Mononuclear Platinum Complexes Research Articles

A new cyclic telluride. Synthesis and reactions of 1,3,5,6,7,8‐hexahydronaphtho[2,3‐c]tellurophene

AbstractReaction of 6,7‐bis(chloromethyl)‐1,2,3,4‐tetrahydronaphthalene with tellurium powder and potassium iodide in 2‐butoxyethanol gave 2,2‐diiodo‐1,3,5,6,7,8‐hexahydro‐naphtho[2,3‐c]tellurophene(1) as a red‐orange solid in 40% yield. Reduction of 1 with hydrazine hydrate gave a pale yellow solid of 1,3,5,6,7,8‐hexahydronaphtho[2,3‐c]telluro‐phene(2) in 80% yield. Chlorination, bromination of 2 and its reaction with benzyl bromide and N‐bromosuccinimide were reported. 2,2‐Bis(dimethyldithiocarbamato)‐, 2,2‐bis (diethyldithiocarbamato)‐ and 2,2‐bis(piperidine‐1‐carbodithioate)‐1,3,5,6,7,8‐hexahydro‐naphtho[2,3‐c]tellurophene were prepared by the reaction of the corresponding sodium dithiocarbamate salt with 1. Mononuclear platinum complex (ie, [(C12H14Te)2PtCl2]) was obtained by the reaction of 2 with K2PtCl4. Reaction of 6,7‐bis(chloromethyl)‐1,2,3,4‐tetrahydronaphthalene with KTeCN in DMSO solution gave 2,2‐dihydroxo‐1,3,5,6,7,8‐hexahydronaphtho[2,3‐c]tellurophene (11) as a white solid in 55% yield. All these new compounds were characterized by elemental analysis, IR, 1H, and 13C NMR, and mass spectroscopic data.

Enhanced anti-cancer efficacy to cancer cells by a novel monofunctional mononuclear platinum(ii) complex containing a mixed S,N,S-donor ligand

A novel platinum–intercalator hybrid complex (1) exhibits a cytotoxicity comparable to that of cisplatin against MCF-7 cell lines, and more potent activities against HeLa and A-549 cell lines, especially against the former.

Four mononuclear platinum(II) complexes: synthesis, DNA/BSA binding, DNA cleavage and cytotoxicity.

Four new platinum(II) complexes: PtII L1·H2O (C1, H2 L1=C20H16N2O2), PtII L2Cl2 (C2, L2=C22H16N2O2), PtII L3Cl2·H2O (C3, L3=C20H16N2), PtII L4Cl2·0.4H2O (C4, L4=C18H14N4) have been synthesized and characterized by using various physico-chemical techniques. The binding interaction of the four platinum(II) complexes C1-C4 with calf thymus (CT)-DNA has been investigated by UV-Vis and fluorescence emission spectrometry. The apparent binding constant (K app) values follow the order: C3>C1>C2>C4. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the four platinum(II) complexes C1-C4 showed that the quenching mechanism might be a static quenching procedure. For C1-C4, the number of binding sites was about one for BSA and the binding constants follow the order: C3 (7.08×105M-1)>C1 (2.82×105M-1)>C2 (0.85×105M-1)>C4 (0.15×105M-1). With the single condition change such as absence of an external agent, the DNA cleavage abilities of C3 exhibit remarkable changes. In addition, the cytotoxicity of C3 in vitro on tumor cells lines (MCF-7, HepG2 and HT29) were examined by MTT and showed better antitumor effects on the tested cells.

