New phases containing tetrameric and pentameric mesitylcopper have been isolated from ether solvents characterized with single-crystal X-ray diffraction. Mesitylcopper crystallized toluene, which is a widely used reagent, has found to contain one lattice solvent molecule. On the basis of these findings cryoscopic molecular weight determinations, an equilibrium between tetramer pentamer in both etheral aromatic solutions proposed.

The crystal structures of [Pr(dbm)3H2O] (1), [Sm(dbm)3H2O] (2), and [Er(dbm)3H2O] (3) have been determined (dbm=dibenzoylmethane). They display seven-coordinate propeller-shaped molecules, which are chiral crystallize as conglomerates in space group R3. Analysis the reveals supramolecular interactions, including formation a quadruple helix, explain how stereochemical information can be transferred between stacks molecules. A method to quantify ee bulk samples stereochemically labile...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSingle-Source Precursors of Lead Titanate: Synthesis, Molecular Structure and Reactivity Pb2Ti2(.mu.4-O)(.mu.3-O-i-Pr)2(.mu.-O-i-Pr)4(O-i-Pr)4Stephane Daniele, Renee Papiernik, Liliane G. Hubert-Pfalzgraf, Susan Jagner, Mikael HakanssonCite this: Inorg. Chem. 1995, 34, 3, 628–632Publication Date (Print):February 1, 1995Publication History Published online1 May 2002Published inissue 1 February...

Abstract Voilà, optical activity : Both enantiomers of 1‐chloroindene have been synthesized in high selectivity from solely achiral starting materials, and without using optically active catalysts (see scheme). These symmetry‐breaking syntheses provide a proof‐of‐concept for new approach to asymmetric synthesis. NCS= N ‐chlorosuccinimide. magnified image

Abstract Three new conglomerates incorporating bidentate sulfide ligands coordinated by Ru II centers have been prepared. Total spontaneous resolution slow crystallization gives highly enantioenriched crystal batches, which are used in enantioselective oxidation of the to give chiral sulfoxide complexes with >98 % ee . All relevant stereoisomers characterized single‐crystal X‐ray diffraction, CD spectroscopy, and HPLC. If ligand range can be extended monodentate sulfides, a large‐scale...

Computational studies of a chiral lithium amide (lithium (2-methoxy-(R)-1-phenylethyl)((S)-1-phenylethyl)amide, 3) using the solid-state structure as reference geometry showed that there were only small differences between X-ray and ab initio PM3 calculated structures. Furthermore, we have shown distances from either or initio/PM3 can be used for calculation Li−H NOE data. The calculations HOESY buildup rates solution 3·THF is similar to obtained in gas phase (calculated) solid (X-ray)....

Turraea robusta and nilotica are African medicinal plants used for the treatment of a wide variety diseases, including malaria. The genus is rich in limonoids other triterpenoids known to possess various biological activities. From stem bark T. six compounds, from parts eleven compounds were isolated by use combination chromatographic techniques. structures elucidated using NMR MS, whilst relative configuration one toonapubesin F, was established X-ray crystallography. antiplasmodial...

Two new six-coordinate Grignard reagents, cis-[(p-CH(3)C(6)H(4))MgBr(dme)(2)] (1) and cis-[MgCH(3)(thf)(dme)(2)]I (2), have been synthesized their crystal structures determined. Both reagents are cis-octahedral therefore chiral. They crystallize as conglomerates racemize rapidly in solution. By utilizing these properties, the absolute asymmetric synthesis of specifically Delta or Lambda enantiomer was achieved for both reagents. Enantiopure 1 2 were then reacted with butyraldehyde...

We have shown by the use of multinuclear and multidimensional NMR that reaction mixture [6Li]lithium (2-methoxy-(R)-1-phenylethyl)((S)-1-phenylethyl)amide (2) cyclohexene oxide in DEE results formation monomeric dimeric complexes between 2 at −80 °C. The complex exhibited a slow substitution rate on time scale was found to be controlled dissociative mechanism. 6Li,1H-HOESY spectrum above showed NOE's lithium protons both monomer dimer 2. A single-crystal X-ray diffraction experiment revealed...

[Ca[Co(ethylenediamine)(oxalato)2]2]n·4H2O gives a 3D-net based on Ca(oxalato)4 8-connected nodes and Co(en)(oxalato)2 4-connected resulting in compound that retains its structure 19% void volume even after residual solvent has been evacuated under vacuum at 160 °C.

Talking about a resolution: Bulk quantities of five-coordinate complexes have been resolved for the first time using zinc and cadmium diethyldithiocarbamate species. The stereochemical outcome can be controlled by seeding with desired isomer, giving access to either enantiomer in high enantiomeric excess yield.

The right- and left-handed propeller-shaped enantiomers of the eight-coordinate SmI(2) complexes shown can be resolved by crystallization from dimethoxyethane (dme) at ambient temperature. Apart representing a new type chiral metal complex, such are potential reagents for enantioselective reductions.

