Reaction Of K2PtCl4 Research Articles

A novel Pt2+ complex containing 1,4-benzodioxan-6-amine: Stability, DNA binding, and antitumor effects against human breast cancer cells

In this work, a new platinum(II) complex was prepared by the reaction of K2PtCl4 with 1,4-benzodioxan-6-amine (bda) at room temperature in the molar ratio 2:1 (L:M). The complex was characterized by physicochemical (elemental analysis, TGA/DTA, and conductivity measurements) and spectroscopic methods (UV–Vis, FTIR, 1H, 13C and 195Pt NMR). According to the spectroscopic data, two bda ligands coordinate to the platinum ion in a monodentate manner through the nitrogen atom to give the complex cis-[PtCl2(bda)2]. Stability studies were carried out under different conditions and showed that the complex is stable in pure DMF, although it undergoes slow solvolysis in DMSO. The interaction of this complex with calf thymus DNA (CT-DNA) was studied using circular dichroism (CD), electronic absorption and fluorescence spectroscopy. The complex binds to CT-DNA with a Kb value of 1.06 ​× ​103 ​M−1 and according to data from CD and fluorescence spectroscopy, appears to interact with DNA by electrostatic forces and or other no intercalative binding mode. Compared to cisplatin, the complex exhibited good cytotoxic activity and selectivity against the MCF-7 tumor cell line, displaying an IC50 value of 17.33 ​± ​1.1 ​μM, as well as inhibited MCF-7 ​cells migration.

Three-Photon AIE Pt(II) Complexes as Cysteine-Targeting Theranostic Agents for Tumor Imaging and Chemotherapy

Herein, we have synthesized a series of three-photon fluorescent Pt(II) complexes targeting a tumor-associated biothiol, cysteine (Cys), which allows it to be detected without any interference from other intracellular proteins. We focused on how to significantly improve the fluorescence response of Cys via regulating the recognition units in probes. The reaction of K2PtCl4 with L-CH3 or L-COOEt in DMSO solution gave Lyso-Pt-CH3 and Lyso-Pt-COOEt, respectively, which present four-coordinated square-planar geometries in mononuclear structures. Lyso-Pt-CH3 consists of a Cys aptamer labeled with typical aggregation-induced emission (AIE) characteristics, which shows strong three-photon absorption cross section (3PA) only in the presence of Cys. It was found that Lyso-Pt-CH3 displayed a perfect signal-to-noise ratio for imaging lysosomes and for rapid detection of Cys. Using Lyso-Pt-CH3, Cys-related cellular mechanisms were proposed. We confirm that cystine (Cyss) could be absorbed in cells through cystine/glutamate antiporters (system xc-) and is then converted to Cys under the effect of enzymes. All of these suggest that Lyso-Pt-CH3 might be a potential candidate as a simple and straightforward biomarker of lysosome-related Cys in vitro. Lyso-Pt-CH3 can effectively identify tumor tissues with excessive levels of Cys. Lyso-Pt-CH3 also showed excellent antitumor activity than cisplatin. This work provides a novel strategy for the rational design of controllably activated and Cys-targeted Pt(II) anticancer prodrugs for clinical diagnosis and treatment.

Synthesis, characterization and anticancer properties of platinum(II) complexes bearing chiral azomethine ligands

AbstractPt(II) complexes bearing one N‐salicylidene‐(S)‐1‐phenylethylamine [HL(S)] or N‐salicylidene‐(R)‐1‐phenylethylamine [HL(R)] were synthesized and characterized by electrospray ionization mass spectroscopy (ESI‐MS), Fourier‐transform infrared (FT‐IR), nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopies. The results of the micro‐analytic and spectroscopic methods disclosed that the reaction of K2PtCl4 with the chiral azomethine ligand in DMSO produced both trans‐ and cis‐[Pt(II)L(DMSO)Cl]. Then only trans‐[Pt(II)L(DMSO)Cl] isomers in Na2CO3 solution can transform to Pt(II) complexes 3 in coordination of the ligands to platinum as tridentate C,N,O‐donors. The photophysical properties of obtained platinum(II) complexes were studied by UV‐visible and luminescent spectra. The results showed that they all exhibited emission in the visible region. Anticancer properties in vitro of obtained Pt(II) complexes were scaned for KB and HepG‐2 cancer cell lines. They had good activity for the tested cancer cells. The cis‐Pt(II) complexes possessed higher anticancer activity than trans‐Pt(II) complexes and R‐enantiomers were found to be more cytotoxic than S‐enantiomers.

