1609574-91-5Relevant articles and documents
Chromium(III) catalysts based on tridentate silicon-bridged tris(diphenylphosphine) ligands for selective ethylene tri-/tetramerization
Alam, Fakhre,Chang, Qiqi,Chen, Yanhui,Dong, Chunhua,Jiang, Tao,Wang, Jiadong,Zhang, Le,Zhang, Qiyao
, p. 278 - 286 (2020)
The chromium(III) catalysts based on tridentate silicon-bridged tris(diphenylphosphine) ligands of the form RSi(CH2PPh2)3 (L1: R = Me; L2: R = Cy; L3: R = Ph) were investigated for selective ethylene tri-/tetramerization. The steric and electronic properties of the substituents attached to the silicon moiety have been observed to have a great impact on the catalytic performance of these catalysts. Single-crystal analysis, high-resolution mass spectrometry (HR-MS), and elemental analysis revealed that these complexes may adopt mononuclear tridentate coordination mode (k3-P, P, P) with Cr center. However, one of the phosphorus atoms in these complexes may act as a hemilabile donor and presumably loses its coordination with chromium in the presence of a competent donor which consequently transformed the tridentate complexes to bidentate (k2-P, P) coordination mode. Backbone modification of L1 of the precatalyst 1 via successive abstraction of methylene spacers may offer MeSi(CH2)n(PPh2)3 (L4: n = 2; L5: n = 1; L6: n = 0) type chromium(III) complexes. Ethylene oligomerization of these systems suggested that the methylene spacers may effectively tune the complex structure and catalytic performance. Precatalyst 1 and 4 respectively based on L1 and L4 deliver 70% C8 selectivity in the liquid oligomeric fraction and considerable activity under experimental conditions. DFT investigations based on catalyst 4 revealed that the catalyst may simultaneously facilitate the single and double coordination pathways for C8 formation, however, the single coordination pathway is thermodynamically more favorable for this system.
Application of Hetero-Triphos Ligands in the Selective Ruthenium-Catalyzed Transformation of Carbon Dioxide to the Formaldehyde Oxidation State
Seibicke, Max,Siebert, Max,Siegle, Alexander F.,Gutenthaler, Sophie M.,Trapp, Oliver
, p. 1809 - 1814 (2019/04/25)
Due to the increasing demand for formaldehyde as a building block in the chemical industry as well as its emerging potential as feedstock for biofuels in the form of dimethoxymethane and the oxymethylene ethers produced therefrom, the catalytic transformation of carbon dioxide to the formaldehyde oxidation state has become a focus of interest. In this work, we present novel ruthenium complexes with hetero-triphos ligands, which show high activity in the selective transformation of carbon dioxide to dimethoxymethane. We substituted the apical carbon atom in the backbone of the triphos ligand platform with silicon or phosphorus and optimized the reaction conditions to achieve turnover numbers as high as 685 for dimethoxymethane. The catalytic systems could also be tuned to preferably yield methyl formate with turnover numbers of up to 1370, which in turn can be converted into dimethoxymethane under moderate conditions.
