Three complexes of bis(N-methyl­benzo­hydro­xamato-O,O′)copper(II)

The first single-crystal studies of three bis-transoid Cu–hydrox­amate salts, bis(3-methoxy-4,N-dimethyl­benzo­hydrox­amato-O,O′)copper(II), [Cu(C₁₀H₁₂NO₃)₂], bis(4-chloro-N-methyl­benzo­hydro­xamato-O,O′)copper(II), [Cu­(C₈­H₇­Cl­NO₂)₂], bis(N-methyl-3,5-di­nitro­benzo­hydro­xamato-O,O′)copper(II)–chloro­form (1/2), [Cu­(C₈­H₆­N₃O₆)₂]·­2CHCl₃, are presented. The Cu atom in each of the title compounds sits at a center of inversion and displays a nearly square-planar geometry with the hydro­xamate-O atoms connected to it in a syn configuration. The N atoms are in a transoid configuration. Each five-membered Cu–hydro­xamate ring is planar, thus providing evidence that a planar N atom is present in each ring. The phenyl groups are twisted with respect to the hydro­xamate group by ∼40–54°. The angular strain of the sp² carbonyl oxy­gen is significant (∼10° from ideal).

S1. Comment

Copper complexes containing derivatives of the N-methylbenzohydroxamate ligand have been prepared for the study of the organic ligand as an α nucleophile. [See, for example, Carey & Sundberg (1990) for a discussion on the α effect.] Unlike the only other previous single crystallographic studies involving Cu hydroxamates [a dimer by Barclay & Raymond (1986) and metallocrown compounds by Stemmler et al. (1999)], we are interested in how the presence of a transition metal will affect the role of the α nucleophile in substitution reactions. Crystal-structure determinations were performed to determine the bonding mode of the organic ligands to the copper center, as well as to serve as a starting point for future molecular modeling studies.

All three of the title compounds have a Cu at a center of inversion so the hydroxamate N atoms are in the transoid configuration, thus making this the first report of bis, transoid Cu hydroxamate structures. The five-membered Cu—O1—N1—C2—O2 groups are planar for (I), (II), and (III) (r.m.s. deviations = 0.010, 0.005, 0.005 Å, respectively). The r.m.s. deviations of C1 and C3 in (I), (II), and (III) are, respectively, 0.062 & 0.030, 0.114 and 0.023, and 0.112 and 0.038 Å. Thus each N1 is essentially planar. The O atoms assume a syn configuration yielding O1—Cu—O2 and supplementary angles of ~84° and ~96° (Table 1), respectively, thus making a nearly square-planar geometry about the Cu.

While most of the selected distances and angles noted in Table 1 are comparable, some significant (> 4σ) ones are noteworthy. In 3 the Cu—O1 distance is longer than in complexes (I) or (II), while the Cu—O2 distance is concomitantly shorter than its counterparts. Similarly, in 1, the O1—N1—C1 angle is smaller than for 2 or 3; C1—N1—C2, larger.

For the most part, the Cu—O1 distances in the three title complexes are shorter than in a few other five-membered, though not hydroxamate, rings. Singly-bonded Cu—O distances of 1.902 (2) & 1.892 (2) Å [with cupferron, Elerman et al., 1995]; 2.011 (2) and 2.013 (2) Å [with 2-amino-2-thiazoline- 4-carboxylic acid, Stocker et al., 1999]; 1.936 (3) and 1.959 (3), and 1.935 (5) and 1.967 (4) Å [with picolinamide hydrazone:alanine and picolinamide hydrazone:glycine, respectively; Thompson et al., 1998] have been reported.

Stemmler et al. (1999) reported an average oxime O—Cu distance for the five metallocrown complexes in their study as 1.934 (6) Å, a difference of ~ 6σ above this work. The average carbonyl O—Cu distance of 1.947 (6) Å is just slightly >3σ above those in this report. In each of their structures, the oxime O atoms have a third coordination to a lanthanide facilitating a bridging of Cu atoms to the Ln. The hydroxamate N atoms are also coordinated to a Cu aiding in the formation of the metallocrown complexes. They also reported an average value for the O1—Cu—O2 (present notation) of 85.8 (2)°, a difference of >7σ from this work. Barclay & Raymond (1986) reported a single dimeric complex in which the N atoms are cisoid, all of which is different from that in this work. Their distances for oxime O—Cu [1.885 (4) Å] and carbonyl O—Cu [1.915 (4) Å] are both <2σ of the present work. Additionally, their average O1—Cu—O2 angle of 84.2 (2)° is <1σ from this work. The stronger similarity of Barclay & Raymond's (1986) complex to the (III) reported here is likely due to the hydroxamate groups being less constrained in all four complexes than in the work of Stemmler et al. (1999).

