Silyl–Silylene Interplay in Cationic PSiP Pincer Complexes of Platinum

Abstract

Herein we report the synthesis and spectroscopic observation of a Pt complex featuring a P 2 Si ligand containing a central silylene donor connected to phosphines via two o-arylene linkers. Species of the type (P 2 Si)PtR undergo a net 1,2-migration of R from Pt to Si, which leads to highly unsaturated Pt cations displaying only a very distant interaction with the weakly coordinating carborane anion.

σ‐Silane Platinum(II) Complexes as Intermediates in C−Si Bond‐Coupling Processes

“…The reaction of platinum(II) complex 1.1 (see the Supporting Information for detailso ft he numbering used in this article) with primary silanesH 3 SiR (R = nBu, Ph) in CD 2 Cl 2 at rt (Scheme 2) is characterized by gas evolution( H 2 ;s ignal detected at 4.64 ppm in the 1 HNMR spectrum) and the formation of an ew speciesd efined by the non-symmetric nature of the N-heterocyclic carbene ligandsa ccording to the 1 Ha nd 13 C{ 1 H} NMR spectra.I np articular, the most characteristicf eature of the 1 HNMR spectrum is the observation of two distinct CH(CH 3 ) 2 methinic protons andf our signals for the =CH imidazole protons, in asimilar way as for the cyclometalated starting complex 1.1.M ost significantly,r esonances at d = 4.04 and 3.52 ppm with ar elativei ntegral of one for 2.1 a and 2.1 b,r espectively,e xhibiting al arge coupling constantt o 195 Pt of around1 20 Hz have been attributed to an SiÀHg roup. [10] This latter resonance correlates with signals at d = À10.8 ppm (2.1 a, 1 J Pt,Si % 1500 Hz) and À1.5 ppm (2.1 b)i nt he 1 H, 29 Si HMQC NMR spectra,i nt he expected region for silyl-platinum complexes. [6b, 10] This information, together with the fact that H 2 was extruded from the system,s uggested that the silyl-cyclometallated Pt II complexes 2.1 a and 2.1 b had been formed (Scheme 2).…”

Transfer hydrogenation of aldehydes catalyzed by silyl hydrido iron complexes bearing a [PSiP] pincer ligand

“…The ligand 1 and 5 were prepared according to the literature. 9,10,12 Fe(PMe 3 ) 4 was prepared according to literature procedures. 23 Infrared spectra (4000-400 cm À1 ), as obtained from Nujol mulls between KBr disks, were recorded on a Bruker ALPHA FT-IR instrument.…”

“…In addition, changing phosphorus ligand would provide transition metal complexes with unique reactivity in catalytic reactions. 9,10 Reduction of aldehydes and a,b-unsaturated aldehydes to alcohols is a fundamental and indispensable process for synthesis of a wide range of alcohols because a lot of alcohols are useful products and precursors for pharmaceutical, agrochemical, material and ne chemical industries. 11 In most cases the transformation of aldehydes and a,b-unsaturated aldehydes to the related alcohols is a metal-catalyzed process.…”

Cationic Platinum(II) σ‐SiH Complexes in Carbon Dioxide Hydrosilation

“…[16] The SiH proton resonates in the 1 H NMR spectrum as a multiplet centered at 3.64 ppm coupled to 195 Pt ( 2 JPt,H = 115 Hz) consistent with the formulation of 2 as a platinum silyl species. [17] The 1 H, 29 Si -HMQC NMR spectrum shows a signal at 18.1 ppm for the silyl group. These experimental observations were further borne out by X-ray diffraction studies (Figure 3), which show the platinum atom surrounded by two I t Bu ligands in a mutually trans disposition and a silyl fragment with no ligand trans to it.…”