The preparations of Pt(theophylline)2Cl2, K[Pt- (theophylline)Cl3], K[Pt(theobromine)Cl3]·H2O (1), trans-[Pt(isocaffeine)2Cl2]·H2O (2), and K(isocaffeinium)[PtCl4]·H2O (3) are reported.Crystals of 1 are monoclinic P21/n with a=7.641- (2), b=11.873(3), c=15.868(4) Å, β=90.80(2)°, Z=4. The structure was refined on 1443 reflections to R=0.028. In the planar [Pt(theobromine)Cl3]− anion Pt-N(9)=2.016(6) Å, Pt-Cl=2.299(2), 2.289(2), and 2.303(2) Å. The imidazole ring is rotated away from the coordination plane by 79.8°. Symmetry related theobromine units pack parallel to each other with a mean inter-ring separation of 3.27 Å.Crystals of 2 are monoclinic P21/a with a=7.345- (2), b=20.021(5), c=8.031(2) Å, β=104.18(2)°, Z=2. The structure was refined on 1132 reflections to R=0.029. The Pt-N(7) distance is 2.003(3) Å and Pt-Cl=2.298(1) Å. The imidazole ring is rotated away from the PtCl2N2 plane by 76.8°. In this compound, the isocaffeine units do not stack, but form a staggered arrangement within the unit cell.Crystals of 3 are monoclinic P1/c with a= 7.382- (1), b=14.014(4), c=15.757(4) », β=92.30(2)°, Z=4. The structure was refined on 2057 reflections to R=0.032. The isocaffeine is protonated at N(7). The Pt-Cl distances in the PtCl42− anion range between 2.29–2.31 Å. The protonated isocaffeine cations and the PtCl42− anions form a very nearly parallel infinitely stacked arrangement with minimum interlayer atomic separations of 3.37 and 3.44 Å. 相似文献
A variety of platinum(II) complexes of methimazole (2-mercapto-1-methylimidazole; HImS = neutral form and ImS = thiolate form), coordinated in both thione and thiolate forms, have been isolated by reacting methimazole with [PtCl(terpy)]Cl (terpy = 2,2′:6′,2″ terpyridine), [PtCl2(bipy)] (bipy = bipyridine), [PtCl2(o-phen)] (o-phen = o-phenanthroline), [PtCl2(CH3CN)2] and [PtCl2(COD)] (COD = 1,5-cyclooctadiene). These complexes were characterized by electronic absorption, IR and NMR (1H, 13C, 195Pt) spectroscopies. Molecular structure of [Pt(bipy)(HImS)2]Cl2·3H2O (3a·3H2O) has been established by single crystal X-ray crystallography. Platinum thiolate complex, [Pt(ImS)2(HImS)2] (5), could be obtained by treatment of [Pt(HImS)4]Cl2 with sodium methoxide in methanol. The solution of 5 in organic solvents yielded bi- and tri-nuclear platinum complexes. The effect of diimine ligands on oxidation of methimazole moiety in the complexes has been studied by electrochemical oxidation and pulse radiolytic oxidation employing specific one-electron oxidant, radical. 相似文献
Chloride anation of trans-Pt(CN)4ClOH2− has been studied with and without Pt(CN)42− present at 25.0°C by use of stopped-flow and conventional spectrophotometry and a 1.00 M perchlorate medium. The rate law in the absence of Pt(CN)42− is Rate=(p1 + p2 [H+] ) [Cl−]2 [complex]/(1 + q [Cl−]) with p1=(3.0 ± 0.1) × 10−5 M−2s−1, p2=(3.6 ± 0.1) × 10−5 M−3 s−1 and q=(0.62 ± 0.02) M−1. It is compatible with a chloride assistance via an intermediate of the type Cl-Cl-Pt(CN)4···OH22−, in which the reactivity of the aqua ligand is enhanced due to a partial reduction of the platinum. This mechanism of halide assistance is in principle the same as the modified reductive elimination oxidative addition (REOA) mechanism proposed by Poë, in which the intermediate is not split into free halogen, platinum(II) and water, and in