research papers\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206
Volume 79| Part 3| June 2023| Pages 213-219
https://doi.org/10.1107/S205252062300327X
ADDENDA AND ERRATA

A correction has been published for this article. To view the correction, click here.

Synthesis and structure of two novel trans-platinum complexes

crossmark logo
Doriana Vincia* and Daniel Chateignerb

aEuropean XFEL GmbH, Holzkoppel 4, Schenefeld, Hamburg 22869, Germany, and bCRISMAT, CNRS, ENSICAEN, Université de Caen Normandie, Caen, France
*Correspondence e-mail: doriana.vinci@xfel.eu

Edited by K. E. Knope, Georgetown University, USA (Received 13 December 2022; accepted 10 April 2023; online 6 May 2023)

Here for the first time the synthesis and characterization of two new trans-platinum complexes, trans-[PtCl2{HN=C(OH)C6H5}2] (compound 1) and trans-[PtCl4(NH3){HN=C(OH)tBu}] (compound 2) [with tBu = C(CH3)3] are described. The structures have been characterized using nuclear magnetic resonance spectroscopy and X-ray single-crystal diffraction. In compound 1 the platinum cation, at the inversion center, is in the expected square-planar coordination geometry. It is coordinated to two chloride anions, trans to each other, and two nitro­gen atoms from the benzamide ligands. The van der Waals interactions between the molecules produce extended two-dimensional layers that are linked into a three-dimensional structure through π⋯π intermolecular interactions. In compound 2 the platinum cation is octahedrally coordinated by four chloride anions and two nitro­gen atoms from the pivalamide and ammine ligands, in trans configuration. The molecular packing is governed by intermolecular hydrogen bonds and van der Waals interactions.

CCDC references: 2255221; 2255222

Similar articles

1. Introduction

Platinum-based drugs have been used for chemotherapeutic treatment of cancer since 1965, when Rosenberg's group discovered the cytotoxic activity of cisplatin Pt(NH3)2Cl2 (Rosenberg et al., 1965[Rosenberg, B., Van Camp, L. & Krigas, T. (1965). Nature, 205, 698-699.]). In 1970, cisplatin was approved for application in testicular and ovarian cancer by the US Food and Drug Administration and in several European countries (Wiltshaw, 1979[Wiltshaw, E. (1979). Plat. Met. Rev. 23, 90-98.]). It is prescribed also for the treatment of a wide array of other tumors such us head-and-neck, esophagus, stomach, colon, bladder, cervix, pancreas, liver, kidney and prostate cancers. Although cisplatin has been used for more than 40 years, the severe side effects and the drug resistance of many cancer types have been the major limitations for its clinical application (Lippert, 1999[Lippert, B. (1999). Cisplatin Chemistry and Biochemistry of a Leading Anticancer Drug. New York: Wiley-VCH.]; Giaccone, 2000[Giaccone, G. (2000). Drugs, 59, 9-17.]; Oberoi et al., 2013[Oberoi, H. S., Nukolova, N. V., Kabanov, A. V. & Bronich, T. K. (2013). Adv. Drug Deliv. Rev. 65, 1667-1685.]). Cisplatin resistance may be associated with reduced drug uptake, enhanced efflux, intracellular detoxification by gluta­thione, increased DNA repair, decreased mismatch repair, defective apoptosis, modulation of signaling pathways or the presence of quiescent non-cycling cells (Steward, 2007[Steward, D. J. (2007). Crit. Rev. Oncol. Hematol. 63, 12-31.]; Rabik & Dolan, 2007[Rabik, C. A. & Dolan, M. E. (2007). Cancer Treat. Rev. 33, 9-23.]; Kuo et al., 2007[Kuo, M. T., Chen, H. H., Song, I. S., Savaraj, N. & Ishikawa, T. (2007). Cancer Metastasis Rev. 26, 71-83.]; Boulikas et al., 2007[Boulikas, T., Pantos, A., Bellis, E. & Christofis, P. (2007). Cancer Ther. 5, 537-583.]; Heffeter et al., 2008[Heffeter, P., Jungwirth, U., Jakupec, M., Hartinger, C., Galanski, M., Elbling, L., Micksche, M., Keppler, B. & Berger, W. (2008). Drug Resist. Updat. 11, 1-16.]; Reedijk, 2011[Reedijk, J. (2011). Pure Appl. Chem. 83, 1709-1719.]). In the last 45 years, although a great effort has been made for synthesizing platinum compounds with reduced side effects and propensity to induce drug resistance (Jakupec et al., 2003[Jakupec, M. A., Galanski, M. & Keppler, B. K. (2003). Rev. Physiol. Biochem. Pharmacol. 146, 1-54.]), none of them has reached worldwide clinical application. Only five complexes (carboplatin, oxaliplatin, nedaplatin, heptaplatin, lobaplatin) have been registered for clinical treatment with regional approval (cisplatin, carboplatin and oxaliplatin are FDA-approved, nedaplatin in Japan and lobaplatin in China). According to early structure–property relationship studies, only platinum compounds with cis-configuration exhibit antitumor activity (Kelland, 2007[Kelland, L. R. (2007). Nat. Rev. Cancer, 7, 573-584.]). In recent decades, however, it has been observed also that many trans-platinum(II) complexes exhibit anticancer activity comparable with the cis-isomer and cisplatin (Farrell et al., 1992[Farrell, N., Kelland, L. R., Roberts, J. D. & Van Beusichem, M. (1992). Cancer Res. 52, 5065-5072.]; Montero et al., 1999[Montero, E. I., Díaz, S., González-Vadillo, A. M., Pérez, J. M., Alonso, C. & Navarro-Ranninger, C. (1999). J. Med. Chem. 42, 4264-4268.]; Kasparkova et al., 2003a[Kasparkova, J., Novakova, O., Farrell, N. & Brabec, V. (2003a). Biochemistry, 42, 792-800.],b[Kasparkova, J., Marini, V., Najajreh, Y., Gibson, D. & Brabec, V. (2003b). Biochemistry, 42, 6321-6332.]). The promising biological activity of trans-platinum(II) complexes encouraged us to synthesize and characterize a novel trans-platinum(II) complex with a benzamide ligand, namely trans-{PtCl2[HN=C(OH)C6H5]2}. Derivatives of benzamide are known to possess cytotoxic activity (Vernhet et al., 1997[Vernhet, L., Petit, J. Y. & Lang, F. (1997). J. Pharmacol. Exp. Ther. 283, 358-365.]; Rauko et al., 2001[Rauko, P., Novotny, L., Dovinova, I., Hunakova, L., Szekeres, T. & Jayaram, H. N. (2001). Eur. J. Pharm. Sci. 12, 387-394.]; Zhang et al., 2022[Zhang, J., Dai, J., Lan, X., Zhao, Y., Yang, F., Zhang, H., Tang, S., Liang, G., Wang, X. & Tang, Q. (2022). Eur. J. Med. Chem. 233, 114215.]) and such a ligand is interesting also owing to the occurrence of a hydroxyl group which can serve as a hydrogen-bond donor or acceptor.

Although the platinum drugs currently used for cancer treatment consist of platinum cations with oxidation state +2, in recent years platinum(IV) species have also been investigated. The interest in PtIV complexes arises from their greater inertness to ligands substitution compared with PtII counterparts, a feature that allows chemical modification of the ligands without breaking the metal–ligand bond. The slow exchange rate of ligands coordinated to PtIV plays an increasingly important role for the development of new nanotechnology for delivering platinum drugs to cancer cells (Dhar et al., 2011[Dhar, S., Kolishetti, N., Lippard, S. J. & Farokhzad, O. C. (2011). Proc. Natl Acad. Sci. USA, 108, 1850-1855.]; Min et al., 2010[Min, Y., Mao, C., Xu, D., Wang, J. & Liu, Y. (2010). Chem. Commun. 46, 8424-8426.]). The presence of two extra coordination sites can also be used in combination with other drugs, or for modifying biological targets other than DNA in the cell. In addition, platinum(IV) complexes are stable in the oxidizing extracellular environment and they can easily reach the platinum(II) oxidation state inside the cell (Wong & Giandomenico, 1999[Wong, E. & Giandomenico, C. M. (1999). Chem. Rev. 99, 2451-2466.]). The increasing interest for PtIV species prompted us to extend our investigation to a platinum(IV) complex, trans-[PtCl4(NH3){HN=C(OH)tBu}]. The bulky substituent (tertiary butyl group) in the amide ligand could potentiate the cellular uptake of the complex via passive diffusion through the cell membrane, because of the greater affinity for lipophilic environments, while the hydroxyl group would preserve the water solubility.

