Novel chiral phosphorus compounds of the formula ##STR1## wherein R signifies lower alkyl, R.sup.1 signifies phenyl and R.sup.2 and R.sup.3 signify hydrogen or lower alkoxy, which are suitable in the form of complexes with a metal of Group VIII as catalysts for asymmetric hydrogenations and for enantioselective hydrogen displacements in prochiral allylic systems.
Axially Dissymmetric Diphosphines in the Biphenyl Series: Synthesis of (6,6′-Dimethoxybiphenyl-2,2′-diyl)bis(diphenylphosphine)(‘MeO-BIPHEP’) and Analogues<i>via</i>an<i>ortho</i>-Lithiation/Iodination<i>Ullmann</i>-Reaction Approach
The newaxiallydissymmetricdiphosphines (R)- and (S)-(6,6′-dimethoxybiphenyl-2,2′-diyl)bis(diphenyl phosphine) ((R)- and (S)-5a; ‘MeO-BIPHEP’) and the analogues (R)- and (S)-5b and 5c have been synthesized in enantiomerically pure form. These ligands have become readily available by a synthetic scheme which employs, as key steps, an ortho-lithiation/iodination reaction of the (m-methoxyphenyl)diprienylphosphine
Rational Design and Assembly of M<sub>2</sub>M‘<sub>3</sub>L<sub>6</sub> Supramolecular Clusters with <i>C</i><sub>3</sub><i><sub>h</sub></i> Symmetry by Exploiting Incommensurate Symmetry Numbers
作者:Xiankai Sun、Darren W. Johnson、Dana L. Caulder、Kenneth N. Raymond、Edward H. Wong
DOI:10.1021/ja0029376
日期:2001.3.1
the respective clusters while NEt(3)H(+) and NMe(4)(+) yield none of the desired products. Extension of the aufbau assembly to produce related [M(2)Pd(3)Cl(6)L(6)](4)(-), [M(2)Pd(3)I(6)L(6)](4)(-), and [M(2)Cr(3)(CO)(12)L(6)](4)(-) (M = Ti, Sn) clusters has also been realized. In addition to this aufbau approach, self-assembly of several of these [M(2)Pd(3)Br(6)L(6)](4)(-) clusters from all eleven
cis-[PtBr2{PPh2(4-catechol)}2]: synthesis, crystal structure, and computational modelling of its binding to nanocrystalline TiO2
作者:Nigel T. Lucas、Andrew M. McDonagh、Ian G. Dance、Stephen B. Colbran、Donald C. Craig
DOI:10.1039/b513354h
日期:——
The complex cis-[PtBr2PPh2(4-catechol)}2] 1 has been synthesized by cleavage of the four methyl groups from cis-[PtCl2PPh2(4-veratrole)}2] using BBr3, followed by work-up in the presence of excess bromide. An X-ray crystal structure of 1·(ethanol)2 confirms that the two catechol rings are adjacent to each other and approximately parallel, and therefore well structured to act as double bidentate ligands for adjacent metal atoms on the surface of a nanocrystal. The crystal packing of 1·(ethanol)2 involves intermolecular hydrogen-bonding interactions and a parallel fourfold phenyl embrace between PPh2 moieties. Density functional calculations have demonstrated that conformational variability of the aryl rings in cis-[PtBr2PPh2(4-catechol)}2] is energetically feasible, and two conformations of cis-[PtBr2PPh2(4-catechol)}2] as a complex ligand for Ti atoms on the various surfaces of the anatase and rutile structures of TiO2 have been assessed for geometrical commensurability. Three structural models for adsorbates of cis-[PtBr2PPh2(4-catechol)}2] on TiO2 are developed for anatase (110), anatase (101), and rutile (001).
Upon irradiation with visible light, neutral pnictogen bonding (PnB) enables single electron transfer (SET) from alkyl amines to chlorophosphines. This process generates PIII radicals and aminoalkyl radicals. Subsequently, the aminoalkyl radicals activate C−X bonds throughhalogen atom transfer (XAT). As a result, cross-electrophile C−PIII coupling between chlorophosphines and organic halides is achieved
在可见光照射下,中性磷元素键合 (PnB) 能够实现从烷基胺到氯膦的单电子转移 (SET)。该过程产生 P III自由基和氨烷基自由基。随后,氨基烷基通过卤素原子转移(XAT)激活CX键。结果,实现了氯膦和有机卤化物之间的交叉亲电子CP III偶联。