Near-infrared emission from binuclear platinum (II) complexes containing pyrenylpyridine and pyridylthiolate units: Synthesis, photo-physical and electroluminescent properties

Two novel binuclear platinum (II) complexes of (Rpypy)2Pt2(pyt)2 were synthesized and characterized, in which Rpypy represents 2-(1-pyrenyl) pyridine (pypy) and 2-(7-tert-butyl-1-pyrenyl)pyridine (tBupypy), pyt refers to pyridyl-2-thiolate, respectively. Their binuclear framework was evidenced by the single crystal of (pypy)2Pt2(pyt)2 with a short PtPt bond distance of 2.8814(3) Å. The intense near-infrared (NIR) emission peaks at 692 and 753 nm were exhibited for both dinuclear platinum complexes, which is similar to the emission of the mono-nuclear platinum complex of (pypy)Pt(acac) under photo-excitation. However, a red-shifted NIR electroluminescence (EL) peaked at 692 nm with a shoulder at 753 nm was observed in their doped polymer light-emitting diodes using PVK/OXD-7 as the host blend, which presented intrinsic character of MMLCT. Better EL performances with the maximum external quantum efficiency of 0.74% and a radiate emittance of 123.4 μw.cm−2 were obtained in the (tBupypy)2Pt2(pyt)2 doped device. To our best knowledge, this is a first reported example on the NIR EL of binuclear platinum complex using pyridyl-2-thiolate as auxiliary ligand.

Water soluble luminescent cyclometalated platinum(II) complex — A suitable probe for bio-imaging applications

A highly water soluble platinum(II) complex, [Pt(ppy)(en)]Cl, (where ppy=2-phenylpyridine and en=ethane-1, 2-diamine) with a strong green luminescence in solution was synthesized in two steps. Initially, an intermediate complex, [Pt(ppy)(ppyH)(Cl)], 1 was isolated which was transformed into the light-emitting mononuclear platinum(II) complex, [Pt(ppy)(en)]Cl, 2. The green emission of 2 was changed into yellow in their solid state. The strong π…π intermolecular interactions that interplays between the phenyl rings lying into the two consecutive molecules which led to the solid state emission. The low cytotoxicity of 2 ensures the feasibility for using these in bioimaging probe. The testing bioimaging results demonstrate that the compound penetrates the cell membrane in both cancer (HeLa, U87MG and Nuro2a) and normal cells (CHO-K1 and 3T3-L1). The cellular uptake was observed to much higher in cancerous cells only. Co-localization study confirmed the localization of it into the cell nucleus.

Synthesis and structure of the cyclometalated hetero-binuclear Pt-Au complexes with bridging 2-diphenylphosphinopyridine ligand

The heterobinuclear cyclometalated PtII-AuI complexes of the type [MePt(bhq)(μ-dppy)AuL]PF6, in which, bhq = benzo{h}quinoline, dppy = 2-diphenylphosphinopyridine, L = PPh3, 5; PPh2Me, 6; PPhMe2, 7; have been prepared by reaction of the mononuclear platinum(II) complex [MePt(bhq)(dppy)], 1, with 1 equiv. [AuL]+. Also, the reaction of complex 1 with 1 equiv AuCl(SMe2) at −60 °C gave the neutral heterobinuclear complex [MePt(bhq)(μ-dppy)AuCl], 8. All of the complexes were characterized using NMR spectroscopy and elemental microanalysis and complexes 5 and 8 were further identified by single crystal X-ray structure determination. Time-dependent density functional theory (TD-DFT) is used to elucidate the origin of the electronic transitions in the heteronuclear complexes5 and 8. The low energy absorptions for the heterobinuclear complex 5 are attributed to an admixture of ligand-to-ligand charge transfer (1LL′CT) and metal-to-ligand charge transfer character (1MLCT).