Synthesis and characterization of platinum(II) and palladium(II) diphosphine complexes with heterocyclic N-acetamide or saccharinate ligands

Abstract New palladium(II) and platinum(II) 1,1′-bis(diphenylphosphino) ferrocene (dppf) complexes with heterocyclic N-acetamide co-ligands [Pt(κ1-O-amp)(κ1-N-amp)(κ2-dppf)], [M(κ2-dap)(κ2-dppf)], (M= Pd, Pt, ampH = N-(2-pyridyl-3-methyl)acetamide, dapyH2 = 2,6-diacetamidopyridine) have been prepared and characterized. The salts K2[PtCl2(sac)2] and Na2[PdCl2(sac)2] have been prepared in excellent yield from the reactions of K2PtCl4 or Na2PdCl4 with Nasac in H2O or MeOH, respectively. Furthermore, the reaction products of the newly prepared salt, K2[PtCl2(sac)2] with diphosphines Ph2P(CH2)nPPh2 (n = 1–4), have been investigated.

Synthesis and Optoelectronic Properties of a Pt(II) Complex with 2-Pyridin-2-Yl-1,3-Thiazole-4-Carboxylic Acid

A carboxyl functionalized Pt(II) complex PtC9H6N2O2SCl2 (I) has been synthesized by the coordination reaction of K2PtCl4 with 2-pyridin-2-yl-1,3-thiazole-4-carboxylic acid. The absorption property and photosensitizing performance of I has been studied. Through assembling the dye-sensitized solar cells (DSSCs) based on complex I, a weak solar-energy-to-electricity conversion is presented. Additionally, when complex I was solved in DMF solution, a novel complex PtC9H7N2O3SCl (II) could be obtained. The structure of II has been confirmed by the single-crystal X-ray diffraction (CIF file CCDC no. 1538911).

Anti-trypanosomatid activity of platinum–sterol hydrazone imidazoline complexes

In the search for effective and less toxic drugs against Leishmania mexicana and Trypanosoma cruzi parasites, two new complexes trans-[Pt(Him1)2(Cl)2] (1) and trans-[Pt(Him2)2(Cl)2] (2) were synthesized by the reactions of K2PtCl4 with sterol hydrazone ligands 20-hydrazone-imidazoline-2-yl-5α-pregnan-3β-ol (Him1) and 22-hydrazone-imidazoline-2-yl-chol-5-ene-3β-ol (Him2). The complexes were characterized by a combination of physicochemical and spectroscopic methods. The ligands and their platinum complexes were evaluated in vitro against promastigotes of L. mexicana and epimastigotes of T. cruzi. Both the free sterol hydrazones and their platinum complexes at 10 µM final concentration induced a potent leishmanicidal activity (LD100 ≤ 48 h). Trypanostatic effect (IC50 ≤ 72 h) was observed with Him1, trans-[Pt(Him1)2(Cl)2] (1) and trans-[Pt(Him2)2(Cl)2] (2), but at 5 µM concentration for the latter. Free Him2 at 5 µM concentration proved to be a potent trypanocidal agent (LD50, 24 h), reaching LD100 after 72 h of exposure. Additionally, Him2 and its platinum derivative when tested against human lymphocytes at twice the anti-Trypanosoma effective concentration did not show cytotoxicity. These findings demonstrate the potent anti-trypanosomatid activity of these sterol hydrazone imidazolines and their platinum complexes, and especially the low cytotoxicity of Him2 and trans-[Pt(Him2)2(Cl)2] against human immunocompetent cells.

