Computer-assisted design of asymmetric PNP ligands for ethylene tri-/tetramerization: A combined DFT and artificial neural network approach

Design of Cr-Pnp Catalysts for Ethylene Tri-/Tetramerization Assisted by a Data-Driven Approach

New P,Nsp3 bidentate ligands containing two chiral carbon centers were developed and applied to palladium-catalyzed asymmetric allylic substitution reactions. Good generalities with various nucleophiles, including carbon, nitrogen and oxygen containing nucleophiles, were achieved with up to 96% ee and 98% yield. This reaction provides an efficient method for the asymmetric formation of C-C, C-N and C-O bonds.

New P,Nsp3 ligands for palladium-catalyzed asymmetric allylic substitutions.

A series of Cr-based complexes 6–10 bearing aminophosphine (P,N) ligands Ph2P–L–NH2 [L = CH2CH2 (1), L = CH2CH2CH2 (2), and L = C6H4CH2 (3)] and phosphine–imine–pyrryl (P,N,N) ligands 2-(Ph2P–L–N=CH)C4H3NH [L = CH2CH2CH2 (4) and L = C6H4CH2 (5)] were prepared, and their catalytic properties were examined for ethylene tri/tetramerization. X-ray crystallographic analysis of complex 8 indicated the κ2-P,N bidentate coordination mode at the Cr(III) center and the distorted octahedral geometry of monomeric P,N–CrCl3. Upon activation by methylaluminoxane (MAO), complexes 7–8 bearing P,N (PC3N backbone) ligands 2–3 showed good catalytic reactivity for ethylene tri/tetramerization. On the other hand, complex 6 bearing the P,N (PC2N backbone) ligand 1 was found active for non-selective ethylene oligomerization, while complexes 9–10 bearing P,N,N ligands 4–5 only produced polymerization products. In particular, the high catalytic activity of 458.2 kg/(g·Cr·h), excellent selectivity of 90.9% (1-hexene and 1-octene combined), and extremely low PE content of 0.1% were obtained with complex 7 in toluene at 45 °C and 45 bar. These results suggest that rational control of P,N and P,N,N ligand backbones, including a carbon spacer and rigidity of a carbon bridge, can lead to the high-performance catalyst for the ethylene tri/tetramerization process.

https://pubs.acs.org/doi/pdf/10.1021/acsomega.3c02083

Chromium-Based Complexes Bearing Aminophosphine and Phosphine–Imine–Pyrryl Ligands for Selective Ethylene Tri/Tetramerization

Cr/PCCP-Catalysed Selective Ethylene Oligomerization: Analysis of Various Conformations and the Hemilabile Methoxy Group

We present a dual-channel resonance acoustic sensor based on a poly-(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) piezoelectric (PE) membrane which combines the Fabry–Pérot (FP) interference and PE effects. The deformation of circular thin films is indicated by interference and PE effects at the same time, and the noise level was decreased by real-time convolution of the two-way parallel signal. Studies reveal that at the film’s resonance frequency, the minimum detection limits for FP interference and the PE impact on acoustic waves are 2.61 and $15.64 ~\mu $ Pa/Hz1/2, respectively. The result of the convolution shows that the background noise has been reduced by 98.81% in relation to the PE signal and by 96.73% in relation to the FP interference signal, respectively. The signal-to-noise ratio (SNR) of the convolution is several times greater than the other two signals at 2 mPa.

Xing Guo

Papers

Cr/PCCP-Catalysed Selective Ethylene Oligomerization: Analysis of Various Conformations and the Hemilabile Methoxy Group

High-Performance Acoustic Wave Sensor Based on PVDF-TrFE Membrane Combing the Piezoelectric and Fabry–Pérot Effects

Mechanistic Insight into the Carboxylic Derivatives Formation from Co2 and Ethylene Over Iron(0)-Based Catalyst

Evolution of Copper Step Beams During Graphene Growth by Cvd Method

Preparation and multilayer transfer of high-quality monocrystalline graphene grown on centimeter-Cu (111) substrate