Though angles about O1 and O2 in this work are all ~110°, Cu—O2—C2 is significantly (> 7σ) larger than Cu—O1—N1 (cf. Table 1). Additionally, the deviation of these angles from that anticipated from the hybridization at each oxygen would indicate more strain at O2. Consistent with this is the average C2═O2 distance of 1.281 (4) Å which is significantly longer than the 1.20 (2) to 1.25 (1) Å for three free hydroxamic acids (Baughman, 1982) and the average of 1.23 (1) Å cited in the International Tables for Crystallography, thus confirming a concomitant weakening of the C2═O2 bond as O2 donates electron density to the Cu. Similar comparisons of the N1—O1 distances in (I)-(III) would best be done with the `free' hydroxamate anion. These studies are currently in progress and will be reported in a future paper.

For (I) the methoxy group is coplanar with the phenyl ring as the dihedral angle is 2.2 (2)°. However, the phenyl rings for (I), (II) and (III) are not coplanar with the hydroxamate group (Table 1), thus reducing delocalization throughout all three systems. The reason for the twisting of the phenyls to comparable dihedral angles (Table 1) is primarily due to to the steric interference of the H on C8 with the C1 methyl group (Table 2). No close (~van der Waals) intermolecular contact with the phenyl is noted for (I); a few are noted for (II) and (III) (Table 2), perhaps explaining why the dihedral angles for (II) and (III) are larger than for (I).

In (III) a molecule of CHCl₃ is hydrogen bonded to O1 (H···O1 = 2.34 Å; C9···O1 = 3.18 Å; N1—O1···H9 = 107°; C9—H9···O1 = 146°). Both nitro groups (O5,N3,O6 and O3,N2,O4) are slightly twisted with respect to the phenyls as the dihedral angles are 9.6 (6) and 19.7 (4)°, respectively, likely due to numerous close contacts noted in Table 2.

S2. Experimental

1. In a method similar to that of Bhattacharyya & Dhar (1982), Cu(NO₃)₂·3H₂O (0.5 mmol) in H₂O (30 ml) was added to 3-methoxy-4-methyl-N-methylbenzohydroxamic acid (1.1 mmol) in EtOH (20 ml). To this mixture NaOH (1 mL of 1M) was added dropwise with stirring. The precipitate that quickly formed was filtered, washed and recrystallized (slow evaporation, ~1 week) from a minimal amount of CHCl₃ and ten drops of benzene.

2. Cu(NO₃)₂·3H₂O (0.5 mmol) in H₂O (30 ml) was added to sodium 4-chloro-N-methylbenzohydroxamate (1.1 mmol) in EtOH (30 ml) with constant stirring. This quickly produced a precipitate which was filtered, washed and recrystallized (slow evaporation, ~1 week) from a minimal amount of CHCl₃.

3. Cu(NO₃)₂·3H₂O (0.5 mmol) in H₂O (25 ml) was combined with sodium 3,5-dinitro-N-methylbenzohydroxamate (1.1 mmol) in EtOH (40 ml) with constant stirring. The quickly appearing resultant yellow powder was recrystallized from a minimal amount of CHCl₃ yielding green crystals in ~3 d.

S3. Refinement

For (III); C—H 0.96 Å; H1A, H1B, and H1C were first selected by SHELXL93. When difference peaks ~exactly between these H's were noted, 3 additional H's were added. All 6 were assigned a multiplicity of 0.5 and were placed into ideal positions. The presence of peaks in the difference map indicated disordered chlorines in the CHCl₃ librating approximately about the C9—H9 bond. Six chlorines, each with a multiplicity of 1/2, were refined without any constraints. As the data reduction program (XDISK, Siemens, 1991b) gave a lower figure of merit for the space group Pc, an alternate refinement in Pc was performed, though the test for the presence of an inversion center indicated a centrosymmetric space group. The refinement in Pc led to many elongated displacement ellipsoids and a higher R₁ than the P2₁/c which was used.

Computing details

For all compounds, data collection: P3/P4-PC Diffractometer Program (Siemens, 1991a); cell refinement: P3/P4-PC Diffractometer Program; data reduction: XDISK (Siemens, 1991b); program(s) used to solve structure: SHELXS86 (Sheldrick, 1990a); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: SHELXTL/PC (Sheldrick, 1990b); software used to prepare material for publication: SHELXTL/PC and SHELXL93.

