Design of Frustrated Lewis Pair in Defective TiO2 for Photocatalytic Non-Oxidative Methane Coupling

The efficient C-H polarization is the prerequisite for the low-temperature photocatalytic CH4 conversion, which however is restricted by the poor stretching ability of short-distanced lattice atoms. Herein, frustrated Lewis pair (FLP) composed of doped ion in TiO2 as Lewis acid (LA) and neighboring Ti-OH as Lewis base (LB) with a long distance (0.31-0.37 nm) were designed through DFT calculation and fabricated by hydrogenation treatment of metal-doped TiO2-SiO2 with macroporous-mesoporous structure. Benefitting from the long LA-LB distance and matched acid-base intensity, hydrogenated Ga-doped composite achieves superior C-H stretching with a high CH4 conversion rate (139 µmol g−1 h−1) to ethane. The photo-irradiation causes the electron excitation from Ga to Ti-OH according to the time-dependent DFT calculation and in situ EPR analysis, which promotes the formation and coupling of ·CH3. This work provides a key underpinning for regulating the characteristics of FLP for C-H activation and C-C coupling via light irradiation.

Frustrated Lewis pair catalyzed hydrodehalogenation of benzyl-halides

10 mol% B(o-C6F2H3)3 in the presence of excess tetramethylpiperidine (TMP) and H2 (or D2) is shown to catalyze the hydrogenative dehalogenation of benzyl-halides to give corresponding toluene derivatives. These reactions...

Towards the development of FLP-catalyzed hydrogenations of tertiary and secondary carboxylic amides

The development of the frustrated Lewis pair catalyzed hydrogenation of tertiary and secondary amides is reviewed. Detailed insight into our strategies in order to overcome challenges during the reaction development process is provided. Furthermore, the developed chemistry is extended to the hydrogenation of poly amides and trifluoroacetyl amides for the convenient introduction of trifluoro ethyl groups into organic molecules.

Frustrated Lewis Pair Stabilized Phosphoryl Nitride (NPO), a Mono Phosphorus Analogue of Nitrous Oxide (N2O)

Phosphoryl nitride (NPO) is a highly reactive intermediate, and its chemistry has only been explored under matrix isolation conditions so far. Here we report the synthesis of an anthracene (A) and phosphoryl azide-based molecule (N3P(O)A) that acts as a molecular synthon of NPO. Experimentally, N3P(O)A dissociates thermally with a first order kinetic half-life that is associated with an activation enthalpy of ΔH⧧ = 27.5 ± 0.3 kcal mol–1 and an activation entropy of ΔS⧧ = 10.6 ± 0.3 cal mol–1 K–1 that are in good agreement with calculated DLPNO-CCSD(T)/cc-pVTZ//PBE0-D3(BJ)/cc-pVTZ energies. In solution N3P(O)A undergoes Staudinger reactivity with tricyclohexylphosphine (PCy3) and subsequent complexation with tris(pentafluorophenyl)borane (B(C6F5)3, BCF) to form Cy3P-NP(A)O-B(C6F5)3. Anthracene is cleaved off photochemically to form the frustrated Lewis pair (FLP) stabilized NPO complex Cy3P⊕-N=P-O-B⊖(C6F5)3. Intrinsic Bond Orbital (IBO) analysis suggests that the adduct is zwitterionic, with a positive and negative charge localized on the complexing Cy3P and BCF, respectively.