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Giovanni Tauzher

Bio: Giovanni Tauzher is an academic researcher from University of Trieste. The author has contributed to research in topics: Ligand & Cobalt. The author has an hindex of 19, co-authored 69 publications receiving 1023 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the preparation of the organocobalt complexes Co II (BAE), Co III (L 2 ]X, Co III(L 2 )X, and Co 3 (LX)LX are described and the UV and visible absorption spectra are reported.

94 citations

Journal ArticleDOI
TL;DR: The crystal structure of pyRh(DH)2Cl (I) and pyCo(DH2Cl) 2Cl (II) is reported in this article, together with the synthesis and the crystal structure for pyCoClO4N5C13H19.

45 citations

Journal ArticleDOI
TL;DR: The first X-ray structural determination of a cobalamin with a Co-Se bond is reported, and the structural features of the Co-S bond in cobalamins are discussed in terms of packing of roughly spherical molecules.
Abstract: Results of the accurate crystal structure determination of NO2Cbl·2LiCl (1), NO2Cbl·NaCl (2), NCSCbl (3) and NCSeCbl (4), based on synchrotron diffraction data collected at 100 K, are described. The nitro group in (1) was found to be disordered with two orientations that differ by a rotation of ∼60° about the Co—NO2 bond, whereas in (2) the nitro group has only one orientation. The first X-ray structural determination of a cobalamin with a Co—Se bond is reported. Comparison of the axial distances indicates that SeCN has a bond length of 2.384 (3) A and that the trans influence on the Co—N bond is only slightly greater than that of SCN. The crystals of the thiocyanate cobalamin contain both the S- and N-bonded coordination isomers in a 3:2 ratio. The structural features of the Co—S bond in cobalamins are discussed. The crystal chemistry of cobalamins is discussed in terms of packing of roughly spherical molecules. The unit-cell parameters can be used to group the cobalamins' crystal structures in different arrays intermediate between distorted hexagonal close packing and primitive hexagonal arrangements. The structural features of cobalamins, and of cobaloximes that have the same axial fragment as the cobalamins, are reviewed and discussed in terms of the cis influence of the equatorial ligand.

39 citations

Journal ArticleDOI
TL;DR: In this article, the crystal structures of [CH 3 Co(DH)(DBPh 2 )( N -MeIm)] (Ib) and [CH3 Co(DB Ph 2 ) 2 CH 3 OH] (IId ) were shown to be analogous to those found in the solid state.

32 citations


Cited by
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Journal ArticleDOI
10 Mar 1970

8,159 citations

01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : 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

1,652 citations

Journal ArticleDOI
TL;DR: 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 met athesis of the acyclic diene diethyl diallylmalonate as discussed by the authors.
Abstract: 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.

631 citations

Journal ArticleDOI
Kenneth L. Brown1

458 citations