trans-Bis[2-(2-bromo­benzamido)-1,3-oxazoline(1−)-κ²N¹,O]copper(II)

In the mononuclear title complex, [Cu(C₁₀H₈BrN₂O₂)₂], the Cu atom, which lies on a centre of symmetry, is in a square-planar geometry defined by a trans-N₂O₂ donor set.

Key indicators

• Single-crystal X-ray study
• T = 291 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.046
• wR factor = 0.105
• Data-to-parameter ratio = 14.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.03
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          7
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  N2      ..       3.37 Ang.

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu          (2)       2.31

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Oxazolines are important structural entities in natural products, can be used as protecting groups for carboxylic acids, and, as well, can be used as building blocks in organic synthesis (Wipf et al., 1992). In addition, oxazolines have been proven to powerful in transition metal-catalyzed organic synthesis (Paintner et al., 2005; Kato et al., 2004). Despite this interest, there are only two relevant structures that have been reported (Zhang et al., 2003; Jiang et al., 2006a,b). In order to extend the work on these complexes, the title mononuclear copper(II) complex, (I), is described herein.

The 2-bromo-N-(4,5-dihydrooxazol-2-yl)benzamide anion serves as a bidentate ligand and ligates the Cu atom through the carbonyl-O2 and oxazoline-N1 atoms. The Cu atom, which lies a centre of inversion, adopts a square planar geometry within a trans-N₂O₂ donor set.

Related literature

For related literature, see: Douglass & Dains (1934); Jiang et al. (2006a, 2006b); Kato et al. (2004); Paintner et al. (2005); Wipf & Miller (1992); Zhang et al. (2003).

S2. Experimental

1-(2-Bromobenzoyl)-3-(2-hydroxyethyl)thiourea was prepared according to literature (Douglass & Dains, 1934). This compound (2 mmol, 0.61 g) was dissolved in acetonitrile (20 ml). Dicyclohexylcarbodiimide (2 mmol, 0.22 g) and pyridine (0.02 mmol, 0.16 g), were added and the mixture was stirred for 12 h. The solvent was removed under reduced pressure. The residue was purified by column chromatography on silica gel to afford desired 2-bromo-N-(4,5-dihydrooxazol-2-yl)benzamide (yield 83%). To an ethanol solution (20 ml) of 2-bromo-N-(4,5-dihydrooxazol-2-yl)benzamide (1 mmol, 0.27 g) was added an ethanol solution (10 ml) of cupric(II) nitrate trihydrate (0.5 mmol, 0.12 g) with stirring. Black block-shaped crystals were formed at the bottom of the vessel upon slow evaporation of the solvent. The crystals were isolated, washed three times with ethanol and dried in a vacuum desiccator (yield 90%). Elemental analysis found: C 40.10, H 2.68, N 9.39%; C₂₀H₁₆Br₂CuN₄O₄ requires: C 40.05, H 2.69.0, N 9.37%.

S3. Refinement

The H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances = 0.93–0.97 Å, and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The structure of the title compound, (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme. Unlabelled atoms are related to labelled atoms by 1 - x, -y, 2 - z.

trans-Bis[2-(2-bromobenzamido)-1,3-oxazoline(1-)-κ²N¹,O]copper(II)

Crystal data

[Cu(C10H8BrN2O2)2]	F(000) = 1180
Mr = 599.73	Dx = 1.955 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 4720 reflections
a = 11.4637 (9) Å	θ = 2.2–27.6°
b = 11.9265 (9) Å	µ = 5.03 mm^−1
c = 14.9016 (12) Å	T = 291 K
V = 2037.4 (3) Å^3	Block, blue
Z = 4	0.27 × 0.20 × 0.16 mm

Data collection

Bruker SMART APEX CCD area-detector diffractometer	2006 independent reflections
Radiation source: sealed tube	1580 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.059
φ and ω scans	θmax = 26.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −14→14
Tmin = 0.31, Tmax = 0.45	k = −12→14
10306 measured reflections	l = −18→13