Figures

Fig. 1. View of (I) showing the labeling of the non-H atoms. Displacement ellipsoids are shown at 50% probability levels. Fig. 2. View of (II) showing the labeling of the non-H atoms. Displacement ellipsoids are shown at 50% probability levels. Fig. 3. View of (III) (prior to refinement of disordered Cl atoms) showing the labeling of the non-H atoms. Displacement ellipsoids are shown at 50% probability levels; H9 is drawn as a small sphere of arbitrary radius.

(I) 'Bis(3-methoxy-4-methyl-N-methylbenzohydroxamato-O,O') copper(II)'

Crystal data

[Cu(C10H12NO3)2]	F(000) = 470
Mr = 451.95	Dx = 1.518 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 7.532 (2) Å	Cell parameters from 50 reflections
b = 9.073 (3) Å	θ = 5.5–21.9°
c = 14.654 (4) Å	µ = 1.15 mm^−1
β = 99.07 (2)°	T = 288 K
V = 988.9 (5) Å^3	Near octahedron, dark green
Z = 2	0.50 × 0.34 × 0.28 mm

Data collection

Siemens/Bruker P3 diffractometer	1384 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.023
Graphite monochromator	θmax = 25.0°, θmin = 2.7°
θ/2θ scans	h = −2→8
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b)	k = −2→10
Tmin = 0.588, Tmax = 0.726	l = −17→17
3051 measured reflections	3 standard reflections every 50 reflections
1735 independent reflections	intensity decay: ave. of 0.65% in σ(I)s

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)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.087	H-atom parameters constrained
S = 1.06	Calculated w = 1/[σ^2(Fo^2) + (0.0488P)^2 + 0.6217P] where P = (Fo^2 + 2Fc^2)/3
1729 reflections	(Δ/σ)max < 0.001
133 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

Special details

Experimental. Absorption correction: empirical: '8 ψ scans, 10° steps; (Siemens, 1991b)

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 on F² for ALL reflections except for 6 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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	0.0000	0.5000	0.5000	0.0328 (2)
O1	−0.0508 (3)	0.3259 (2)	0.56077 (12)	0.0398 (5)
O2	0.0714 (3)	0.5752 (2)	0.62391 (12)	0.0365 (5)
O3	0.0818 (3)	0.8279 (2)	0.93774 (13)	0.0476 (6)
N1	−0.0082 (3)	0.3465 (3)	0.65503 (15)	0.0327 (5)
C1	−0.0504 (4)	0.2178 (3)	0.7059 (2)	0.0415 (7)
H1A	−0.0191	0.2360	0.7710	0.080*
H1B	−0.1767	0.1972	0.6914	0.080*
H1C	0.0166	0.1348	0.6891	0.080*
C2	0.0563 (4)	0.4749 (3)	0.6839 (2)	0.0286 (6)
C3	0.1084 (3)	0.5100 (3)	0.7835 (2)	0.0281 (6)
C4	0.0664 (4)	0.6505 (3)	0.8121 (2)	0.0302 (6)
H4A	0.0036	0.7185	0.7683	0.080*
C5	0.1151 (4)	0.6922 (3)	0.9038 (2)	0.0319 (6)
C6	0.2068 (4)	0.5944 (3)	0.9687 (2)	0.0324 (6)
C7	0.2504 (4)	0.4572 (3)	0.9385 (2)	0.0355 (7)
H7A	0.3146	0.3894	0.9820	0.080*
C8	0.2037 (4)	0.4141 (3)	0.8467 (2)	0.0332 (6)
H8A	0.2374	0.3185	0.8272	0.080*
C9	−0.0061 (5)	0.9355 (4)	0.8769 (2)	0.0484 (8)
H9A	−0.0199	1.0244	0.9106	0.080*
H9B	0.0643	0.9556	0.8291	0.080*
H9C	−0.1224	0.8997	0.8496	0.080*
C10	0.2551 (5)	0.6395 (4)	1.0686 (2)	0.0444 (8)
H10D	0.3171	0.5600	1.1033	0.080*
H10A	0.3315	0.7247	1.0730	0.080*
H10B	0.1474	0.6623	1.0931	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0480 (3)	0.0274 (3)	0.0217 (2)	−0.0025 (2)	0.0010 (2)	−0.0024 (2)
O1	0.0627 (14)	0.0320 (11)	0.0223 (9)	−0.0081 (10)	−0.0003 (9)	−0.0051 (8)
O2	0.0576 (13)	0.0264 (11)	0.0238 (9)	−0.0041 (9)	0.0008 (9)	−0.0007 (8)
O3	0.080 (2)	0.0318 (11)	0.0294 (10)	0.0144 (11)	0.0031 (10)	−0.0048 (9)
N1	0.0444 (14)	0.0296 (12)	0.0234 (11)	−0.0032 (11)	0.0035 (10)	−0.0002 (9)
C1	0.057 (2)	0.032 (2)	0.036 (2)	−0.0078 (14)	0.0092 (14)	0.0029 (13)
C2	0.0329 (14)	0.0267 (15)	0.0259 (13)	0.0016 (12)	0.0032 (11)	−0.0009 (11)
C3	0.0319 (13)	0.0289 (13)	0.0234 (12)	−0.0017 (12)	0.0041 (10)	−0.0008 (11)
C4	0.038 (2)	0.0277 (14)	0.0247 (13)	0.0038 (12)	0.0040 (11)	0.0033 (11)
C5	0.043 (2)	0.0263 (14)	0.0264 (13)	0.0020 (12)	0.0065 (12)	−0.0020 (11)
C6	0.039 (2)	0.035 (2)	0.0221 (13)	−0.0038 (13)	0.0024 (11)	0.0018 (12)
C7	0.043 (2)	0.034 (2)	0.0282 (14)	0.0033 (13)	0.0013 (13)	0.0065 (11)
C8	0.041 (2)	0.0249 (14)	0.0326 (14)	0.0052 (12)	0.0026 (12)	−0.0002 (12)
C9	0.063 (2)	0.033 (2)	0.048 (2)	0.012 (2)	0.005 (2)	−0.0021 (15)
C10	0.063 (2)	0.044 (2)	0.0241 (14)	−0.004 (2)	0.0002 (14)	0.0006 (13)

