12012-50-9Relevant academic research and scientific papers
Influence of steric and electronic factors in the stabilization of five-coordinate ethylene complexes of platinum(II): X-ray crystal structure of [PtCl2(2,9-dimethyl-1,10-phenanthroline-5,6-dione)]
Margiotta, Nicola,Bertolasi, Valerio,Capitelli, Francesco,Maresca, Luciana,Moliterni, Anna G.G.,Vizza, Francesco,Natile, Giovanni
, p. 149 - 158 (2004)
Reactions of Zeise's salt (K[Pt(??2-C2H 4)Cl3]) with oxidized phenanthroline ligands (1,10-phenanthroline-5,6-dione, phedon, and 2,9-dimethyl-1,10-phenanthroline-5, 6-dione, Me2phedon) are reported. Comparison with analogous reactions involving unoxidized phen (1,10-phenanthroline) and Me 2phen (2,9-dimethyl-1,10-phenanthroline) ligands indicates that these latter ligands are less capable to stabilize the five-coordinate species [PtCl2(η2-C2H4)(phenanthroline)] in which the phenanthroline and the olefin share the trigonal plane and two chlorines are in the axial positions. The X-ray structure of the four-coordinate species [PtCl2(Me2phedon)] indicates that the major difference between oxidized and unoxidized phenanthrolines is the loss of aromaticity of the central ring of phenanthroline. As a consequence, the oxidized phenanthroline becomes more flexible and can undergo a bow-like distortion so to reduce steric interaction between ortho substituents of phenanthroline and cis chlorine ligands. The increase in stability of the four-coordinate species with Me2phedon is concomitant with an increase in stability of the five-coordinate precursor complex with ethylene. In the latter case the stabilization is not of sterical origin but stems from reduced electron-donor properties of oxidized phenanthrolines. The balance of the two effects is such that the equilibrium between five- and four-coordinate species is more shifted in favour of the former species in the case of Me 2phedon than in the case of Me2phen.
A fast and easy approach to the synthesis of Zeise's salt using microwave heating
Shoemaker, Krista A.,Leadbeater, Nicholas E.
, p. 341 - 342 (2009)
A fast and easy approach to the synthesis of Zeise's salt, KPtCl3(C2H4), is reported using microwave heating. The reaction is complete after 15 min at 130 °C using K2PtCl4 as starting material, a 1:1:
Formation and decomposition of the methylplatinum(IV) complex in the mechanically activated K2PtCl4 powder-MeI vapor system
Mitchenko,Khomutov,Zhikharev,Beletskaya
, p. 475 - 483 (2002)
Mechanical treatment of the K2PtCl4 solid salt in a vibrating mill results in Pt-Cl bond heterolysis to form coordinatively unsaturated Pt(II) complexes. At room temperature, the freshly treated K2PtCl4 salt absorbs methyl bromide and evolves methyl chloride to the gas phase. The reaction mechanism involves the following sequence of steps: the oxidative addition of methyl iodide to Pt(II) with the intermediate formation of Pt(IV) methyl complexes and the decomposition of the latter due to intramolecular reductive elimination with methyl chloride formation. The first step of the reaction of MeI with the preactivated surface of the K2PtCl4 salt is assisted by active sites, which are regenerated in each act of the chemical transformation of MeI into MeCl involving in the chain substitution of halogen in methyl iodide. The coordinatively unsaturated surface platinum complexes can act as such active sites. Due to their effective positive charge, they can provide electrophilic assistance to nucleophilic substitution. Chain termination is probably due to the coordination of the complex with a coordination vacancy and an interstitial chloride ion to the inactive K2PtCl4 complex.
