	Cu—N12—C13—C8	179.9 (4)
N12—Cu—N1—C14	−2.0 (3)	C11—N12—C13—C14	−179.8 (4)
Br2—Cu—N1—C14	−85.8 (3)	Cu—N12—C13—C14	−1.4 (5)
Br1—Cu—N1—C14	89.9 (3)	C9—C8—C13—N12	−1.5 (7)
C14—N1—C2—C3	−1.1 (7)	C7—C8—C13—N12	177.5 (5)
Cu—N1—C2—C3	178.6 (4)	C9—C8—C13—C14	179.8 (4)
N1—C2—C3—C4	0.5 (9)	C7—C8—C13—C14	−1.1 (7)
C2—C3—C4—C5	1.1 (9)	C2—N1—C14—C5	0.2 (7)
C3—C4—C5—C14	−1.9 (8)	Cu—N1—C14—C5	−179.6 (4)
C3—C4—C5—C6	177.3 (5)	C2—N1—C14—C13	−178.4 (4)
C4—C5—C6—C7	−178.8 (5)	Cu—N1—C14—C13	1.8 (5)
C14—C5—C6—C7	0.4 (8)	C4—C5—C14—N1	1.4 (7)
C5—C6—C7—C8	−1.8 (9)	C6—C5—C14—N1	−177.9 (4)
C6—C7—C8—C9	−178.9 (6)	C4—C5—C14—C13	179.8 (4)
C6—C7—C8—C13	2.1 (8)	C6—C5—C14—C13	0.5 (7)
C13—C8—C9—C10	0.3 (8)	N12—C13—C14—N1	−0.3 (6)
C7—C8—C9—C10	−178.6 (5)	C8—C13—C14—N1	178.4 (4)
C8—C9—C10—C11	0.7 (9)	N12—C13—C14—C5	−178.9 (4)
C9—C10—C11—N12	−0.7 (9)	C8—C13—C14—C5	−0.2 (7)
C10—C11—N12—C13	−0.4 (8)	N12—Cu—O15—S16	179.6 (6)
C10—C11—N12—Cu	−178.5 (4)	N1—Cu—O15—S16	−151.5 (3)
O15—Cu—N12—C11	−150.8 (7)	Br2—Cu—O15—S16	65.0 (3)
N1—Cu—N12—C11	180.0 (5)	Br1—Cu—O15—S16	−44.6 (3)
Br2—Cu—N12—C11	−36.4 (4)	Cu—O15—S16—C17	113.5 (4)
Br1—Cu—N12—C11	73.3 (4)	Cu—O15—S16—C18	−142.2 (3)
O15—Cu—N12—C13	31.1 (9)