Crystal structure of cis-bis­{4-phenyl-1-[(3R)-1,7,7-tri­methyl-2-oxobi­cyclo­[2.2.1]heptan-3-ylidene]thio­semicarbazidato-κ3 O,N 1,S}cadmium(II) with an unknown solvent mol­ecule

Vanessa Senna Nogueira; Leandro Bresolin; Christian Näther; Inke Jess; Adriano Bof de Oliveira

doi:10.1107/S2056989015021428

. 2015 Nov 21;71(Pt 12):m234–m235. doi: 10.1107/S2056989015021428

Crystal structure of cis-bis{4-phenyl-1-[(3R)-1,7,7-trimethyl-2-oxobicyclo[2.2.1]heptan-3-ylidene]thiosemicarbazidato-κ³ O,N ¹,S}cadmium(II) with an unknown solvent molecule

Vanessa Senna Nogueira ^a, Leandro Bresolin ^a,^*, Christian Näther ^b, Inke Jess ^b, Adriano Bof de Oliveira ^c

PMCID: PMC4719850 PMID: 26870441

Abstract

The reaction between the racemic mixture of the camphor-4-phenylthiosemicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C₁₇H₂₀N₃OS)₂]. The Cd^II ion is six-coordinated in a distorted octahedral environment by two deprotonated thiosemicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the molecules are connected via pairs of N—H⋯S and C—H⋯S interactions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent molecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9–18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information.

Keywords: crystal structure, ONS-thiosemicarbazone donor, camphor-thiosemicarbazone, cadmium-thiosemicarbazone complex

Related literature

For one of the first reports of the synthesis of thiosemicarbazone derivatives, see: Freund & Schander (1902 ▸). For one example of camphor oxidation to 1,2-diketone, see: Młochowski & Wójtowicz-Młochowska (2015 ▸). For the synthesis and crystal structure of an octahedral Cd^II complex with a thiosemicarbazone derivative, see: Fonseca et al. (2012 ▸). For a review on the coordination chemistry of thiosemicarbazone derivatives, see: Lobana et al. (2009 ▸). graphic file with name e-71-0m234-scheme1.jpg

Experimental

Crystal data

[Cd(C₁₇H₂₀N₃OS)₂]
M _r = 741.24
Triclinic,
a = 10.3613 (3) Å
b = 12.3817 (4) Å
c = 16.5366 (6) Å
α = 68.727 (3)°
β = 72.094 (3)°
γ = 89.892 (3)°
V = 1866.74 (12) Å³
Z = 2
Mo Kα radiation
μ = 0.73 mm⁻¹
T = 170 K
0.18 × 0.14 × 0.08 mm

Data collection

Stoe IPDS-1 diffractometer
Absorption correction: numerical (X-RED32 and X-SHAPE; Stoe & Cie, 2008 ▸) T _min = 0.831, T _max = 0.957
27175 measured reflections
8157 independent reflections
7089 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.038
wR(F ²) = 0.103
S = 1.04
8157 reflections
439 parameters
20 restraints
H-atom parameters constrained
Δρ_max = 0.52 e Å⁻³
Δρ_min = −0.77 e Å⁻³

Data collection: X-AREA (Stoe & Cie, 2008 ▸); cell refinement: X-AREA; data reduction: X-AREA; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015 ▸); molecular graphics: DIAMOND (Brandenburg, 2006 ▸); software used to prepare material for publication: publCIF (Westrip, 2010 ▸) and enCIFer (Allen et al., 2004 ▸).

Supplementary Material

Crystal structure: contains datablock(s) I, General. DOI: 10.1107/S2056989015021428/is5430sup1.cif

e-71-0m234-sup1.cif^{(42.5KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015021428/is5430Isup2.hkl

e-71-0m234-Isup2.hkl^{(399KB, hkl)}

Click here for additional data file.^{(1.6MB, tif)}

. DOI: 10.1107/S2056989015021428/is5430fig1.tif

The molecular structure of the title compound with labeling and displacement ellipsoids drawn at the 30% probability level. Disorder is shown with full and open bonds.

Click here for additional data file.^{(2.2MB, tif)}

a R b S . DOI: 10.1107/S2056989015021428/is5430fig2.tif

(a) Isotropic representation of the title compound with the disordered R-camphor entity. This ligand is labelled with C32, C33 and C34. (b) Isotropic representation of the title compound with the disordered S-camphor entity. This ligand is labelled with C32′, C33′ and C34′. The figure is valid for the asymmetric unit only and simplified for clarity.

Click here for additional data file.^{(1.7MB, tif)}

a . DOI: 10.1107/S2056989015021428/is5430fig3.tif

A packing diagram of the title compound viewed along the crystallographic a-axis, showing the N—H⋯ S hydrogen bonds (dashed lines). The C—H⋯S interactions are not shown for clarity. The disordered atoms are not shown..