Geometric parameters (Å, º)

Cu—O1	1.882 (2)	N1—C1	1.447 (4)
Cu—O1^i	1.882 (2)	C2—C3	1.485 (4)
Cu—O2^i	1.935 (2)	C3—C8	1.385 (4)
Cu—O2	1.935 (2)	C3—C4	1.393 (4)
O1—N1	1.381 (3)	C4—C5	1.388 (4)
O2—C2	1.283 (3)	C5—C6	1.401 (4)
O3—C5	1.366 (3)	C6—C7	1.378 (4)
O3—C9	1.414 (4)	C6—C10	1.508 (4)
N1—C2	1.307 (3)	C7—C8	1.392 (4)
O1—Cu—O1^i	180.0	N1—C2—C3	122.4 (2)
O1—Cu—O2^i	95.79 (8)	C8—C3—C4	119.5 (2)
O1^i—Cu—O2^i	84.21 (8)	C8—C3—C2	123.4 (2)
O1—Cu—O2	84.21 (8)	C4—C3—C2	117.0 (2)
O1^i—Cu—O2	95.79 (8)	C5—C4—C3	120.2 (2)
O2^i—Cu—O2	180.0	O3—C5—C4	124.3 (2)
N1—O1—Cu	109.1 (2)	O3—C5—C6	115.0 (2)
C2—O2—Cu	110.6 (2)	C4—C5—C6	120.7 (2)
C5—O3—C9	119.1 (2)	C7—C6—C5	118.1 (2)
C2—N1—O1	117.4 (2)	C7—C6—C10	121.5 (3)
C2—N1—C1	130.8 (2)	C5—C6—C10	120.3 (3)
O1—N1—C1	111.8 (2)	C6—C7—C8	121.8 (2)
O2—C2—N1	118.6 (2)	C3—C8—C7	119.6 (2)
O2—C2—C3	118.9 (2)

Symmetry code: (i) −x, −y+1, −z+1.

(II) 'Bis(4-chloro-N-methylbenzohydroxamato-O,O') copper(II)'

Crystal data

[Cu(C8H7ClNO2)2]	F(000) = 438
Mr = 432.74	Dx = 1.689 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.5953 (9) Å	Cell parameters from 50 reflections
b = 19.503 (2) Å	θ = 7.2–23.6°
c = 7.387 (1) Å	µ = 1.62 mm^−1
β = 116.454 (9)°	T = 288 K
V = 850.7 (2) Å^3	Prism, dark green
Z = 2	0.43 × 0.38 × 0.33 mm

