Search results for "chirality"

Designing P*-chirogenic Organophosphorus Compounds: from Ligands to Organocatalysts

2015

The interest of organophosphorus compounds bearing chirality on the phosphorus atom has greatly expanded in last decade, due to the development of efficient stereoselective synthetic methods, using...

Diastereospecific control in the synthesis of enantiomerically pure bis-equatorial rhodium(II) catalysts by chiral phosphanes

2000

The reaction of Rh2(O2CR)4 [R = CH3, CF3] with the chiral phosphane (1S,2S,5R)-(2-hydroxy-5-isopropenyl-2-methylcyclohexyl)(diphenyl)phosphane, (+)PPh2(CH−R*−OH) or its enantiomer (1R,2R,5S)-(2-hydroxy-5-isopropenyl-2-methylcyclohexyl)(diphenyl)phosphane, (−)-PPh2(CH−R*−OH), results in the specific formation of the products (P)-Rh2(μ-O2CR)2(η1-O2CR)2{η2-(+)PPh2(CH−R*−OH)}2 [P(+)1, R = CH3; P(+)2 R = CF3] and (M)-Rh2(μ-O2CR)2(η1-O2CR)2{η2-(−)-PPh2(CH−R*−OH)}2 [M(−)1, R = CH3; M(−)2, R = CF3] in a high yield. Their synthesis, characterisation and catalytic behaviour in metal−carbenoid reactions are reported. X-ray analysis of P(+)2 and M(−)2 shows, in each case, a Rh24+ unit supported by two …

Synthesis and X-ray structure of metalated Rhodium(II) catalysts with a chiral phospholane

2001

The reaction of Rh2(O2CR)4 (R = CH3, CF3) with the chiral phosphane (2S,5S)-2,5-dimethyl-1-phenylphospholane (PC*H), results in the formation of two diastereoisomers of Rh2(O2CCR)2(PC*)2, with (P) and (M) configuration. These can easily be isolated by chromatographic methods to obtain enantiomerically pure RhII compounds. Preliminary catalytic studies have shown that they induce moderate asymmetry in the cyclization of 5-aryl-1-diazo-2-pentanones and 1-diazo-5-hexen-2-one. X-ray analysis of the (M) diastereoisomer with formula Rh2(O2CCCH3)2(PC*)2 is reported. The crystallographic parameters are as follows: space group P21212 (orthorhombic) with a = 12.1347(11) A, b = 14.5870(13) A, c = 9.81…

Enantiopure Conducting Salts of Dimethylbis(ethylenedithio)tetrathiafulvalene (DM‐BEDT‐TTF) with the Hexachlororhenate(IV) Anion

2014

Invited for the cover of this issue is the group of Narcis Avarvari (CIMI team) at the Laboratory MOLTECH-Anjou, UMR 6200 CNRS – Universite d'Angers, France. The cover image shows the enantiopure tetrathiafulvalene precursors used for the preparation of chiral radical cation conducting salts, together with an artwork of their packing diagrams and the suggested mirror image relationship between them.

Structural and magnetic studies of mononuclear lanthanide complexes derived from Ν-rich chiral Schiff bases.

2021

Zn(II) complexes containing N, N,N and N,N,N pyridine (dPy) ligands tend to display improved fluorescence efficiencies in comparison with their starting ligands benefiting from the chelation enhanced effect (CHEF) and preventing photoinduced electron transfer (PET) mechanisms by the coordination of their lone pair electrons. Nevertheless, the size of Zn(II) makes steric crowding an important factor to be considered, since it can promote the elongation of the coordination bonds that weakens their strength and favors the reduction of fluorescence efficiencies through PET processes. For that reason, in this contribution we have performed a systematic study of Zn(II) compounds based on α-acetam…

The First P ‐Stereogenic 1D Coordination Polymers with the Metal Centers in the Backbone

2011

The enantiomeric ligands (R,R)- and (S,S)-bis(o-anisylphenylphosphanyl)methane (R,R-22 and S,S-22) and (R,R)- and (S,S)-bis(phenyl-m-xylylphosphanyl)methane (R,R-23 and S,S-23; dppm*), were treated with [Cu(NCCH3)4](BF4) and AgBF4 to produce the binuclear complexes [Cu2(dppm*)2(NCCH3)4](BF4)2 or [Ag2(dppm*)2](BF4)2, respectively. Then, these complexes were used as building blocks to prepare the first P-chirogenic 1D coordination polymers {[M2(dppm*)2(dmb)2](BF4)2}n [dppm* = (R,R)-22, (S,S)-22, (R,R)-23, (S,S)-23, M = Cu, Ag, dmb = 1,8-diisocyano-p-menthane] where M is part of the backbone of the polymer chain. The isostructural nature of these new polymers with the achiral parent polymers, …

Chiral Self‐Sorting of trans ‐Chelating Chiral Ligands upon Formation of Pd II Complexes (Eur. J. Inorg. Chem. 15/2014)

2014

Enantiopure Conducting Salts of Dimethylbis(ethylenedithio)tetrathiafulvalene (DM‐BEDT‐TTF) with the Hexachlororhenate(IV) Anion (Eur. J. Inorg. Chem…

2014

1,1′,2,2′-Tetrakis(diphenylphosphino)-4,4′-di-tert-butylferrocene, a new cisoid arrangement of phosphino groups

2001

Abstract The action of two equivalents of 1,2-bis(diphenylphosphino)-4- tert -butylcyclopentadienyllithium on FeCl 2 led to the corresponding 1,1′,2,2′-tetraphosphinoferrocene. The X-ray structure of this bulky ferrocene is described. The spectroscopic results reveal a conformational chirality with a cisoid disposition of the phosphino groups. The first results about the complexation with representative elements of Group IX and X (Rh, Pd, Ir) are reported.

Insertion of a [Fe II (pyimH) 3 ] 2+ [pyimH = 2‐(1 H ‐Imidazol‐2‐yl)pyridine] Spin‐Crossover Complex Inside a Ferromagnetic Lattice Based on a Chiral…

2015

The insertion of the [FeII(pyimH)3]2+ [pyimH = 2-(1H-imidazol-2-yl)pyridine] spin-crossover complex into a ferromagnetic bimetallic oxalate network affords the hybrid compound [FeII(pyimH)3][MnIICrIII(ox)3]2·X (ox = C2O42–). This spin-crossover complex templates the growth of crystals formed by a chiral 3D oxalate network. The magnetic properties of this hybrid magnet show the coexistence of long-range ferromagnetic ordering at 4.5 K and a spin crossover of the intercalated [FeII(pyimH)3]2+ complex above 250 K. The compound presents a light-induced excited spin-state trapping (LIESST) effect below 60 K although with limited photoconversion (less than 8 %).