2. Experimental

2.1. trans-[PtCl2{HN=C(OH)C6H5}2] synthesis

Compound 1 was prepared by protonation of the K2{trans-[PtIICl2(H2NC(=O)C6H5)2]} salt: the reactant (0.6 g, 1 mmol) was dissolved in ice-cold water and treated with an excess of hydro­chloric acid (10 ml, 6 M). The yellow precipitate separated from the solution was collected by filtration of the mother liquor, washed with ice cold water and dried in a stream of dry air. Compound 1 was isolated, crystallized in chloro­form giving yellow lamellar crystals (Fig. 1[link]) and then characterized using NMR spectroscopy and X-ray diffraction.

[Figure 1]
Figure 1
Crystal of trans-[PtIICl2{HN=C(OH)C6H5}2] complex selected for X-ray diffraction measurement.

2.2. trans-[PtCl4(NH3){HN=C(OH)tBu}] synthesis

The trans-[PtIICl2(NH3)(NCtBu)] precursor [0.1780 g, 0.49 mmol, Mr (molecular weight) = 366 g mol−1] was suspended in chloro­form (30 ml) and Cl2 (2 ml), and stirred at 293 K for 30 min. The resulting solution was taken to dryness under reduced pressure, giving a yellow precipitate of trans-[PtIVCl4(NH3)(NCtBu)]. The obtained complex was treated with KOH, then neutralized with HCl. The complex was isolated, crystallized in a mixture of chloro­form/pentane, and characterized by NMR spectroscopy followed by X-ray diffraction.

2.3. X-ray single crystal determination

Reflections were collected on a Bruker AXS X8 APEX CCD diffractometer equipped with a four-circle Kappa goniometer and a 4K CCD detector (Mo Kα radiation). Data reduction and unit-cell refinement were carried out with the SAINT package (Bruker, 2003[Bruker (2003). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]). The reflections were indexed, integrated and corrected for Lorentz, polarization and absorption effects with the program SADABS (Sheldrick, 2010[Sheldrick, G. M. (2010). SADABS. University of Gottingen, Germany.]). All calculations and molecular graphics were carried out using SIR92 (Altomare et al., 1993[Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Camalli, M., Burla, M. C. & Polidori, G. (1993). Acta Cryst. A49, c55.]), PARST97 (Nardelli, 1995[Nardelli, M. (1995). J. Appl. Cryst. 28, 659-659.]), WinGX (Farrugia, 1999[Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837-838.]), CRYSTALS (Carruthers et al., 2003[Bruker (2003). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), MERCURY (Macrae et al., 2020[Macrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226-235.]) and ORTEP-3 for Windows packages (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]). Details of the experiment and crystal data are given in Table 1[link]. Selected bond lengths and angles are listed in Table 2[link].

Table 1
Experimental details

  Compound 1 Compound 2
Crystal data
Chemical formula trans-[PtCl2{HN=C(OH)C6H5}2] trans-[PtCl4(NH3){HN=C(OH)tBu}]
Mr 508.27 455.08
Crystal system, space group Triclinic, P[\overline{1}] Monoclinic, P21
Temperature (K) 293 293
a, b, c (Å) 4.1881 (1), 9.4591 (2), 10.1852 (2) 6.0583 (2), 12.1949 (4), 17.7364 (5)
α, β, γ (°) 102.793 (1), 91.304 (1), 100.914 (1) 90, 97.302 (2), 90
V (Å3) 385.48 (2) 1299.74 (7)
Z 1 4
Radiation type Mo Kα Mo Kα
No. of reflections for cell measurement 7402 9512
μ (mm−1) 9.45 11.59
Density (g cm−3) 2.181 2.325
Crystal size (mm) 0.36 × 0.06 × 0.02 Not measured
 
Data collection
Diffractometer Bruker AXS X8 APEX CCD Bruker AXS X8 APEX CCD
Absorption correction Multi-scan (SADABS) Multi-scan (SADABS)
Tmin, Tmax 0.03, 0.05 1.00, 1.00
θ range (°) for data collection 2.06–39.88 3.47–36.34
No. of measured, independent and observed [I > 2.0σ(I)] reflections 17097, 4472, 3466 32159, 6519, 5194
Rint 0.032 0.049
(sin θ/λ)max (Å−1) 0.902 0.834
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.028, 0.021, 1.09 0.029, 0.031, 1.03
No. of reflections 3134 5204
No. of parameters 107 319
No. of restraints 16 209
H-atom treatment H-atom parameters constrained H atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å−3) 0.61, −0.52 2.07, −1.13
Computer programs: COLLECT (Nonius, 2001[Nonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.]), DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]), CrysAlis (Oxford Diffraction, 2002[Oxford Diffraction (2002). CrysAlis. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.]), SUPERFLIP (Palatinus & Chapuis, 2007[Palatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786-790.]), CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487-1487.]), CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.]).

Table 2
Selected bond lengths and angles (Å, °) for compound 1 and 2

Compound 1
Cl1—Pt1 2.3084 (6) N1—C1 1.274 (3)
O1—C1 1.325 (6) N1—Pt1 2.0072 (18)
O2—C1 1.327 (7)    
O2—C1—C2 112.5 (6) N1—Pt1—Cl1 84.05 (6)
O1—C1—C2 114.8 (4) N1i—Pt1—Cl1i 84.05 (6)
O2—C1—N1 120.9 (6) N1—Pt1—Cl1i 95.95 (6)
O1—C1—N1 119.3 (6) N1i—Pt1—Cl1 95.95 (6)
N1—C1—C2 124.5 (2) C1—N1—Pt1 136.41 (17)
 
Compound 2
Cl5—Pt2 2.3204 (16) Cl1—Pt1 2.307 (3)
Cl6—Pt2 2.3070 (15) Cl2—Pt1 2.291 (3)
Cl7—Pt2 2.3041 (17) Cl3—Pt1 2.295 (3)
Cl8—Pt2 2.3228 (18) Cl4—Pt1 2.318 (2)
N3—Pt2 2.054 (5) N1—Pt1 2.038 (7)
N4—Pt2 2.022 (5) N2—Pt1 2.035 (6)
C6—N4 1.279 (7) C10—O10 1.373 (8)
C6—O21 1.322 (9) C11—O11 1.364 (10)
C6—O20 1.323 (9) C10—N2 1.166 (7)
    C11—N2 1.152 (8)
N3—Pt2—N4 176.5 (3) N1—Pt1—Cl1 87.9 (3)
N3—Pt2—Cl8 86.60 (19) N1—Pt1—Cl2 91.4 (3)
N4—Pt2—Cl8 93.60 (17) N1—Pt1—Cl3 88.0 (3)
N3—Pt2—Cl6 87.57 (16) N1—Pt1—Cl4 91.0 (3)
N4—Pt2—Cl6 88.94 (18) Cl4—Pt1—Cl3 178.93 (14)
Cl8—Pt2—Cl6 90.61 (7) Cl1—Pt1—Cl3 91.81 (16)
N3—Pt2—Cl7 90.67 (19) Cl3—Pt1—Cl2 89.53 (17)
N4—Pt2—Cl7 89.14 (17) Cl4—Pt1—Cl2 89.97 (15)
Cl8—Pt2—Cl7 177.27 (8) Cl1—Pt1—N2 92.3 (2)
Cl6—Pt2—Cl7 89.48 (7) Cl2—Pt1—N2 88.4 (2)
N3—Pt2—Cl5 89.81 (17) Cl3—Pt1—N2 93.3 (2)
N4—Pt2—Cl5 93.67 (18) Cl4—Pt1—N2 87.6 (2)
Cl8—Pt2—Cl5 90.13 (8) N1—Pt1—N2 178.6 (3)
Cl6—Pt2—Cl5 177.24 (7) Cl1—Pt1—Cl2 178.47 (16)
Cl7—Pt2—Cl5 89.65 (8) Cl4—Pt1—Cl1 88.68 (14)
N4—C6—O21 121.5 (6) O10—C10—N2 114.09 (10)
N4—C6—O20 121.1 (6) O11—C11—N2 114.05 (10)
    N2—C10—C2 134.04 (10)
    N2—C11—C2 134.04 (10)
    Pt1—N2—C10 141.3 (4)
    Pt1—N2—C11 140.2 (5)
Symmetry code: (i): −x + 1, −y + 2, −z.