Data collection

Siemens/Bruker P3 diffractometer	1269 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.013
Graphite monochromator	θmax = 25.0°, θmin = 2.1°
θ/2θ scans	h = 0→7
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b)	k = 0→23
Tmin = 0.527, Tmax = 0.586	l = −8→7
1616 measured reflections	3 standard reflections every 50 reflections
1487 independent reflections	intensity decay: ave. of 0.92% in σ(I)s

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H-atom parameters constrained
S = 1.10	Calculated w = 1/[σ^2(Fo^2) + (0.0378P)^2 + 0.5359P] where P = (Fo^2 + 2Fc^2)/3
1478 reflections	(Δ/σ)max < 0.001
115 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.25 e Å^−3

Special details

Experimental. Absorption correction: empirical: '8 ψ scans, 10° steps; (Siemens, 1991b)

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 on F² for ALL reflections except for 9 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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	0.0000	0.0000	0.5000	0.0314 (2)
Cl	0.7297 (2)	0.36082 (4)	0.49705 (13)	0.0543 (2)
O1	0.3087 (3)	−0.01377 (9)	0.6787 (3)	0.0385 (5)
O2	0.0990 (3)	0.08963 (9)	0.4608 (3)	0.0378 (5)
N1	0.4280 (4)	0.04429 (11)	0.6805 (4)	0.0333 (5)
C1	0.6642 (5)	0.0409 (2)	0.8256 (5)	0.0454 (8)
H1A	0.7388	0.0826	0.8204	0.080*
H1B	0.6758	0.0351	0.9589	0.080*
H1C	0.7347	0.0028	0.7938	0.080*
C2	0.3131 (4)	0.09554 (13)	0.5658 (4)	0.0306 (6)
C3	0.4271 (4)	0.16039 (13)	0.5560 (4)	0.0298 (6)
C4	0.3423 (5)	0.22191 (13)	0.5893 (4)	0.0332 (6)
H4A	0.2166	0.22153	0.6218	0.080*
C5	0.4382 (5)	0.28373 (14)	0.5757 (4)	0.0361 (6)
H5A	0.3831	0.32620	0.6026	0.080*
C6	0.6143 (5)	0.28318 (14)	0.5231 (4)	0.0345 (6)
C7	0.7003 (5)	0.22280 (15)	0.4881 (4)	0.0373 (7)
H7A	0.8238	0.22355	0.4528	0.080*
C8	0.6061 (5)	0.16117 (14)	0.5051 (4)	0.0351 (6)
H8A	0.6646	0.11881	0.4814	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0332 (3)	0.0219 (2)	0.0404 (3)	−0.0048 (2)	0.0175 (2)	−0.0015 (2)
Cl	0.0689 (5)	0.0346 (4)	0.0607 (5)	−0.0198 (4)	0.0299 (4)	0.0028 (4)
O1	0.0384 (11)	0.0223 (10)	0.0519 (12)	−0.0050 (8)	0.0173 (9)	0.0056 (8)
O2	0.0319 (10)	0.0274 (10)	0.0497 (12)	−0.0029 (8)	0.0142 (9)	0.0050 (9)
N1	0.0341 (12)	0.0234 (11)	0.0430 (13)	−0.0047 (10)	0.0178 (10)	0.0002 (10)
C1	0.035 (2)	0.037 (2)	0.051 (2)	−0.0035 (13)	0.0081 (14)	0.0059 (14)
C2	0.0354 (15)	0.0224 (13)	0.0355 (15)	−0.0033 (11)	0.0171 (12)	−0.0031 (11)
C3	0.0304 (14)	0.0232 (13)	0.0324 (14)	−0.0019 (10)	0.0109 (12)	0.0017 (11)
C4	0.0331 (15)	0.0283 (14)	0.040 (2)	−0.0006 (11)	0.0178 (12)	−0.0012 (12)
C5	0.047 (2)	0.0234 (13)	0.038 (2)	−0.0004 (12)	0.0195 (13)	−0.0011 (12)
C6	0.038 (2)	0.0267 (14)	0.0318 (14)	−0.0107 (12)	0.0097 (12)	0.0028 (11)
C7	0.0327 (15)	0.038 (2)	0.043 (2)	−0.0011 (12)	0.0192 (13)	0.0068 (13)
C8	0.035 (2)	0.0288 (14)	0.043 (2)	0.0027 (12)	0.0188 (13)	0.0010 (12)

Geometric parameters (Å, º)