Role of anagostic interactions in cycloplatination of telluroethers: Synthesis and structural characterization

Reactions of K2PtCl4 with TeRRʹ gave complexes of composition [PtCl2(TeRRʹ)2] (R/Rʹ = Ph2(1a), o-tol2 (1b), Mes2(1c), Ph/Mes (1d), o-tol/Mes (1e)). The complex [PtCl2(TeMes2)2] in refluxing THF afforded a mononuclear cyclometalated complex [PtCl{(CH2C6H2Me2-4,6)TeMes}(TeMes2)] (2). It tends to remain in equilibrium with a binuclear derivative [Pt(μ-Cl){(CH2C6H2Me2-4,6)TeMes}]2 (3) in CDCl3 solution. The complexes 1d and 1e did not undergo cyclometalation reaction under similar reaction conditions. The 2 on treatment with PPh3 gave [PtCl{(CH2C6H2Me2-4,6)TeMes}(PPh3)] (4). All the complexes have been characterized by elemental analysis and NMR (1H, 31P, 125Te, 195Pt) spectroscopy. Anagostic interactions have been recognised for facilitation of cyclometalation reactions. The molecular structures of trans-[PtCl2(TeMes2)2] (1c), trans-[PtCl2(PhTeMes)2] (1d), trans-[PtCl2(o-tolTeMes)2] (1e), [PtCl{(CH2C6H2Me2-4,6)TeMes}(TeMes2)] (2) and [PtCl{(CH2C6H2Me2-4,6)TeMes}(PPh3)] (4) have been established unambiguously by single crystal X-ray diffraction analyses.

Platinum(II) and palladium(II) aryl-thiosemicarbazone complexes: synthesis, characterization, molecular modeling, cytotoxicity, and antimicrobial activity

Platinum(II) and palladium(II) complexes [ML2] have been isolated from reaction of K2PtCl4 or K2PdCl4 and ligands (L) derived from thiosemicarbazones. The complexes were characterized by elemental analysis, Raman, IR, and NMR spectroscopy. In addition, quantum mechanical calculations were used to predict their structures and spectroscopic properties. For the first time, theoretical calculations using 195Pt NMR data were used to support the suggested structures. The results indicate that the thionic sulfur and the azomethine nitrogen are bonded to the metal ion in a trans configuration. Antibacterial activities and cytotoxicities of the complexes to B16-F10 and CT26.WT cell lines were also investigated. Some of the complexes demonstrated superior cytotoxic activity compared to cisplatin.

Synthesis, characterization, EDX, thermal, antioxidant, antibacterial, topographical, and gas adsorption studies of supramolecular tetraammoniumplatinate

Reaction of K2PtCl4 with N-alkyl-N-benzyl-N,N-dimethyl ammonium chloride (n = 8, 10, 12 and 14 for alkyl) yielded supramolecular bis(benzyldimethylalkylazaniumyl) tetrachloroplatinumdiuide (metallobenzalkonium8 (MBK8), MBK10, MBK12, MBK14) characterized with spectroscopic and energy dispersive X-ray techniques. X-ray difraction powder analysis was performed which confirmed the crystalline nature of the compound. UV/Vis study performed in dimethylformamide, dimethylsulphoxide (DMSO)/H2O, and DMSO/phosphate buffers under physiological conditions show stability of the supramolecular units, with [PtCl4]2−. Zeta potential with particle size distribution of MBK8 obtained with DLS-confirmed agglomeration of the coordinate units. Thermal analysis by differential scattering calorimetric showed an effect of alkyl chain on their heat retention. For MBK8, topographical analysis and specific surface area were investigated with atomic force microscopy and nitrogen adsorption method, illustrating an outstanding alignment in arrays of ionic units, and an extent of apparent cross-sectional areas, respectively. Antioxidant and antibacterial activities were determined with 1–2,5-diphenyl-2-picrylhydrazyl-scavenging effect and Gram-positive and Gram-negative bacteria, respectively. The compounds exhibited activities for both scavenging and bacteria.

