Browsing by Author "Contreras, R"
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- ItemC-Pt(IV) activation in new trimethylplatinum(IV) complexes: nucleophilic attack at metal-carbon bond(ELSEVIER SCIENCE SA, 2003) Romero, P; Valderrama, M; Contreras, R; Boys, DReaction of the tetranuclear complex [Me3PtI](4) with the ligand o-Ph2P(E)C6H4SMe (E = S, Se) in a 1:4 molar ratio yields the mononuclear neutral complexes [Me3PtI(eta(2)-MeSC6H4P(E)Ph-2-S,S)] (E = S(1), Se(2)). Iodide abstraction from these compounds with AgPF6 in the presence of a ligand L (PPh3, py) leads to cationic complexes of the type [Me3Pt(eta(2)-MeSC6H4P(E)Ph-2-E,S)L]PF6 [E = S, L = PPh3 (3), Py (4); E = Se, L = Py (5)]. However, using complex 2 and the ligand PPh3 under identical conditions induces a reductive elimination reaction affording the Pt(II) complex [MePt(eta(2)-MeSC6H4PPh2-P,S)(PPh3)]PF6 (6). Reactions of complexes 3 and 4 with NaI reveal a nucleophilic attack of the iodide to one of the methyl groups bonded to the platinum center generating a series of subsequent side reactions. Complex [Me3Pt{eta(2)-MeSC6H4P(S)Ph-2-S,S}(py)]PF6.CH2Cl2 (4) was additionally characterised by X-ray diffraction. The platinum atom exhibits a distorted octahedral coordination, bonded to three methyl carbon atoms in a facial arrangement; a bidentate chelate S,S'-bonded ligand and a nitrogen atom of the pyridine ligand complete the metal coordination sphere. (C) 2003 Elsevier Science B.V. All rights reserved.
- ItemD-serine released by astrocytes in brainstem regulates breathing response to CO2 levels(2017) Bernhardi Montgomery, Rommy von; Eugenin, J; Llona, I; Zúñiga, G; Contreras, R; Olivares, M; Beltrán, S
- ItemPlatinum(II) complexes with dithiolates and phosphinites as ligands: Crystal structure of [Pt{S2CO}{P(OMe)Ph(2)}(2)](PERGAMON-ELSEVIER SCIENCE LTD, 1996) Contreras, R; Valderrama, M; Riveros, O; Moscoso, R; Boys, DReaction of the complex [PtCl{P(O)Ph(2)} {P(OH)Ph(2)}(2)] with silver or thallium derivatives of dithiolate ligands led to neutral complexes of general formula [Pt{S-S} {P(O)Ph(2)} {P(OH)Ph(2)}], where {S-S}(-) ={S(2)CNEt(2)}(-) (1), {S2P(OEt)2}(-) (2) and {S(2)COEt}(-) (3). Complexes 2 and 3 reacted with an excess of NaI in acetone solution by dealkylation of the coordinated dithiolate ligand and formation of the compounds [Pt{S2P(O) (OEt)} {P(O)Ph(2)} {P(OH)Ph(2)}] Na (4) and [Pt{S2CO}{P(O)Ph(2)}{P(OH)Ph(2)}] Na (5), respectively. The corresponding tetraphenylphosphonium derivatives (6, 7) were prepared by a metathetical reaction of these complexes with Ph(4)PBr in acetone solution. Related dithiolate complexes were obtained by reaction of the complex [Pt{S-S}(2)] with P(OMe)Ph(2) in molar ratio 1:2. Thus, the reaction of [Pt{S(2)COEt}(2)] in dichloromethane solution at room temperature gave [Pt{S(2)COEt} {P(OMe)Ph(2)}(2)] Cl (8). This complex reacted with NaI in acetone to form the neutral compound [Pt{S2CO} {P(OMe)Ph(2)}(2)] (9). When the reaction was carried out in dichloromethane at reflux temperature using [Pt{S2P(OEt)(2)}(2)] as starting material, the neutral compound [Pt{S2P(O)(OEt)} {P(OMe)Ph(2)}(2)] (10) was obtained. The crystal structure of the complex 9 has been determined by X-ray diffraction. The neutral complex shows a nearly square-planar coordination of the metal and a planar dithiocarbonate ligand.
- ItemRhodium(III) and ruthenium(II) complexes with the chiral phosphine-alcohol PH2PCH2CHMeCH2OH. Synthesis and characterisation(SOC CHILENA QUIMICA, 2002) Sanhueza, J; Contreras, R; Valderrama, MReaction of the dinuclear complex [{(eta(5)-C5Me5)RhCl}(2)(mu-Cl)(2)] with the chiral phosphine (R)-Ph2PCH2CHMeCH2OH leads to the complex [{(eta(5)-C5Me5)RhCl2(eta(1)-Ph2PCH2CHMeCH2OH-P)}](1). This reaction, in the presence of AgBF4, yields the cationic compound [{(eta(5)-C5Me5)RhCl(eta(2)-Ph2PCH2CHMeCH2OH-P,O)}]BF4 (2). Variable-temperature H-1 NMR and circular dichroism experiments support the stereoselective eta(2)-chelate coordination of the ligand and the proposed configuration for the metal centre. In a similar way, the reaction of the dimer [{(eta(6)-C6Me6)RuCl}(2)(mu-Cl)(2)] with the ligands (R)- and (S)-Ph2PCH2CHMeCH2OH afford the neutral complexes [(eta(6)-C6Me6)RuCl2{eta(1)-PPh2CH2CHMeCH2OH-P}] [R-ligand (3), S-ligand (4)], which in turn react with AgBF4 to give the cationic compounds [(eta(6)-C6Me6)RuCl{eta(2)-PPh2CH2CHMeCH2OH-P,O}]BF4 [R-ligand (5), S-ligand (6)]. All complexes have been characterised by elemental analysis, IR and multinuclear NMR spectroscopies.
- ItemSynthesis and reactivity of new trimethylplatinum(IV) complexes containing chiral Schiff bases as ligands: Crystal structure of (OC-6-44-C)-[PtIMe3{kappa(2)-(R)-Ph2P(C6H4)CH=NC*H(Ph)Me-P,N}](ELSEVIER SCIENCE SA, 2006) Ramirez, P; Contreras, R; Valderrama, M; Boys, DReaction of the tetranuclear complex [PtIMe3](4) with the ligand (S)- and (R)-Ph2P(C6H4)CH=NC*H(Ph)Me in a 1:4 molar ratio yields the mononuclear neutral complexes in diastereoisomeric mixtures [PtIMe3{K-2-Ph2P(C6H4)CH=NC*H(Ph)Me-P,N}]. Iodide abstraction from mixture with AgBF4 in the presence of pyridine (Py) induces a reductive elimination reaction with loss of ethane, leading to the cationic complex [PtMe(Py) {kappa(2) -Ph2P(C6H4)CH=NC*H(Ph)Me-P,N}[BF4] [C* = (S)-, 3; (R)-, 4]. When this reaction was carried out in the presence of PPh3 a consecutive orthometallation reaction with loss of methane is produced, forming the cationic complex [Pt(PPh3){kappa(3)-Ph2P(C6H4)CH=NC*H(C6H4)Me-C,P,N][BF4], [(S)-, 5; (R)-, 6]. All species were characterised in solution by H-1 and P-31{H-1} NMR spectroscopy, elemental analysis and mass spectrometry.