Cu—O1	1.888 (2)	N1—C1	1.446 (4)
Cu—O1^i	1.888 (2)	C2—C3	1.490 (3)
Cu—O2	1.932 (2)	C3—C8	1.390 (4)
Cu—O2^i	1.932 (2)	C3—C4	1.391 (4)
Cl—C6	1.744 (3)	C4—C5	1.386 (4)
O1—N1	1.376 (3)	C5—C6	1.379 (4)
O2—C2	1.278 (3)	C6—C7	1.381 (4)
N1—C2	1.311 (3)	C7—C8	1.384 (4)
O1—Cu—O1^i	180.0	O2—C2—C3	119.5 (2)
O1—Cu—O2	84.39 (8)	N1—C2—C3	121.3 (2)
O1^i—Cu—O2	95.61 (8)	C8—C3—C4	119.7 (2)
O1—Cu—O2^i	95.61 (8)	C8—C3—C2	122.0 (2)
O1^i—Cu—O2^i	84.39 (8)	C4—C3—C2	118.2 (2)
O2—Cu—O2^i	180.0	C5—C4—C3	120.3 (3)
N1—O1—Cu	108.90 (14)	C6—C5—C4	118.8 (2)
C2—O2—Cu	110.3 (2)	C5—C6—C7	121.8 (2)
C2—N1—O1	117.2 (2)	C5—C6—Cl	119.2 (2)
C2—N1—C1	129.5 (2)	C7—C6—Cl	118.9 (2)
O1—N1—C1	113.1 (2)	C6—C7—C8	119.0 (3)
O2—C2—N1	119.2 (2)	C7—C8—C3	120.3 (3)

Symmetry code: (i) −x, −y, −z+1.

(III) 'Bis(3,5-dinitro-N-methylbenzohydroxamato-O,O') copper(II): chloroform (1:1)'

Crystal data

[Cu(C8H6N3O6)2]·CHCl3	F(000) = 782
Mr = 663.22	Dx = 1.730 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.197 (2) Å	Cell parameters from 50 reflections
b = 9.571 (1) Å	θ = 6.3–18.2°
c = 14.676 (2) Å	µ = 1.33 mm^−1
β = 107.21 (1)°	T = 293 K
V = 1502.4 (4) Å^3	Parallelepiped, green
Z = 2	0.44 × 0.40 × 0.15 mm

Data collection

Siemens/Bruker P3 diffractometer	1770 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.014
Graphite monochromator	θmax = 25.0°, θmin = 1.9°
θ/2θ scans	h = 0→13
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b)	k = 0→11
Tmin = 0.647, Tmax = 0.820	l = −17→16
2750 measured reflections	3 standard reflections every 50 reflections
2611 independent reflections	intensity decay: ave. of 1.1 % in σ(I)s

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.05	Calculated w = 1/[σ^2(Fo^2) + (0.0583P)^2 + 1.1817P] where P = (Fo^2 + 2Fc^2)/3
2597 reflections	(Δ/σ)max < 0.001
241 parameters	Δρmax = 0.39 e Å^−3
15 restraints	Δρmin = −0.33 e Å^−3

Special details

Experimental. 'Sample was sealed in a capillary tube with mother liquor.' Absorption correction: empirical: '7 ψ scans, 10° steps; (Siemens, 1991b)

