Platinum(II) Complexes Containing Quaternized Nitrogen Ligands: Synthesis, Stability, and Evaluation as Catalysts for Methane and Benzene H/D Exchange

Abstract

This paper describes an efficient synthesis of the cationic platinum complex [(N-CH 3 -bpym)PtCl 2 ] þ (N-CH 3 -bpym=N-methylbipyrimidinium) and evaluation of its catalytic activity in H/D exchange reactions of CH 4 (with D 2 SO 4 ) and benzene (with CF 3 CO 2 D). With both substrates [(N-CH 3 -bpym) PtCl 2 ] þ shows C-H activation reactivity comparable to that of its neutral analogue (bpym)PtCl 2 (bpym=bipyrimidine). The origin of this similar reactivity is proposed to be the in situ formation of the same active catalyst in both cases.

Platinum and Palladium Complexes Containing Cationic Ligands as Catalysts for Arene H/D Exchange and Oxidation

“…Despite this initial success, it remains challenging to develop new generations of Group 10 metal catalysts that display higher turnover frequencies and operate in different, less corrosive media 3. 4 A key goal of our efforts has been to identify ligands that mimic the desirable properties of protonated bipyrimidine but are stable in the absence of strong acids 7. Herein, we describe the application of dicationic‐bipyridine‐based ligands in platinum‐ and palladium‐catalyzed arene H/D exchange and oxidation reactions.…”

“…Third, the quaternized nitrogen atoms are not susceptible to decomposition by dealkylation or deprotonation, which has been problematic in related systems 5. 7 Fourth, substituents can easily be added to the pyridinium ring to tune the solubility of these dications. Finally, ligands 2 a and 2 b are readily available in four steps from commercially available 2,2′‐bipyridine (bpy) in 33 % and 24 % overall yield, respectively (for details, see the Supporting Information) 9…”

Short‐Cut Bio‐Inspired Synthesis of Tricyclic Guanidinic Motifs of Crambescidins and Batzelladines Marine Alkaloids

“…[18] Thus, a desymmetrization of 2-aminopyrimidine moiety would be necessary for the deprotection. After some unsuccessful alkylation trials even with the strongest alkylating agents such as methyl triflate or trimethyloxonium trifluoroborate, we found serendipitously that under acidic conditions of HBF 4 resulting from hydrolysis of trimethyloxonium trifluoroborate, [19] the intra-cyclic nitrogen of the 2-aminopyrimidine moiety attacks the ketone function quantitatively leading to the hemiaminal 4, where its structure was determined by extensive 2D-NMR experiments and confirmed X-ray diffraction of one crystallized cis diasterisomer (Scheme 2). The driving force of this cyclization is obviously the functional group proximity.…”

C−H Functionalisation for Hydrogen Isotope Exchange

“…Indeed, this was the case in the earlier of Sanford's aforementioned deuterium labeling studies, where cationic bipyridine ligands were employed to produce advantageously Lewis acidic catalysts, 65 and 66 (versus 64), for the deuterium labeling of benzene in the presence of CD3CO2D (Scheme 26). [110,111,112] Although both metals produced highly active HIE catalysts compared to the parent catalyst of the study (64), Pt was more useful than Pd, as Pt provided the most highly acidic catalyst.…”