Chemistry and Chemical Engineering

The relative merits of the methods employed to determine enantiomeric excess (ee) values and absolute configurations of chiral arene and alkene cis-1,2-diol metabolites, including boronate formation, using racemic or enantiopure (+) and (-)-2-(1-methoxyethyl)phenylboronic acid (MEPBA), are discussed. Further applications of: 1) MEPBA derived boronates of chiral mono- and poly-cyclic arene cis-dihydrodiol, cyclohex-2-en-1-one cis-diol, heteroarene cis/trans-2,3-diol, and catechol metabolites in estimating their ee values, and 2) new chiral phenylboronic acids, 2-[1-methoxy-2,2-dimethylpropyl]phenyl boronic acid (MDPBA) and 2-[1-methoxy-1-phenylmethyl]phenyl boronic acid (MPPBA) and their advantages over MEPBA, as reagents for stereochemical analysis of arene and alkene cis-diol metabolites, are presented.

As with gold, relativistic effects are important in the chemistry of mercury. Together with the closed-shell d10 configuration of Hg2+ they account for the special bonding schemes as preferred linear coordination with highly covalent contributions to chemical bonding or special affinities to nitrogen and sulfur that are so prominent in mercuric chemistry. This research report summarizes recent research on coordination compounds with halogen, oxygen and, especially, nitrogen as direct bonding partners of divalent mercury and their competition with each other. In a rather systematic way N-donor ligands with one, two and more than two nitrogen atoms have been inspected in order to elucidate the influences that lead to the special bonding schemes of HgII-N compounds.Wie bei Gold so spielen auch bei Quecksilber relativistische Effekte eine bedeutende Rolle für die physikalischen und chemischen Eigenschaften. Gemeinsam mit der speziellen Elektronenkonfiguration einer aufgefüllten d-Schale ("closed-shell"-d10-Konfiguration) sind sie für die speziellen Bindungsarten (Bevorzugung der linearen Koordination mit stark kovalenten Bindungsanteilen) und eine spezielle Affinität zu N- oder S-haltigen Liganden des Hg2+-Ions verantwortlich. Dieser "Forschungsbericht" fasst Ergebnisse jüngster Untersuchungen an HgII-Komplexen mit Halogen-, Sauerstoff- und insbesondere Stickstoff-Atomen als direkten Bindungspartnern und ihre Konkurrenz miteinander zusammen. In eher systematischer Weise wurden N-Donor-Liganden mit ein, zwei und mehr Stickstoff-Atomen eingesetzt, um Einflüsse herauszufinden, die für die speziellen HgII-N-Bindungsschemata verantwortlich sind.

# # h,k,l, Fc-squared, Fo-squared, sigma(Fo-squared) and status flag # data_I _shelx_title ' M31BR IN P 42 P42/M' _shelx_refln_list_code 4 _shelx_F_calc_maximum 610.69 _exptl_crystal_F_000 1340.00 _reflns_d_resolution_high 0.8107 loop_ _symmetry_equiv_pos_as_xyz ...

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Abstract. Colourless single crystals of [Ag3(Dat)2](NO3)3 were ob-tained from a reaction of silver(I) nitrate and 3,5-dimethyl-4-am-ino-1,2,4-triazole (Dat). In the crystal structure (orthorhombic, Fdd2, Z 8, a 1100.1(2), b 3500.3(2), c 1015.4(3) pm, R1 0.0434) there are ...

# # h,k,l, Fc-squared, Fo-squared, sigma(Fo-squared) and status flag # data_I _shelx_title ' Wg20 in P2(1)2(1)2(1)' _shelx_refln_list_code 4 _shelx_F_calc_maximum 227.88 _exptl_crystal_F_000 1128.00 _reflns_d_resolution_high 0.8140 loop_ _symmetry_equiv_pos_as_xyz ...