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 on F² for ALL reflections except for 14 with very negative F² or flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating R factor obs 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	Occ. (<1)
Cu	−0.5000	0.0000	0.0000	0.0467 (2)
O1	−0.3454 (3)	−0.0108 (3)	−0.0287 (2)	0.0514 (7)
O2	−0.4815 (2)	0.1975 (3)	−0.0128 (2)	0.0511 (8)
O3	−0.6489 (4)	0.6217 (4)	−0.1924 (3)	0.0932 (13)
O4	−0.5211 (4)	0.7761 (4)	−0.2161 (3)	0.0894 (12)
O5	−0.0936 (4)	0.7639 (4)	−0.0132 (4)	0.1000 (14)
O6	−0.0255 (3)	0.5829 (4)	0.0729 (3)	0.0807 (11)
N1	−0.3086 (3)	0.1219 (3)	−0.0433 (3)	0.0460 (9)
N2	−0.5430 (4)	0.6681 (4)	−0.1813 (3)	0.0650 (11)
N3	−0.1066 (4)	0.6460 (4)	0.0142 (3)	0.0624 (11)
C1	−0.1964 (4)	0.1255 (5)	−0.0734 (4)	0.0625 (13)
H1A	−0.1553	0.2129	−0.0528	0.080*	0.50
H1B	−0.1275	0.1364	−0.0165	0.080*	0.50
H1C	−0.1430	0.0502	−0.0426	0.080*	0.50
H1D	−0.1862	0.0405	−0.1050	0.080*	0.50
H1E	−0.2140	0.1171	−0.1413	0.080*	0.50
H1F	−0.1985	0.2033	−0.1151	0.080*	0.50
C2	−0.3803 (4)	0.2244 (4)	−0.0333 (3)	0.0446 (10)
C3	−0.3547 (4)	0.3736 (4)	−0.0488 (3)	0.0406 (10)
C4	−0.4547 (4)	0.4516 (4)	−0.1037 (3)	0.0436 (10)
H4	−0.5355	0.4090	−0.1276	0.080*
C5	−0.4368 (4)	0.5902 (4)	−0.1197 (3)	0.0455 (10)
C6	−0.3242 (4)	0.6569 (4)	−0.0833 (3)	0.0497 (11)
H6	−0.3121	0.7538	−0.0947	0.080*
C7	−0.2291 (4)	0.5778 (4)	−0.0276 (3)	0.0453 (10)
C8	−0.2390 (4)	0.4374 (5)	−0.0085 (3)	0.0475 (11)
H8	−0.1702	0.3870	0.0332	0.080*
Cl1A	−0.1815 (11)	−0.2534 (9)	0.2287 (8)	0.217 (5)	0.50
Cl1B	−0.2221 (5)	−0.2626 (8)	0.2094 (5)	0.103 (2)	0.50
Cl2A	−0.2661 (10)	0.0212 (10)	0.2167 (7)	0.105 (2)	0.50
Cl2B	−0.2359 (14)	0.0450 (14)	0.2146 (8)	0.204 (6)	0.50
Cl3A	−0.0348 (9)	−0.0355 (14)	0.1893 (6)	0.216 (6)	0.50
Cl3B	−0.0025 (7)	−0.1009 (8)	0.2313 (5)	0.116 (2)	0.50
C9	−0.1736 (6)	−0.0985 (7)	0.1773 (5)	0.098 (2)
H9	−0.1991	−0.0966	0.1089	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0424 (4)	0.0330 (4)	0.0717 (5)	−0.0074 (4)	0.0276 (3)	−0.0020 (4)
O1	0.048 (2)	0.0320 (14)	0.083 (2)	−0.0056 (14)	0.0322 (15)	0.001 (2)
O2	0.044 (2)	0.0360 (15)	0.084 (2)	−0.0058 (13)	0.037 (2)	−0.0020 (15)
O3	0.063 (2)	0.077 (3)	0.121 (3)	0.006 (2)	−0.002 (2)	0.015 (2)
O4	0.102 (3)	0.072 (3)	0.098 (3)	0.017 (2)	0.035 (2)	0.040 (2)
O5	0.074 (3)	0.055 (2)	0.168 (4)	−0.030 (2)	0.031 (3)	0.005 (3)
O6	0.054 (2)	0.080 (3)	0.098 (3)	−0.017 (2)	0.006 (2)	−0.010 (2)
N1	0.042 (2)	0.033 (2)	0.069 (2)	−0.010 (2)	0.026 (2)	−0.002 (2)
N2	0.070 (3)	0.055 (3)	0.070 (3)	0.010 (2)	0.021 (2)	0.006 (2)
N3	0.054 (2)	0.050 (2)	0.088 (3)	−0.013 (2)	0.029 (2)	−0.021 (2)
C1	0.051 (3)	0.043 (3)	0.106 (4)	−0.005 (2)	0.043 (3)	0.003 (3)
C2	0.045 (2)	0.036 (2)	0.056 (3)	−0.010 (2)	0.020 (2)	−0.005 (2)
C3	0.042 (2)	0.035 (2)	0.051 (2)	−0.005 (2)	0.022 (2)	−0.003 (2)
C4	0.044 (2)	0.038 (2)	0.051 (3)	−0.006 (2)	0.018 (2)	−0.006 (2)
C5	0.053 (3)	0.039 (2)	0.048 (2)	0.004 (2)	0.021 (2)	0.002 (2)
C6	0.060 (3)	0.035 (2)	0.062 (3)	−0.006 (2)	0.030 (2)	−0.004 (2)
C7	0.042 (2)	0.039 (2)	0.060 (3)	−0.014 (2)	0.023 (2)	−0.008 (2)
C8	0.049 (3)	0.043 (2)	0.054 (3)	−0.009 (2)	0.021 (2)	−0.006 (2)
Cl1A	0.340 (12)	0.154 (7)	0.192 (9)	0.152 (8)	0.133 (9)	0.074 (6)
Cl1B	0.079 (2)	0.137 (5)	0.099 (3)	−0.038 (3)	0.035 (2)	−0.013 (3)
Cl2A	0.158 (5)	0.094 (4)	0.093 (4)	0.037 (3)	0.083 (4)	0.014 (3)
Cl2B	0.292 (14)	0.183 (10)	0.106 (7)	0.133 (9)	0.009 (6)	−0.039 (6)
Cl3A	0.110 (6)	0.409 (17)	0.142 (7)	−0.063 (8)	0.057 (5)	−0.085 (8)
Cl3B	0.084 (3)	0.150 (4)	0.116 (5)	−0.022 (3)	0.032 (3)	−0.045 (3)
C9	0.108 (5)	0.114 (6)	0.081 (4)	0.026 (4)	0.040 (4)	−0.008 (4)

