Shilov alkane platinum chemistry: 45 years

Reversible PtII-CH3 deuteration without methane loss: metal-ligand cooperation vs. ligand-assisted PtII-protonation

Di(2-pyridyl)ketone dimethylplatinum(ii), (dpk)Pt^II(CH₃)₂, reacts with CD₃OD at 25 °C to undergo complete deuteration of Pt-CH₃ fragments in ∼5 h without loss of methane to form (dpk)Pt^II(CD₃)₂ in virtually quantitative yield. The deuteration can be reversed by dissolution in CH₃OH or CD₃OH. Kinetic analysis and isotope effects, together with support from density functional theory calculations indicate a metal-ligand cooperative mechanism wherein DPK enables Pt-CH₃ deuteration by allowing non-rate-limiting protonation of Pt^II by CD₃OD. In contrast, other model di(2-pyridyl) ligands enable rate-limiting protonation of Pt^II, resulting in non-rate-limiting C-H(D) reductive coupling. Owing to its electron-poor nature, following complete deuteration, DPK can be dissociated from the Pt^II-centre, furnishing [(CD₃)₂Pt^II(μ-SMe₂)]₂ as the perdeutero analogue of [(CH₃)₂Pt^II(μ-SMe₂)]₂, a commonly used Pt^II-precursor.

Reactions of organoplatinum complexes with dimethylamine-borane

Reactions of organoplatinum complexes with dimethylamineborane are reported.

Regioselective C–H hydroxylation of n-alkanes using Shilov-type Pt catalysis in perfluorinated micro-emulsions

In this work, the potential of combining Shilov-type Pt^II and micellar catalysis to realize the challenging terminal C–H hydroxylation of saturated n-alkanes using water as the reaction medium is demonstrated.

PtII -Catalyzed Hydroxylation of Terminal Aliphatic C(sp3 )-H Bonds with Molecular Oxygen

The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C-H bonds remains a formidable challenge, due to difficulties in replacing Pt^IV with a more economically viable oxidant, particularly O₂ . We report the potential of employing FeCl₂ as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O₂ in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O₂ in comparison to current state-of-the-art systems (TON<10). In this regard, essential reaction parameters affecting the overall activity were identified, along with specific additives to attain catalyst stability at longer reaction times. Notably, deactivation by reduction to Pt⁰ was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N₂ in the gaseous atmosphere. Finally, stability tests revealed the involvement of Pt^II and FeCl₂ in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C-H bonds with O₂ is presented.

Platinum-mediated B–H methoxylation of bis(pyrazolyl)borate

Mechanistic investigations into the role of Pt(ii) in mediating methoxylation of B–H fragments of bis(pyrazolyl)borate.

Rational design of model Pd(ii)-catalysts for C–H activation involving ligands with charge-shift bonding characteristics

A palladium(ii) complex with a bis-2-borabicyclo[1.1.0]but-1(3)-ene ligand having charge-shift bonding characteristics contributes to better performance for C–H bond activation.

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

A series of methylpalladium(II) complexes with pyrimidine-NHC ligands carrying different aryl- and alkyl substituents R ([((pym)^(NHC-R))Pd^II(CH₃)X] with X = Cl, CF₃COO, CH₃) has been prepared by transmetalation reactions from the corresponding silver complexes and chloro(methyl)(cyclooctadiene)palladium(II). The dimethyl(1-(2-pyrimidyl)-3-(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(II) complex was synthesized via the free carbene route. All complexes were fully characterized by standard methods and in three cases also by a solid state structure.

p-Tolylimido rhenium(v) complexes with phenolate-based ligands: synthesis, X-ray studies and catalytic activity in oxidation with tert-butylhydroperoxide

The reactions of mer-[Re(p-NTol)X₃(PPh₃)₂] with phenolate-based ligands gave 16 new rhenium(v) complexes. Only a few of them exhibited high catalytic activity.