The title compound, [Cu2(C17H17N4S)2Cl2], exhibits a dimeric structure related by a centre of symmetry. The monomers are linked to each other by the longest Cu—S apical distance observed to date among CuII square-pyramidal complexes of N4-substituted thiosemicarbazones. Each CuII atom deviates from the coordination square plane, which contains the pyridyl and imine N atoms, the thiolate S atom and the Cl− anion, towards the S atom of the adjacent monomer. The dimers pack in a zigzag manner through the crystal.
Supporting information
CCDC reference: 238501
The ligand HBpypTsc was prepared by adapting the procedure of Scovill (1991). A solution of HBpypTsc (1 mmol) in chloroform (5 ml) was then refluxed with a solution of copper chloride (1 mmol) in methanol (5 ml) for 15 min. The resulting solution was cooled and allowed to stand for 2 d to isolate light-blue single crystals of (I). Elemental analysis, found (calculated): C 49.86 (49.20), H 4.27 (4.13), N 23.95 (23.63)%.
The H atom attached to atom C3 was geometrically fixed, while the other H atoms were located from the difference Fourier map and refined isotropically. The C—H distances are in the range 0.88 (3)–1.01 (3) Å.
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).
Chloro(2-benzoylpyridine-
κN)(butane-1,4-diyl)thiosemicarbazonato-
κ2N1,
S)copper(II)
top
Crystal data top
[CuCl(C17H17N4S)] | F(000) = 836 |
Mr = 408.40 | Dx = 1.596 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 564 reflections |
a = 11.1069 (18) Å | θ = 2.0–26.9° |
b = 8.2919 (14) Å | µ = 1.57 mm−1 |
c = 18.642 (3) Å | T = 293 K |
β = 98.061 (3)° | Rectangular, light blue |
V = 1699.9 (5) Å3 | 0.35 × 0.30 × 0.30 mm |
Z = 4 | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 3680 independent reflections |
Radiation source: fine-focus sealed tube | 2911 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.024 |
Detector resolution: 0.3 pixels mm-1 | θmax = 26.9°, θmin = 2.0° |
ω scans | h = −14→14 |
Absorption correction: multi-scan (SADABS; Sheldrick,1996) | k = −10→9 |
Tmin = 0.583, Tmax = 0.624 | l = −21→23 |
12249 measured reflections | |
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)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.080 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0455P)2 + 0.4986P] where P = (Fo2 + 2Fc2)/3 |
3392 reflections | (Δ/σ)max = 0.006 |
281 parameters | Δρmax = 0.37 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
Crystal data top
[CuCl(C17H17N4S)] | V = 1699.9 (5) Å3 |
Mr = 408.40 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 11.1069 (18) Å | µ = 1.57 mm−1 |
b = 8.2919 (14) Å | T = 293 K |
c = 18.642 (3) Å | 0.35 × 0.30 × 0.30 mm |
β = 98.061 (3)° | |
Data collection top
Bruker SMART APEX CCD area-detector diffractometer | 3680 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick,1996) | 2911 reflections with I > 2σ(I) |
