18629-57-7Relevant academic research and scientific papers
Cationic Group 4 Complexes (M = Ti, Zr, Hf): Modifications and Limitations in the Design of Tridentate Cp,O,P-Ligand Frameworks Built Directly in the Coordination Sphere of the Metal
Fischer, Malte,Jaugstetter, Maximilian,Schaper, Raoul,Schmidtmann, Marc,Beckhaus, Rüdiger
, p. 5146 - 5159 (2018)
The reactions of monopentafulvene complexes Ti1, Zr1, and Hf1 with bidentate O,P-ligand precursors L1–L3 to form the corresponding cationic complexes employing an established three-step synthetic protocol [insertion, methylation, activation with B(C6F5)3] are investigated. Ligands L1–L3 are designed to have different sized spacers between the carbonyl and diphenylphosphine functional groups. The attempts to react Ti1, Zr1, and Hf1 with acetyldiphenylphosphine (L1) proved to yield undesired products at various steps in the synthetic sequence. When Ti1 is used, Ti2 is formed and diphenylphosphine is released at the same time. Compound Ti2, with the exocyclic double bond, is the formal product of insertion of the smallest ketene (H2C=C=O) into the Ti–Cexo bond. Starting with Zr1 results in isolation of the insertion product Zr2 without loss of diphenylphosphine, but a byproduct is formed during the reaction with L1. Subsequent methylation with methyllithium yields a complex reaction mixture. Hf1 reacts cleanly with L1 to the insertion product Hf2. Also, the methylation reaction selectively yields Hf3 as the result of chloride/methyl exchange, but final activation with B(C6F5)3 causes decomposition and release of diphenylphosphine. The use of the ligand precursors L2 and L3 with two methylene groups or an aryl group as linkers between the functional groups selectively provides the desired cationic complexes Ti6, Zr6, Hf6, and Ti9 in good to excellent overall yields.
Differentially Substituted Phosphines via Decarbonylation of Acylphosphines
Yu, Rongrong,Chen, Xingyu,Martin, Stephen F.,Wang, Zhiqian
, p. 1808 - 1811 (2017/04/11)
A new route to phosphines was developed by a method that features a "pre-join and transform" process that proceeds via acylphosphine intermediates that may be readily prepared from carboxylic acids and disubstituted phosphines. The efficient decarbonylations of these acylphosphines using a nickel catalyst delivered the corresponding phosphines. This method shows that the carboxyl group can play a role similar to halides or triflates for introducing a substituted phosphorus atom on an aromatic ring.
Asymmetric synthesis of α-chiral hydroxyalkylphosphines by a catalytic enantioselective reduction of acylphosphines
Hayashi, Minoru,Ishitobi, Hiroyuki,Matsuura, Yutaka,Matsuura, Takashi,Watanabe, Yutaka
supporting information, p. 5830 - 5833 (2015/01/16)
Enantioselective reduction of acylphosphines, after precomplexation with borane, proceeded smoothly in the presence of a chiral oxazaborolidine catalyst and catecholborane. α-Hydroxyalkylphosphine products were obtained as phosphine-borane complexes in good yield and enantioselectivity. One of the products of the enantioselective reduction was successfully applied as an optically active phosphine ligand for asymmetric catalysis after suitable derivatization.
Synthesis and transition metal chemistry of 'phosphomide' ligands: A comparison of the reactivity and electronic properties of diphenyl-P-perfluoro-octanoyl-phosphine, P-acetyl-dyphenylphophine and P-anisoyl-diphenylphosphine. X-ray crystal structure of [RhCp*(Ph2PC(O)CH3)Cl2]
Baber, R. Angharad,Clarke, Matthew L.,Orpen, A. Guy,Ratcliffe, David A.
, p. 112 - 119 (2007/10/03)
A convenient synthesis of several 'phosphomide' ligands (P adjacent to carbonyl group) from secondary phosphines is reported. The new anisoyl substituted phosphines are considerable more stable to hydrolysis, and are stronger σ-donor ligands than P-acetyldiphenylphosphine as determined by the measurement of ν(CO) for the corresponding rhodium carbonyl complexes trans - [RhL2(CO)Cl]. In contrast, a new phosphomide derived from perfluoro-octanoyl chloride was found to be a highly unstable, electron poor π-acceptor ligand. The crystal structure of [RhCp*Cl2{Ph2PC(O)CH3}] showed a normal pseudo-octahedral pianostool molecular geometry with a Rh-P bond length of 2.3186(5) A?. The extra stability observed for the P-anisoyl phosphomides has led us to apply this class of ligand in rhodium catalysed hydroformylation for the first time.