Organoplatinum(II) Complexes with 2-Acetylthiophene Thiosemicarbazone: Synthesis, Characterization, Crystal Structures, and in Vitro Antitumor Activity

Novel organoplatinum(II) complexes with 2-acetylthiophene thiosemicarbazone (ATTSC) were synthesized. The reaction of K2PtCl4 with ATTSC in 1:1 and 1:2 metal to ligand ratios yielded 1 [Pt4(ATTSC-2H)4·4DMF] and 2 [Pt(ATTSC-H)(ATTSC)Cl·3CH3OH)]. The crystal structures of these platinum chelates have been solved by single-crystal X-ray diffraction structure determinations and revealed metalation of the thiophene ring at C2 through platinum atoms. Further characterization of 1 and 2 was performed using electronic, IR, UV/vis, and NMR spectroscopies and elemental analysis. The in vitro antitumor activity of the ligand as well as 1 and 2 was determined against two different human tumor cell lines (HT-29 and HuTu-80). These tests revealed that the platinum(II) complexes are more cytotoxic than their ligand. The tetranuclear complex 1 shows higher antiproliferative activity (IC50 = 1.2 and 1.5 μM) when compared to 2 (IC50 = 3 and 5.9 μM), while the ligand has IC50 values of 8.6 and >10 μM. Compounds 1 and 2 can ...

Reaction of platinum(II) diamine and triamine complexes with selenomethionine

We have reacted [Pt(dien)Cl]Cl, [Pt(en)(D2O)2]2+, and [Pt(Me4en)(D2O)2]2+ [Me4en=N,N,N′,N′-tetramethylethylenediamine] with selenomethionine (SeMet). When [Pt(dien)Cl]Cl is reacted with SeMet, [Pt(dien)(SeMet-Se)]2+ is formed; two Se–CH3 resonances are observed due to the different chiralities at the Se atom upon platination. In a reaction of [Pt(dien)Cl]Cl with an equimolar mixture of SeMet and Met, the SeMet product forms more quickly though a slow equilibrium with approximately equal amounts of both products is reached. [Pt(Me4en)(D2O)2]2+ reacts with SeMet to form [Pt(Me4en)(SeMet-Se)(D2O)]2+ initially but forms [Pt(Me4en)(SeMet-Se,N)]+ ultimately. One stereoisomer of the chelate, assigned to the R chirality at the Se atom, dominates within the first few minutes of reaction. [Pt(en)(D2O)2]2+ forms a variety of products depending on reaction stoichiometry; when one equivalent or less of SeMet is added, the dominant product is [Pt(en)(SeMet-Se,N)]+. In the presence of excess SeMet, [Pt(en)(SeMet-Se)2]2+ is the dominant initially, but displacement of the en ligand occurs leading to [Pt(SeMet-Se,N)2] as the eventual product. Displacement of the en ligand from [Pt(en)(SeMet-Se,N)]+ does not occur. In reactions of K2PtCl4 with two equivalents of SeMet, [Pt(SeMet-Se,N)2] is formed, and three sets of resonances are observed due to different chiralities at the Se atoms. Only the cis geometric isomers are observed by 1H and 195Pt NMR spectroscopy.

