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The evolution of [{Ph2P(CH2)(n)PPh2}Pt(mu-S)(2)Pt{Ph2P(CH2)(n)PPh2}] (n=2,3) metalloligands in protic acids: A cascade of sequential reactions

Lookup NU author(s): Paul Anthony Champkin, Professor William Clegg

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Abstract

Given the nucleophilicity of the {Pt2S2} ring, the evolution of [Pt-2(mu-S)(2)(P boolean AND P)(2)] (P boolean AND P = 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)) metallo-ligands in the presence of the simplest electrophilic species, the proton, has been studied. Combined use of experimental and theoretical data has allowed the whole set of reactions ensuing the protonation of the {Pt2S2} core to be established. The titration of [Pt-2(mu-S)(2)(P boolean AND P)(2)] with HCl or HClO4 was monitored mainly by P-31{H-1} NMR and mass techniques. Characterization of all the species involved was completed with the determination of the crystal structure of [Pt(SH)(2)(P boolean AND P)], for dppe and dppp, and [Pt-3(mu(3)-S)(2)(dppp)(3)] (PF6)(2). The first protonation step of the {Pt2S2} core leads to the stable [Pt-2(mu-S)(mu-SH)(P boolean AND P)(2)](+) complex, but the second step implies disintegration of the ring, thus giving rise to various mononuclear species. The subsequent evolution of some of these species allows regeneration of [Pt-2(mu-S)(mu-SH)(P boolean AND P)(2)](+), evidencing the cyclic nature of this process. Whereas the reaction pathway is essentially common for both phosphine ligands, dppe and dppp, the different coordinating ability of Cl- or ClO4- determines the nature of the final products, [PtCl2(P boolean AND P)], [Pt-3(mu-S)(2)(P boolean AND P)(3)]Cl-2 or [Pt-3(mu(3)-S)(2)(P boolean AND P)(3)](ClO4)(2). DFT calculations have corroborated the thermodynamic feasibility of the reactions proposed on the basis of experimental data.

Publication metadata

Author(s): Mas-Balleste R, Aullon G, Champkin PA, Clegg W, Megret C, Gonzalez-Duarte P, Lledos A

Publication type: Article

Publication status: Unknown

Journal: CHEMISTRY-A EUROPEAN JOURNAL

Year: 2003

Volume: 9

Issue: 20

Pages: 5023-5035

ISSN (print):

ISSN (electronic):

DOI: 10.1002/chem.200304983

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