12080-32-9Relevant articles and documents
Preparation of platinum(II) cyclooctadiene complexes by photoirradiation
De Vekki,Uvarov,Skvortsov
, p. 321 - 324 (2005)
Preparation of platinum cyclooctadiene complexes under photoirradiation was studied, and the reaction mechanism was suggested. 2005 Pleiades Publishing, Inc.
A Self-Assembling Ligand Switch That Involves Hydroxide Addition to an sp2 Hybridised Phosphorus Atom – A System Allowing OH– Mediated Uptake of [MCl2] (M = Pd, Pt) Centres
Cabon, Yves,Ricard, Louis,Frison, Gilles,Carmichael, Duncan
, p. 1544 - 1551 (2019)
The coordination chemistry of the 1,1′-diphosphacobaltocenium salt [Co(η5-2-TBS-3,4-Me2-PC4H)2]+ BF4– (rac-1) and its derivatives with respect to [MCl2] (M = Pd, Pt) centres is presented. Rac-1, showing two sp2 hybridised phosphorus atoms and a positive charge, is stable towards strong electrophiles (PhCH2Br, MeI), but undergoes attack by hydroxide at phosphorus with subsequent rearrangement to form the neutral conjugate base [Co{η5-(2-TBS-3,4-Me2-PC4H)}{η4-(1-O,1-H-2-TBS-3,4-Me2-PC4H)}] (rac-2). Rac-1 undergoes reaction with [MCl2(PhCN)2] (M=Pd, Pt) in damp chloroform to form the Psp2–Psp3 chelating sec-phosphinite complexes [MCl2{Co{η5-(2-TBS-3,4-Me2-PC4H)}{η4-(1-OH-2-TBS-3,4-Me2-PC4H)}}] 4 (M = Pd, Pt), which are also accessible directly, but under more forcing conditions, from rac-2. Computational analysis (M06/def2-TZVP) indicates that the conjugate base, in the form of its sec-phosphinite tautomer rac-3, shows significantly stronger bonding to the metal centre than does the parent 1,1′-diphosphacobaltocenium salt rac-1. The uptake and subsequent release of a [PtCl2] centre as a function of the pH of the reaction medium hints at the potential for employing the rac-1/rac-2 ligand acid-base couple as a pH-driven coordination switch.
IClick Reactions of Square-Planar Palladium(II) and Platinum(II) Azido Complexes with Electron-Poor Alkynes: Metal-Dependent Preference for N1 vs N2 Triazolate Coordination and Kinetic Studies with 1H and 19F NMR Spectroscopy
Peng, Kun,Mawamba, Viviane,Schulz, Ellina,L?hr, Mario,Hagemann, Carsten,Schatzschneider, Ulrich
, p. 11508 - 11521 (2019)
Two square-planar palladium(II) and platinum(II) azido complexes [M(N3)(L)] with L = N-phenyl-2-[1-(2-pyridinyl)ethylidene]hydrazine carbothioamide reacted with four different electron-poor alkynes R-CC-R′ with R = R′ = COOCH3, COOEt, COOCH2CH2OCH3 or R = CF3, R′' = COOEt in a [3 + 2] cycloaddition "iClick" reaction. The resulting triazolate complexes [M(triazolateR,R')(L)] were isolated by simple precipitation and/or washing in high purity and good yield. Six out of the eight new compounds feature the triazolate ligand coordinated to the metal center via the N2 nitrogen atom, but fortuitous solubility properties allowed isolation of the N1 isomer in two cases from acetone. When the solvent was changed to DMSO, the N1 → N2 isomerization could be studied by NMR spectroscopy and took several days to complete. 19F NMR studies of the iClick reaction with F3C-CC-COOEt led to identification of a putative early linear intermediate in addition to the N1 and N2 isomers, however with the latter as the final product. Rate constants determined by 1H or 19F NMR spectroscopy increased in the order Pd > Pt and CF3/COOEt > COOR/COOR with R = CH3, Et, CH2CH2OCH3. The second-order rate constant k2 > 3.7 M-1 s-1 determined for the reaction of [Pd(N3)(L)] with F3C-CC-COOEt is the fastest observed for an iClick reaction so far and compares favorably with that of the most evolved strained alkynes reported for the SPAAC (strain-promoted azide-alkyne cycloaddition) to date. Selected title compounds were evaluated for their anticancer activity on the GaMG human glioblastoma brain cancer cell line and gave EC50 values in the low micromolar range (2-16 μM). The potency of the Pd(II) complexes increased with the chain length of the substituents in the 4- and 5-positions of the triazolate ligand.
