142421-57-6Relevant articles and documents
Catalytic Dehydrocoupling of Amine-Boranes using Cationic Zirconium(IV)-Phosphine Frustrated Lewis Pairs
Metters, Owen J.,Flynn, Stephanie R.,Dowds, Christiana K.,Sparkes, Hazel A.,Manners, Ian,Wass, Duncan F.
, p. 6601 - 6611 (2016)
A series of novel, intramolecular Zr(IV)/P frustrated Lewis pairs (FLPs) based on cationic zirconocene fragments with a variety of ancillary cyclopentadienyl and 2-phosphinoaryloxide (-O(C6H4)PR2, R = tBu and 3,5-CF3-(C6H3)) ligands are reported and their activity as catalysts for the dehydrocoupling of dimethylamine-borane (Me2NH·BH3) assessed. The FLP system [(C9H7)2ZrO(C6H4)PtBu2][B(C6F5)4] is shown to give unprecedented turnover frequencies (TOF) for a catalyst based on a group 4 metal (TOF ≥ 600 h-1), while also proving to be the most efficient FLP catalyst reported to date. The mechanism of this reaction has been probed using analogous intermolecular Zr(IV)/P FLPs, permitting deconvolution of the reactions taking place at both the Lewis acidic and basic sites. Elucidation of this mechanism revealed an interesting cooperative two-cycle process where one cycle is FLP mediated and the other, a redistribution of a linear diborazane intermediate, relies solely on the presence of a Zr(IV) Lewis acid.
Systematic Study of the Stereoelectronic Properties of Trifluoromethylated Triarylphosphines and the Correlation of their Behaviour as Ligands in the Rh-Catalysed Hydroformylation
Herrera, Daniel,Peral, Daniel,Cordón, Mercedes,Bayón, J. Carles
supporting information, p. 354 - 363 (2020/12/30)
The stereoelectronic properties of a series of trifluoromethylated aromatic phosphines have been studied using different approaches. The σ-donating capability has been evaluated by nuclear magnetic resonance (NMR) spectroscopy of the selenide derivatives and the protonated form of the different trifluoromethylated phosphines. The coupling constants between phosphorous and selenium (1JSeP) and phosphorous and hydrogen (1JHP) can be predicted by empirical equations and correlate the basicity of the phosphines with the number and relative position of trifluoromethyl groups. In contrast, the π-acceptor character of the ligands has been evaluated by measuring the frequency of the CO vibration in the infrared (IR) spectra of the corresponding Vaska type iridium complexes ([IrCl(CO)(PAr3)2], PAr3=triarylphosphine). Moreover, the correlation between the electronic properties and the performance of these phosphines as ligands in the rhodium-catalysed hydroformylation of 1-octene has been established. Phosphines with the lowest basicity, that are those with the highest number of trifluoromethyl groups, gave rise to more active catalytic systems.
Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
Stankevi?, Marek
, p. 6082 - 6102 (2015/06/08)
Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