Tmin = 0.583, Tmax = 0.624 | Rint = 0.024 |
12249 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.031 | 0 restraints |
wR(F2) = 0.080 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.37 e Å−3 |
3392 reflections | Δρmin = −0.19 e Å−3 |
281 parameters | |
Special details top
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 (Å2) top | x | y | z | Uiso*/Ueq | |
Cu1 | −0.05079 (2) | 0.91688 (3) | 0.087331 (14) | 0.03345 (11) | |
S1 | 0.02125 (5) | 0.77519 (7) | −0.00075 (3) | 0.03724 (15) | |
Cl1 | −0.24762 (5) | 0.85605 (8) | 0.05610 (4) | 0.04820 (17) | |
N1 | −0.06982 (16) | 1.0398 (2) | 0.17903 (10) | 0.0326 (4) | |
N2 | 0.12220 (15) | 0.9400 (2) | 0.12846 (9) | 0.0291 (4) | |
N3 | 0.21409 (16) | 0.8701 (2) | 0.09906 (9) | 0.0321 (4) | |
N4 | 0.25764 (17) | 0.7216 (2) | 0.00372 (10) | 0.0389 (4) | |
C1 | 0.14635 (18) | 1.0201 (2) | 0.18903 (11) | 0.0291 (4) | |
C2 | 0.03811 (19) | 1.0844 (2) | 0.21705 (11) | 0.0287 (4) | |
C3 | 0.0436 (2) | 1.1865 (3) | 0.27657 (12) | 0.0327 (5) | |
H3 | 0.1181 | 1.2180 | 0.3017 | 0.039* | |
C4 | −0.0643 (2) | 1.2403 (3) | 0.29763 (13) | 0.0366 (5) | |
C5 | −0.1732 (2) | 1.1917 (3) | 0.26005 (13) | 0.0400 (5) | |
C6 | −0.1726 (2) | 1.0925 (3) | 0.20108 (14) | 0.0386 (5) | |
C7 | 0.27070 (19) | 1.0448 (2) | 0.22824 (11) | 0.0294 (4) | |
C8 | 0.2991 (2) | 0.9979 (3) | 0.30024 (12) | 0.0349 (5) | |
C9 | 0.4151 (2) | 1.0204 (3) | 0.33699 (13) | 0.0410 (5) | |
C10 | 0.5028 (2) | 1.0926 (3) | 0.30287 (15) | 0.0447 (6) | |
C11 | 0.4755 (2) | 1.1412 (3) | 0.23149 (15) | 0.0435 (6) | |
C12 | 0.3609 (2) | 1.1159 (3) | 0.19356 (13) | 0.0362 (5) | |
C13 | 0.1735 (2) | 0.7916 (3) | 0.03760 (11) | 0.0319 (5) | |
C14 | 0.2310 (3) | 0.6201 (3) | −0.06078 (14) | 0.0440 (6) | |
C16 | 0.4353 (3) | 0.7240 (4) | −0.04910 (16) | 0.0559 (7) | |
C15 | 0.3553 (3) | 0.5888 (4) | −0.08361 (17) | 0.0559 (7) | |
C17 | 0.3879 (2) | 0.7539 (4) | 0.02210 (15) | 0.0490 (7) | |
H4 | −0.062 (2) | 1.305 (3) | 0.3364 (13) | 0.035 (6)* | |
H5 | −0.245 (2) | 1.229 (3) | 0.2713 (13) | 0.042 (7)* | |
H6 | −0.240 (2) | 1.057 (3) | 0.1712 (15) | 0.046 (7)* | |
H8 | 0.243 (2) | 0.950 (3) | 0.3231 (12) | 0.029 (6)* | |
H9 | 0.429 (2) | 0.995 (3) | 0.3832 (14) | 0.037 (6)* | |
H10 | 0.579 (2) | 1.112 (3) | 0.3248 (14) | 0.044 (7)* | |
H11 | 0.534 (3) | 1.198 (4) | 0.2085 (16) | 0.065 (9)* | |
H12 | 0.341 (2) | 1.143 (3) | 0.1429 (14) | 0.039 (6)* | |
H14B | 0.181 (2) | 0.673 (3) | −0.0951 (15) | 0.047 (7)* | |
H14A | 0.192 (2) | 0.516 (4) | −0.0485 (14) | 0.053 (8)* | |
H15A | 0.386 (3) | 0.481 (4) | −0.0644 (17) | 0.072 (9)* | |
H15B | 0.355 (3) | 0.584 (3) | −0.1306 (18) | 0.060 (9)* | |
H16A | 0.516 (3) | 0.704 (4) | −0.0438 (17) | 0.069 (9)* | |
H16B | 0.427 (2) | 0.820 (3) | −0.0745 (14) | 0.045 (8)* | |
