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).
Supporting information
CCDC references: 145514; 145515; 145516
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.
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.
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.
(I) 'Bis(3-methoxy-4-methyl-
N-methylbenzohydroxamato-O,
O') copper(II)'
top
Crystal data top
[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) Å3 | Near octahedron, dark green |
Z = 2 | 0.50 × 0.34 × 0.28 mm |
Data collection top
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 top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.035 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.087 | H-atom parameters constrained |
S = 1.06 | Calculated w = 1/[σ2(Fo2) + (0.0488P)2 + 0.6217P] where P = (Fo2 + 2Fc2)/3 |
1729 reflections | (Δ/σ)max < 0.001 |
133 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.39 e Å−3 |
Crystal data top
[Cu(C10H12NO3)2] | V = 988.9 (5) Å3 |
Mr = 451.95 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.532 (2) Å | µ = 1.15 mm−1 |
b = 9.073 (3) Å | T = 288 K |
c = 14.654 (4) Å | 0.50 × 0.34 × 0.28 mm |
β = 99.07 (2)° | |
Data collection top
Siemens/Bruker P3 diffractometer | 1384 reflections with I > 2σ(I) |
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b) | Rint = 0.023 |
Tmin = 0.588, Tmax = 0.726 | 3 standard reflections every 50 reflections |
3051 measured reflections | intensity decay: ave. of 0.65% in σ(I)s |
1735 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.087 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.37 e Å−3 |
1729 reflections | Δρmin = −0.39 e Å−3 |
133 parameters | |
Special details top
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 (Å2) top | 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 (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
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) top
Cu—O1 | 1.882 (2) | N1—C1 | 1.447 (4) |
Cu—O1i | 1.882 (2) | C2—C3 | 1.485 (4) |
Cu—O2i | 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—O1i | 180.0 | N1—C2—C3 | 122.4 (2) |
O1—Cu—O2i | 95.79 (8) | C8—C3—C4 | 119.5 (2) |
O1i—Cu—O2i | 84.21 (8) | C8—C3—C2 | 123.4 (2) |
O1—Cu—O2 | 84.21 (8) | C4—C3—C2 | 117.0 (2) |
O1i—Cu—O2 | 95.79 (8) | C5—C4—C3 | 120.2 (2) |
O2i—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)'
top
Crystal data top
[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) Å3 | Prism, dark green |
Z = 2 | 0.43 × 0.38 × 0.33 mm |
Data collection top
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 top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.076 | H-atom parameters constrained |
S = 1.10 | Calculated w = 1/[σ2(Fo2) + (0.0378P)2 + 0.5359P] where P = (Fo2 + 2Fc2)/3 |
1478 reflections | (Δ/σ)max < 0.001 |
115 parameters | Δρmax = 0.35 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
Crystal data top
[Cu(C8H7ClNO2)2] | V = 850.7 (2) Å3 |
Mr = 432.74 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.5953 (9) Å | µ = 1.62 mm−1 |
b = 19.503 (2) Å | T = 288 K |
c = 7.387 (1) Å | 0.43 × 0.38 × 0.33 mm |
β = 116.454 (9)° | |
Data collection top
Siemens/Bruker P3 diffractometer | 1269 reflections with I > 2σ(I) |
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b) | Rint = 0.013 |
Tmin = 0.527, Tmax = 0.586 | 3 standard reflections every 50 reflections |
1616 measured reflections | intensity decay: ave. of 0.92% in σ(I)s |
