Search results for "BOND"
showing 10 items of 3527 documents
Synthesis of various natural 8,12-elemanolides from artemisin
1989
Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.
Sustainable carbon–carbon bond formation catalyzed by new oxamate-containing palladium(II) complexes in ionic liquids
2013
Abstract New and versatile bis(oxamato)palladate(II) complexes of formula ( n -Bu 4 N) 2 [Pd(2-Mepma) 2 ]·4H 2 O ( 1a ) and ( n -Bu 4 N) 2 [Pd(4-Mepma) 2 ]·2H 2 O·MeCN ( 1b ) ( n -Bu 4 N + = tetra- n -buthylammonium, 2-Mepma = N -2-methylphenyloxamate and 4-Mepma = N -4-methylphenyloxamate) have been synthesized and characterized by spectroscopic methods and single crystal X-ray diffraction. Each palladium(II) ion in 1a and 1b is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated oxamate ligands building a centrosymmetric square planar surrounding. Their catalytic role has been investigated for both Heck and Suzuki coupling reactions using a series of aryl…
Molecular Recognition-Induced Function and Competitive Replacement by Hydrogen-Bonding Interactions: Amphiphilic Barbituric Acid Derivatives, 2,4,6-…
1998
The phenomenon of molecular recognition inducing further function is common in nature. However, there are few synthetic systems which achieve this cascade type mechanism, and those are generally ca...
The influence of aromatic cations on the geometries of the Bi(III) halide polyhedra. Synthesis and crystal structures of quinolinium, isoquinolinium …
2001
Abstract The compounds [quinolinium]4[Bi2Cl10] (1), [isoquinolinium]4[Bi2Cl10].2H2O (2) and [8-hydroxyquinolinium]4[BiCl6]·Cl·2H2O (3) have been obtained by reacting bismuthate oxide and the appropriate base in HCl acid medium. The crystal structures of 1 and 2 consist of quinolinium and isoquinolinium cations, respectively, interacting through hydrogen bonding with [Bi2Cl10]4− dimers. The different degree of interactions in the two derivatives causes significant differences in the bond distances of the anions. The crystal structure of 3 is made of [BiCl6]3− and Cl− anions and 8-hydroxyquinolinium cations. Hydrogen bond interactions including the N-bonded and O-bonded H atoms together with …
Complexes of organometallic compounds
1972
Abstract The novel organobismuth(V) derivatives Ph 3 BiCl(Ox) and Ph 3 BiBr(Ox) (Ox − = 8-quinolinate) have been synthesized, and their configuration investigated in the solid state and in solution. The complexes are assumed to be octahedral in the solid, with Ox − acting as a chelating base and the halide atoms coordinating to bismuth. Tentative assignments of infrared bands in the 300–80 cm −1 region to BiHal and other skeletal modes are proposed. The main effect of solvents appears to be the weakening and breaking of BiN-bonds.
ChemInform Abstract: Cryptand-Like Anion Receptors
2010
The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…
Cryptand-like anion receptors
2010
The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…
Cycloaddition reactions of benzothiete and hetero dienophiles for the synthesis of heterocyclic systems
1986
Abstract Benzothiete ( 1 ) undergoes cycloaddition reactions with hetero dienophiles with NN-, NO- or CO- double bonds, leading to six-membered heterocyclic ring systems of 2H-3,4-dihydro-1,2,3-benzothiadiazine ( 3 ), 4H-3,1,2-benzoxathiazine ( 4 ) and 4H-3,1-benzoxathiin.
Cyclometallation reactions in complexes of the type Rh(oq)(CO)(P(o-BrC6F4)Ph2)
1986
Abstract The complex [uRh(oq)Br(P( o -Cu 6 F 4 )Ph 2 )(H 2 O)] 2 is obtained by refluxing a solution of Rh(oq)(CO)(P( o -BrC 6 F 4 )Ph 2 ) (oq = 8-oxyquinolinate) in toluene. The structure of this compound has been determined by X-ray diffraction and refined to R = 0.061 and R w = 0.065 factors. The cell has monoclinic symmetry, space group P 2 1 / n ; a 19.513(2), b 17.049(1), c 16.898(1) A and β 99.69(1)°. The structure consists of two independent Rh(oq)Br(P( o -C 6 F 4 )Ph 2 )H 2 O) units linked by hydrogen bonds between the coordinated water molecules and oq ligands to form a distorted boat (six atom ring of junction between the two units). In each unit the metal atom has a distorted oc…
Interactions of organotins with biological systems
1992
The bonding and structure in the environments of tin atoms in organotin-biological molecules has been investigated by 119Sn Mossbauer spectroscopy, mainly through the rationalization of the nuclear quadrupole splitting parameter by pointcharge model approaches. Organotin moieties R2SnIV and R3SnIV (R = Me, nBu, Ph) generally assume trigonal-bipyramidal type configurations in membranes of human erythrocytes, when incubated with whole erythrocytes and erythrocyte ghosts at the level of micromolar (μmol dm−3) organotin per mg of membrane protein. Corresponding structures are assumed by Me2SnIV and Me3SnIV in the cytoplasm. Ethanolic Me2SnCl2 yielded distorted trans-octahedral species when reac…