Acetamidate-bridged paddlewheel dirhodium complex sandwiched by mononuclear platinum complexes with axial metal–metal bonds affording neutral heterometallic one-dimensional alignments

One-dimensional (1-D) chain complexes, [{Rh2(acam)4}{Pt(piam)2(NH3)2}2]·4MeOH·3H2O (2, acam=acetamidate, piam=pivalamidate), have been constructed containing unbridged Rh–Pt bonds between two types of complexes, and characterized by single-crystal X-ray analysis and diffuse reflectance spectroscopy. In 2, the paddlewheel or lantern-type complex, [Rh2(acam)4] (i.e., [Rh2]), has a vacant σ∗ orbital that accepts the electrons from cis-[Pt(piam)2(NH3)2] (i.e., [Pt]) to afford a tetranuclear complex, [Pt]–[Rh2]–[Pt]. Each tetranuclear complex is further linked by Pt–Pt interactions with a distance of 3.1283(6)Å, to afford a neutral 1-D chain of –Rh–Rh–Pt–Pt–. The Pt–Pt distance in 2 is longer than that (2.9332(9)Å) of [{Rh2(acam)4}{Pt2(piam)2(NH3)4}]n(CF3CO2)2n·2nEtOH (1) which has a similar metal repetition of –Rh–Rh–Pt–Pt–, where diffuse reflectance spectra show that the gaps between filled and vacant σ-type orbitals for 2 are wider than for 1.

Water-Molecule-Driven Vapochromic Behavior of a Mononuclear Platinum(II) System with Mixed Bipyridine and Thioglucose

A mononuclear platinum(II) complex with mixed bpy and H4tg(-) ligands, [Pt(H4tg-S)2(bpy)]·2H2O (1a; bpy = 2,2'-bipyridine and H5tg = 1-thio-β-D-glucose), is photoluminescent in the solid state and undergoes facile and reversible removal of solvated water molecules accompanied by changes in its absorption and emission wavelengths. The analogous dmbpy complex, [Pt(H4tg-S)2(dmbpy)]·H2O (2a; dmbpy = 4,4'-dimethyl-2,2'-bipyridine), is also emissive in the solid state, but its absorption and emission spectra remain unchanged after dehydration. X-ray crystallographic analyses revealed that the difference in the chromism of 1a and 2a is due to the difference in their hydrogen-bonding networks, which involve solvated water molecules.

Synthesis and optoelectronic properties of a novel dinuclear cyclometalated platinum(II) complex containing triphenylamine-substituted indolo[3,2-b]carbazole derivative in the single-emissive-layer WPLEDs

A novel bi-picolinic acid derivative of H2dipic-BTICz containing binary triphenylamine-substituted indolo[3,2-b]carbazole (BTICz) unit and its dinuclear platinum(II) complex of (dfppy)2Pt2(dipic-BTICz) were synthesized as a single-component emitter used in the white polymer light-emitting diodes (WPLEDs), where dfppy is 2-(2,4-difluorophenyl)pyridine and dipic-BTICz is an anion of H2dipic-BTICz. The photophysical and electrochemical properties of (dfppy)2Pt2(dipic-BTICz) were investigated. Compared with the reported mononuclear platinum complex of (dfppy)Pt(pic), (dfppy)2Pt2(dipic-BTICz) exhibited a red-shifted photoluminescent peak at 434 nm in dilute dichloromethane (10−5 M), but a weakened and red-shifted aggregation emission peak at 640 nm besides its intrinsic emission at 445 nm in its neat films. Stable pure white emissions with CIE coordinates of (0.325±0.005, 0.345±0.015) and a maximum brightness of 208 cd/m2 were observed in the (dfppy)2Pt2(dipic-BTICz)-doped single-emissive-layer (SEL) PLEDs using a blend of poly(vinylcarbazole) and 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as a host matrix at 1 wt % dopant concentrations under applied voltages from 9 to 14 V. It indicates that the intrinsic and aggregation emissions of this dinuclear platinum complex were effectively tuned by inserting a new BTICz fluorophore in the dual picolinic acid derivative. Therefore, it is a promising single-component emitter to get white emission in SEL PLEDs.