The low-temperature X-ray structures of bis(η2-ethene)(2,4-pentanedionato)rhodium(I) (1)and bis(η2-ethene)(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)rhodium(I) (2) were determined. Very similar Rh−ethene coordination geometries are found in the solid state, i.e., 1, Rh−C = 2.127(5) Å, and 2, 2.121(3) good accord with DFT calculations, 2.132 2.136 Å. calculated 103Rh NMR chemical shifts (GIAO-B3LYP/II level) for a range bis(η2-alkene)(2,4-pentanedionato)rhodium(I) complexes also agree well...

The reaction between Mg(viph)2 (viph = o-vinylphenyl) and copper(I) chloride has been found to be the best way of preparing homoleptic tetramer [Cu4(viph)4]. MgR2 reagent crystallizes as monomeric [Mg(THF)2(viph)2] from a THF solution. In Grignard (viph)MgBr chloride, two unstable mixed halide/aryl intermediates, [Mg(THF)6][Cu5(viph)2Br4]2·THF (3) [Mg(THF)5Cl][Cu5(viph)4Br2]·THF (4), were isolated reduce yield [Cu4(viph)4] markedly. crystal structures 3 4 determined exhibit unusual...

Abstract Helical complexes formed between aluminum tris(2,6‐diphenylphenoxide) (ATPH) and five different aldehydes have been prepared structurally characterized by X‐ray diffraction. It was found that [Al(OC 6 H 3 Ph 2 ) PhCHO] ( ), (4‐CH C 4 CHO)] (4‐ t BuC p ‐CH OC 5 all crystallize as conglomerates, while crystals of o are racemic. Supramolecular CH/π interactions molecules in – enable stereochemical information to be mediated three dimensions identified explain the high frequency...

The pyridine adduct of bis(benzoylacetonato-O,O′)copper(II) crystallises in both its cis- and trans-isomers within the same crystal. Copper(II) exhibits square pyramidal coordination geometry isomers with weak pyridine. planes are mutually orthogonal, forming a grid, channels which molecules stacked, approximately perpendicular to c-axis. Pyridine is readily lost from crystals unprotected by solvent, crystalline powder. This powder absorbs vapour reform microcrystalline...

Because Na5[Dy(oda)3](H2O)6(BF4)2 (oda = oxodiacetate) (1a), Na5[Er(oda)3](H2O)6(BF4)2 (1b) and Na5[Pr(oda)3](H2O)6(BF4)2 (1c) all crystallise in a Sohncke space group (R32), absolute asymmetric synthesis has been possible; we have obtained an optically active crystal batch of eg1b without using chiral starting materials. Nine-coordinate enantiomers thus resolved (without the use ligands). The structures analysed order to identify factors favouring spontaneous resolution, two racemic phases...

Syntheses of [Co(bpy)3](2+) yield racemic solutions because the Δ- and Λ-enantiomers are stereochemically labile. However, crystallization attrition-enhanced deracemization can give homochiral crystal batches either handedness in quantitative yield. Subsequently, solvent-free oxidation with bromine vapour fixes chirality [Co(bipy)3](3+) does not enantiomerize solution at ambient temperature. This combination Viedma ripening labile/inert Co(II)/Co(III) couple constitutes a convenient method...

Stereochemically labile copper and zinc complexes with the N,N'-dimethylethylenediamine ligand (dmeda) have been shown to be promising precursors for total spontaneous resolution of chiral covalent networks. (N,N')-[Cu(NO3)2(dmeda)]infinity crystallises as a conglomerate yields either enantiopure (R,R)-1 or (S,S)-1. A mixed-valence copper(I/II) complex, [{Cu(II)Br2(dmeda)}3(Cu(I)Br)2]infinity (2), which pair interpenetrating (10,3)-a nets, is formed from CuBr, CuBr2 dmeda. One net contains...

After you, Sir Edward: By following in the footsteps of Frankland and Wanklyn, it has been discovered that simple hydridoalkylzincates(II) (see picture) can be prepared essentially quantitative yield from mixtures sodium an excess neat dialkylzinc reagent, which also acts as solvent.

The utility of R22(9) biimidazole-carboxylate, R22(10) biimidazole-oxalate/squarate and biimidazole-(tris-oxalate) synthons is considered for crystal engineering hydrogen-bonded networks based on [CoIII(H2biim)3]3+ cations (H2biim = 2,2-biimidazole) oxalate, squarate or [MIII(C2O4)3]3− anions. Syntheses structures are described [CoIII(H2biim)3][MIII(C2O4)3]·2H2O (M Cr, 1; M Co, 2), [CoIII(H2biim)3](HC4O4)3·2H2O, 3, [CoIII(H2biim)3](C2O4)Cl·5.5H2O, 4. Compounds 1 2 isostructural comprise...

The reaction of diethylzinc, pyridine, and water followed by crystallization-induced asymmetric transformation yields homochiral batches crystals containing the corner-capped octanuclear cubane [Zn8(Et)8O4(py)8]. crystal structure exhibits channels pyridine molecules that are ordered along helices same handedness.