Platinum-catalyzed hydrosilylation of alkynes
Lewis, Larry N.,Sy, Karen G.,Bryant Jr., Garok J. L.,Donahue, Paul E.
, p. 3750 - 3759 (1991)
The reaction of terminal alkynes with several SiH compounds was investigated. The alkynes included phenylacetylene and 1-pentyne. Silanes investigated were triphenylsilane, diphenylmethylsilane, phenyldimethylsilane, triethylsilane, and triethoxysilane. All the reactions were catalyzed by highly active platinum catalysts. Comparison of product yields to those of reactions with other platinum catalysts and with rhodium catalysts were made in a few cases. Comprehensive analysis of product distribution and structure was made by GC and 1H and 13C NMR spectroscopy (APT and HETCOR). Further structural confirmation was achieved with single-crystal X-ray structures for trans-Ph3SiCH=C(H)Ph (1-trans) and for Ph3Si(Ph)C=CH2 (1-α). Compound 1-trans, C26H22Si, was monoclinic, P21, with a = 7.410 (6) A?, b = 11.349 (8) A?, c = 12.594 (10) A?, β = 99.43 (6)°, and Z = 2. Compound 1-α, C26H22Si, was monoclinic, P21/c, with a = 10.121 (7) A?, b = 10.225 (6) A?, c = 20.116 (11) A?, β = 93.03 (5)°, and Z = 4.
Photochemistry of 1,5-Cyclooctadiene Platinum Complexes for Photoassisted Chemical Vapor Deposition
Liu, Hanwen,Brewer, Christopher R.,Walker, Amy V.,McElwee-White, Lisa
, p. 4565 - 4574 (2020)
Quantum yields for disappearance of (COD)PtMe2 (1a) and (COD)PtMeCl (1b) were determined at 334 nm in C6D6 solvent. Chain reactions initiated by formation of a methyl radical were proposed to be the cause of quantum yields higher than unity (φ = 5.52 ± 0.40 for 1a) when the reaction mixtures included C4F9I. The chain reactions were suppressed in the presence of the radical trap 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), which resulted in measured disappearance quantum yields of φ = 0.037 ± 0.003 for (COD)PtMe2 and φ = 0.44 ± 0.02 for (COD)PtMeCl at 334 nm. Weak luminescence was observed for 1a and 1b, and it was determined that emissive decay is not competitive with Pt-CH3 bond homolysis. DFT studies enabled assignment of both SBLCT and MLCT transitions in the UV/vis spectra of 1a, while 1b only exhibits MLCT transitions. These effects can be attributed to the symmetry of the molecule and its electronic structure.
Palladium, rhodium and platinum complexes of ortho-xylyl-linked bis-N-heterocyclic carbenes: Synthesis, structure and catalytic activity
Baker, Murray V.,Brown, David H.,Simpson, Peter V.,Skelton, Brian W.,White, Allan H.,Williams, Charlotte C.
, p. 5845 - 5855 (2006)
New Pd(II), Pt(II) and Rh(I) N-heterocyclic carbene (NHC) complexes containing two NHC units linked by an ortho-xylyl group are described and structurally and spectroscopically characterised. The Pt(II) complexes represent the first examples of Pt-bis(NHC) complexes where the NHC units are linked by an ortho-xylyl group. Functionalisation of the bis(NHC) ligands with heptyl groups has been used as a means of enhancing the solubility of the complexes, in order to facilitate spectroscopic characterisation and catalytic studies. The catalytic activity of the palladium(II) complexes in Heck and Suzuki cross-coupling reactions has been examined to investigate any effects of the diverse structural changes, though these appear to be insignificant.