H17A | 0.400 (2) | 0.867 (4) | 0.0370 (15) | 0.053 (8)* | |
H17B | 0.419 (2) | 0.678 (3) | 0.0568 (16) | 0.052 (8)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cu1 | 0.02831 (16) | 0.04074 (17) | 0.02978 (16) | 0.00010 (11) | −0.00126 (11) | −0.00471 (11) |
S1 | 0.0376 (3) | 0.0411 (3) | 0.0306 (3) | 0.0023 (2) | −0.0037 (2) | −0.0073 (2) |
Cl1 | 0.0333 (3) | 0.0589 (4) | 0.0503 (4) | −0.0099 (3) | −0.0015 (3) | −0.0050 (3) |
N1 | 0.0301 (9) | 0.0375 (9) | 0.0297 (9) | 0.0002 (7) | 0.0028 (7) | 0.0005 (8) |
N2 | 0.0290 (9) | 0.0329 (9) | 0.0245 (9) | 0.0016 (7) | 0.0008 (7) | −0.0006 (7) |
N3 | 0.0314 (9) | 0.0381 (9) | 0.0260 (9) | 0.0055 (8) | 0.0016 (7) | −0.0043 (8) |
N4 | 0.0395 (10) | 0.0444 (11) | 0.0319 (10) | 0.0084 (9) | 0.0016 (8) | −0.0095 (8) |
C1 | 0.0291 (10) | 0.0307 (10) | 0.0270 (10) | −0.0001 (8) | 0.0026 (8) | 0.0001 (9) |
C2 | 0.0276 (10) | 0.0307 (10) | 0.0278 (11) | −0.0011 (8) | 0.0041 (8) | 0.0039 (8) |
C3 | 0.0316 (11) | 0.0369 (11) | 0.0294 (11) | −0.0020 (9) | 0.0038 (9) | 0.0003 (9) |
C4 | 0.0436 (13) | 0.0380 (12) | 0.0297 (12) | 0.0022 (10) | 0.0107 (10) | −0.0023 (10) |
C5 | 0.0315 (12) | 0.0509 (14) | 0.0395 (13) | 0.0057 (10) | 0.0117 (10) | 0.0014 (11) |
C6 | 0.0276 (11) | 0.0482 (13) | 0.0395 (13) | −0.0002 (10) | 0.0028 (10) | 0.0021 (11) |
C7 | 0.0293 (11) | 0.0308 (10) | 0.0276 (11) | 0.0028 (8) | 0.0021 (8) | −0.0048 (9) |
C8 | 0.0364 (12) | 0.0373 (12) | 0.0306 (12) | 0.0000 (10) | 0.0041 (10) | −0.0028 (10) |
C9 | 0.0464 (14) | 0.0434 (13) | 0.0299 (13) | 0.0083 (11) | −0.0061 (10) | −0.0052 (10) |
C10 | 0.0302 (12) | 0.0538 (15) | 0.0469 (15) | 0.0006 (11) | −0.0060 (11) | −0.0115 (12) |
C11 | 0.0320 (12) | 0.0498 (14) | 0.0491 (15) | −0.0043 (10) | 0.0076 (11) | −0.0036 (12) |
C12 | 0.0362 (12) | 0.0399 (12) | 0.0329 (13) | 0.0005 (10) | 0.0061 (10) | −0.0019 (10) |
C13 | 0.0369 (11) | 0.0316 (11) | 0.0262 (11) | 0.0041 (9) | 0.0007 (9) | 0.0010 (9) |
C14 | 0.0554 (16) | 0.0433 (14) | 0.0318 (13) | 0.0106 (12) | 0.0005 (11) | −0.0084 (11) |
C16 | 0.0478 (17) | 0.077 (2) | 0.0434 (16) | 0.0132 (15) | 0.0102 (13) | −0.0078 (15) |
C15 | 0.0667 (19) | 0.0610 (18) | 0.0409 (16) | 0.0187 (14) | 0.0106 (14) | −0.0116 (14) |
C17 | 0.0400 (14) | 0.0683 (19) | 0.0377 (14) | 0.0136 (13) | 0.0022 (11) | −0.0097 (14) |
Geometric parameters (Å, º) top
Cu1—N2 | 1.9756 (17) | C6—H6 | 0.92 (3) |
Cu1—N1 | 2.0268 (18) | C7—C8 | 1.391 (3) |
Cu1—Cl1 | 2.2396 (7) | C7—C12 | 1.397 (3) |
Cu1—S1 | 2.2550 (7) | C8—C9 | 1.384 (3) |
Cu1—S1i | 3.0627 (4) | C8—H8 | 0.90 (2) |
S1—C13 | 1.746 (2) | C9—C10 | 1.374 (4) |
N1—C6 | 1.340 (3) | C9—H9 | 0.88 (3) |
N1—C2 | 1.356 (3) | C10—C11 | 1.383 (4) |
N2—C1 | 1.305 (3) | C10—H10 | 0.91 (3) |
N2—N3 | 1.355 (2) | C11—C12 | 1.382 (3) |
N3—C13 | 1.340 (3) | C11—H11 | 0.95 (3) |
N4—C13 | 1.332 (3) | C12—H12 | 0.97 (2) |