1487 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.076 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.35 e Å−3 |
1478 reflections | Δρmin = −0.25 e Å−3 |
115 parameters | |
Special details top
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 (Å2) top | 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 (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
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) top
Cu—O1 | 1.888 (2) | N1—C1 | 1.446 (4) |
Cu—O1i | 1.888 (2) | C2—C3 | 1.490 (3) |
Cu—O2 | 1.932 (2) | C3—C8 | 1.390 (4) |
Cu—O2i | 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—O1i | 180.0 | O2—C2—C3 | 119.5 (2) |
O1—Cu—O2 | 84.39 (8) | N1—C2—C3 | 121.3 (2) |
O1i—Cu—O2 | 95.61 (8) | C8—C3—C4 | 119.7 (2) |
O1—Cu—O2i | 95.61 (8) | C8—C3—C2 | 122.0 (2) |
O1i—Cu—O2i | 84.39 (8) | C4—C3—C2 | 118.2 (2) |
O2—Cu—O2i | 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)'
top
Crystal data top
[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) Å3 | Parallelepiped, green |
Z = 2 | 0.44 × 0.40 × 0.15 mm |
Data collection top
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 top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.050 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.05 | Calculated w = 1/[σ2(Fo2) + (0.0583P)2 + 1.1817P] where P = (Fo2 + 2Fc2)/3 |
2597 reflections | (Δ/σ)max < 0.001 |
241 parameters | Δρmax = 0.39 e Å−3 |
15 restraints | Δρmin = −0.33 e Å−3 |
Crystal data top
[Cu(C8H6N3O6)2]·CHCl3 | V = 1502.4 (4) Å3 |
Mr = 663.22 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 11.197 (2) Å | µ = 1.33 mm−1 |
b = 9.571 (1) Å | T = 293 K |
c = 14.676 (2) Å | 0.44 × 0.40 × 0.15 mm |
β = 107.21 (1)° | |
Data collection top
Siemens/Bruker P3 diffractometer | 1770 reflections with I > 2σ(I) |
Absorption correction: empirical (using intensity measurements) (Siemens, 1991b) | Rint = 0.014 |
Tmin = 0.647, Tmax = 0.820 | 3 standard reflections every 50 reflections |
2750 measured reflections | intensity decay: ave. of 1.1 % in σ(I)s |
2611 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.050 | 15 restraints |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.39 e Å−3 |
2597 reflections | Δρmin = −0.33 e Å−3 |
241 parameters | |
Special details top
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 (Å2) top | 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 (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
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) top
Cu—O1i | 1.901 (3) | C3—C4 | 1.388 (6) |
Cu—O1 | 1.901 (3) | C3—C8 | 1.395 (6) |
Cu—O2i | 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) | | |
| | | |
O1i—Cu—O1 | 180.0 | C4—C5—N2 | 117.6 (4) |
O1i—Cu—O2i | 84.27 (11) | C7—C6—C5 | 116.1 (4) |
O1—Cu—O2i | 95.73 (11) | C6—C7—C8 | 124.4 (4) |
O1i—Cu—O2 | 95.73 (11) | C6—C7—N3 | 117.9 (4) |
O1—Cu—O2 | 84.27 (11) | C8—C7—N3 | 117.7 (4) |
O2i—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. |
Experimental details
| (I) | (II) | (III) |
Crystal data |
Chemical formula | [Cu(C10H12NO3)2] | [Cu(C8H7ClNO2)2] | [Cu(C8H6N3O6)2]·CHCl3 |
Mr | 451.95 | 432.74 | 663.22 |
Crystal system, space group | Monoclinic, P21/n | Monoclinic, P21/n | Monoclinic, P21/c |
Temperature (K) | 288 | 288 | 293 |
a, b, c (Å) | 7.532 (2), 9.073 (3), 14.654 (4) | 6.5953 (9), 19.503 (2), 7.387 (1) | 11.197 (2), 9.571 (1), 14.676 (2) |