The unit-cell parameters were calculated from all reflections. Anisotropic displacement parameters (ADPs) for hydrogen and all non-hydrogen atoms were refined isotropically and anisotropically, respectively. The crystal structure was solved using direct methods in space groups [P{\overline 1}] and P21 for compounds 1 and 2, respectively, and the models were refined using full-matrix least-squares.

2.3.1. Compound 1

The difference Fourier synthesis shows one maximum at the midpoint of two oxygen positions with the refinement resulting in grossly anisotropic displacement parameters corresponding to a `cigar-shaped' ellipsoid. The disorder is refined using the so-called split-atom model strategy. The two partial atoms are refined independently, even with the sum of their site occupancies constrained to unity (Fig. 2[link]). The hydrogen atoms were located by Fourier difference except for the hydrogen atoms located on oxygen sites which were placed at calculated positions. All hydrogen atoms were refined isotropically.

[Figure 2]
Figure 2
Oxygen splitting in compound 1. Color coding for atoms: red: oxygen; dark gray: carbon; violet: nitro­gen; light grey: platinum; green: chloride.
2.3.2. Compound 2

The asymmetric unit includes two disordered complexes: the disorder of the first complex (a) involves the methyl in the tertiary butyl group [–C(CH3)3] and the oxygen atom in the amide moiety (NCO). The split-atom model has been used to model the disorder (Fig. 3[link]). Since the hydrogen atoms bound to the split oxygen atoms have not been found by Fourier difference, they were added manually and refined isotropically. In the second complex (b) in the asymmetric unit of compound 2 shows an electron density symmetrically distributed around a a local plane through the N2 and C2 atoms of the pivalo­amide group. The disorder was modeled by splitting the C1 carbon atom and the tertiary butyl group (Fig. 4[link]).

[Figure 3]
Figure 3
Oxygen and methyl splitting in compound 2a. Color coding for atoms: red: oxygen; dark gray: carbon; violet: nitro­gen; light grey: platinum; green: chloride.
[Figure 4]
Figure 4
Amide ligand splitting in compound 2b. Color coding for atoms: red: oxygen; dark gray: carbon; violet: nitro­gen; light grey: platinum; green: chloride.

3. Results and discussion

3.1. NMR spectroscopy

3.1.1. Compound 1: platinum(II)

The H1-NMR spectrum was recorded on a Bruker Avance DPX 300 MHz WB instrument at 295 K in acetone-d6. 1H chemical shifts were referenced to TMS by using the residual protic peak of acetone-d6 as internal reference. The 1H-NMR spectrum (Fig. 5[link]) shows two broad signals at ∼11.08 ppm and ∼8.31 ppm assigned to the OH and NH protons in the amide ligand, respectively, and three aromatic proton contributions at 7.96 ppm, 7.68 ppm and 7.58 ppm from the ortho, para and meta protons, respectively.

[Figure 5]
Figure 5
1H-NMR spectrum of compound 1. Chemical shift (ppm): a δ[OH] ∼11.08, b δ[NH] ∼8.31, c δ[Ph(o)] ∼7.96, δ[Ph(p)] ∼7.68, δ[Ph(m)] ∼7.58. (m = meta, o = ortho, p = para).
3.1.2. Compound 2: platinum(IV)

1H-NMR spectrum was collected at 295 K in CDCl3. 1H chemical shifts were referenced to TMS by using the residual protic peak of CDCl3 as internal reference. The 1H-NMR spectrum (Fig. 6[link]) contains a sharp signal at ∼1.33 δ and a broad signal at ∼4.63 δ assigned to the tert-butyl group and NH3 protons, respectively, in good agreement with a previous work on a trans-PtIII complex with similar ligands {δ[tert-butyl] ∼1.20, δ[NH3] ∼5.00 in Vinci & Chateigner (2022[Vinci, D. & Chateigner, D. (2022). Acta Cryst. B78, 835-841.])}. Moreover, two single proton resonances at ∼6.90 δ and 10.25 δ can be assigned to the NH and OH groups in the amide moiety. It is worth noting that the shape of the hydroxyl proton peak depends upon the nature of R [–C(CH3)3 in compound 2 or —C6H5 in compound 1]: the signal is sharp for the tBu derivative and broader for the phenyl group. This feature may be explained by the chemical exchange process involving the hydroxyl proton and water impurities. The exchange rate is expected to increase with the acidity of the hydroxyl proton.

[Figure 6]
Figure 6
1H-NMR spectrum of compound 2. Chemical shift (ppm): a δ[OH] ∼10.25, b δ[NH] ∼6.9, c δ[NH3] ∼4.63 and d δ[tert-butyl] ∼1.33.

3.2. X-ray crystal structures

3.2.1. Compound 1: platinum(II)

The asymmetric unit comprises half a molecule of the trans-[PtCl2{HN=C(OH)C6H5}2] complex. The structure is composed of one platinum cation, coordinated by two chloride anions and two benzamide ligands. The central platinum atom lies on the crystallographic inversion center in a slightly distorted square planar coordination geometry (Fig. 7[link]). This distortion is due to the differences in the metal–ligand bond lengths as reported for analogous complexes (Fabijańska et al., 2015[Fabijańska, M., Studzian, K., Szmigiero, L., Rybarczyk-Pirek, A. J., Pfitzner, A., Cebula-Obrzut, B., Smolewski, P., Zyner, E. & Ochocki, J. (2015). Dalton Trans. 44, 938-947.]). The N1, C1, C2 and O1 ligand atoms are coplanar as expected owing to the sp2 hybridization of the N1 and C1 atoms linked with a double bond. The Pt—N bond distance length, 2.0072 (18) Å, agrees with previously reported values for trans-complexes with similar ligands [Pt—N from the literature: 2.01 (2)–2.067 (4) Å; Fabijańska et al., 2015[Fabijańska, M., Studzian, K., Szmigiero, L., Rybarczyk-Pirek, A. J., Pfitzner, A., Cebula-Obrzut, B., Smolewski, P., Zyner, E. & Ochocki, J. (2015). Dalton Trans. 44, 938-947.]; Grabner & Bukovec, 2015[Grabner, S. & Bukovec, P. (2015). Acta Chim. Slov. 62, 389-393.]; Cini et al., 1999[Cini, R., Cavaglioni, A., Intini, F. P., Fanizzi, F. P., Pacifico, C. & Natile, G. (1999). Polyhedron, 18, 1863-1868.]]. The lengths of the C1—N1, C1—O1 and C1—O2 bonds [1.274 (3), 1.325 (6) and 1.327 (7) Å, respectively] are shorter than those found for the corresponding single bonds, but larger than double bonds [from literature: C(sp3)—N(sp3) = 1.469 (14) Å, C(sp2)=N(sp2) = 1.279 (8) Å, C(sp3)—OH = 1.426 (11) Å, C(sp2)=O = 1.210 (8) Å; Allen et al., 1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L. & Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-S19.]]. This means that a double bond is delocalized over the N—C—O moiety. The same behavior has already been reported for N-coordinated amidato (Erxleben et al., 1994[Erxleben, A., Mutikainen, I. & Lippert, R. (1994). J. Chem. Soc. Dalton Trans. pp. 3667-3675]) and imino­ether ligands (Casas et al., 1991[Casas, J. M., Chisholm, M. H., Sicilia, M. V. & Streib, W. E. (1991). Polyhedron, 10, 1573-1578.]). The length of the platinum–chloride bond, 2.3084 (6) Å, is nearly the same as found in complexes with the same trans influence. For example, in trans-Pt(3-af)2Cl2 [where 3-af = 3-amino­flavone (3-amino-2-phenylchromen-4-one, C15H11NO2) the Pt—Cl bond is 2.298 (1) Å; in trans-[PtCl2(dmso)L] [where L = 3-(pyridin-2-yl­methyl)­oxazolidin-2-one], the Pt—Cl bonds are 2.2965 (9) and 2.3025 (8) Å, whereas in trans-[PtCl2{HN=C(OH)C(CH3)3}2] an average value of 2.299 (3) Å is observed (Fabijańska et al., 2015[Fabijańska, M., Studzian, K., Szmigiero, L., Rybarczyk-Pirek, A. J., Pfitzner, A., Cebula-Obrzut, B., Smolewski, P., Zyner, E. & Ochocki, J. (2015). Dalton Trans. 44, 938-947.]; Van Beusichem & Farrell, 1992[Van Beusichem, M. & Farrell, N. (1992). Inorg. Chem. 31, 634-639.]; Cini et al., 1999[Cini, R., Cavaglioni, A., Intini, F. P., Fanizzi, F. P., Pacifico, C. & Natile, G. (1999). Polyhedron, 18, 1863-1868.]). The Pt1—N1—C1 angle is ∼137 (2)°, which is well above the expected values (120°), in agreement with the values observed for trans-[PtCl2{HN=C(OH)C(CH3)3}2] and trans-[PtCl2{HN=C(OMe)tBu}2] complexes (Cini et al., 1999[Cini, R., Cavaglioni, A., Intini, F. P., Fanizzi, F. P., Pacifico, C. & Natile, G. (1999). Polyhedron, 18, 1863-1868.]). The benzamide plane and the platinum coordination plane, PtN2Cl2, make a dihedral angle of 20.86°. This orientation optimizes the intramolecular hydrogen bond interaction within the molecule.

