Synthetic Endeavors toward Titanium Based Frustrated Lewis Pairs with Controlled Electronic and Steric Properties
摘要:
A new family of cationic Ti complexes 4' with a pendant phosphine of general formula [(CpCpTiOAr)-Ti-P][BPh4] (Cp = eta(5)-C5H5; Cp-P = eta(5)-C5H4(CMe2)PR2) has been prepared in four steps from 6,6-dimethylfulvene. These complexes were designed to behave as Ti based frustrated Lewis pairs (FLPs). The key synthetic step is a reduction oxidation sequence from [(CpCpTiClOAr)-Ti-P] complexes 3 using lithium phosphide salts as the reductants and ferricinium tetraphenylborate as the oxidant. Four complexes have been structurally characterized by X-ray diffraction and show elongated Ti-P bonds, above 2.60 angstrom. One complex (4b': OAr = 2,6-Me2C6H3; PR2 = PCy2) reacted with benzaldehyde to form a typical FLP activation product. Complex 4b' also reacted with 2 equiv of trans-chalcone to form a 10-membered Ti phosphonium macrocycle (6b') by extrusion of 6,6-dimethylfulvene.
Cationic Nickel(II)-Catalyzed Hydrosilylation of Alkenes: Role of P, N-Type Ligand Scaffold on Selectivity and Reactivity
作者:Istiak Hossain、Joseph A. R. Schmidt
DOI:10.1021/acs.organomet.0c00551
日期:2020.9.28
Seven structurally similar cationic nickel(II)–alkyl complexes were synthesized by using a series of P, N ligands, and their reactivity was explored in the hydrosilylation of alkenes. More electron-rich phosphines enhanced the overall reactivity of the transformation; in contrast, groups on the imine donor had little impact. Overall, these catalysts displayed reactivity and selectivity that was previously
Modulation of σ-Alkane Interactions in [Rh(L<sub>2</sub>)(alkane)]<sup>+</sup> Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η<sup>2</sup>,η<sup>2</sup>-σ-Alkane Rh(I), η<sup>1</sup>-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation
作者:Antonio J. Martínez-Martínez、Bengt E. Tegner、Alasdair I. McKay、Alexander J. Bukvic、Nicholas H. Rees、Graham J. Tizzard、Simon J. Coles、Mark R. Warren、Stuart A. Macgregor、Andrew S. Weller
DOI:10.1021/jacs.8b09364
日期:2018.11.7
snapshots marking the onset of Rh···alkane interactions along a C-H activation trajectory. These are negligible in [Rh(Cy2P(CH2)3PCy2)][COA⊂BArF4]; in [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(η1-COA)][BArF4], σC-H → Rh σ-donation is supported by Rh → σ*C-H "pregostic" donation, and in [Rh(Cy2P(CH2) nPCy2)(η2η2-NBA)][BArF4] ( n = 2-4), σ-donation dominates, supported by classical Rh(dπ) → σ*C-H π-back-donation
Room-Temperature Reduction of Sulfur Hexafluoride with Metal Phosphides
作者:Blake Stanley Norman Huchenski、Alexander William Harrison Speed
DOI:10.1039/d1cc01943k
日期:——
treatment with sulfur hexafluoride, alkali metal diphenyl or dicyclohexyl phosphides are oxidized within seconds to tetraphenyl or tetracyclohexyl diphosphines. When bulky di-tert-butylphosphide is employed, fluorophosphine intermediates are detected. This is the first reported reaction of sulfur hexafluoride with metal phosphides, and a rare example of reactivity of sulfur hexafluoride at ambient temperature
Rhodium(i)-catalysed conjugate phosphination of cyclic α,β-unsaturated ketones with silylphosphines as masked phosphinides
作者:Verena T. Trepohl、Martin Oestreich
DOI:10.1039/b706137d
日期:——
Nucleophile-activation of the phosphorus(iii)-silicon linkage in silylphosphines generates a nucleophilic phosphorus(iii) equivalent thereby allowing for a rhodium-catalysed conjugate phosphination of beta-substituted alpha,beta-unsaturated acceptors.
Conjugate phosphination of cyclic and acyclic acceptors using Rh(I)–phosphine or Rh(I)–carbene complexes. Probing the mechanism with chirality at the silicon atom or the phosphorus atom of the Si–P reagent
作者:Verena T. Trepohl、Roland Fröhlich、Martin Oestreich
DOI:10.1016/j.tet.2009.04.038
日期:2009.8
The Rh(I)-catalyzed conjugate phosphinyl transfer from an Si–P reagent to an electron-deficient acceptor requires individual protocols for cyclic and acyclic α,β-unsaturatedcarbonyls and carboxyls. While 1,4-addition to cyclic acceptors is catalyzed by a Rh(I)–phosphine complex, a Rh(I)–carbene complex is needed to promote conjugate phosphination of acyclic acceptors. General procedures for both systems