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σ‐Silane Platinum(II) Complexes as Intermediates in C−Si Bond‐Coupling Processes
Author(s) -
Ríos Pablo,
Fouilloux Hugo,
Díez Josefina,
Vidossich Pietro,
Lledós Agustí,
Conejero Salvador
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902226
Subject(s) - agostic interaction , carbene , chemistry , silanes , platinum , hydride , isomerization , bond cleavage , silylation , silane , hydrosilylation , ligand (biochemistry) , aryl , medicinal chemistry , stereochemistry , crystallography , photochemistry , alkyl , catalysis , organic chemistry , hydrogen , receptor , biochemistry , metal
Platinum complexes [Pt(NHC′)(NHC)][BAr F ] (in which NHC′ denotes a cyclometalated N‐heterocyclic carbene ligand, NHC) react with primary silanes RSiH 3 to afford the cyclometalated platinum(II) silyl complexes [Pt(NHC‐SiHR′)(NHC)][BAr F ] through a process that involves the formation of C−Si and Pt−Si bonds with concomitant extrusion of H 2 . Low‐temperature NMR studies indicate that the process proceeds through initial formation of the σ‐SiH complexes [Pt(NHC′)(NHC)(HSiH 2 R)][BAr F ], which are stable at temperatures below −10 °C. At higher temperatures, activation of one Si−H bond followed by a C−Si coupling reaction generates an agostic SiH platinum hydride derivative [Pt(H)(NHC′‐SiH 2 R)(NHC)][BAr F ], which undergoes a second Si−H bond activation to afford the final products. Computational modeling of the reaction mechanism indicates that the stereochemistry of the silyl/hydride ligands after the first Si−H bond cleavage dictates the nature of the products, favoring the formation of a C−Si bond over a C−H bond, in contrast to previous results obtained for tertiary silanes. Furthermore, the process involves a trans ‐to‐ cis isomerization of the NHC ligand before the second Si−H bond cleavage.