which electron transfer not necessarily involves complete reduction to platinum(II). To avoid confusion with complete reductive eliminations, reactions without split of the intermediates are here termed halide-assisted reactions. The pH-dependence indicates acid catalysis via a protonated intermediate ClClPt(CN)4···OH3−.The Pt(CN)42−accelerated path has the rate law Rate= [Cl-] [Pt(CN)42−] [complex] where k=(39.9±0.5) M−2 s−1 and Ka=(4.0±0.2)10−2 M is the protolysis constant of trans-Pt(CN)4ClOH2−.Reaction between PtCl5OH2− and chloride is accelerated by Pt(CN)42− and gives PtCl62− as the reaction product. The rate law is Rate=k [Cl−] [Pt(CN)42−] [PtCl5OH2−] with k=(5.6 ± 0.2)10−3 M−2 s−1 at 35.0°C and for a 1.50 M perchlorate acid medium. The reaction takes place without central ion exchange. Alternative mechanisms with two consecutive central ion exchanges can be excluded. The role of Pt(CN)42− in this reaction is very similar to that of the assisting halide in the halide assisted anations. [p ]Reaction between trans-Pt(CN)4ClOH2− and PtCl42− gives Pt(CN)42− and PtCl5OH2− as products and has the rate law Rate=k[PtCl42−] [trans-Pt(CN)4ClOH2−] with k=(3.32 ± 0.02) M−1 s−1 at 25 °C for a 1.00 M perchloric acid medium. The formation of an aqua complex as the primary reaction product and the rate independent of [Cl−] shows that formation of a bridged intermediate of the type Pt(II)Cl4ClPt(IV)(CN)4OH23− is formed in the initial reaction step, not five-coordinated PtCl53−. 相似文献
Neutral and cationic platinum(IV) isocyanide complexes of the type [PtCl4(CNR)2], [PtCl4(CNR) (PMe2Ph)], [PtCl3(CNR)(PMe2Ph)2]+, [PtCl2(CNR)2 (PMe2Ph)2]2+, where R = methyl, t-butyl, cyclohexyl, p-tolyl, have been prepared by chlorine addition to the corresponding platinum(II) derivatives. The complexes [PtCl2(CN)2(CNR)2] and [PtCl2(CN)(CNR) (PMe2Ph)2]+ (R = t-butyl), are also reported. The cationic t-butylisocyanide derivatives are noteworthy in the way they readily lose the t-butyl cation at room temperature to give the corresponding cyano complexes. The compounds have been characterized by elemental analysis, molecular weights and conductivity measurements, and their i.r. and n.m.r. data are discussed in relation to structures and to the nature of the platinum-isocyanide bond. 相似文献
New tetrazolate complexes trans-[PtCl2(RCN4)2]2−, trans-[PtCl4(RCN4)2]2− with Ph3PCH2Ph+ and (CH3)2NH2+ counterions have been obtained by azidation of nitriles coordinated to Pt(II) and Pt(IV) {trans-[PtCl2(RCN)2] and trans-[PtCl4(RCN)2] (R = Et, Ph)} and characterized. The composition and the molecular structure of the complexes obtained were established by the СHN elemental analyses, 1Н and 13С NMR spectroscopy, IR spectroscopy, mass spectrometry, and X-ray diffraction. The coordination of nitriles to Pt(II) and Pt(IV) is shown significantly activate the azidation: the reaction proceeds with a higher rate and at relatively low temperature compared with the classical 1,3-dipolar addition of azides to nitriles. 相似文献
