Rearrangement or C-H Activation processes Promoted by Reaction with the Solvate [cis-Pt(C6F5)2(thf)2]

Résumé

A new series of functionalized (μ-hydride)(μ-acetylide) isomeric derivatives [trans-(PPh3)(C6F5)Pt(μ-H)(μ- 1κCα:η2-C≡CR)Pt(C6F 5)(PPh3) (3) and [cis,cis-(PPh3) 2Pt(μ-H)(μ-1κCα:η2- C≡CR)Pt(C6F5)2] (4) (R = (4-CH 3)C6H4, a; (4-CN)C6H4, b; CMe=CH2, c; C(OH)Me2, d; C(OH)EtMe, e; C(OH)Ph 2, f) have been prepared by reaction in mild conditions of the disolvated [cis-Pt(C6F5)2(thf)2] with the corresponding Pt(II) [trans-PtH(C≡CR)(PPh3) 2] (1) or Pt(0) [Pt(η2-HC≡CR)(PPh 3)2] (2) isomers. The course of these reactions seems to be rather general, but in the case of the diphenylhydroxy precursors is strongly influenced by an easy gem (4f) to trans (3f) isomerization and the presence of water, which leads to the formation of the unexpected (μ-hydroxy)(μ-vinyl) complex [cis,cis-(PPh3)2Pt{μ-1κC α:η2-CH=CHC(OH)Ph2}(μ-OH)Pt(C 6F5)2] (5f). Control of the latter reaction has allowed us to detect the mixed-valence intermediate [cis,cis-(PPh 3)2Pt{μ-η2:η2- HC≡C(OH)Ph2}Pt(C6F5)2(thf)] (6f). Starting from [Pt(η2-HC≡C5H 4N-4)(PPh3)2] (2g) and [cis-Pt(C 6F5)2(thf)2] only the trinuclear mixed-valence adduct [{(PPh3)2Pt(μ-η2: 2κN-HC≡C5H4N-4)}2{cis-Pt(C 6F5)2}] (7g) is obtained. © 2007 American Chemical Society.