Activation of trans geometry in bifunctional mononuclear platinum complexes by a non-bulky methylamine ligand

In order to shed light on the mechanism that underlies activity of bifunctional mononuclear PtII analogs of transplatin we examined in the present work a DNA binding mode of the analog of transplatin, namely trans-[Pt(CH3NH2)2Cl2], in which NH3 groups were replaced only by a small, non-bulky methylamine ligand. This choice was made because we were interested to reveal the role of the bulkiness of the amines used to substitute NH3 in transplatin to produce antitumor-active PtII drug. The results indicate that trans-[Pt(CH3NH2)2Cl2] forms a markedly higher amount of more distorting intrastrand cross-links than transplatin which forms in DNA preferentially less distorting and persisting monofunctional adducts. Also importantly, the accumulation of trans-[Pt(CH3NH2)2Cl2] in tumor cells was considerably greater than that of transplatin and cisplatin. In addition, the results of the present work demonstrate that the replacement of ammine groups by the non-bulky methylamine ligand in the molecule of ineffective transplatin results in a radical enhancement of its activity in tumor cell lines including cisplatin-resistant tumor cells. Thus, activation of the trans geometry in bifunctional mononuclear PtII complexes can be also accomplished by replacement of ammine groups in transplatin by non-bulky methylamine ligands so that it is not limited only to the replacement by relatively bulky and stereochemically more demanding amino ligands.

Synthesis and Coordination Behavior of a Bipyridine Platinum(II) Complex with Thioglucose

A mononuclear platinum(II) complex with two monodentate-S H4tg(-) ligands, [Pt(H4tg-κS)2(bpy)] (1), was newly synthesized by the reaction of [PtCl2(bpy)] (bpy = 2,2'-bipyridyl) with NaH4tg (NaH4tg =1-thio-β-d-glucose sodium salt) in water. Complex 1 reacted with additional [PtCl2(bpy)] in water to give an S-bridged dinuclear complex, [Pt2(μ2-H4tg-κ(1)S:κ(1)S)2(bpy)2](2+) ([2](2+)), in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [Pt(bpy)](2+) moiety through two thiolato groups. Treatments of 1 with Cu(2+) and Ni(2+) in water in the presence of bpy produced S-bridged dinuclear complexes [PtCu(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([3](2+)) and [PtNi(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([4](2+)), respectively, in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [M(bpy)](2+) (M = Cu(II), Ni(II)) moiety through two thiolato and two hydroxyl groups to form a chiral [M(N)2(O)2(S)2] octahedron with the Δ configuration. On the other hand, similar treatment with Cd(2+) in the presence of bpy resulted in the formation of an S-bridged trinuclear complex, [Cd{Pt(μ2-H4tg-κ(1)S:κ(2)O,S)(μ2-H4tg-κ(1)S:κ(1)S)(bpy)}2](2+) ([5](2+)), in which each of two square-planar [Pt(H4tg)2(bpy)] units binds to a Cd(II) ion through two thiolato groups and one hydroxyl group to form a chiral [Cd(O)2(S)4] octahedron with the Λ configuration. Of two geometrical configurations, syn and anti, which arise from the relative arrangement of two β-D-pyranose moieties, [2](2+) adopts the syn configuration with symmetric bridging sulfur atoms, while [3](2+), [4](2+), and [5](2+) all have the anti configuration with R configurational bridging sulfur atoms. All of the complexes were fully characterized by electronic absorption, CD, and NMR spectroscopies, along with single-crystal X-ray crystallography.

Efficacy of newly developed platinum complexes against osteosarcoma, bone-targeting platinum, and proteasome inhibitory platinum.