The synthesis of new platinum bipy (bipy = 2,2′-bipyridyl) complexes containing phenoxide ligands is reported, together with kinetic studies of their oxidative addition reactions with MeI to produce phenoxo platinum(IV) complexes. Complexes of the form [(bipy)Pt(OC6H4-4-X)2] (X = OCH3, CH3, H, Br, Cl) are prepared by the reaction of the chloro complex [(bipy)PtCl2] with substituted phenols and KOH in a two phase system of water and chloroform in the presence of benzyl triphenylphosphonium chloride. Platinum(IV) complexes are formed by oxidative addition of MeI to the platinum(II) complexes obtained. The complexes are characterized by elemental analysis, UV-Vis, IR, mass spectrometry and 1H and 13C NMR spectroscopy.The reaction of methyl iodide with [(bipy)Pt(OC6H4-4-OMe)2] to give [(bipy)PtMe(I)(OC6H4-4-OMe)2] follows the rate law rate = k2[(bipy)Pt(OC6H4-4-OMe)2][MeI]. The values of k2 increase with increasing polarity of the solvent, suggesting a polar transition state for the reaction. 相似文献
Reaction of dimeric trans-[PtCl2(PR3)]2 with 1-aza-4-oxo-1,3-butadienes [R1NC(R2)C(R3)O, R3 = Me, Ph, OMe, NEt2] in a 1:2 molar ratio results in almost quantitative formation of mononuclear complexes trans·[PtCl2(PR3){σ-N-(R1NC(R2)C(R3)O)}]. The ligands are bonded in the monodentate σ-N bonding mode to the platinum(II) centre. This has been established by an X-ray structure determination of trans-[PtCl2(PEt3){σ-N-(t-BuNCHC(Me)O)}]. Crystals of the latter compound are orthorhombic with space group Pc21n; cell constants are a = 14.712(3), b = 15.053(2), c = 9.025(5) Å, Z= 4 and Rw = 0.056 for 3281 reflections. The 1aza4oxol,3butadiene (α-iminoketone for R3 is alkyl or aryl) has the E-configuration about the imine bond (CN 1.34(4) Å), with a C(5)C(6) distance of 1.44(5) Å and a NC(5)/ C(6)O torsion angle of 89(4)°. As a result of this ligand conformation, the acetyl hydrogen atoms are positioned (on average) into the neighbourhood of the Pt-atom above the Pt-coordination plane. Infrared and NMR (1H, 13C, 31p) data show that these structural features are also predominant in solution. 相似文献
The title salt was obtained by a reaction of [TTF]3 [BF4]2 (TTF = tetrathiafulvalene) with [NMe4]2 [V(mnt)3] [mnt = 1,2-dicyanoethylene-1,2- dithiolate(2−)] in a mixture of 1,2-dichloroethane and acetonitrile (3:2 ν/ν). A single crystal X-ray analysis of it revealed a TTF columnar structure consisting of both TTF0 and the TTF·+ radical cation and the distorted octahedral geometry of the [V(mnt)3]2− anion. The salt crystallizes in a monoclinic system, space group C2/c with unit cell constants a = 25.428(3), b = 12.434(2), c = 25.477(3) Å, β = 92.428(3)° and Z = 8. The structure was solved by the direct method and refined, on the basis of 3854 [|Fo| > 3σ(F)] observed data, to an R value of 0.078. The salt e`xhibits electrical conductivity of 1.7 x 10−4 S cm−1 at 25°C for a compacted pellet. 相似文献
The thiocarbamates 4-RC6H4NHC(S)NR2′ (R = H, Cl; R′ = Me, Et), 4-ClC6H4NHC(S)NR (NR = 2-pyridylpiperazine) react with cis-[PtCl2(PTA)2] (PTA = 1,3,5-triaza-7-phosphaadamantane) in the presence of base to afford the monocationic platinum(II) complexes cis-[Pt{SC(NR2′) = NC6H4R}(PTA)2]+ (R = H, Cl; R′ = Me, Et), cis-[Pt{SC(NR) = NC6H4Cl}(PTA)2]+ (NR = 2-pyridylpiperazine), which were isolated as their PF6 salts in high yields. The complexes were fully characterised spectroscopically and also by X-ray crystallography. Cytotoxicity of these complexes was studied in vitro in three human cancer cell lines (CH1, A549 and SW480) using the MTT assay. 相似文献