CCDC reference: 1436346

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N21—H21⋯S21ⁱ	0.88	2.58	3.363 (3)	148
C23—H23⋯S21ⁱ	0.95	2.97	3.629 (4)	128

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

We gratefully acknowledge financial support by the State of Schleswig–Holstein, Germany, and thank Professor Dr Wolfgang Bensch, University of Kiel, for access to his experimental facilities.

supplementary crystallographic information

S1. Structural commentary

Our ongoing research deals with the synthesis and crystal structure analysis of thiosemicarbazone derivatives from natural products with an supramolecular approach. Herein we report the synthesis and the crystal structure of a new Cd^II complex with the R,S-camphor-4-phenylthiosemicarbazone, a derivative from a racemic mixture of camphor. In the title compound the molecular structure matches the asymmetric unit and the metal ion is six-coordinated in a distorted octahedral environment by two thiosemicarbazonate ligands (Fig. 1). The ligands are ONS-donors and build a chelate coordination mode, where each ligand forms two five-membered rings. The maximum deviation from the mean plane of the Cd1/S1/C1/N2/N3/C8/C9/O1 chelating group amounts to 0.0811 (11) Å for S1 and for the Cd1/S21/C21/N22/N23/C28/C29/O21 chelating group amounts to 0.0801 (26) Å for C29, with the dihedral angle between the two chelate entities being measured as 73.16 (5)°. The two ligands are deprotonated and the negative charge is delocalized over the C—N—N—C—S fragment as suggested by their intermediate bond distances. The imine and thioamide C—N distances indicate considerable double bond character, while the C—S distance is consistent with increased single bond character. This change on the bond character is a key feature to distinguish neutral/free or deprotonated/coordinated thiosemicarbazones. For the title compound, these distances are C8—N3 = 1.280 (3) Å, N2—N3 = 1.362 (3) Å, N2—C1 = 1.319 (3) Å and C1—S1 = 1.734 (3) Å for one ligand and C28—N23 = 1.278 (4) Å, N22—N23 = 1.367 (3) Å, N22—C21 = 1.313 (4) Å and C21—S21 = 1.743 (3) Å for the another one. The bond distances and the meridional coordination geometry agree with a similar Cd^II thiosemicarbazonate octahedral complex (Fonseca et al., 2012) and are supported by literature data (Lobana et al., 2009). The camphor molecule has two chiral carbon atoms and a racemic mixture was used in the synthesis.

From the two crystallographically independent ligands in the asymmetric unit, one is disordered in the campher unit with S. O. F. = 0.7:0.3 (Fig. 2). The complex molecules are connected into centrosymmetric dimers via pairs of N—H···S and C—H···S intermolecurar interactions. The dimers are stacked along the crystallographic a-direction (Fig. 3 and Table 1).

S2. Synthesis and crystallization

Starting materials were commercially available and were used without further purification. An R,S-camphor racemic mixture was oxidized with SeO₂ to the respective 1,2-diketone (Młochowski & Wójtowicz-Młochowska, 2015). The synthesis of the R,S-camphor-4-phenylthiosemicarbazone derivative was adapted from a procedure reported previously (Freund & Schander, 1902). The ligand (2 mmol) was dissolved in ethanol (20 mL) and deprotonated with 1 mL of a 1 M KOH aqueous solution. Stirring was maintained for 40 min, while the reaction mixture turns yellow. A solution of cadmium acetate dihydrate (1 mmol) also in ethanol (20 mL) was added under continuous stirring and under slight warming to 333 K. After 3 h a yellow solid was formed. This solid was filtered-off, washed with small portions of cool ethanol and dried at room conditions. A bulk, rough material was observed and it was impossible to isolate enough quantities of the title compound for complementar analysis or for yield calculation. Colourless crystals of the complex, suitable for X-ray analysis, were obtained by recrystallization from an ethanol solution.

S3. Refinement

All non-hydrogen atoms except the disordered C atoms of lower occupancy were refined anisotropic. The C—H and N—H H atoms were positioned with idealized geometry and were refined isotropic with U_iso(H) = 1.2 U_eq(C,N) (1.5 for methyl H atoms) using a riding model.

The campher unit in one of the two independent ligands is disordered. This part was refined using a split model with S. O. F. = 0.7:0.3 and with similarity restraints (SAME). The site occupation factors were selected in order that the disordered atoms exhibits similar isotropic displacement parameters based on the isotropic refinement. If the isotropic displacement parameters are fixed and the S. O. F. is refined, similar values are obtained. Finally, the disordered atoms of higher occupancy were refined anisotropic.

The refined structure contained additional disordered solvate molecules. Because no reasonable split model was found, the data were corrected for disordered solvent using the SQUEEZE option in PLATON (Spek, 2015). The void volume and void count electrons amount to 234 Å³ and 55 e^-·Å^-3. The void electrons count of 55 can be assigned to two solvent ethanol molecules (52 electrons in total). Ethanol was the synthesis solvent. Since the disordered solvents were removed by data processing, and the estimated number of two ethanol molecules was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal informations.