[Figure 7]
Figure 7
ORTEP drawing of compound 1 with intramolecular hydrogen bond interactions: [O1⋯Cl1 2.978 Å, H12⋯Cl1 2.184 Å, O1—H12⋯Cl1 163.56°] and [O2⋯Cl1 2.956 Å, H21⋯Cl1 2.165 Å, O2—H21⋯Cl1 162.04°]. The ellipsoids enclose 30% probability. Color coding for atoms: white: hydrogen; green: chlorine; blue: nitro­gen; gray: carbon; red: oxygen. Symmetry code (i): −x + 1, −y + 2, −z.

The hydroxyl group points toward the chloride ligand resulting in an intramolecular hydrogen bond that stabilizes the complex (Fig. 7[link]).

The molecular crystal packing is mainly governed by π⋯π stacking interactions and van der Waals intermolecular forces, involving the benzene ring of adjacent molecules with an intermolecular distance of ∼3.62 Å (Sinnokrot & Sherrill, 2006[Sinnokrot, M. & Sherrill, C. D. (2006). J. Phys. Chem. A, 110, 10656-10668.]). The van der Waals intermolecular interactions involve hydrogen of the benzene ring and oxygen atom of the hydroxyl group [C7⋯O1A 3.280 (3) Å, H31⋯O2 2.613  (1) Å, C3—H31⋯O2 146.03 (8)°], resulting in the crystal packing shown in Fig. 8[link].

[Figure 8]
Figure 8
Molecular packing of compound 1, view normal to the (100). Color coding for atoms: white: hydrogen; green: chlorine; blue: nitro­gen; gray: carbon; red: oxygen.
3.2.2. Compound 2: platinum(IV)

The crystal structure features two enantiomers in the cell [Flack parameter = 0.47 (1)]. The PtIV atom has an octahedral coordination geometry with four chloride ligands and two nitro­gen atoms (with hybridization sp2 and sp3 for amide and ammine ligands, respectively) in trans configuration (Fig. 9[link]). The bond distances between platinum and ligands (Pt—N and Pt—Cl distances in Table 2[link]) are in good agreement with values found previously for compound 1 and in the literature for platinum(III) and platinum(II) complexes (Vinci & Chateigner, 2022[Vinci, D. & Chateigner, D. (2022). Acta Cryst. B78, 835-841.]; Fabijańska et al., 2015[Fabijańska, M., Studzian, K., Szmigiero, L., Rybarczyk-Pirek, A. J., Pfitzner, A., Cebula-Obrzut, B., Smolewski, P., Zyner, E. & Ochocki, J. (2015). Dalton Trans. 44, 938-947.]; Grabner & Bukovec, 2015[Grabner, S. & Bukovec, P. (2015). Acta Chim. Slov. 62, 389-393.]; Cini et al., 1999[Cini, R., Cavaglioni, A., Intini, F. P., Fanizzi, F. P., Pacifico, C. & Natile, G. (1999). Polyhedron, 18, 1863-1868.]; Van Beusichem & Farrell, 1992[Van Beusichem, M. & Farrell, N. (1992). Inorg. Chem. 31, 634-639.]). In the amide ligand, the C—N and C—O distances average 1.20 (7) Å and 1.13 (1) Å, respectively, due to the double bond delocalization over the N—C—O moiety as observed also for compound 1. The C6—N4—Pt2, Pt1—N2—C11 and Pt1—N2—C10 angles are 132.7 (5)°, 140.2 (5)° and 141.3 (4)°, respectively, similar to the angle found for compound 1. The larger angle is probably due to intramolecular hydrogen bonds involving the hydroxyl hydrogen and the chloride ligand (Fig. 10[link]). The bond angles within the coordination sphere deviate significantly from the ideal value of 90°. For instance, in compound 2 with the atom labeled Pt2 (Fig. 9[link]), two angles are particularly large [93.67 (19)° and 93.60 (17)°] for N4—Pt2—Cl5 and N4—Pt2—Cl8 angles, respectively) and two are particularly small [87.57 (16)° and 86.60 (19)°] for N3—Pt2—Cl6 and N3—Pt2—Cl8 angles, respectively). This feature is due to the hydrogen bond interactions between the hydroxyl group and the chloride ligands. The same behavior has been observed in the second enantiomer in the unit cell.

[Figure 9]
Figure 9
ORTEP diagram of two enantiomers of compound 2. The ellipsoids enclose 30% probability. Color coding for atoms: white: hydrogen; green: chlorine; blue: nitro­gen; gray: carbon; red: oxygen.
[Figure 10]
Figure 10
ORTEP drawing of two molecules of compound 2 linked by intramolecular hydrogen bonds (Table 3[link]). The ellipsoids enclose 30% probability. Color coding for atoms: white: hydrogen; green: chlorine; blue: nitro­gen; gray: carbon; red: oxygen.

The molecular packaging (Fig. 11[link]) is governed by hydrogen bonds and van der Waals interactions (Table 3[link]). The intermolecular hydrogen bonds are observed between amide and chloride ligands. The intermolecular van der Waals interactions occur between the tert-butyl groups and the chloride ligands.

Table 3
Intra and intermolecular hydrogen bonds, and intermolecular van der Waals interactions (Å, °) for compound 2

D—H⋯A H⋯A D⋯A D—H⋯A
Intramolecular hydrogen bonds
O10—H101⋯Cl3 1.93 2.90 (2) 179
O11—H111⋯Cl1 1.96 2.94 (5) 179
O10—H101⋯Cl3 2.01 2.96 (7) 159
O21—H211⋯Cl5 2.62 3.25 (3) 131
       
Intermolecular hydrogen bonds
N1—H12⋯Cl8i 2.74 3.60 (3) 166
N1—H13⋯Cl7ii 2.66 3.48 (1) 154
N3—H31⋯Cl7iii 2.73 3.57 (6) 158
N3—H32⋯Cl6iv 2.49 3.32 (2) 156
N3—H33⋯Cl4iii 2.54 3.25 (4) 139
       
Intermolecular van der Waals interactions
C40—H401⋯Cl1iii 2.68 3.46 (5) 139
C80—H803⋯Cl8ii 2.68 3.361 (2) 139
Symmetry codes: (i) −x, y + ½, −z; (ii) x − 1, y, z; (iii) x + 1, y, z; (iv) −x + 1, y − ½, −z.
[Figure 11]
Figure 11
ORTEP drawing of packing of compound 2 governed by intermolecular hydrogen bonds and van der Waals interactions. The ellipsoids enclose 30% probability. Atom color coding: white for hydrogen, green for chlorine, blue for nitro­gen, gray for carbon and red for oxygen.

4. Conclusions

For compound 1 we observed that the protonation of K2{trans-[PtCl2(H2NC(=O)C6H5)2]} salt in ice-cold water, treated with an excess of hydro­chloric acid, gives the new trans-[PtCl2{HN=C(OH)C6H5}2] complex stable at room temperature. Spectroscopic studies indicate that the benzamide ligand is present in compound 1. The X-ray structural determination confirmed that the central platinum(II) atom is four-coordinated via two nitro­gen atoms of the benzamide ligands and two chloride anions. The dihedral angle between PtCl2N2 and the benzene ring plane is 21 (1)°. The crystal lattice framework is governed by π⋯π and van der Waals intermolecular interactions.

Compound 2 was prepared by neutralization with HCl of a trans-[PtCl4(NH3)(NCtBu)] solution in KOH. As expected, the X-ray structure contains a platinum(IV) atom six-coordinated by an ammine, four chloride and a pivalamide ligands with trans configuration. NMR spectroscopy confirmed the presence of the pivalamide ligand and the octahedral geometry.

A common feature between these two structures is the occurrence of intramolecular hydrogen bonds between the hydroxyl group and the chloride ligand. The next step in this work is the evaluation of the cytotoxic effect of these new platinum compounds against human and murine cancer cell lines, as well as the toxicity towards healthy cells and these effects will be compared with those of other cisplatin compounds.