The organometallic tin(IV) complexes [SnPh2(SRF)2] SRF = −SC6F4-4-H (1), −SC6F5 (2), were synthesized and their reactivity with [MCl2(PPh3)2] M = Ni, Pd and Pt explored. Thus, transmetallation products were obtained affording polymeric [Ni(SRF)(μ-SRF)]n, monomeric cis-[Pt(PPh3)2(SC6F4-4-H)2] (3) and cis-[Pt(PPh3)2(SC6F5)2] (4) and dimeric species [Pd(PPh3)(SC6F4-4-H)(μ-SC6F4-4-H)]2 (5) and [Pd(PPh3)(SC6F5)(μ-SC6F5)]2 (6) for Ni, Pt and Pd, respectively. The crystal structures of complexes 1, 2, 3, 4 and 6 were determined. 相似文献
Arytellurol complexes [PtCl(TeAr)(PPh3)2] (I) and [Pt(TeAr)2(PPh3)2] (II) are readily obtained from cis-[PtCl2(PPh)3)2] and NaTeAr (Ar = C6H5, 4-CH3OC6H4 and 4-CH3CH2OC6H4) in ethanolbenzene at room temperature. 31P NMR spectra of (I) and (II) indicate their trans configuration in solution. Metathetical reactions between I (Ar = 4-CH3OC6H4) and NaX (X = I, Br, SCN) occur in methanol to give [Pt(X)(TeC6H4OCH3-4)(PPh3)2]. 1H NMR shows that equimolar proportions of NaTeC6H5, NaTeC6H4OCH2CH3-4 and cis-[PtCl2(PPh3)2] give a mixture of three complexes: II, Ar = C6H5; II, Ar = 4-CH3CH2OC6H4; and [Pt(TeC6H5)(TeC6H4OCH2CH3-4)(PPh3)2]. Polymeric complexes [PtCl(TeAr)]n (III) and [Pt(TeAr)2]n (IV) result from reaction between K2[PtCl4] and NaTeAr in aqueaous ethanol. They react with excess of PPh3 in CDCl3 to yield monomeric complexes I and II respectively which were characterized in situ by 1H and 31P NMR of the reaction mixtures. IR spectra indicate the presence of bridging chloride ligands in III. An alternating chloride and tellurol bridged chain structure for III and a tellurol bridged for IV have been proposed. Reaction between equimolar amounts of III and PPh3 in dichloromethane yielded a tellurol bridged dimeric complex [PtCl(μ-TeAr)(PPh3)]2 (V) with terminal chloride ligand as suggested by IR study. Ethanolic solutions of diarylditellurides also react readily with an aqueous solution of K2[PtCl4] at 10 °C to give complexes for which the structure trans-[PtCl2(ArTeTeAr)2] (VI) is suggested from their elemental analyses, IR, Raman (in one case only), 1H, 125Te (in one case only), and 195Pt NMR spectra and reactions with triphenylphosphine which liberated free ditellurides. At 40 °C or above the same ditellurides form polymeric complexes III with K2[PtCl4] in aquaeous ethanol. 相似文献
The compound [Cr(en)3][ZnCl4]Cl has been synthesized by reaction of CrCl3·6H2O, Zn and [Cr(en)3]2(SO4)3 in HCl. Its molecular and crystalline structure was determined by X-ray diffraction methods, being monoclinic, P21/c, a=21.215(3), b=12.532(2), c=13.707(2) Å, β=95.21°, V= 3629(2) Å3, Dx=1.738g cm−3, MW=474.9, Z= 8, F(000)=1928, λ(Mo Kα)=0.71069 Å, μ(Mo Kα)= 27.04 cm−1, 288 K. No significant exchange interactions between Cr(III) cations in the crystalline lattice were found. Curie-Weiss behavior was found in the three directions tested (g1=2.06±0.02,g2= 2.08±0.02,g3=2.09±0.01), T=1.2-1.4 K. 相似文献
trans -[PtCl4(NH3)(thiazole)] (1), trans-[PtCl4(cha)(NH3)] (2), cis-[PtCl4(cha)(NH3)] (3) (cha =cyclohexylamine), and cis-[PtCl4(NH3)2] (4) has been investigatedat 25 °C in a 1.0 M aqueous medium at pH 2.0–5.0 (1) and 4.5–6.8 (2–4) using stopped-flow spectrophotometry. The redox reactions follow the second-order rate law , where k is a pH-dependent rate constant and [GSH]tot the total concentration of glutathione. The reduction takes place via parallel reactions between the platinum(IV) complexes