Crystal Structure Of Tetracyanoplatinate(IV) Dihydrate, Pt(CN)4 · 2H2O

C4H4N4O2Pt, monoclinic, C12/c1 (no. 15), a = 10.867(1) A, b = 6.5314(6) A, c = 11.706(1) A, = 94.029(2)°, V = 828.8 A, Z = 4, Rgt(F) = 0.019, wRref(F) = 0.052, T = 293 K. Source of material An excess of diluted sulfuric acid and some drops of H2O2 solutionwere added to an aqueous solution of K2Pt(CN)4 · 3H2O. The latter was obtained by the reaction of K2PtCl4 (Alfa-Aesar, 99,9 %) and KCN (Sigma-Aldrich, 97 %) as described previously [1]. The solution was slowly evaporated at room temperature and transparent crystals with a pale brown colour of the fully oxidized [Pt(CN)4 · 2H2O] were obtained, besides colorless crystals of KHSO4 and a yellow, amorphous residue which could not be identified yet. If only small amounts of H2SO4 and H2O2 are added, bronze needles of the partially oxidized K1.75[Pt(CN)4] · 1.5H2O form [2]. Discussion In monoclinic Pt(CN)4 · 2H2O the Pt—C distances of 2.010A, in good agreement with the literature [3,4], are similar to the short Pt—O distances of 2.017 A. Therefore the platinum is octahedrally coordinated by four cyanide ligands and two oxygen atoms of the water molecules. This arrangement is similar to the potassium tetracyanoplatinate halogenides K2[Pt(CN)4X2] (X = Cl, Br, I) [5] with the water molecules replacing the halogene atoms. The Pt atoms, as the center of the octahedra, are forming a face centered arrangement, and the Pt(CN)4 · 2H2Ooctahedra are linked to each other by hydrogen bonds between the nitrogen atoms and the H2Omolecules of neighbouring complexes forming a 3D network, with N—H distances of 1.713 and 1.743A and the N$H···O distances of 2.631 and 2.602 A. Z. Kristallogr. NCS 224 (2009) 9-10 / DOI 10.1524/ncrs.2009.0006 9 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless block, size 0.15 × 0.30 × 0.70 mm Wavelength: Mo K0 radiation (0.71073 A) %: 168.88 cm Diffractometer, scan mode: SMART APEX, Bruker AXS, 2 2max: 69.14° N(hkl)measured, N(hkl)unique: 5955, 1688 Criterion for Iobs, N(hkl)gt: Iobs > 2 !(Iobs), 1229 N(param)refined: 61 Programs: SHELXS-97 [6], SHELXL-97 [7], ATOMS [8] Table 1. Data collection and handling. H(1) 8f 0.040(6) 0.215(6) 0.565(5) 0.05(2) H(2) 8f 0.131(5) 0.063(6) 0.630(4) 0.09(2) Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso _____________ * Correspondence author (e-mail: M.Jansen@fkf.mpg.de) Unauthenticated Download Date | 9/19/15 8:23 PM

Tetrakis- and Tris(1-Methyluracil) Complexes of PtII: Formation and Properties of a Carbon-Bonded Nucleobase Species as Well as of Heternonuclear Derivatives

The reaction of K2PtCl4 with an excess of 1-methyluracilate (1-MeU) in water at 60 degrees C leads to the formation of two major products, K2[Pt(1-MeU-N3)4].10H2O (1) and trans-K[Pt(1-MeU-N3)2(1-MeU-C5)(H2O)].3H2O (2). Addition of CuCl2 to an aqueous solution of 2 yields the mixed-metal complex trans-[PtCl(1-MeU-N3,O4)2(1-MeU-C5,O4)Cu(H2O)].H2O (4). Single-crystal X-ray analysis was carried out for 1 and 4. In both compounds, the heterometals (K+ in 1 and Cu2+ in 4) are bonded to exocyclic oxygens atoms of the 1-MeU ligands, giving rise to intermetallic distances of 3.386(2) and 3.528(2) A in 1 and 2.458(1) A in 4. The shortness of the Pt-Cu separation in 4 is consistent with a dative bond between PtII and CuII. The aqua ligand in 2 is readily substituted by a series of other ligands (e.g., 1-MeC, 9-MeGH, and CN-), as demonstrated by 1H NMR spectroscopy, with 3J(195Pt-1H(6)) coupling constants being sensitive indicators. Acid-base equilibria of 1 and 2 have been studied in detail and reveal some unexpected features: 1 has a relatively high basicity, with protonation starting below pH 5, and first and second pKa values being ca. 3.4 and 0.4, respectively. These pKa values are markedly higher than those of related neutral 2:1 or cationic 1:1 complexes and are attributed to both charge effects (-2 charge of 1) and a favorable stabilization of oxygen-protonated species by the arrangement of four exocyclic oxygen groups of 1-MeU ligands at either sides of the platinum coordination planes. Whereas in 2, H+ affinities of the three uracil ligands are in the normal range, there is a surprisingly low acidity of N(3)H of the C5-bonded uracil with a pKa of approximately 12.2, which compares with 9.75 for free 1-methyluracil. This implies that the C5-bonded PtII does not induce the typical acidifying effect of a PtII metal entity when bonded to a ring nitrogen atom of a neutral nucleobase. Rather, the effect is qualitatively similar to that of a metal ion bonded to N3 of an anionic 1-MeU ligand, which likewise increases its overall basicity as compared to neutral 1-MeUH.