10075 Background: Cisplatin is one of the most effective anti-cancer drugs available for the treatment of human solid tumors including osteosarcoma. As we had already reported, we have utilized caffeine in our chemotherapy protocol. And we achieved excellent clinical results. But effectiveness of cisplatin has been limited by side effects, and resistance. Here we developed two novel platinum compounds. 3Pt is trinuclear platinum complex bearing geminal bisphosphonate moieties, 1Pt is mononuclear platinum complex which has proteasome inhibitory activity. We performed comparative studies of our novel platinum compounds with osteosarcoma. Methods: Two novel platinum complexes were synthesized by Prof. Odani at school of pharmaceutical sciences of our university and cisplatin and caffeine were obtained from constructor. Three cell lines (MG63, 143B, and LM8) were used. Cell survival after a 72 hrs exposure to these compounds was assessed by WST-8 assay, and IC50 value was calculated for each compound. Apoptosis was assessed by DNA fragmentation and Annexin V-FITC/propidium iodine assay. Results: Each compound strongly caused concentration-dependent cytocidal effect. IC50 value of trinuclear compound is superior to cisplatin, and both complexes showed caffeine potentiation. Apoptosis induction and acetylation of histon H2AX were observed. In vivo, 1Pt showed almost same, 3Pt showed strong antitumor effect compared to cisplatin. Conclusions: Two novel platinum compounds that we developed showed strong ant-tumor effect in osteosarcoma in vitro and in vivo. As bisphosphonate has high affinity to calcium ions, 3Pt targets bone tissue and expected to reduce side effects at extraskeletal sites and to overcome the drug resistance. Proteasome inhibitory platinum compound has never been reported before, we will investigate its anti-tumor mechanism precisely.

Highly Dichroic Metallomesogen of Dinuclear Platinum Complex: Synthesis and Liquid Crystal and Photophysical Properties

A novel dinuclear platinum complex of (biC12ppy-fl)Pt2C12DBM)2 with liquid crystal luminescent property has been prepared, as well as its liquid crystal, optophysical properties and hole mobility have been studied, where biC12ppy-fl is 6,6′-[4,4′-(9,9-didodecyl-9H-fluorene-2,7-diyl)bis(1,4-phenylene)]bis[3-(dodecyloxymethyl)pyridine] and C12DBM is 1,3-bis[4-(dodecyloxy)phenyl]propane-1,3-dione. This dinuclear platinum complex displayed a smectic mesophase and excellent opto-physical properties. Compared to the reported mononuclear platinum complex of (CnROppy)Pt(acac) (R = H, F), this dinuclear platinum complex exhibited higher emission quantum yield and higher stability, as well as higher hole mobility of 8.4 × 10–4 cm2/(V s). Moreover, a highly polarized ratio of 10.3 was obtained for the aligned film of (biC12ppy-fl)Pt2(C12DBM)2 on the aligned polyimide at room temperature.

Structural diversity in the coordination of 1,4‐dihydro‐1,4‐diarsinine as a cyclic ditopic organoarsenic ligand to metal ions

AbstractA number of different complexation structures of cis‐1,4‐dihydro‐1,4‐dimethyl‐2,3,5,6‐tetrakis(t‐butoxycarbonyl)‐1,4‐diarsinine (cis‐DHDAtBu) with gold(I) and iridium(III) were synthesized and characterized by 1H, 13C NMR spectra, X‐ray crystallography, and elemental analysis. Mono‐ and di‐nuclear gold(I) chloride complexes with cis‐DHDAtBu were obtained by simple addition of gold(I) chloride to cis‐DHDAtBu. A hetero‐trinuclear gold‐platinum‐gold complex (PtAu2Cl4(cis‐DHDAtBu)2) was obtained by complexation of a mononuclear platinum(II) complex (trans‐PtCl2(cis‐DHDAtBu)2), which was obtained by complexation of cis‐DHDAtBu with a half‐equimolar amount of PtCl2(PhCN)2, with a twice‐equimolar amount of gold(I) chloride. An iridium(III) complex with cis‐DHDAtBu (IrCl3(cis‐DHDAtBu)2) was prepared from hydrated iridium(III) chloride and cis‐DHDAtBu. The complex comprises a five‐membered chelate cis‐DHDAtBu and an usual monodentate cis‐DHDAtBu. The interior angles at around the arsenic and the As–C—C bond angles were significantly varied from 113.4° to 129.4° in the present crystal. These observations suggest that the flexibility of the bond angles at around the arsenic center is inherent property in the present organoarsenic compounds. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:16–26, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20747