Practical Gas Cylinder-Free Preparations of Important Transition Metal-Based Precatalysts Requiring Gaseous Reagents
Ahrens, Alexander,Donslund, Bjarke S.,Gausas, Laurynas,Kristensen, Steffan K.,Skrydstrup, Troels,Sun, Hongwei
supporting information, p. 2300 - 2307 (2021/09/28)
A simple and safe setup for the synthesis of a selection of important transition metal-based precatalysts is reported, all requiring low-molecular weight gaseous reagents for their preparation. Hydrogen, carbon monoxide, ethylene, and acetylene are each liberated in a controlled manner from a corresponding easy-to-handle precursor in a closed two-chamber reactor. Gas cylinders and elaborate setups/techniques connected to handling toxic and/or flammable gases as reported in the literature can thus be avoided. The corresponding precatalysts are of high relevance in the active research fields of C-H bond activation, dehydrogenation, hydrogenation, and coupling reactions. The selection of complexes shown is meant to serve as examples for the usefulness and broadness of the presented methods, allowing precatalysts requiring gaseous reagents to become available for the research community.
Highly selective metal mediated ortho-alkylation of phenol. First platinum containing organometallic chromane analogues
Vecchio, Vita M.,Benedetti, Michele,Migoni, Danilo,De Pascali, Sandra A.,Ciccarese, Antonella,Marsigliante, Santo,Capitelli, Francesco,Fanizzi, Francesco P.
, p. 5720 - 5725 (2008/04/06)
We were able, for the first time, to synthesize and characterize Pt derivatives with a structural shape similar to vitamin E, having a metalla-chromane core. The formation reaction mechanism includes an unexpected highly selective ortho aromatic electrophilic substitution on phenol, operated by [PtCl(η1-C2H4OR)(N-N)], R = Me or Ph, and a final cyclization step. The X-ray structure of one of the new metalla-chromane complexes [Pt(EtPh)(phen)], 1a, (EtPh = 2-(ethan-2′-yl- kC1)-1-phenolato-kO1, phen = 1,10-phenanthroline) is reported. Cytotoxicity and Pt uptake measurements, performed on HeLa cancer cells, show an interesting structure-activity correlation for the new metalla-chromane analogues 1a and [Pt(MeOEtPh)(phen)], 1b, (MeOEtPh = 2-(ethan-2′-yl-kC1)-4-(methoxy)-1-phenolato-kO1), being the structurally closest to vitamin E and also the most active. This journal is The Royal Society of Chemistry.
Mechanistic aspects of the oxidative functionalization of ethane and ethanol by platinum(II) salts in aqueous medium. Role of platinum(II)-olefin and platinum(IV) - alkyl intermediates
Hutson, Alan C.,Lin, Minren,Basickes, Naomi,Sen, Ayusman
, p. 69 - 74 (2007/10/03)
The relative rate of C-H bond activation by the Pt(II) ion decreased in the order H-CH2CH3 > H-CH2CH2OH > H-CH(OH)CH3.The platinum(II)-ethylene complex, -, 1, was the key intermediate in the oxidation of ethane, ethanol, and diethyl ether to 1,2-ethanediol by platinum(II) in aqueous medium.In particular, the intermediacy of 1 in the oxidation of ethanol to 1,2-ethanediol and 2-chloroethanol was verified through labeling studies.In D2O, 1, upon oxidation with one of a number of oxidants, converted to 2-, 2. 2 in turn decomposed to a mixture of 1,2-ethanediol and 2-chloroethanol on heating.The rate conversion of 1 was a function of pH, the anions present, and the oxidant used.While the conversion of 1 to 2 involved a nucleophilic attack by water (or hydroxide ion), such a step was not observed in the absence of an oxidant.In basic D2O, the sequential replacement of Cl- by OD- in 1 occurred to successively form -, - and -.The process was reversed upon acidification.The species 2-, 3, appeared to be the source for the small quantities of hydroxy- and/or chloroacetaldehyde formed during the oxidation of 1. 3 was synthesized independently by the reaction of acetaldehyde with a mixture of PtCl42-, and PtCl62- in aqueous medium.When 1 was oxidized by Cl2 in CD3OD solution, the principal product was 2- 4, when a small amount of water was present, and CD3OCH2CH2OCD3 in the absence of water. Keywords: Platinum complex; C-H activation; Oxidation; Ethane; Ethylene; Ethanol