Supporting information

CCDC references: 2255221; 2255222

Crystal structure: contains datablocks global, 1, 2. DOI: https://doi.org/10.1107/S205252062300327X/yv5009sup1.cif

Structure factors: contains datablock 1. DOI: https://doi.org/10.1107/S205252062300327X/yv50091sup2.hkl

Structure factors: contains datablock 2. DOI: https://doi.org/10.1107/S205252062300327X/yv50092sup3.hkl


Computing details top

Data collection: COLLECT (Nonius, 2001) for (1); COLLECT (Nonius, 2001). for (2). For both structures, cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: CrysAlis, (Oxford Diffraction, 2002); program(s) used to solve structure: Superflip (Palatinus & Chapuis, 2007); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: CAMERON (Watkin et al., 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

(1) top
Crystal data top
C14H14Cl2N2O2PtZ = 1
Mr = 508.27F(000) = 240
Triclinic, P1Dx = 2.189 Mg m−3
a = 4.1881 (1) ÅMo Kα radiation, λ = 0.71073 Å
b = 9.4591 (2) ÅCell parameters from 7402 reflections
c = 10.1852 (2) Åθ = 4.1–39.5°
α = 102.793 (1)°µ = 9.45 mm−1
β = 91.304 (1)°T = 293 K
γ = 100.914 (1)°Prism, orange
V = 385.48 (2) Å30.36 × 0.06 × 0.02 mm
Data collection top
Bruker AXS X8 APEX CCD
diffractometer		3466 reflections with I > 2.0σ(I)
Graphite monochromatorRint = 0.032
ω/2θ scansθmax = 39.9°, θmin = 2.1°
Absorption correction: multi-scan
SADABS		h = −6→7
Tmin = 0.03, Tmax = 0.05k = −16→16
17097 measured reflectionsl = −16→18
4472 independent reflections
Refinement top
Refinement on FPrimary atom site location: other
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.028H-atom parameters constrained
wR(F2) = 0.021
S = 1.09(Δ/σ)max = 0.001
3134 reflectionsΔρmax = 0.61 e Å−3
107 parametersΔρmin = −0.52 e Å−3
16 restraints
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cl10.4874 (2)1.17763 (7)0.19493 (6)0.0550
O10.669 (9)0.6672 (8)0.0157 (19)0.07310.60 (7)
O20.812 (11)0.687 (3)−0.0020 (8)0.05980.40 (7)
N10.7347 (5)0.9066 (2)0.1212 (2)0.0443
C10.8032 (6)0.7799 (3)0.1157 (2)0.0426
C20.9654 (6)0.7386 (3)0.2280 (2)0.0402
C30.9921 (8)0.5922 (3)0.2159 (3)0.0523
C41.1403 (9)0.5511 (3)0.3202 (3)0.0620
C51.2598 (8)0.6541 (4)0.4367 (3)0.0595
C61.2382 (8)0.8006 (4)0.4493 (3)0.0571
C71.0896 (7)0.8427 (3)0.3451 (3)0.0492
Pt10.50001.00000.00000.0356
H310.90610.52080.13790.0633*
H411.15030.45130.31210.0743*
H511.35420.62480.50680.0720*
H611.32710.87240.52750.0681*
H711.08110.94360.35310.0589*
H110.82540.97000.19250.0542*
H120.56430.6933−0.04080.1209*0.5960
H210.78890.7247−0.06610.0821*0.4040
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0794 (4)0.0499 (3)0.0350 (2)0.0254 (3)−0.0079 (2)−0.0015 (2)
O10.116 (11)0.042 (2)0.052 (4)0.006 (3)−0.026 (5)0.0037 (19)
O20.109 (13)0.041 (5)0.034 (3)0.032 (6)−0.004 (4)0.003 (2)
N10.0539 (11)0.0412 (9)0.0361 (8)0.0141 (8)−0.0073 (8)0.0027 (7)
C10.0507 (12)0.0380 (10)0.0377 (10)0.0071 (9)0.0002 (8)0.0076 (8)
C20.0463 (11)0.0382 (10)0.037 (1)0.0093 (8)0.0050 (8)0.0107 (8)
C30.0715 (17)0.0392 (11)0.0477 (12)0.0156 (11)0.0022 (11)0.0091 (9)
C40.083 (2)0.0492 (14)0.0635 (17)0.0285 (14)0.0042 (15)0.0207 (13)
C50.0694 (18)0.0634 (17)0.0550 (15)0.0237 (14)−0.0007 (13)0.0248 (13)
C60.0687 (17)0.0559 (15)0.0467 (13)0.0138 (13)−0.0099 (12)0.0118 (11)
C70.0637 (15)0.0410 (11)0.0433 (11)0.0142 (10)−0.0053 (10)0.0081 (9)
Pt10.03862 (6)0.03513 (6)0.03130 (5)0.00815 (4)−0.00222 (4)0.00360 (4)
Geometric parameters (Å, º) top
Cl1—Pt12.3084 (6)C2—C71.386 (3)
O1—C11.325 (6)C3—C41.382 (4)
O1—H120.823C3—H310.935
O2—C11.327 (7)C4—C51.373 (5)
O2—H210.823C4—H410.938
N1—C11.274 (3)C5—C61.384 (4)
N1—Pt12.007 (2)C5—H510.927
N1—H110.859C6—C71.387 (4)
C1—C21.478 (3)C6—H610.941
C2—C31.389 (3)C7—H710.947
C1—O1—H12112.1C3—C4—H41119.3
C1—O2—H21112.1C5—C4—H41120.3
C1—N1—Pt1136.41 (17)C4—C5—C6120.1 (3)
C1—N1—H11111.5C4—C5—H51119.6
Pt1—N1—H11111.9C6—C5—H51120.4
O2—C1—O127.7 (5)C5—C6—C7119.9 (3)
O2—C1—N1120.9 (6)C5—C6—H61120.4
O1—C1—N1119.3 (6)C7—C6—H61119.6
O2—C1—C2112.5 (6)C6—C7—C2120.1 (2)
O1—C1—C2114.8 (4)C6—C7—H71119.6
N1—C1—C2124.5 (2)C2—C7—H71120.3
C1—C2—C3119.2 (2)N1—Pt1—N1i179.994
C1—C2—C7121.4 (2)N1—Pt1—Cl1i95.95 (6)
C3—C2—C7119.4 (2)N1i—Pt1—Cl1i84.05 (6)
C2—C3—C4120.1 (3)N1—Pt1—Cl184.05 (6)
C2—C3—H31120.1N1i—Pt1—Cl195.95 (6)
C4—C3—H31119.8Cl1i—Pt1—Cl1179.995
C3—C4—C5120.4 (3)
Symmetry code: (i) −x+1, −y+2, −z.
(2) top
Crystal data top
C5H14Cl4N2OPtZ = 4
Mr = 455.08F(000) = 848.008
Monoclinic, P21Dx = 2.325 Mg m−3
Hall symbol: P 2ybMo Kα radiation, λ = 0.71073 Å
a = 6.0583 (2) ÅCell parameters from 9512 reflections
b = 12.1949 (4) Åθ = 4.2–36.3°
c = 17.7364 (5) ŵ = 11.59 mm−1
β = 97.302 (2)°T = 293 K
V = 1299.74 (7) Å3Lamellar, yellow
Data collection top
Bruker AXS X8 APEX CCD
diffractometer		5194 reflections with I > 2.0σ(I)
Graphite monochromatorRint = 0.049
ω/2θ scansθmax = 36.3°, θmin = 3.5°
Absorption correction: multi-scan
SADABS		h = −10→3
Tmin = 1.00, Tmax = 1.00k = −20→20
32159 measured reflectionsl = −29→29
6519 independent reflections
Refinement top
Refinement on FHydrogen site location: difference Fourier map
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.029 Method, part 1, Chebychev polynomial, (Watkin, 1994, Prince, 1982) [weight] = 1.0/[A0*T0(x) + A1*T1(x) ··· + An-1]*Tn-1(x)]