Synthesis, structural characterisation and biological studies of new mononuclear platinum(II) complexes with sterically hindered heterocyclic ligands

Three novel cisplatin analogues were synthesized, designed according to an approach which violates the “classical” structure–activity relationship, by replacing the diamine ligands with a planar N donor heterocycle giving a sterically hindered complex. Moreover, the sterical hindrance of antitumor drug candidates potentially makes them less susceptible to deactivation by sulphur-containing proteins and helping to overcome resistance mechanisms. The resulting mononuclear complexes of sterically hindered polidentate heterocyclic N ligands [PtCl(bbp)]Cl ( 1) [bbp = 2,6-bis(2-benzimidazolyl)pyridine], [PtCl 2(dptdn)](H 2O) ( 2) [dptdn = sodium 5,6-diphenyl-3-(2′-pyridyl)-1,2,4-triazine-4″,4″′-disulfonate] and [(dptdn)(dpt)Pt]Cl 2(H 2O) ( 3) [dpt = 5,6-diphenyl-3-(2′-pyridyl)-1,2,4-triazine] have been prepared and structurally characterised. Both neutral and ionic complexes are present, with monofunctional ( 1) and bifunctional Pt(II) moieties ( 2) and coordinatively saturated Pt(II) ions in the mixed ligand complex ( 3), whose size and shape enable them to behave as novel scaffolds for DNA binding. All complexes were tested “ in vitro” for their biological activity on human HT29 colorectal carcinoma and HepG2 hepatoma cells. The complexes ( 1) and ( 3), endowed with a positive charge, showed a potent cytotoxic activity and reduced cell viability with an efficacy higher than that of cisplatin; whilst the neutral bifunctional compound ( 2) was inactive. IC50 values have been calculated for the active compounds. The cytotoxic effects were confirmed by the accumulation of treated cells in subG0/G1 phase of cell cycle, by the loss of mitochondrial potential (Δ ψ m) and by the chromatin condensation or fragmentation observed by means of fluorescence microscopy after Hoechst 33258 nuclear staining. A study on intracellular platinum uptake in HT29 cell line has been also performed and data obtained strongly suggest that the cytotoxicity of new tested complexes reported in this work is based on a different pharmacodynamic pattern with respect to cisplatin.

Synthesis and Structural Characterization of New Chiral (Biscarbene)platinum(II) Complexes

AbstractNew chiral bis(triazolium) salts have been prepared in good yields. The corresponding mononuclear platinum(II) complexes [Pt{bis(NHC)}X2] (X = Br, I) have been synthesized and spectroscopically characterized. One of the synthesized biscarbene complexes has also been characterised by X‐ray crystallography. These complexes are efficient catalyst precursors for the hydrosilylation of 1‐octene.

Walking of antitumor bifunctional trinuclear Pt II complex on double-helical DNA

The trinuclear BBR3464 ([{trans-PtCl(NH3)2}2µ-(trans-Pt(NH3)2(H2N(CH2)6NH2)2)]4+) belongs to the polynuclear class of platinum-based anticancer agents. DNA adducts of this complex differ significantly in structure and type from those of clinically used mononuclear platinum complexes, especially, long-range (Pt, Pt) intrastrand and interstrand cross-links are formed in both 5′–5′ and 3′–3′ orientations. We show employing short oligonucleotide duplexes containing single, site-specific cross-links of BBR3464 and gel electrophoresis that in contrast to major DNA adducts of clinically used platinum complexes, under physiological conditions the coordination bonds between platinum and N7 of G residues involved in the cross-links of BBR3464 can be cleaved. This cleavage may lead to the linkage isomerization reactions between this metallodrug and double-helical DNA. Differential scanning calorimetry of duplexes containing single, site-specific cross-links of BBR3464 reveals that one of the driving forces that leads to the lability of DNA cross-links of this metallodrug is a difference between the thermodynamic destabilization induced by the cross-link and by the adduct into which it could isomerize. The rearrangements may proceed in the way that cross-links originally formed in one strand of DNA can spontaneously translocate from one DNA strand to its complementary counterpart, which may evoke walking of the platinum complex on DNA molecule.