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.105	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0539P)^2] where P = (Fo^2 + 2Fc^2)/3
2006 reflections	(Δ/σ)max < 0.001
142 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.65 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
Br1	0.55307 (4)	0.37304 (4)	0.91935 (4)	0.04221 (18)
C1	0.6284 (4)	−0.1319 (4)	1.1432 (4)	0.0517 (15)
H1A	0.5970	−0.2010	1.1188	0.062*
H1B	0.5843	−0.1113	1.1962	0.062*
C2	0.7570 (4)	−0.1433 (4)	1.1642 (4)	0.0394 (11)
H2A	0.7695	−0.1511	1.2283	0.047*
H2B	0.7900	−0.2079	1.1340	0.047*
C3	0.7293 (4)	0.0068 (3)	1.0760 (3)	0.0273 (8)
C4	0.7008 (4)	0.1421 (3)	0.9690 (3)	0.0285 (9)
C5	0.7599 (4)	0.2323 (3)	0.9150 (3)	0.0284 (9)
C6	0.7067 (4)	0.3302 (4)	0.8842 (3)	0.0315 (9)
C7	0.7635 (4)	0.4066 (4)	0.8315 (3)	0.0395 (11)
H7	0.7256	0.4713	0.8125	0.047*
C8	0.8791 (5)	0.3862 (5)	0.8064 (4)	0.0469 (13)
H8	0.9185	0.4371	0.7700	0.056*
C9	0.9347 (4)	0.2900 (5)	0.8359 (4)	0.0457 (12)
H9	1.0115	0.2757	0.8195	0.055*
C10	0.8756 (4)	0.2159 (4)	0.8896 (3)	0.0356 (10)
H10	0.9143	0.1521	0.9098	0.043*
Cu	0.5000	0.0000	1.0000	0.0329 (2)
N1	0.6269 (3)	−0.0407 (3)	1.0754 (3)	0.0360 (9)
N2	0.7688 (3)	0.0945 (3)	1.0295 (3)	0.0322 (8)
O1	0.8085 (3)	−0.0406 (3)	1.1313 (2)	0.0365 (7)
O2	0.5968 (3)	0.1175 (2)	0.9485 (2)	0.0373 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0329 (3)	0.0295 (3)	0.0642 (4)	0.00341 (19)	0.0062 (2)	−0.0014 (2)
C1	0.035 (3)	0.048 (3)	0.073 (4)	−0.013 (2)	−0.015 (3)	0.030 (3)
C2	0.037 (3)	0.028 (2)	0.053 (3)	0.0020 (18)	−0.007 (2)	0.008 (2)
C3	0.0254 (19)	0.026 (2)	0.031 (2)	0.0027 (17)	−0.0070 (16)	−0.0004 (17)
C4	0.023 (2)	0.0236 (19)	0.039 (2)	−0.0005 (16)	−0.0003 (18)	0.0049 (16)
C5	0.026 (2)	0.027 (2)	0.033 (2)	−0.0025 (16)	−0.0076 (18)	−0.0024 (16)
C6	0.029 (2)	0.028 (2)	0.037 (2)	−0.0023 (17)	0.0001 (19)	0.0004 (18)
C7	0.037 (2)	0.027 (2)	0.055 (3)	−0.0020 (19)	−0.001 (2)	0.013 (2)
C8	0.037 (3)	0.052 (3)	0.052 (3)	−0.011 (2)	0.010 (2)	0.010 (2)
C9	0.028 (2)	0.057 (3)	0.052 (3)	−0.001 (2)	0.002 (2)	0.012 (3)
C10	0.025 (2)	0.032 (2)	0.050 (3)	−0.0009 (17)	−0.0042 (19)	0.0025 (19)
Cu	0.0224 (3)	0.0276 (4)	0.0486 (5)	−0.0066 (3)	−0.0093 (3)	0.0110 (3)
N1	0.0219 (18)	0.0317 (19)	0.054 (3)	−0.0098 (15)	−0.0098 (16)	0.0111 (18)
N2	0.0247 (18)	0.0276 (17)	0.044 (2)	−0.0064 (15)	−0.0043 (16)	0.0052 (16)
O1	0.0267 (15)	0.0387 (16)	0.0442 (18)	−0.0036 (13)	−0.0134 (14)	0.0090 (14)
O2	0.0254 (16)	0.0268 (16)	0.060 (2)	−0.0065 (12)	−0.0076 (15)	0.0156 (14)

Geometric parameters (Å, º)

Br1—C6	1.907 (4)	C5—C10	1.393 (6)
C1—N1	1.484 (6)	C5—C6	1.395 (6)
C1—C2	1.513 (6)	C6—C7	1.368 (6)
C1—H1A	0.9700	C7—C8	1.399 (7)
C1—H1B	0.9700	C7—H7	0.9300
C2—O1	1.446 (5)	C8—C9	1.385 (8)
C2—H2A	0.9700	C8—H8	0.9300
C2—H2B	0.9700	C9—C10	1.371 (7)
C3—N1	1.304 (6)	C9—H9	0.9300
C3—N2	1.333 (5)	C10—H10	0.9300
C3—O1	1.350 (5)	Cu—N1^i	1.901 (4)
C4—O2	1.265 (5)	Cu—N1	1.901 (4)
C4—N2	1.319 (5)	Cu—O2	1.945 (3)
C4—C5	1.504 (6)	Cu—O2^i	1.945 (3)
N1—C1—C2	102.6 (4)	C6—C7—C8	119.3 (5)
N1—C1—H1A	111.2	C6—C7—H7	120.4
C2—C1—H1A	111.2	C8—C7—H7	120.4
N1—C1—H1B	111.2	C9—C8—C7	119.7 (5)
C2—C1—H1B	111.2	C9—C8—H8	120.2
H1A—C1—H1B	109.2	C7—C8—H8	120.2
O1—C2—C1	104.6 (4)	C10—C9—C8	119.5 (4)
O1—C2—H2A	110.8	C10—C9—H9	120.2
C1—C2—H2A	110.8	C8—C9—H9	120.2
O1—C2—H2B	110.8	C9—C10—C5	122.6 (4)
C1—C2—H2B	110.8	C9—C10—H10	118.7
H2A—C2—H2B	108.9	C5—C10—H10	118.7
N1—C3—N2	130.0 (4)	N1^i—Cu—N1	180.000 (1)
N1—C3—O1	115.3 (4)	N1^i—Cu—O2	91.11 (15)
N2—C3—O1	114.7 (4)	N1—Cu—O2	88.89 (15)
O2—C4—N2	128.4 (4)	N1^i—Cu—O2^i	88.89 (15)
O2—C4—C5	117.4 (4)	N1—Cu—O2^i	91.11 (15)
N2—C4—C5	114.0 (4)	O2—Cu—O2^i	180.00 (12)
C10—C5—C6	116.4 (4)	C3—N1—C1	107.7 (4)
C10—C5—C4	118.3 (4)	C3—N1—Cu	125.5 (3)
C6—C5—C4	125.3 (4)	C1—N1—Cu	126.8 (3)
C7—C6—C5	122.5 (4)	C4—N2—C3	119.5 (4)
C7—C6—Br1	114.7 (3)	C3—O1—C2	106.7 (3)
C5—C6—Br1	122.6 (3)	C4—O2—Cu	127.6 (3)

Symmetry code: (i) −x+1, −y, −z+2.