Geometric parameters (Å, º)

Cu—O1^i	1.901 (3)	C3—C4	1.388 (6)
Cu—O1	1.901 (3)	C3—C8	1.395 (6)
Cu—O2^i	1.916 (3)	C4—C5	1.372 (6)
Cu—O2	1.916 (3)	C5—C6	1.372 (6)
O1—N1	1.372 (4)	C6—C7	1.364 (6)
O2—C2	1.281 (4)	C7—C8	1.384 (6)
O3—N2	1.230 (5)	Cl1A—C9	1.677 (11)
O4—N2	1.210 (5)	Cl1A—Cl3B	2.471 (14)
O5—N3	1.220 (5)	Cl1B—C9	1.770 (10)
O6—N3	1.212 (5)	Cl2A—C9	1.753 (11)
N1—C2	1.303 (5)	Cl2B—C9	1.702 (13)
N1—C1	1.450 (5)	Cl3A—Cl3B	0.878 (13)
N2—C5	1.467 (6)	Cl3A—C9	1.628 (12)
N3—C7	1.478 (5)	Cl3B—C9	1.845 (10)
C2—C3	1.487 (5)
O1^i—Cu—O1	180.0	C4—C5—N2	117.6 (4)
O1^i—Cu—O2^i	84.27 (11)	C7—C6—C5	116.1 (4)
O1—Cu—O2^i	95.73 (11)	C6—C7—C8	124.4 (4)
O1^i—Cu—O2	95.73 (11)	C6—C7—N3	117.9 (4)
O1—Cu—O2	84.27 (11)	C8—C7—N3	117.7 (4)
O2^i—Cu—O2	180.0	C7—C8—C3	117.3 (4)
N1—O1—Cu	108.6 (2)	C9—Cl1A—Cl3B	48.3 (4)
C2—O2—Cu	110.5 (2)	Cl3B—Cl3A—C9	89.6 (13)
C2—N1—O1	117.1 (3)	Cl3A—Cl3B—C9	61.9 (10)
C2—N1—C1	129.4 (3)	Cl3A—Cl3B—Cl1A	104.3 (11)
O1—N1—C1	113.4 (3)	C9—Cl3B—Cl1A	42.7 (3)
O4—N2—O3	124.1 (5)	Cl3A—C9—Cl1A	117.0 (7)
O4—N2—C5	117.7 (4)	Cl3A—C9—Cl2B	97.8 (8)
O3—N2—C5	118.2 (4)	Cl1A—C9—Cl2B	119.2 (6)
O6—N3—O5	123.9 (4)	Cl3A—C9—Cl2A	111.2 (7)
O6—N3—C7	118.8 (4)	Cl1A—C9—Cl2A	108.3 (5)
O5—N3—C7	117.3 (5)	Cl2B—C9—Cl2A	13.7 (7)
O2—C2—N1	119.5 (4)	Cl3A—C9—Cl1B	131.2 (6)
O2—C2—C3	117.0 (4)	Cl1A—C9—Cl1B	15.3 (5)
N1—C2—C3	123.5 (3)	Cl2B—C9—Cl1B	116.3 (6)
C4—C3—C8	120.0 (4)	Cl2A—C9—Cl1B	103.6 (5)
C4—C3—C2	116.5 (4)	Cl3A—C9—Cl3B	28.4 (5)
C8—C3—C2	123.5 (4)	Cl1A—C9—Cl3B	89.0 (6)
C5—C4—C3	119.1 (4)	Cl2B—C9—Cl3B	110.1 (7)
C6—C5—C4	123.1 (4)	Cl2A—C9—Cl3B	120.4 (6)
C6—C5—N2	119.2 (4)	Cl1B—C9—Cl3B	103.7 (5)

Symmetry code: (i) −x−1, −y, −z.