N4—C14 | 1.464 (3) | C14—C15 | 1.523 (4) |
N4—C17 | 1.464 (3) | C14—H14B | 0.90 (3) |
C1—C2 | 1.476 (3) | C14—H14A | 1.00 (3) |
C1—C7 | 1.483 (3) | C16—C17 | 1.515 (4) |
C2—C3 | 1.390 (3) | C16—C15 | 1.516 (4) |
C3—C4 | 1.386 (3) | C16—H16A | 0.90 (3) |
C3—H3 | 0.9300 | C16—H16B | 0.93 (3) |
C4—C5 | 1.370 (3) | C15—H15A | 1.01 (3) |
C4—H4 | 0.90 (2) | C15—H15B | 0.88 (3) |
C5—C6 | 1.374 (3) | C17—H17A | 0.99 (3) |
C5—H5 | 0.91 (3) | C17—H17B | 0.93 (3) |
| | | |
N2—Cu1—N1 | 80.48 (7) | C9—C8—H8 | 119.2 (15) |
N2—Cu1—Cl1 | 169.58 (5) | C7—C8—H8 | 120.1 (15) |
Cl1—Cu1—S1 | 97.27 (3) | C10—C9—C8 | 120.1 (2) |
S1—Cu1—S1i | 88.59 (3) | C10—C9—H9 | 121.0 (16) |
N1—Cu1—Cl1 | 96.84 (5) | C8—C9—H9 | 118.8 (16) |
N2—Cu1—S1 | 84.73 (5) | C9—C10—C11 | 119.9 (2) |
N1—Cu1—S1 | 164.98 (5) | C9—C10—H10 | 123.6 (16) |
Cl1—Cu1—S1i | 102.92 (3) | C11—C10—H10 | 116.5 (16) |
C13—S1—Cu1 | 94.78 (7) | C12—C11—C10 | 120.7 (2) |
C6—N1—C2 | 118.69 (19) | C12—C11—H11 | 119.0 (18) |
C6—N1—Cu1 | 128.08 (16) | C10—C11—H11 | 120.3 (18) |
C2—N1—Cu1 | 112.89 (14) | C11—C12—C7 | 119.7 (2) |
C1—N2—N3 | 119.52 (17) | C11—C12—H12 | 122.0 (15) |
C1—N2—Cu1 | 117.13 (14) | C7—C12—H12 | 118.2 (15) |
N3—N2—Cu1 | 123.25 (13) | N4—C13—N3 | 116.28 (19) |
C13—N3—N2 | 111.81 (17) | N4—C13—S1 | 118.38 (16) |
C13—N4—C14 | 124.5 (2) | N3—C13—S1 | 125.34 (16) |
C13—N4—C17 | 123.05 (19) | N4—C14—C15 | 103.9 (2) |
C14—N4—C17 | 112.12 (19) | N4—C14—H14B | 109.8 (17) |
N2—C1—C2 | 114.28 (18) | C15—C14—H14B | 112.5 (17) |
N2—C1—C7 | 124.12 (18) | N4—C14—H14A | 110.5 (16) |
C2—C1—C7 | 121.59 (18) | C15—C14—H14A | 110.5 (15) |
N1—C2—C3 | 121.31 (19) | H14B—C14—H14A | 110 (2) |
N1—C2—C1 | 114.89 (18) | C17—C16—C15 | 103.8 (3) |
C3—C2—C1 | 123.77 (19) | C17—C16—H16A | 113 (2) |
C4—C3—C2 | 118.7 (2) | C15—C16—H16A | 115 (2) |
C4—C3—H3 | 120.7 | C17—C16—H16B | 106.4 (16) |
C2—C3—H3 | 120.7 | C15—C16—H16B | 114.1 (16) |
C5—C4—C3 | 119.8 (2) | H16A—C16—H16B | 104 (3) |
C5—C4—H4 | 120.5 (15) | C16—C15—C14 | 104.8 (2) |
C3—C4—H4 | 119.7 (15) | C16—C15—H15A | 110.8 (18) |
C4—C5—C6 | 118.9 (2) | C14—C15—H15A | 109.3 (17) |
C4—C5—H5 | 121.7 (16) | C16—C15—H15B | 112.3 (19) |
C6—C5—H5 | 119.3 (16) | C14—C15—H15B | 114 (2) |
N1—C6—C5 | 122.7 (2) | H15A—C15—H15B | 106 (3) |
N1—C6—H6 | 111.6 (16) | N4—C17—C16 | 102.6 (2) |
C5—C6—H6 | 125.6 (16) | N4—C17—H17A | 109.5 (16) |
C8—C7—C12 | 119.0 (2) | C16—C17—H17A | 110.6 (16) |
C8—C7—C1 | 120.44 (19) | N4—C17—H17B | 107.2 (17) |
C12—C7—C1 | 120.60 (19) | C16—C17—H17B | 111.0 (17) |
C9—C8—C7 | 120.6 (2) | H17A—C17—H17B | 115 (2) |
Symmetry code: (i) −x, −y+2, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6···Cl1 | 0.92 (2) | 2.71 (3) | 3.348 (3) | 127.7 (19) |
C3—H3···N3ii | 0.93 | 2.74 | 3.631 (3) | 160 |
Symmetry code: (ii) −x+1/2, y+1/2, −z+1/2. |
Experimental details
Crystal data |
Chemical formula | [CuCl(C17H17N4S)] |