Syntheses, Characterization, and Photo-Hydrogen-Evolving Properties of Tris(2,2'-bipyridine)ruthenium(II) Derivatives Tethered to an H2-Evolving (2-phenylpyridinato)platinum(II) Unit

With the aim of developing new molecular devices having higher photo-hydrogen-evolving activity, Pt(ppy)ClX units (ppy = 2-phenylpyridinate, X = Cl- or DMSO; DMSO = dimethylsulfoxide) have been employed as an H2-evolving site, as the catalytic activity of [Pt(ppy)Cl2]- was confirmed to be higher than those of other mononuclear platinum(II) complexes. In the present study, two new heterodinuclear Ru(II)Pt(II) complexes, produced by condensation of [Ru(bpy)2(5-amino-phen)]2+ (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) with [Pt(cppy)Cl2]- and Pt(cppy)(DMSO)Cl (cppy = 9-carboxy-phenylpyridinate), respectively, have been prepared and their photo-hydrogen-evolving activities have been evaluated in detail. The ineffectiveness of these systems as photo-hydrogen-evolving molecular devices are interpreted in terms of their negative driving forces for the photoinduced electron transfer from the triplet MLCT excited state of the Ru chromophore to the π*(ppy) orbital of the catalyst moiety.

Mono- and dinuclear metallacyclic complexes of Pt(II) synthesized from some eugenol derivatives

The complexes K[PtCl3(Meug)] (1; Meug = methyleugenol), K[PtCl3(Meteug)] (2; Meteug = methyl eugenoxyacetate), and K[PtCl3(Eteug)] (3; Eteug = ethyl eugenoxyacetate) reacted with AgNO3, SnCl2, KOH, or ethanol–water solutions to lose one aryl proton and form dinuclear metallacyclic complexes Pt2Cl2(Meug-1H)2 (4), Pt2Cl2(Meteug-1H)2 (5), and Pt2Cl2(Eteug-1H)2 (6), respectively. Complexes 4–6 reacted with aliphatic, aromatic, and heterocyclic amines to give various mononuclear metallacyclic platinum complexes 7–15. 1H NMR spectra showed that in 4–15 Meug, Meteug, and Eteug are bound with Pt(II) both at the benzene carbon and at the ethylenic double bond of the side chain. NOESY spectra and single-crystal X-ray diffraction indicated that in 7–15 the amines are in cis-position with respect to the ethylenic double bond.

Mononuclear Platinum(II) Complexes of a Bis(bidentate) Ligand Based on 1,3,4‐Oxadiazole and Their Reactions with Copper(I) Salts

AbstractReaction of the bis(bidentate) ligand 2,5‐bis[2‐(dimethylamino)phenyl]‐1,3,4‐oxadiazole (oxanMe) with the precursors trans‐[PtMeCl(SMe2)2] and [(PhCN)2PtCl2] afforded the mononuclear complexes [(oxanMe)Pt(Me)Cl] and [(oxanMe)PtCl2], respectively. [(oxanMe)PtMe2] was observed in equilibrium with oxanMe, [Pt2Me4(μ‐SMe2)2], and [PtMe2(SMe2)2], but could not be isolated. Reaction of [(oxanMe)PtCl2] with silver acetate gave access to [(oxanMe)Pt(OAc)2] in excellent yield. The latter was treated with [Cu(NCMe)4]BArF, resulting in a disproportionation reaction that afforded the novel trimetallic complex {[(oxanMe)Pt(OOCCH3)2]2Cu}{BArF}2. This complex features a linear PtII–CuII–PtII chain consisting of two Pt→Cu dative bonds supported by two bridging acetate ligands each.