and the various protolytic species of glutathione. The pH dependence of the redox kinetics is ascribed to displacement of
these protolytic equilibria. The thiolate species GS− is the major reductant under the reaction conditions used. The second-order rate constants for reduction of compounds 1–4 by GS− are (1.43±0.01)×107, (3.86±0.03)×106, (1.83±0.01)×106, and (1.18±0.01)×106 M−1 s−1, respectively. Rate constants for reduction of 1 by the protonated species GSH are more than five orders of magnitude smaller. The mechanism for the reductive elimination
reactions of the Pt(IV) compounds is proposed to involve an attack by glutathione on one of the mutually trans coordinated chloride ligands, leading to two-electron transfer via a chloride-bridged activated complex. The kinetics results
together with literature data indicate that platinum(IV) complexes with a trans Cl-Pt-Cl axis are reduced rapidly by glutathione as well as by ascorbate. In agreement with this observation, cytotoxicity
profiles for such complexes are very similar to those for the corresponding platinum(II) product complexes. The rapid reduction
within 1 s of the platinum(IV) compounds with a trans Cl-Pt-Cl axis to their platinum(II) analogs does not seem to support the strategy of using kinetic inertness as a parameter
to increase anticancer activity, at least for this class of compounds.
Received: 8 December 1999 / Accepted: 15 February 2000 相似文献
Reduction of the model platinum(IV) complexes cis-[PtCl4(NH3)2] (1), trans-[PtCl4(NH3)2] (2), trans-[PtCl2(en)2]2+ (3), trans-[PtBr2(NH3)4]2+ (4), [PtCl6]2− (5), and [PtBr6]2− (6) with l-ascorbic acid (H2Asc) in 1.0 M aqueous medium at 25 °C in the region 1.75≤pH≤7.20 has been investigated using stopped-flow spectrophotometry. The redox reactions follow the rate law: −d[Pt(IV]/dt=k[H2Asc]tot[Pt(IV)] where k is a pH-dependent second-order rate constant and [H2Asc]tot, the total concentration of ascorbic acid. The pH-dependence of k is attributed to parallel reduction of Pt(IV) by the protolytic species HAsc− and Asc2−. Analysis of the kinetics data reveals that the ascorbate anion Asc2− is up to seven orders of magnitude more reactive than HAsc− while H2Asc is unreactive. Electron transfer from HAsc−/Asc2− to the Pt(IV) compounds is suggested to take place by a mechanism involving a reductive attack on any one of the mutually trans-halide ligands by Asc2− and/or HAsc− forming a halide-bridged activated complex. The rapid reduction of these complexes supports the assumption that ascorbate Asc2− might be an important reductant at physiological conditions for anticancer active Pt(IV) pro-drugs capable of undergoing reductive trans elimination. The parameters ΔH≠ and ΔS≠ for reduction of Pt(IV) with Asc2− have been determined from the study of the temperature dependence of k. 相似文献
Treatment of [Bun4N][Ru(N)Cl4] with Na(OR) afforded [Bun4N][Ru(N)(OR)4] (R = C6F5 (1), C6F4H (2), C6Br5 (3)), whereas that with [Bun4N][Os(N)Cl4] gave [Bun4N][Os(N)(OR)3Cl] (R = C6F5 (4), C6F4H (5), C6Br5 (6)). Treatment of [Bun4N][M(N)Cl4] with Na(SC6F4H) and Na(Sxyl) (xyl = 2,6-dimethylphenyl) afforded [Bun4N][M(N)(SC6F4H)4] (M = Ru (7), Os (8)) and [Bun4N][M(N)(Sxyl)4] (M = Ru (9), Os (10)), respectively. The crystal structures of compounds 1, 6 and 9 have been determined. 相似文献