where Ai are the Chebychev coefficients listed below and x = F /Fmax Method = Robust Weighting (Prince, 1982) W = [weight] * [1-(deltaF/6*sigmaF)2]2 Ai are: 0.968 0.427E-01 0.672
wR(F2) = 0.031(Δ/σ)max = 0.008
S = 1.03Δρmax = 2.07 e Å−3
5204 reflectionsΔρmin = −1.13 e Å−3
319 parametersAbsolute structure: Parsons, Flack & Wagner (2013), 0 Friedel Pairs
209 restraintsAbsolute structure parameter: 0.47 (1)
Primary atom site location: Other
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
Cl60.4509 (3)0.6162 (2)−0.00744 (10)0.0420
Cl7−0.0049 (3)0.4855 (2)−0.06676 (10)0.0435
Cl80.5883 (3)0.4232 (2)0.11958 (11)0.0480
C60.1131 (11)0.5401 (5)0.1710 (2)0.0418
C70.0216 (8)0.6276 (4)0.2174 (2)0.0434
N1−0.8144 (15)0.6668 (7)−0.1954 (4)0.0545
Cl2−0.4005 (6)0.7321 (3)−0.2721 (2)0.0867
N30.4606 (10)0.3752 (5)−0.0466 (3)0.0370
N40.1227 (9)0.5461 (5)0.0995 (3)0.0339
Cl1−0.9599 (5)0.4749 (3)−0.2975 (2)0.0823
Pt20.28636 (3)0.45696 (16)0.028055 (11)0.0272
Cl3−0.8990 (6)0.7261 (4)−0.36172 (18)0.0959
Cl4−0.4606 (5)0.4848 (3)−0.20833 (13)0.0749
Cl50.1251 (3)0.2928 (2)0.05842 (12)0.0482
O210.151 (6)0.4469 (12)0.2085 (8)0.04850.47 (7)
O200.225 (6)0.4641 (18)0.2132 (4)0.05230.53 (7)
Pt1−0.68097 (4)0.60491 (16)−0.286338 (12)0.0358
C50−0.665 (2)0.3765 (13)−0.5395 (8)0.09380.673 (11)
C30−0.390 (3)0.5191 (12)−0.5469 (8)0.09910.673 (11)
C10−0.5822 (12)0.5245 (6)−0.4404 (4)0.07260.685 (11)
O10−0.776 (2)0.5724 (13)−0.4736 (6)0.09620.685 (11)
C40−0.297 (3)0.3816 (12)−0.4568 (7)0.09480.673 (11)
N2−0.5425 (12)0.5410 (7)−0.3753 (4)0.0559
O11−0.636 (5)0.3742 (12)−0.3862 (10)0.08850.315 (11)
C41−0.393 (5)0.3336 (13)−0.4992 (9)0.09130.327 (11)
C31−0.299 (4)0.520 (2)−0.4966 (9)0.08330.327 (11)
C11−0.5640 (17)0.4682 (7)−0.4170 (5)0.07330.315 (11)
C2−0.4915 (14)0.4460 (7)−0.4948 (4)0.0785
C51−0.665 (3)0.472 (2)−0.5602 (7)0.08590.327 (11)
C1200.2298 (15)0.6876 (13)0.2587 (11)0.06110.69 (5)
C1210.220 (2)0.7083 (19)0.2392 (19)0.05060.31 (5)
C90−0.121 (3)0.7110 (11)0.1662 (4)0.04550.69 (5)
C91−0.172 (4)0.691 (2)0.1702 (8)0.04260.31 (5)
C80−0.120 (3)0.5790 (7)0.2758 (9)0.05360.69 (5)
C81−0.062 (6)0.5803 (8)0.2897 (12)0.04930.31 (5)
H501−0.71050.3194−0.50750.1400*0.673 (11)
H502−0.79090.4208−0.55790.1400*0.673 (11)
H503−0.60500.3440−0.58170.1400*0.673 (11)
H301−0.23220.5063−0.54230.1490*0.673 (11)
H302−0.41850.5937−0.53410.1490*0.673 (11)
H303−0.45540.5042−0.59810.1490*0.673 (11)
H401−0.18440.4319−0.43430.1419*0.673 (11)
H402−0.23680.3357−0.49360.1419*0.673 (11)
H403−0.34790.3361−0.41760.1420*0.673 (11)
H411−0.39540.2975−0.43590.1370*0.327 (11)
H412−0.51530.2860−0.54730.1370*0.327 (11)
H413−0.20800.3488−0.51570.1370*0.327 (11)
H311−0.32320.5663−0.54050.1250*0.327 (11)
H312−0.16770.4760−0.49910.1250*0.327 (11)
H313−0.27970.5636−0.45140.1250*0.327 (11)
H511−0.70250.5487−0.55950.1290*0.327 (11)
H512−0.60740.4549−0.60690.1290*0.327 (11)
H513−0.79570.4287−0.55640.1290*0.327 (11)
H12010.18320.74710.28840.0910*0.69 (5)
H12020.32020.71540.22190.0909*0.69 (5)
H12030.31530.63700.29180.0909*0.69 (5)
H12110.16490.78300.23360.0770*0.31 (5)
H12120.33300.69620.20580.0770*0.31 (5)
H12130.28210.69500.29160.0770*0.31 (5)
H901−0.16210.77040.19700.0679*0.69 (5)
H902−0.03550.73870.12840.0680*0.69 (5)
H903−0.25310.67590.14180.0679*0.69 (5)
H911−0.25010.73330.20380.0649*0.31 (5)
H912−0.11270.73830.13460.0650*0.31 (5)
H913−0.27270.63930.14310.0650*0.31 (5)
H801−0.17990.63760.30340.0800*0.69 (5)
H802−0.02820.53260.31070.0800*0.69 (5)
H803−0.24100.53620.25020.0800*0.69 (5)
H811−0.05130.63560.32850.0740*0.31 (5)
H8120.02950.51870.30750.0740*0.31 (5)
H813−0.21390.55660.27820.0740*0.31 (5)
H310.60400.3930−0.03870.0561*
H320.44530.3027−0.04150.0561*
H330.40710.3934−0.09370.0560*
H11−0.95300.6879−0.21020.0820*
H12−0.73400.7238−0.17650.0821*
H13−0.81380.6147−0.16020.0821*
H410.04810.60020.07810.0409*
H21−0.39680.5528−0.36590.0841*0.6603
H22−0.39680.5532−0.36600.0840*0.3438
H2110.21530.39340.18940.0720*0.47 (7)
H2010.36910.44590.19420.0799*0.53 (7)
H101−0.81820.6233−0.43630.1145*0.685 (11)
H111−0.74320.4071−0.35690.1068*0.315 (11)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl60.0540 (9)0.0269 (6)0.0469 (8)−0.0116 (6)0.0136 (7)−0.0004 (6)
Cl70.0347 (7)0.0544 (10)0.0406 (7)−0.0013 (6)0.0015 (6)0.0026 (6)
Cl80.0361 (7)0.0584 (10)0.0487 (9)0.0048 (7)0.0021 (6)0.0099 (8)
C60.050 (3)0.042 (3)0.036 (2)0.009 (2)0.013 (2)0.003 (2)
C70.041 (3)0.054 (3)0.035 (2)0.005 (2)0.005 (2)−0.010 (2)
N10.074 (5)0.049 (4)0.046 (3)0.004 (3)0.030 (3)−0.004 (3)
Cl20.0908 (19)0.0780 (18)0.101 (2)−0.0402 (16)0.0513 (17)−0.0372 (17)
N30.045 (3)0.030 (2)0.040 (3)−0.002 (2)0.020 (2)−0.006 (2)
N40.032 (2)0.035 (2)0.036 (2)0.0044 (19)0.0090 (19)−0.003 (2)
Cl10.0615 (13)0.084 (2)0.105 (2)−0.0292 (14)0.0255 (13)−0.0172 (17)
Pt20.02760 (7)0.02382 (6)0.03147 (8)−0.00072 (8)0.00928 (6)−0.00026 (8)
Cl30.105 (2)0.117 (3)0.0722 (17)0.065 (2)0.0371 (16)0.0476 (18)
Cl40.0705 (13)0.115 (3)0.0418 (9)0.0419 (15)0.0183 (9)0.0226 (12)
Cl50.0560 (10)0.0303 (7)0.0638 (11)−0.0096 (6)0.0293 (8)0.0020 (7)
O210.056 (8)0.054 (6)0.040 (5)0.010 (6)0.021 (5)0.012 (5)
O200.063 (8)0.050 (6)0.048 (5)0.019 (6)0.023 (4)0.011 (5)
Pt10.03948 (11)0.04067 (12)0.02912 (9)0.00033 (9)0.01137 (8)0.00150 (9)
C500.097 (8)0.111 (10)0.070 (7)0.008 (8)0.000 (7)−0.031 (8)
C300.106 (9)0.112 (10)0.080 (8)0.005 (9)0.013 (7)−0.013 (8)
C100.082 (6)0.091 (6)0.045 (4)0.016 (5)0.010 (4)−0.017 (5)
