A family of upper bounds for the ground-state second-order energy, derived from the Perturbation Theory, has been obtained. The bounds have been evaluated for the static electric dipole polarizability of the hydrogen atom.
Synthesis and catalytic properties of a heterogenized RN(CH3)3ClW(CO)5 metathesis catalyst. W(CO)6 was attached to a strong anion exchange resin to form [resin]-N(CH3)3ClW(CO)5. Addition of C2H5AlCl2 to this compound in chlorobenzene catalyses the metathesis reaction of oct-1-ene.
The importance of ruthenium in inorganic chemistry is increasing, and its use as catalyst in either homogeneous or heterogeneous catalysis has been reported.1,2,3 There is no doubt that the interest in this metal will continue. A knowledge of the electronic environment of the ruthenium atom in various circumstances is therefore important
The title compounds were prepared by a series of stereocontrolled chemical transformations using appropriately functionalized sugar derivatives or branched-chain sugar derivatives from D-xylose and/or D-glucose.
The crystal structure of biferrocene, [C5H5FeC5H4]2, has been reinvestigated by X-ray diffraction methods at room temperature. Data were collected on a four-circle diffractometer equipped with graphite-crystal monochromator for Mo-?? radiation. To assess the degree of disorder, data were collected over one hemisphere, although the crystal class is known to be monoclinic. Exhaustive least-squares refinement (R = 0,066) failed to produce a model that accounts for all of the observed electron density. The unexplained peaks define a distorted five-membered ring which is recognized as the remnant of an ordered low-temperature phase.
Extraction of maize inoculated with a culture of Aspergillus ustus led to the isolation of new metabolites, viz. three substituted 3a, 12a-dihydro[3',2':4,5]furo[3,2-b]xanthen-5-one derivatives, together with 7-chloro-2-(3-furyl)-1,3,8-trimethoxyxanthone, 8-deoxy-6-O-methylversicolorin A, and the austalides. In addition, the following known metabolites were identified: austocystins A,B,D, and H, averufin, averufanin, and versicolorin C.
Intramolecular nucleophilic displacement of halide ion from the ?-haloethyl-substituted amidoesters of phosphoric acid was studied under conditons of electrophilic and basic catalysis. 1,3-Substitution by the amide nitrogen atom, leading to the aziridine derivatives, was found to be the preferred reaction pathway; the alternative 1,5-reaction, involving the amide nitrogen or phosphoryl oxygen atoms, was not observed.