Photophysical Properties and Kinetic Studies of 2-Vinylpyridine-Based Cycloplatinated(II) Complexes Containing Various Phosphine Ligands

A series of cycloplatinated(II) complexes with general formula of [PtMe(Vpy)(PR3)], Vpy = 2-vinylpyridine and PR3 = PPh3 (1a); PPh2Me (1b); PPhMe2 (1c), were synthesized and characterized by means of spectroscopic methods. These cycloplatinated(II) complexes were luminescent at room temperature in the yellow–orange region’s structured bands. The PPhMe2 derivative was the strongest emissive among the complexes, and the complex with PPh3 was the weakest one. Similar to many luminescent cycloplatinated(II) complexes, the emission was mainly localized on the Vpy cyclometalated ligand as the main chromophoric moiety. The present cycloplatinated(II) complexes were oxidatively reacted with MeI to yield the corresponding cycloplatinated(IV) complexes. The kinetic studies of the reaction point out to an SN2 mechanism. The complex with PPhMe2 ligand exhibited the fastest oxidative addition reaction due to the most electron-rich Pt(II) center in its structure, whereas the PPh3 derivative showed the slowest one. Interestingly, for the PPhMe2 analog, the trans isomer was stable and could be isolated as both kinetic and thermodynamic product, while the other two underwent trans to cis isomerization.

The mechanism of oxidative addition of Pd(0) to Si–H bonds: electronic effects, reaction mechanism, and hydrosilylation

Mechanistic studies reveal the rate law, an H/D KIE, and that the silane’s electronics impact the thermodynamic and kinetic energetics of the oxidative addition reaction. These electronic effects are relevant in the hydrosilylation of alkynes.

The Oxidative Addition Reaction of Tris(2-Methoxy-5-Chlorinephenyl)Antimony With Trifluoropropionic Acid

The interaction of tris(2-methoxy-5-chlorophenyl)antimony with 3,3,3–trifluoropropionic acid in the presence of hydrogen peroxide (1:2:1 mol) in ether proceeds according to the oxidative addition reaction scheme with the formation of bis(3,3,3-trifluoropropionyl)tris(2-methoxy-5-chlorophenyl)antimony [(MeO-2)(Cl-5)C6H3]Sb[OC(O)CH2F3]2. The IR spectra of compound 2, recorded on a Shimadzu IRAffinity-1S Fourier transform IR spectrometer in a KBr pellet in the region of 4000–400 cm–1, contain absorption bands of carbonyl groups, which are shifted to the low-frequency vibration region in comparison with the IR spectra of the initial acids. According to the X-ray diffraction data obtained on a Bruker D8 QUEST diffractometer, compound 1 has the following crystallographic parameters of the unit cell: crystal size 0.23×0.21×0.08 mm3, space group P21/n, а = 8.883(7), b = 21.184(15), c = 13.642(15) Å, α = 90.00°, β = 107.34(3)°, γ = 90.00°, V = 2451(4) Å3, ρcalc = 1.587 g/cm3, Z = 4; crystal 2 has the following crystallographic parameters of the unit cell: 0.3×0.25×0.08 mm3, P21/c, а = 12.00(5), b =16.81(7), c =16.30(9) Å, α =90.00°, β =108.3(3)°, γ =90.00°, V =3121(25) Å3, ρcalc = 1.704 g/cm3, Z = 4. The antimony atom in 2 has a distorted trigonal-bipyramidal coordination with carboxylate ligands in axial positions. The OSbО angles are 174.2(5)°, the sums of the СSbC angles in the equatorial plane are 360°, the axial Sb–O bonds equal 2.073(15), 2.092(15) Å, and the equatorial Sb–С bonds equal 2.05–2.13 Å, which is close to the sum of the covalent radii of the atoms. The intramolecular Sb∙∙∙OМе distances (3.035(3), 3.037(3), 2.992(4) Å (1), 3.03(2), 3.119(17), 3.147(19) Å (2)), as well as Sb∙∙∙OMe for compound 2 (3.232(19), 2.99(2) Å), are much smaller than the sum of the van der Waals radii of atoms.

An in-depth investigation on the C–I bond activation by rollover cycloplatinated(ii) complexes bearing monodentate phosphane ligands: kinetic and kinetic isotope effect

The oxidative addition reaction of MeI reagent to some cycloplatinated(ii) complexes was performed and kinetically investigated.