Synthetic and structural studies of NHC–Pt(dvtms) complexes and their application as alkene hydrosilylation catalysts (NHC=N-heterocyclic carbene, dvtms=divinyltetramethylsiloxane)

Coordination environment friendly silicon in copper(I) chloride π-complexes with tetravinylsilane and dimethyltetravinyldisiloxane

“…The tendency of C@C bond elongation is observed in other d 10 metal p-complexes containing silicon ligand, i.e., with Ni(0) [28,31,32], Pt(0) [32][33][34]. Because of the lower electronic charge on the metal centre the stronger donor metal properties are observed here by increasing values of C@C distance compared to the analogous Cu(I) complexes.…”

Highly Stable Water‐Soluble Platinum Nanoparticles Stabilized by Hydrophilic N‐Heterocyclic Carbenes

“…The signal for the carbenic carbon center is slightly shifted to higher field with respect to that found in 1 (d = 185-182 ppm) or in related [(NHC)Pt 0 (dvtms)] complexes (d = 200-180 ppm; dvtms = divinyltetramethyldisiloxane). As expected, the carbene carbon atom is less strongly coupled to the 195 Pt center in 13 C-2 c than in molecular (NHC)Pt 0 complexes (around 1365 Hz), [18] although the interaction is still more intense than in the precursor 13 C-1 c (767 Hz), in which the oxidation state of the metal (+ 2) helps to decrease the magnitude of the coupling. [19] The carbenic carbon resonance signal was very weak in the case of 2 a, 2 b, and 2 d, and undetectable for 2 c. To clear up uncertainties, we prepared nanoparticles 13 C-2 c containing a 13 C-labelled carbon in the C 2 position (i.e.…”

“…No resonance signals are detected attributable to protons on the Pt À CH 3 and Pt À DMSO moieties in the spectra of the PtNPs (Figure 2 c for PtNP 2 b). [14,18] We have previously observed the same effect in Pt/PVP/ 13 CO and Pt/dppb/ 13 CO nanoparticles (PVP = poly(N-vinyl-2-pyrrolidone); dppb = 1,4-bis(diphenylphosphino)butane) and proposed that it could be related to the Knight shift. It appears that NHCs are the only ligands to remain attached to the nanoparticle surface (not counting water molecules), thus resulting in broad 13 C signals in the expected regions for the imidazole methine carbon centers (d = 124-122 ppm), the a, b, and g-methylenes (d = 49, 26, and 49 ppm), the methyl groups in 2 c-d (d = 22-18 ppm), and the CH isopropyl carbon center in 2 d (d = 28 ppm).…”

A New Class of Modular Oxazoline‐NHC Ligands and Their Coordination Chemistry with Platinum Metals

“…Another interesting observation is the splitting of the SiMe 2 proton resonance into two distinct signals for the pseudo-equatorial and pseudo-axial positions at δ = 0.3 and -0.5 respectively. [25] This behavior has already been reported for other Pt(0) complexes bearing a chelating dvtms ligand. The two conformers observed in solution may correspond to the two pseudo-chair conformations of the dvtms, or to hindered rotations of the (dimethyl)methylene bridge.…”