O100.100 (7)0.119 (9)0.064 (6)0.028 (7)−0.011 (6)−0.015 (6)
C400.100 (8)0.113 (10)0.070 (8)0.016 (8)0.004 (7)−0.016 (8)
N20.052 (3)0.075 (5)0.043 (3)0.002 (3)0.016 (3)−0.015 (3)
O110.102 (11)0.091 (10)0.077 (10)0.003 (10)0.026 (9)−0.015 (9)
C410.102 (10)0.102 (10)0.070 (9)0.012 (9)0.010 (9)−0.019 (10)
C310.090 (9)0.107 (10)0.055 (9)0.009 (8)0.018 (9)−0.029 (9)
C110.080 (7)0.087 (7)0.056 (6)0.003 (7)0.021 (6)−0.024 (6)
C20.085 (5)0.101 (6)0.051 (3)0.011 (5)0.014 (3)−0.029 (4)
C510.091 (10)0.107 (11)0.059 (8)0.008 (10)0.004 (8)−0.027 (9)
C1200.062 (6)0.070 (7)0.049 (6)−0.006 (6)−0.004 (5)−0.007 (6)
C1210.047 (8)0.058 (8)0.043 (8)0.002 (7)−0.012 (7)−0.015 (8)
C900.048 (5)0.043 (5)0.046 (5)0.008 (5)0.006 (4)0.002 (4)
C910.040 (8)0.050 (8)0.039 (8)0.003 (7)0.007 (6)−0.003 (7)
C800.052 (6)0.076 (7)0.034 (4)0.008 (5)0.007 (4)−0.008 (4)
C810.040 (8)0.069 (9)0.041 (7)0.015 (7)0.014 (7)−0.010 (7)
Geometric parameters (Å, º) top
Cl6—Pt22.3070 (15)C40—C21.501 (9)
Cl7—Pt22.3041 (17)C40—H4010.966
Cl8—Pt22.3228 (18)C40—H4020.967
C6—C71.497 (5)C40—H4030.968
C6—N41.279 (7)N2—H210.889
C6—O211.322 (9)N2—H220.889
C6—O201.323 (9)N2—C111.152 (8)
C7—C1201.558 (9)N2—H210.889
C7—C901.551 (8)N2—H220.889
C7—C801.547 (8)O11—C111.364 (10)
C7—C1211.561 (10)O11—H1110.970
C7—C911.555 (10)C41—C21.501 (10)
C7—C811.548 (10)C41—H4111.207
N1—Pt12.038 (7)C41—H4121.207
N1—H110.885C41—H4131.207
N1—H120.889C31—C21.475 (10)
N1—H130.890C31—H3110.961
Cl2—Pt12.291 (3)C31—H3120.962
N3—Pt22.054 (5)C31—H3130.961
N3—H310.889C11—C21.525 (7)
N3—H320.894C2—C511.498 (10)
N3—H330.885C51—H5110.961
N4—Pt22.022 (5)C51—H5120.962
N4—H410.860C51—H5130.962
Cl1—Pt12.307 (3)C120—H12010.960
Pt2—Cl52.3204 (16)C120—H12020.964
Cl3—Pt12.295 (3)C120—H12030.957
Cl4—Pt12.318 (2)C121—H12110.970
O21—H2110.853C121—H12120.973
O20—H2010.999C121—H12130.973
Pt1—N22.035 (6)C90—H9010.959
C50—C21.496 (9)C90—H9020.960
C50—H5010.960C90—H9030.961
C50—H5020.957C91—H9110.960
C50—H5030.960C91—H9120.960
C30—C21.472 (9)C91—H9130.961
C30—H3010.963C80—H8010.961
C30—H3020.958C80—H8020.963
C30—H3030.961C80—H8030.963
C10—O101.373 (8)C81—H8110.960
C10—N21.166 (7)C81—H8120.962
C10—C21.512 (7)C81—H8130.963
O10—H1010.966
C7—C6—N4124.8 (4)H401—C40—H403109.9
C7—C6—O21112.80 (10)H402—C40—H403109.6
N4—C6—O21121.5 (6)Pt1—N2—C10141.3 (4)
C7—C6—O20112.78 (10)Pt1—N2—H21106.9
N4—C6—O20121.1 (6)C10—N2—H21106.8
O21—C6—O2021.6 (9)Pt1—N2—H22106.8
C6—C7—C120105.02 (9)C10—N2—H22106.7
C6—C7—C90111.29 (9)H21—N2—H220.4
C120—C7—C90108.92 (9)Pt1—N2—C11140.2 (5)
C6—C7—C80111.84 (9)Pt1—N2—H21106.9
C120—C7—C80110.58 (9)C11—N2—H21105.9
C90—C7—C80109.11 (9)Pt1—N2—H22106.8
C6—C7—C121105.00 (9)C11—N2—H22106.0
C6—C7—C91111.29 (9)H21—N2—H220.4
C121—C7—C91108.90 (9)C11—O11—H11197.9
C6—C7—C81111.86 (9)C2—C41—H411103.5
C121—C7—C81110.58 (9)C2—C41—H412105.2
C91—C7—C81109.12 (9)H411—C41—H412113.7
Pt1—N1—H11109.3C2—C41—H413105.1
Pt1—N1—H12109.6H411—C41—H413113.9
H11—N1—H12109.8H412—C41—H413114.0
Pt1—N1—H13108.9C2—C31—H311109.8
H11—N1—H13109.5C2—C31—H312109.0
H12—N1—H13109.8H311—C31—H312109.5
Pt2—N3—H31110.6C2—C31—H313109.5
Pt2—N3—H32110.3H311—C31—H313109.6
H31—N3—H32109.7H312—C31—H313109.4
Pt2—N3—H33109.2O11—C11—N2114.05 (10)
H31—N3—H33108.7O11—C11—C2110.83 (10)
H32—N3—H33108.3N2—C11—C2134.04 (10)
C6—N4—Pt2132.7 (5)C10—C2—C40111.83 (9)
C6—N4—H41113.2C10—C2—C50114.09 (9)
Pt2—N4—H41114.1C40—C2—C50113.59 (9)
N3—Pt2—N4176.5 (3)C10—C2—C30103.35 (9)
N3—Pt2—Cl886.60 (19)C40—C2—C30103.48 (9)
N4—Pt2—Cl893.60 (17)C50—C2—C30109.39 (9)
N3—Pt2—Cl687.57 (16)C11—C2—C41111.79 (9)
N4—Pt2—Cl688.94 (18)C11—C2—C31103.36 (9)
Cl8—Pt2—Cl690.61 (7)C41—C2—C31103.48 (9)
N3—Pt2—Cl790.67 (19)C11—C2—C51114.12 (9)
N4—Pt2—Cl789.14 (17)C41—C2—C51113.59 (9)
Cl8—Pt2—Cl7177.27 (8)C31—C2—C51109.39 (9)
Cl6—Pt2—Cl789.48 (7)C2—C51—H511109.9
N3—Pt2—Cl589.81 (17)C2—C51—H512108.9
N4—Pt2—Cl593.67 (18)H511—C51—H512109.7
Cl8—Pt2—Cl590.13 (8)C2—C51—H513109.3
Cl6—Pt2—Cl5177.24 (7)H511—C51—H513109.7
Cl7—Pt2—Cl589.65 (8)H512—C51—H513109.3
C6—O21—H211121.0C7—C120—H1201109.6
C6—O20—H201111.9C7—C120—H1202110.1
N1—Pt1—Cl491.0 (3)H1201—C120—H1202109.7
N1—Pt1—Cl187.9 (3)C7—C120—H1203109.2
Cl4—Pt1—Cl188.68 (14)H1201—C120—H1203108.9
N1—Pt1—Cl388.0 (3)H1202—C120—H1203109.4
Cl4—Pt1—Cl3178.93 (14)C7—C121—H1211109.0
Cl1—Pt1—Cl391.81 (16)C7—C121—H1212109.5
N1—Pt1—Cl291.4 (3)H1211—C121—H1212109.8
Cl4—Pt1—Cl289.97 (15)C7—C121—H1213109.0
Cl1—Pt1—Cl2178.47 (16)H1211—C121—H1213109.8
Cl3—Pt1—Cl289.53 (17)H1212—C121—H1213109.7
N1—Pt1—N2178.6 (3)C7—C90—H901109.1
Cl4—Pt1—N287.6 (2)C7—C90—H902109.3
Cl1—Pt1—N292.3 (2)H901—C90—H902109.5
Cl3—Pt1—N293.3 (2)C7—C90—H903110.0
Cl2—Pt1—N288.4 (2)H901—C90—H903109.4
C2—C50—H501109.4H902—C90—H903109.5
C2—C50—H502109.7C7—C91—H911109.4
H501—C50—H502109.6C7—C91—H912109.6
C2—C50—H503109.7H911—C91—H912109.7
H501—C50—H503109.0C7—C91—H913109.6
H502—C50—H503109.4H911—C91—H913109.3
C2—C30—H301109.8H912—C91—H913109.4
C2—C30—H302109.0C7—C80—H801109.5
H301—C30—H302109.9C7—C80—H802109.2
C2—C30—H303108.9H801—C80—H802109.5
H301—C30—H303109.5C7—C80—H803110.2
H302—C30—H303109.7H801—C80—H803109.3
O10—C10—N2114.09 (10)H802—C80—H803109.1
O10—C10—C2110.83 (10)C7—C81—H811109.5
N2—C10—C2134.04 (10)C7—C81—H812109.2
C10—O10—H101105.5H811—C81—H812109.3
C2—C40—H401109.1C7—C81—H813110.0
C2—C40—H402110.0H811—C81—H813109.6
H401—C40—H402109.7H812—C81—H813109.3
C2—C40—H403108.7
 