X-ray powder study of cis-dichloridobis(methylamine)platinum(II)

The title compound, cis-[PtCl2(CH3NH2)2], was obtained from the reaction of K2PtCl4 with CH3NH2·HCl and CH3COOK. The single-crystal structure has been reported previously [Wimmer, Wimmer, Jaud, Johnson & Castan (1988). Inorg. Chim. Acta, 144, 25–30], but no three-dimensional coordinates are available. We have carried out an ab initio crystal structure determination using X-ray powder diffraction techniques. The crystal structure consists of discrete molecules, with the PtII atom in a slightly distorted square-planar coordination environment. The methyl groups lie on the same side of the plane defined by the two N and two Cl atoms. Molecules are connected via intermolecular N—H...Cl hydrogen bonds to form two-dimensional layers perpendicular to the b axis. The methylamine groups protrude from these layers, forming organic interlayers.

Synthesis and crystal structure of a Pt(II) complex with 3-amino-5-methyl-5-phenylhydantoin

The reaction of K2PtCl4 with 3-amino-5-methyl-5-phenylhydantoin (amphh, L) and KI in aqueous ethanol yields dark violet crystals of a binuclear platinum(II) complex. The molecular structure of the complex was determined by single-crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group with a = 8.458(3), b = 11.016(2), c = 16.249(3) (Å), α = 94.630(14), β = 100.63(2), γ = 108.55(4)° and Z = 2. The structure consists of [K2L4]2+ cations and [Pt2I6]2− anions bridged by K–I bonds to form quasi-one-dimensional chains along the b axis. Chains are linked by K+ ··· π(Ph) interactions and N–H ··· O hydrogen bonds. The complex is compared with data for related structures.

Reaction of platinum complexes with (+)-α-pinene and (+)-limonene. Synthesis, molecular structure, and catalytic activity of dichloro(η4-[p-mentha-1,8{9}-diene])platinum(II)

The transformations of platinum(II) and platinum(IV) complexes with inner-and outer-sphere ligands by the action of (+)-α-pinene and (+)-limonene were studied. Reduction of the metal complex is the main process whose rate increases in the following outer-sphere ligand series: (Me2SO)2H+ < Et3NH+ < K− < H+. The reaction of K2PtCl4 with α-pinene gave cis-terpine monohydrate and dichloro-η4-[p-mentha-1,8(9)-diene]platinum(II), and their structure was proved by X-ray analysis. The complex belongs to monoclinic crystal system, the Pt-Cl and Pt-C bonds therein have different lengths, the ClPtCl angle is 85.88°, and the C=C bond plane is orthogonal to the square coordination core. Dichloro-η4-[p-mentha-1,8(9)-diene]-platinum(II) was tested as catalyst in the hydrosilylation of acetophenone with diphenylsilane.

