Platinum(II) Complexes Containing Quaternized Nitrogen Ligands: Synthesis, Stability, and Evaluation as Catalysts for Methane and Benzene H/D Exchange
作者:Janette M. Villalobos、Amanda J. Hickman、Melanie S. Sanford
DOI:10.1021/om900889k
日期:2010.1.11
This paper describes an efficient synthesis of the cationic platinumcomplex [(N-CH3-bpym)PtCl2]+ (N-CH3-bpym = N-methylbipyrimidinium) and evaluation of its catalytic activity in H/D exchange reactions of CH4 (with D2SO4) and benzene (with CF3CO2D). With both substrates [(N-CH3-bpym)PtCl2]+ shows C−H activation reactivity comparable to that of its neutral analogue (bpym)PtCl2 (bpym = bipyrimidine)
Quantitative Assay for the Direct Comparison of Platinum Catalysts in Benzene H/D Exchange
作者:Amanda J. Hickman、Janette M. Villalobos、Melanie S. Sanford
DOI:10.1021/om900495n
日期:2009.9.28
This paper describes a protocol for the direct comparison of diverse Pt catalysts in the H/D exchange between C6H6 and TFA-d(1), CD3CO2D, and TFE-d(3) using turnover number (TON) as a standard metric. An initial survey of Pt complexes, including commercial Pt salts (PtCl2, K2PtCl4) and Pt chloride complexes containing bidentate and tridentate nitrogen donor ligands, has been conducted. These studies have established that the addition of AgOAc (in TFA-d(1)) or AgBF4 (in CD3CO2D and TFE-d(3)) displaces the Cl ligands on the Pt precatalyst, which leads to dramatically increased turnover numbers, In general, PtCl2 and K2PtCl4 provided the fewest turnovers, and species containing bidentate ligands afforded higher turnover numbers than those with tridentate ligands. A diimine Pt complex was found to be a top performing catalyst for H/D exchange with all deuterium sources examined. Interestingly, the relative reactivity of many of the catalysts varied dramatically upon changing the deuterium source, highlighting the need tothoroughly assay potential catalysts under a variety of conditions.