J. Appl. Cryst.の発刊に際して

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Several ruthenium-based olefin metathesis catalysts of the formula (PR3)2X2RuCHCHCPh2 have been synthesized, and relative catalyst activities were determined by monitoring the ring-closing metathesis of the acyclic diene diethyl diallylmalonate. The following order of increasing activity was determined:  X = I < Br < Cl and PR3 = PPh3 ≪ PiPr2Ph < PCy2Ph < PiPr3 < PCy3. Additional studies were conducted with the catalyst (PCy3)2Cl2RuCH2 to probe the mechanism of olefin metathesis by this class of catalysts. The data support a scheme in which there are two competing pathways:  the dominant one in which a phosphine dissociates from the ruthenium center and a minor one in which both phosphines remain bound. Higher catalyst activites could be achieved by the addition of CuCl to the reaction.

Well-defined ruthenium olefin metathesis catalysts: Mechanism and activity

Structural chemistry of transition metal complexes of oximes

Chemistry and enzymology of vitamin B12.

Di-organocobalt complexes of macrocyclic ligands

The synthesis and characterization of a series of RM(DBPh2)2(H2O) complexes (M = Co and Rh) and the X-ray structure of the dinuclear n-PrRh(DH)(DBPh2) 2 (1) obtained by recrystallization of nPrRh(DBPh2)2(H2O) in non coordinating solvent are reported. The crystals of (1) are built up by neutral centrosymmetric dinuclear n-PrRh(DH)(DBPh2) 2 units and CH2Cl2 crystallization molecules in the ratio 1:1. The Rh ion of one n-PrRh(DH)(DBPh2) unit achieves hexacoordination by coordination of one of the oxime O atoms of the other unit. The formation of the dimer by recrystallization of n-PrRh(DBPh2)2(H2O) in non coordinating solvent may be ascribed to the concomitant effect of the weak metal–water bond in the monomeric aqua complex, the strong tendency of Rh to achieving hexacoordination in such organo derivatives, and the ease of losing a BPh2 bridge of the diphenylborylated organorhodoximes.

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The weak metal-water bond in diphenylborylated organoaquacobaloximes and rhodoximes leads to the formation of an unusual dinuclear rh(iii) complex

On an unusual shortening of the C(sp3)–C(sp3) bonds in n-propylcobaloximes

New cobalt(II) chelates containing quinones as axial ligands

Kristall- und molekularstruktur der 1 zu 1-additionsverbindung von molekularem sauerstoff mit pyridin-n,n′-aethylen-bis-(acetylacetoniminato)-kobalt(ii)

Giovanni Tauzher

Papers

Di-organocobalt complexes of macrocyclic ligands

The weak metal-water bond in diphenylborylated organoaquacobaloximes and rhodoximes leads to the formation of an unusual dinuclear rh(iii) complex

On an unusual shortening of the C(sp3)–C(sp3) bonds in n-propylcobaloximes

New cobalt(II) chelates containing quinones as axial ligands

Kristall- und molekularstruktur der 1 zu 1-additionsverbindung von molekularem sauerstoff mit pyridin-n,n′-aethylen-bis-(acetylacetoniminato)-kobalt(ii)