Kinetic and mechanistic studies of 1,3-bis(2-pyridylimino)isoindolate Pt(ii) derivatives. Experimental and new computational approach
Wekesa, Isaac M.,Jaganyi, Deogratius
, p. 2549 - 2558 (2014)
The rate of substitution of the chloride ligand by three bio-relevant nucleophiles, thiourea (Tu), N,N-dimethylthiourea (Dmtu) and N,N,N,N-tetramethylthiourea (Tmtu), in the complexes: 1,3-bis(2-pyridylimino) isoindoline platinum(ii) chloride (Pt2), 1,3-bis(2-pyridylimino)benz(f) isoindoline platinum(ii) chloride (Pt3) and 1,3-bis(1-isoquinolylimino) isoindoline platinum(ii) complex (Pt4) was investigated under pseudo first-order conditions as a function of concentration and temperature using stopped-flow and UV-Visible spectrophotometry. Computational modeled data of bis(pyridylimino)3,4-pyrrolate platinum(ii) chloride (Pt1) were incorporated in the study for comparison. The observed pseudo first-order rate constants for substitution reactions obey the rate law kobs = k2[Nu]. High negative activation entropies and second-order kinetics for the displacement reactions all support an associative mode of activation. The reactivity is dependent on stabilization of the LUMO energy and inversely proportional to the number of phenyl rings added irrespective of the site of attachment. The electron density on the ligand moiety plays a significant role in the substitution behavior of the platinum(ii) complexes, as supported by DFT descriptors {electrophilicity index (ω) and chemical hardness (η)}.
Probing the 'Venus fly-trap' parameters of cyclo-octadiene in selected β-diketonato complexes of platinum(II) and the nickel-triad from a spectroscopic, X-ray crystallographic and DFT study
Hill,Roodt,Steyl
, p. 82 - 89 (2013)
Synthetic, structural and theoretical studies of Pt(II) complexes of a series of β-diketonato ligands with a variation of sterics, namely acetylacetonato (acac) and thenyoltrifluoroactonato (thtfac), are reported. The crystal structures of [Pt(cod)(acac)]PF6(I), [Pt(cod)(acac)]BF 4(II) and [Pt(cod)(thtfac)]BF4(III) are presented while the complexes were characterized spectroscopically by IR, 1H and 13C NMR spectroscopy. DFT calculations of the group 10 transition metals in the nickel triad, utilising the model complex, [M(cod)(acac)] +, to gain further insights in the variation of the transition metal within the complex and the interactions with both the β-diketonato and cis,cis-1,5-cyclo-octadiene (cod) co-ordinating ligands are reported. In particular, the variation in the 'Venus fly-trap' bite and jaw dihedral angles, χ and ψ, is ca. 2° and 4°, respectively, and therefore quite small, but significant. The HOMO and LUMO energy gaps between the Ni(II) and Pd(II) complexes were insignificant, while that of Pt(II) is >1 eV higher than the corresponding 3rd and 4th row congener complexes.
Competition between carbon monoxide and alkenes in chloro complexes of platinum(II)
Dell'Amico, Daniela Belli,Bini, Riccardo,Calderazzo, Fausto,Carbonaro, Laura,Labella, Luca,Vitullo, Anna
, p. 4427 - 4431 (2005)
Alkenes (cyclohexene; 1-octene) and dienes (cyclooctadiene, COD; norbornadiene, NBD) react with cis-PtCl2(CO)2, leading, respectively, to partial and complete displacement of coordinated carbon monoxide. Equilibrium constants at 21 °
How to obtain Pt(IV) complexes suitable for conjugation to nanovectors from the oxidation of [PtCl(terpyridine)]+
Gabano,Perin,Fielden,Platts,Gallina,Rangone,Ravera
, p. 10246 - 10254 (2017)
Oxidation of [Pt(II)Cl(terpy)]+ (terpy = 2,2′:6′,2′′-terpyridine) has been attempted with several oxidizing agents and under different experimental conditions in order to obtain a Pt(iv) complex suitable for the conjugation to nanovectors to be used in drug delivery targeting for anticancer therapy. The best compromise in terms of yield and purity of the final complex was obtained by microwave-assisted reaction at 70 °C in 50% aqueous H2O2 for 2 h. Under these conditions the quantitative formation of [Pt(IV)Cl(OH)2(terpy)]+ was observed. The subsequent synthetic steps were, (i) functionalization of [Pt(IV)Cl(OH)2(terpy)]+ in the axial position with succinic anhydride to obtain [Pt(IV)Cl(OH)(succinato)(terpy)]+ and (ii) reaction of the latter with nonporous silica nanoparticles (SNPs) with an external shell containing primary amino groups to obtain a nanovector able to transport the Pt(iv) antitumor prodrug in the form of a conjugate Pt-SNP. Finally, the antiproliferative activity and cell accumulation of [Pt(II)Cl(terpy)]+, [Pt(IV)Cl(OH)2(terpy)]+, and the Pt-SNP conjugate were measured on three cancer cell lines. Despite highly effective accumulation of Pt-SNP in cells, a modest increase in activity was observed with respect to the molecular species. Further experiments showed that the Pt-SNP conjugate can release [Pt(II)Cl(terpy)]+ upon reduction, but this metabolite may undergo hydrolysis, and the resulting aquo complex could coordinate once again the free amino groups of the SNPs. In the resulting tetraamine form, the Pt(ii) complex conjugated to the SNPs cannot completely perform its antiproliferative activity.