β (°) | 99.07 (2) | 116.454 (9) | 107.21 (1) |
V (Å3) | 988.9 (5) | 850.7 (2) | 1502.4 (4) |
Z | 2 | 2 | 2 |
Radiation type | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 1.15 | 1.62 | 1.33 |
Crystal size (mm) | 0.50 × 0.34 × 0.28 | 0.43 × 0.38 × 0.33 | 0.44 × 0.40 × 0.15 |
|
Data collection |
Diffractometer | Siemens/Bruker P3 diffractometer | Siemens/Bruker P3 diffractometer | Siemens/Bruker P3 diffractometer |
Absorption correction | Empirical (using intensity measurements) (Siemens, 1991b) | Empirical (using intensity measurements) (Siemens, 1991b) | Empirical (using intensity measurements) (Siemens, 1991b) |
Tmin, Tmax | 0.588, 0.726 | 0.527, 0.586 | 0.647, 0.820 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3051, 1735, 1384 | 1616, 1487, 1269 | 2750, 2611, 1770 |
Rint | 0.023 | 0.013 | 0.014 |
(sin θ/λ)max (Å−1) | 0.596 | 0.595 | 0.596 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.087, 1.06 | 0.030, 0.076, 1.10 | 0.050, 0.113, 1.05 |
No. of reflections | 1729 | 1478 | 2597 |
No. of parameters | 133 | 115 | 241 |
No. of restraints | 0 | 0 | 15 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.37, −0.39 | 0.35, −0.25 | 0.39, −0.33 |
Selected geometric parameters (Å, º) for (I) topCu—O1 | 1.882 (2) | O2—C2 | 1.283 (3) |
Cu—O2i | 1.935 (2) | N1—C2 | 1.307 (3) |
O1—N1 | 1.381 (3) | N1—C1 | 1.447 (4) |
| | | |
O1i—Cu—O2i | 84.21 (8) | C2—N1—C1 | 130.8 (2) |
N1—O1—Cu | 109.1 (2) | O1—N1—C1 | 111.8 (2) |
C2—O2—Cu | 110.6 (2) | O2—C2—N1 | 118.6 (2) |
C2—N1—O1 | 117.4 (2) | | |
Symmetry code: (i) −x, −y+1, −z+1. |
Selected geometric parameters (Å, º) for (II) topCu—O1 | 1.888 (2) | O2—C2 | 1.278 (3) |
Cu—O2 | 1.932 (2) | N1—C2 | 1.311 (3) |
O1—N1 | 1.376 (3) | N1—C1 | 1.446 (4) |
| | | |
O1—Cu—O2 | 84.39 (8) | C2—N1—C1 | 129.5 (2) |
N1—O1—Cu | 108.90 (14) | O1—N1—C1 | 113.1 (2) |
C2—O2—Cu | 110.3 (2) | O2—C2—N1 | 119.2 (2) |
C2—N1—O1 | 117.2 (2) | | |
Selected geometric parameters (Å, º) for (III) topCu—O1 | 1.901 (3) | O2—C2 | 1.281 (4) |
Cu—O2 | 1.916 (3) | N1—C2 | 1.303 (5) |
O1—N1 | 1.372 (4) | N1—C1 | 1.450 (5) |
| | | |
O1i—Cu—O2i | 84.27 (11) | C2—N1—C1 | 129.4 (3) |
N1—O1—Cu | 108.6 (2) | O1—N1—C1 | 113.4 (3) |
C2—O2—Cu | 110.5 (2) | O2—C2—N1 | 119.5 (4) |
C2—N1—O1 | 117.1 (3) | | |
Symmetry code: (i) −x−1, −y, −z. |
Close intermolecular contacts (Å) to nitro Oxygens (O3, O4, O5, O6) in
(III) topContact | Distance | Σ van der Waals radii (Pauling, 1960) |
O3···H1Ei | 2.47 | 2.6 |
O4···Cl2Aii | 3.07 (1) | 3.2 |
O5···H1Aiii | 2.68 | 2.6 |
O5···H1Biii | 2.57 | 2.6 |
O5···Cl3Aiv | 3.43 (1) | 3.2 |
O6···Cl3Bv | 3.303 (8) | 3.2 |
O6···N3iii | 3.121 (6) | 2.9 |
O6···O6iii | 2.855 (8) | 2.8 |
Symmetry codes: (i) -1-x,0.5+y,-0.5-z; (ii) -1-x,1-y,-z; (iii) -x,1-y,-z;
(iv) x,1+y,z; (v) -x, 0.5+y, 0.5-z. |
Close inter- and intramolecular contacts to the phenyl-C atoms
in (I)\dag, (II)\ddag and (III)\S topContact | Distance | Σ van der Waals radii |
\dag H8A···H1A | 2.11 | 2.4 |
\dag H8A···C1 | 2.74 | 3.2 |
\ddag H8A···H1A | 2.43 | 2.4 |
\ddag H8A···C1 | 2.74 | 3.2 |
\S H8···H1A | 2.13 | 2.4 |
\S H8···H1B | 2.59 | 2.4 |
\S H8···H1C | 2.74 | 2.4 |
\S H8···C1 | 2.96 | 3.2 |
\ddag C8···Cli | 3.483 (3) | 3.5 |
\S C4···O4ii | 3.076 (5) | 3.1 |
\S C5···O2iii | 3.131 (5) | 3.1 |
Symmetry codes: (i) -0.5+x,0.5-y,-0.5+z; (ii) -1-x,-0.5+y,-0.5-z;
(iii) -1-x,1-y,-z. |
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.