Mr | 408.40 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 11.1069 (18), 8.2919 (14), 18.642 (3) |
β (°) | 98.061 (3) |
V (Å3) | 1699.9 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.57 |
Crystal size (mm) | 0.35 × 0.30 × 0.30 |
|
Data collection |
Diffractometer | Bruker SMART APEX CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick,1996) |
Tmin, Tmax | 0.583, 0.624 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12249, 3680, 2911 |
Rint | 0.024 |
(sin θ/λ)max (Å−1) | 0.637 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.080, 1.04 |
No. of reflections | 3392 |
No. of parameters | 281 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.37, −0.19 |
Selected geometric parameters (Å, º) topCu1—N2 | 1.9756 (17) | S1—C13 | 1.746 (2) |
Cu1—N1 | 2.0268 (18) | N2—C1 | 1.305 (3) |
Cu1—Cl1 | 2.2396 (7) | N2—N3 | 1.355 (2) |
Cu1—S1 | 2.2550 (7) | N3—C13 | 1.340 (3) |
Cu1—S1i | 3.0627 (4) | | |
| | | |
N2—Cu1—N1 | 80.48 (7) | N2—Cu1—S1 | 84.73 (5) |
N2—Cu1—Cl1 | 169.58 (5) | N1—Cu1—S1 | 164.98 (5) |
Cl1—Cu1—S1 | 97.27 (3) | Cl1—Cu1—S1i | 102.92 (3) |
S1—Cu1—S1i | 88.59 (3) | C1—N2—N3 | 119.52 (17) |
N1—Cu1—Cl1 | 96.84 (5) | | |
Symmetry code: (i) −x, −y+2, −z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C6—H6···Cl1 | 0.92 (2) | 2.71 (3) | 3.348 (3) | 127.7 (19) |
C3—H3···N3ii | 0.93 | 2.74 | 3.631 (3) | 160 |
Symmetry code: (ii) −x+1/2, y+1/2, −z+1/2. |
Recently, there has been considerable interest in the coordination chemistry of thiosemicarbazones, mainly due to their interesting physicochemical and biological properties (Sreekanth et al., 2005; John et al., 2002, 2004; Philip et al., 2004; Joseph et al., 2004; Sreekanth & Kurup, 2003). Thiosemicarbazones act as chelating agents with the copper(II) ion by bonding through the thioketo S and hydrazine N atoms, and hence these types of compounds can coordinate in vivo to the metal ion. Because of such coordination, the thiosemicarbazone moiety undergoes a steric reorientation that could favour its biological activity. As far as the present study is concerned, there are only a few reports in the literature on the crystal structures of metal complexes of similar compounds (Rebolledo et al., 2003; Demertzi et al., 1999; Liu et al., 1999). Recently, we reported the crystal structures of the uncomplexed ligand, 2-benzoylpyridine N4,N4-(butane-1,4-diyl)thiosemicarbazone (HBpypTsc), and its FeIII complex (Sreekanth & Kurup, 2004). Crystal structures of some CuII complexes (Sreekanth & Kurup, 2003) and one AuIII complex (Sreekanth et al., 2004) of the same thiosemicarbazone have also been reported. However, the present crystal structure of the title compound, (I) or CuBpypTscCl, is the first report where the copper(II) complexes `dimerize' around an inversion centre using a long Cu—S contact.