K2PtCl4 reacts with L-lysine and with D,L-diaminiopropionic acid (Dap) forming the neutral complexes [PtCl2(N,O-Lys)]·H20 (1) and [PtCl2(N,O-Dap)], (2) respectively.Compound 1 is monoclinic, space group P21 with a = 11.262(3), b = 11.041(2), c = 9.690(2) Å, β = 102.07(5)°, V = 1178(1) Å3 and Z = 4. Compound 2 is monoclinic, space group P21/n with a = 8.777(1), b = 10.615(2), c = 7.947(1) Å, β = 94.98(3)°, V = 738(1) Å3 and Z = 4. In both compounds, the zwitterionic ligands form an N,O-five membered chelate with the platinum atom. Structures 1 and 2 were refined to R values of 3.3% and 6.3% respectively. 相似文献
Knoevenagel condensation of 4-(dimethylamino)benzaldehyde with 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) gives the donor-acceptor ligand 2-(4-dimethylaminobenzylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (dbpcd). The reaction of dbpcd with PtCl2(cod) affords the platinum(II) complex PtCl2(dbpcd) in high yield. The free dbpcd ligand and PtCl2(dbpcd) have been isolated and fully characterized in solution by IR and NMR spectroscopies, and the solid-state structure of PtCl2(dbpcd) determined by X-ray diffraction analysis. PtCl2(dbpcd), as the 1.5CH2Cl2 solvate, crystallizes in the triclinic space group , a = 11.7412(7) Å, b = 12.0486(7) Å, c = 14.4781(9) Å, α = 82.866(1), β = 75.049(1), γ = 83.905(1), V = 1957.6(2) Å3, Z = 2, and Dcalc = 1.678 mg/m3, R = 0.0291 and wR2 = 0.0723 for 8315 reflections with I > 2σ(I). The molecular structure of PtCl2(dbpcd)·1.5CH2Cl2 consists of a square-planar platinum architecture containing two chlorines and the ancillary dbpcd diphosphine ligand. The redox properties of the dbpcd ligand and PtCl2(dbpcd) have been explored by cyclic voltammetry, and these data are discussed with respect to extended Hückel MO calculations. 相似文献
Trityl borate salts [4-RPyCPh3][B(C6F5)4] (R = H 1, tBu 2, Et 3, NMe24) and [R3PCPh3][B(C6F5)4] (R = Me 5, nBu 6, Ph[1] 7, p-MeC6H48) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh3][B(C6F5)4]. The analogous reactions of PiPr3 affords the product [(p-iPr3P-C6H4)Ph2CH][B(C6F5)4] (9) while the corresponding reactions of Cy3P and tBu3P gave the cyclohexadienyl derivatives [(p-R3PC6H5)CPh2][B(C6F5)4] (R = Cy 10, tBu 11). X-ray structures of 5 and 9 are reported. 相似文献
Treatment of the ligands 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo), 1,9-bis(3,5-dimethyl-1-pyrazolyl)-3,7-dithianonane (bddn), and 1,6-bis(3,5-dimethyl-1-pyrazolyl)-2,5-dithiahexane (bddh) with several platinum starting materials as K2PtCl4, PtCl2, [PtCl2(CH3CN)2] and [PtCl2(PhCN)2] was developed under different conditions. The reactions did not yield pure products. The ratio of the NSSN, NS, SS, NN, and 2NS isomers has been calculated through NMR experiments. Treatment of the mixtures of complexes with NaBPh4 affords [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn). These Pt(II) complexes have been characterised by elemental analyses, conductivity measurements, IR and 1H and 13C NMR spectroscopy. The X-ray structures of the complexes [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn) have also been determined. In these complexes, the metal atom is tetracoordinated by the two azine nitrogen atoms of the pyrazole rings and two thioether sulfur atoms. When the [Pt(NSSN)](BPh4)2 (NSSN = bddo, bddn) complexes were heated under reflux in a solution of Et4NBr in CH2Cl2/CH3OH (1:1), a mixture of isomers was obtained. 相似文献
