Ross Fu

Arene C–H activation using Rh(I) catalysts supported by bidentate nitrogen chelates

The Rh(I) complexes [(FlDAB)Rh(coe)(TFA)] (1) and [(BOZO)Rh(coe)(TFA)] (2) [FlDAB = N,N-bis-(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene, coe = cyclooctene, TFA = trifluoroacetate, BOZO = bis(2-oxazolin-2-yl)] are efficient catalyst precursors for H/D exchange between arenes and DTFA. Catalyst precursor 1 exhibits a TOF of 0.06 s−1 at 150 °C for benzene H/D exchange. DFT calculations revealed that H/D exchange through reversible oxidative addition or internal electrophilic substitution of benzene is a viable pathway.

Rhodium Bis(quinolinyl)benzene Complexes for Methane Activation and Functionalization

A series of rhodium(III) bis(quinolinyl)benzene (bisq(x)) complexes was studied as candidates for the homogeneous partial oxidation of methane. Density functional theory (DFT) (M06 with Poisson continuum solvation) was used to investigate a variety of (bisq(x)) ligand candidates involving different functional groups to determine the impact on Rh(III)(bisq(x))-catalyzed methane functionalization. The free energy activation barriers for methane C-H activation and Rh-methyl functionalization at 298 K and 498 K were determined. DFT studies predict that the best candidate for catalytic methane functionalization is Rh(III) coordinated to unsubstituted bis(quinolinyl)benzene (bisq). Support is also found for the prediction that the η(2)-benzene coordination mode of (bisq(x)) ligands on Rh encourages methyl group functionalization by serving as an effective leaving group for SN2 and SR2 attack.

Design and validation of non-metal oxo complexes for C–H activation

We use our recent discovery of the reduction-coupled oxo activation (ROA) principle to design a series of organometallic molecules that activate C-H bonds through this unique proton/electron-decoupled hydrogen abstraction mechanism, in which the main group oxo moiety binds to the proton while the electron is transferred to the transition metal. Here we illustrate this general class of catalyst clusters with several examples that are validated through quantum mechanics calculations.