Controlling the extent of π-backbonding in platinum(ii) terpyridyl systems: A detailed kinetic, mechanistic and computational approach
Reddy,Jaganyi
, p. 6724 - 6731 (2008)
The rate of substitution of the chloride ligand from [Pt(terpy)Cl] + (Pt1) (where terpy = 2,2′:6′,2″-terpyridine) and its corresponding analogue [Pt(tBu3terpy)Cl]+ (Pt2) (where tBu3terpy = 4,4′,4″-tri-tert- butyl-2,2′:6′,2″-terpyridine) by a series of neutral and anionic nucleophiles, viz. thiourea (TU), 1,3-dimethyl-2-thiourea (DMTU), 1,1,3,3-tetramethyl-2-thiourea (TMTU), iodide (I-) and thiocyanate (SCN-), was determined under pseudo first-order conditions as a function of concentration and temperature using standard stopped-flow spectrophotometric techniques. The observed pseudo first-order rate constants for the substitution reactions obeyed the simple rate law kobs = k2[nucleophile]. Second-order kinetics and negative activation entropies support an associative mode of activation. The rate of substitution of chloride is observed to decrease with an increase in the steric bulk of the neutral nucleophiles, whilst rate of substitution by I- was observed to be faster than that by SCN-, in correlation with their polarizability and the softness of the metal centre. A comparison of the second-order rate constants, k2, at 298 K, obtained for the substitution reactions of Pt1 and Pt2 shows that the introduction of strong σ-donating groups on the periphery of the terpyridyl backbone in Pt2 results in a corresponding decrease in the reactivity. DFT calculations at the B3LYP/LACVP** level of theory for the two complexes, Pt1 and Pt2, and a series of similar analogues containing either electron-donating or electron-withdrawing groups in the periphery positions demonstrate that the introduction of electron-donating groups decreases the positive charge on the metal centre and increases energy separation of the frontier molecular orbitals (EHOMO-ELUMO) of the ground state platinum(ii) complexes leading to a less reactive metal centre whilst the introduction of electron-withdrawing groups has an opposite effect leading to increased reactivity of the metal centre.
Remarkable anticancer activity of ferrocenyl-terpyridine platinum(ii) complexes in visible light with low dark toxicity
Mitra, Koushambi,Basu, Uttara,Khan, Imran,Maity, Basudev,Kondaiah, Paturu,Chakravarty, Akhil R.
, p. 751 - 763 (2014)
Ferrocenyl platinum(ii) complexes (1-3), viz. [Pt(Fc-tpy)Cl]Cl (1), [Pt(Fc-tpy)(NPC)]Cl (2, HNPC = N-propargyl carbazole) and [Pt(Fc-bpa)Cl]Cl (3), were prepared, characterized and their anti-proliferative properties in visible light in human keratinocyte (HaCaT) cell lines have been studied. [Pt(Ph-tpy)Cl]Cl (4) was prepared and used as a control. Complexes 1 and 3, structurally characterized by X-ray crystallography, show distorted square-planar geometry for the platinum(ii) centre. Complexes 1 and 2 having the Fc-tpy ligand showed an intense absorption band at ～590 nm. The ferrocenyl complexes are redox active showing the Fc+-Fc couple near 0.6 V vs. SCE in DMF-0.1 M tetrabutylammonium perchlorate (TBAP). Complexes 1-3 showed external binding to calf thymus DNA. Both 1 and 2 showed remarkable photocytotoxicity in HaCaT cell lines giving respective IC50 values of 9.8 and 12.0 μM in visible light of 400-700 nm with low dark toxicity (IC50 >60 μM). Fluorescent imaging studies showed the spread of the complexes throughout the cell localising both in cytoplasm and the nucleus. The ferrocenyl complexes triggered apoptosis on light exposure as evidenced from the Annexin V-FITC/PI and DNA ladder formation assays. Spectral studies revealed the formation of ferrocenium ions upon photo-irradiation generating cytotoxic hydroxyl radicals via a Fenton type mechanism. The results are rationalized from a TDDFT study that shows involvement of ferrocene and the platinum coordinated terpyridine moiety as respective HOMO and LUMO.