Compound (I) crystallizes with one independent molecule in the unit cell (Fig. 1). The thiosemicarbazone loses an H atom from its tautomeric thiol form and acts as a tridentate ligand coordinating to the CuII atom through the pyridyl N, azomethine N and thiolate S atoms. The thiosemicarbazone moiety in the free ligand (Sreekanth & Kurup, 2004) shows Z configurations about both the C1—N2 and N3—C13 bonds, whereas in the present CuII complex, it exists in an E conformation about the C1—N2 bond and a Z configuration about the N3—C13 bond; this suggests that a possible rotation about the azomethine double bond occurs during coordination.
A novel aspect of the molecular structure of (I) is that, in the crystal lattice, two inversion symmetry-related monomers are arranged so that each S atom of the monomeric part is at the apical position of the square-pyramidal structure of the other part, with Cu—Si = 3.0627 (4) Å [symmetry code: (i) −x, 2 − y, −z Please check added symmetry code]. Such square-pyramidal structures occur through bridging by either the thiolate or the coordinating halide anion for CuII complexes of thiosemicarbazones. This unique feature is not observed in the bromo analogue, CuBpypTscBr (Sreekanth & Kurup, 2003), where the S atom is positioned 6.084 Å from the CuII centre of the adjacent molecule in the unit cell. The present compound contains the longest apical Cu—S distance reported to date for square-pyramidal CuII complexes of N4-substituted thiosemicarbazones. In a CuII complex of S-methylisothiosemicarbazone (Kravtsov et al., 1993), the Cu—S apical distance between adjacent molecules is also long, at 3.126 Å, longer than the Cu—Si value in (I). In addition, where the square-pyramidal geometry exists through the bridging of adjacent molecules, the in-plane Cu—S (2.924 Å; Joseph et al., 2004), Cu—Cl (2.777 Å; Sreekanth & Kurup, 2003) and Cu—Cl (2.779 Å; Dallavalle et al., 2002) distances are shorter compared with the corresponding ones in (I).
The copper(II) ion of (I) lies 0.1299 (1) Å out of the square plane described by atoms N1, N2, S1 and Cl1, towards the apical S atom. The two coordinated N atoms have Cu—N bond distances differing by 0.051 (1) Å. The thiosemicarbazone moiety comprising atoms C1, N2, N3, C13, S1 and N4 retains its planarity even after coordination, as evidenced by the maximum out-of-plane deviation of 0.0110 (2) Å for N2. The ring-puckering analyses (Cremer & Pople, 1975) reveal that the pyrrolidine ring comprising atoms N4, C14, C15, C16 and C17 exists in an envelope conformation, with C16 as the flap atom.
The C13—S1 bond lengthens by 0.065 (2) Å upon coordination to the CuII atom. The free ligand exists as the thione tautomer and it coordinates to the CuII atom in the deprotonated thiolate form, thus rendering a single-bond character for the C—S bond. Similarly, coordination of the azomethine N atom to central CuII atom results in a redistribution of the electron density along the thiosemicarbazone chain, giving rise to changes in the bond distances along the moiety compared with those of the uncoordinated thiosemicarbazone. For instance, the azomethine bond distance increases by 0.010 (3) Å, while the N2—N3 and N3—C13 bond distances decrease by 0.011 (2) and 0.020 (3) Å, respectively, in (I) compared with the free ligand. Comparisons with CuBpypTscSH and CuBpypTscBr show that the metal–ligand bond lengths (Table 1) do not show any regular trends among the related structures.
A crystal-packing diagram for (I) is shown in Fig. 2. The unit cell contains two centrosymmetric dimer molecules packed in a zigzag manner in the crystal lattice. One intermolecular contact (entry 2 in Table 2) is observed. A C6—H6···Cl1 intramolecular hydrogen-bonding interaction (Table 2) leads to the formation of a five-membered ring in the molecule.