title: Reactivity of cationic agostic and carbene structures derived from platinum(II) metallacycles.
abstract: This paper describes the formation of new platinacyclic complexes derived from the phosphine ligands PiPr2 Xyl, PMeXyl2 , and PMe2 Ar Xyl 2 (Xyl=2,6-Me2 C6 H3 and Ar Xyl 2=2,6-(2,6-Me2 C6 H3 )2 -C6 H3 ) as well as reactivity studies of the trans-[Pt(C^P)2 ] bis-metallacyclic complex 1 a derived from PiPr2 Xyl. Protonation of compound 1 a with [H(OEt2 )2 ][BArF ] (BArF =B[3,5-(CF3 )2 C6 H3 ]4 ) forms a cationic δ-agostic structure 4 a, whereas α-hydride abstraction employing [Ph3 C][PF6 ] produces a cationic platinum carbene trans-[Pt{PiPr2 (2,6-CH(Me)C6 H3 }{PiPr2 (2,6-CH2 (Me)C6 H3 }][PF6 ] (8). Compounds 4 a and 8 react with H2 to yield the same 1:3 equilibrium mixture of 4 a and trans-[PtH(PiPr2 Xyl)2 ][BArF ] (6), in which one of the phosphine ligands participates in a δ-agostic interaction. DFT calculations reveal that H2 activation by 8 occurs at the highly electrophilic alkylidene terminus with no participation of the metal. The two compounds 4 a and 8 experience C-C coupling reactions of a different nature. Thus, 4 a gives rise to complex trans-[PtH{(E)-1,2-bis(2-(PiPr2 )-3-MeC6 H3 )CHCH}] (7) that contains a tridentate diphosphine-alkene ligand, through agostic CH oxidative cleavage and C-C reductive coupling steps, whereas the C-C coupling reaction in 8 involves classical migratory insertion of its [PtCH] and [PtCH2 ] bonds promoted by platinum coordination of CO or CNXyl. The mechanisms of the CC bond-forming reactions have also been investigated by computational methods.
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).|Current address: Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR (UK).
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).
authors.forename: Laura
authors.initials: L
authors.lastname: Ortega-Moreno
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).
authors.forename: Salvador
authors.initials: S
authors.lastname: Conejero
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).
authors.forename: Riccardo
authors.initials: R
authors.lastname: Peloso
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).
authors.forename: Joaquín
authors.initials: J
authors.lastname: López-Serrano
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain).
authors.forename: Celia
authors.initials: C
authors.lastname: Maya
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Inorgánica, CSIC-Universidad de Sevilla, Avenida Américo Vespucio 49, 41092 Sevilla (Spain). guzman@us.es.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carmona
keywords: CC coupling; DFT; Pt carbenes; agostic interactions; metallacycles