Synthesis of Phosphorescent Platinum Complexes with 3-Aryl Pyridazine as Prominent Emitting Materials in Organic Light-Emitting Device

The synthesis and characterization of a series of square planar Pt(II) complexes, which are luminescent at room temperature, are reported. The complexes have the general structure of (C^N)Pt(O^O), where HC^N is 3-phenylpyridazine (ppdz), 3-(4’-biphenyl)pyridazine (4’phppdz), 3-(2’-naphthyl)pyridazine (2’napdz), or 3-(1’-naphthyl)pyridazine (1’napdz), and HO^O is acetylacetone (Hacac). The reaction of K2PtCl4 with HC^N forms the chloro-bridged dimer, (C^N)Pt( µ-Cl)2Pt(C^N), which are cleaved with an ancillary ligand to give the corresponding monomeric (C^N)Pt(O^O) complexes. The emission bands of these complexes are governed by the structure of the cyclometalating ligands, with emission band (lem) ranging from 516 to 645 nm. The two emission bands at (515 and 550 nm) of (ppdz)Pt(acac) complex have 7 and 6 ms of life time which imply those bands are due to phosphorescence decay. The conjugating ring on the pyridazine makes the emission more red shifted which is expected based on molecular orbital calculation. In addition to the alteration of cyclometalating ligands, ancillary ligands also change. These results can be compared with the corresponding Ir(III) complexes.

Coordination isomerism in salicylhydroxamate complexes of platinum(ii) and palladium(ii)

The syntheses of a range of platinum(II) and palladium(II) complexes containing salicylhydroxamate ligands are described. The ancillary ligands, together with the synthetic route, influence the coordination mode of the salicylhydroxamate ligand. Reaction of cis-[PtCl2(PPh3)2] with salicylhydroxamic acid and trimethylamine in hot methanol gave O,O′-bonded [Pt{OC(NO)C6H4OH}(PPh3)2], but [PtCl2(cod)] (cod = cycloocta-1,5-diene) gave N,O-bonded [Pt{OC6H4C(O)NOH}(cod)]. Ligand substitution gives other N,O bonded complexes, including [Pt{OC6H4C(O)NOH}(PPh3)2]. Reaction of K2PtCl4 with 2 equiv. of EPh3 (E = As or Sb), salicylhydroxamic acid and excess trimethylamine gives products whose structures depend on E; AsPh3 gives [Pt{OC(NO)C6H4OH}(AsPh3)2], while SbPh3 gives [Pt{OC6H4C(O)NOH}(SbPh3)2].

Synthesis and X-ray crystal structure of cis-dichloro(cyclopentylamine) (dimethyl sulphoxide)platinum(II)

cis-Dichlorocyclopentylamine(dimethyl sulphoxide)-platinum(II) is obtained, in addition to small quantities of the corresponding trans compound, by reaction of K2PtCl4 with cyclopentylamine in DMSO solution, where it is formed as the thermodynamically favoured isomer. An X-ray crystal structure analysis confirms the cis configuration. Coordination around the metal centre is square planar, and the ligand bond angles at the Pt atom are close to the expected values of 90 and 180°. The DMSO ligand is S-coordinated to Pt. The Pt-Cl bond lengths, 2.299(2) and 2.317(2) A, are normal for structures of this type, as are the Pt-N and Pt-S bond distances, 2.059(5) and 2.191(2) A, respectively.

Exo-H- andendo-H-?4-pentamethylcyclopentadiene complexes of platinum

A mixture ofendo-H andexo-H isomers (1a and1b) of the (η4-C5Me5H)PtCl2 complex was prepared by the reaction of K2PtCl4 with C5Me5H in MeOH. The mixture of isomers reacts with CpTl in the presence of TiBF4 to give a novel complex, [(η4-C5Me5H)Pt(η5-C5H5)]+BF4−, as a mixture ofendo-H- andexo-H-isomers (2a and2b). The data of1H and13C NMR spectroscopy of the resulting complexes are discussed.