Acknowledgements

The authors thank the University of Bari, Italy, and gratefully acknowledge Professor F. P. Intini for the technical support during the NMR data collection. Open access funding enabled and organized by Projekt DEAL.

References

First citationAllen, F. H., Kennard, O., Watson, D. G., Brammer, L. & Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–S19.  CrossRef Web of Science Google Scholar
 First citationAltomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Camalli, M., Burla, M. C. & Polidori, G. (1993). Acta Cryst. A49, c55.  CrossRef Web of Science IUCr Journals Google Scholar
 First citationBetteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487–1487.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationBoulikas, T., Pantos, A., Bellis, E. & Christofis, P. (2007). Cancer Ther. 5, 537–583.  Google Scholar
 First citationBruker (2003). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
 First citationCasas, J. M., Chisholm, M. H., Sicilia, M. V. & Streib, W. E. (1991). Polyhedron, 10, 1573–1578.  CSD CrossRef CAS Web of Science Google Scholar
 First citationCini, R., Cavaglioni, A., Intini, F. P., Fanizzi, F. P., Pacifico, C. & Natile, G. (1999). Polyhedron, 18, 1863–1868.  Web of Science CSD CrossRef CAS Google Scholar
 First citationDhar, S., Kolishetti, N., Lippard, S. J. & Farokhzad, O. C. (2011). Proc. Natl Acad. Sci. USA, 108, 1850–1855.  Web of Science CrossRef CAS PubMed Google Scholar
 First citationErxleben, A., Mutikainen, I. & Lippert, R. (1994). J. Chem. Soc. Dalton Trans. pp. 3667–3675  CrossRef Web of Science Google Scholar
 First citationFabijańska, M., Studzian, K., Szmigiero, L., Rybarczyk-Pirek, A. J., Pfitzner, A., Cebula-Obrzut, B., Smolewski, P., Zyner, E. & Ochocki, J. (2015). Dalton Trans. 44, 938–947.  Web of Science PubMed Google Scholar
 First citationFarrell, N., Kelland, L. R., Roberts, J. D. & Van Beusichem, M. (1992). Cancer Res. 52, 5065–5072.  PubMed CAS Web of Science Google Scholar
 First citationFarrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838.  CrossRef CAS IUCr Journals Google Scholar
 First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationGiaccone, G. (2000). Drugs, 59, 9–17.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationGrabner, S. & Bukovec, P. (2015). Acta Chim. Slov. 62, 389–393.  Web of Science CrossRef CAS PubMed Google Scholar
 First citationHeffeter, P., Jungwirth, U., Jakupec, M., Hartinger, C., Galanski, M., Elbling, L., Micksche, M., Keppler, B. & Berger, W. (2008). Drug Resist. Updat. 11, 1–16.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationJakupec, M. A., Galanski, M. & Keppler, B. K. (2003). Rev. Physiol. Biochem. Pharmacol. 146, 1–54.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationKasparkova, J., Marini, V., Najajreh, Y., Gibson, D. & Brabec, V. (2003b). Biochemistry, 42, 6321–6332.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationKasparkova, J., Novakova, O., Farrell, N. & Brabec, V. (2003a). Biochemistry, 42, 792–800.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationKelland, L. R. (2007). Nat. Rev. Cancer, 7, 573–584.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationKuo, M. T., Chen, H. H., Song, I. S., Savaraj, N. & Ishikawa, T. (2007). Cancer Metastasis Rev. 26, 71–83.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationLippert, B. (1999). Cisplatin Chemistry and Biochemistry of a Leading Anticancer Drug. New York: Wiley-VCH.  Google Scholar
 First citationMacrae, C. F., Sovago, I., Cottrell, S. J., Galek, P. T. A., McCabe, P., Pidcock, E., Platings, M., Shields, G. P., Stevens, J. S., Towler, M. & Wood, P. A. (2020). J. Appl. Cryst. 53, 226–235.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationMin, Y., Mao, C., Xu, D., Wang, J. & Liu, Y. (2010). Chem. Commun. 46, 8424–8426.  Web of Science CrossRef CAS Google Scholar
 First citationMontero, E. I., Díaz, S., González-Vadillo, A. M., Pérez, J. M., Alonso, C. & Navarro-Ranninger, C. (1999). J. Med. Chem. 42, 4264–4268.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationNardelli, M. (1995). J. Appl. Cryst. 28, 659–659.  CrossRef CAS IUCr Journals Google Scholar
 First citationNonius (2001). COLLECT. Nonius BV, Delft, The Netherlands.  Google Scholar
 First citationOberoi, H. S., Nukolova, N. V., Kabanov, A. V. & Bronich, T. K. (2013). Adv. Drug Deliv. Rev. 65, 1667–1685.  Web of Science CrossRef CAS PubMed Google Scholar
 First citationOtwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.  Google Scholar
 First citationOxford Diffraction (2002). CrysAlis. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.  Google Scholar
 First citationPalatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786–790.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationRabik, C. A. & Dolan, M. E. (2007). Cancer Treat. Rev. 33, 9–23.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationRauko, P., Novotny, L., Dovinova, I., Hunakova, L., Szekeres, T. & Jayaram, H. N. (2001). Eur. J. Pharm. Sci. 12, 387–394.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationReedijk, J. (2011). Pure Appl. Chem. 83, 1709–1719.  Web of Science CrossRef CAS Google Scholar
 First citationRosenberg, B., Van Camp, L. & Krigas, T. (1965). Nature, 205, 698–699.  CrossRef PubMed CAS Web of Science Google Scholar
 First citationSheldrick, G. M. (2010). SADABS. University of Gottingen, Germany.  Google Scholar
 First citationSinnokrot, M. & Sherrill, C. D. (2006). J. Phys. Chem. A, 110, 10656–10668.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationSteward, D. J. (2007). Crit. Rev. Oncol. Hematol. 63, 12–31.  Web of Science PubMed Google Scholar
 First citationVan Beusichem, M. & Farrell, N. (1992). Inorg. Chem. 31, 634–639.  CSD CrossRef CAS Web of Science Google Scholar
 First citationVernhet, L., Petit, J. Y. & Lang, F. (1997). J. Pharmacol. Exp. Ther. 283, 358–365.  CAS PubMed Web of Science Google Scholar
 First citationVinci, D. & Chateigner, D. (2022). Acta Cryst. B78, 835–841.  Web of Science CSD CrossRef IUCr Journals Google Scholar
 First citationWatkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.  Google Scholar
 First citationWiltshaw, E. (1979). Plat. Met. Rev. 23, 90–98.  CAS Google Scholar
 First citationWong, E. & Giandomenico, C. M. (1999). Chem. Rev. 99, 2451–2466.  Web of Science CrossRef PubMed CAS Google Scholar
 First citationZhang, J., Dai, J., Lan, X., Zhao, Y., Yang, F., Zhang, H., Tang, S., Liang, G., Wang, X. & Tang, Q. (2022). Eur. J. Med. Chem. 233, 114215.  Web of Science CrossRef PubMed Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206
Volume 79| Part 3| June 2023| Pages 213-219
https://doi.org/10.1107/S205252062300327X
Follow Acta Cryst. B
Sign up for e-alerts
E-alerts
Follow Acta Cryst. on Twitter
Twitter
Follow us on facebook
Facebook
Sign up for RSS feeds
RSS