Novel azine reactivity: facile N-N bond cleavage, C-H activation, and N-N coupling mediated by RhI.
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Biomedical subjects
Jan M L Martin
Publications and source records attributed to Jan M L Martin.
Mechanistic aspects of acetone addition to metalloaromatic complexes of iridium: a DFT investigation.
DFT calculations were used to reveal the unexpected reactivity and mechanism of the addition of acetone to metallabenzene, metallapyrylium and metallathiabenzene complexes of iridium.
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Active site electronic structure and dynamics during metalloenzyme catalysis.
Zinc-dependent enzymes play important roles in many cellular processes. Assignment of their reaction mechanisms is often a subject of debate because the zinc ion is silent in several spectroscopic techniques. We have combined time-resolved X-ray absorption spectroscopy, pre-steady state kinetics and computational quantum chemistry to study the active site zinc ion of bacterial alcohol dehydrogenase during single substrate turnover. We detect a series of alternations in the coordination number and structure of the catalytic zinc ion with concomitant changes in metal-ligand bond distances. These structural changes are reflected in the effective charge of the metal ion. The present work emphasizes the flexibility of catalytic zinc sites during catalysis and provides novel mechanistic insights into alcohol dehydrogenase catalysis.
Alcohol Dehydrogenase↗
TpPtMe(H)(2): why is there H/D scrambling of the methyl group but not methane loss?
The reactivity of TpPtMe(H)(2) (Tp = hydrido-tris(pyrazolyl)borate) was investigated. This complex is remarkably resistant to methane loss; heating it in methanol at 55 degrees C does not lead to either methane or hydrogen loss. When CD(3)OD is used, reversible H/D scrambling of the hydrides and the methyl hydrogens occurs. This reactivity was investigated by density functional theory (DFT) methods at the mPW1k/LANL2DZ+P//mPW1k/LANL2DZ level. It was found that methane loss cannot occur due to the rigidity of the Tp ligand, which does not allow the trans geometry which would be required for the product of methane elimination, TpPtH. The resulting complex is very high in energy, and therefore the loss of methane is unfavorable. On the other hand, H/D scrambling of the methyl ligand is relatively facile. It proceeds through an eta(2-CH)-CH(4) complex, even though methane loss is not observed. The model system, [(NH(3))(3)PtMe(H)(2)](+) was examined to verify that the cause of the observations is the rigidity of the Tp system. The reaction was investigated at a number of levels of DFT. It was concluded that investigations of similar sized systems should be examined at the above level of theory or the mPW1k/SDB-cc-pVDZ//mPW1k/SDD level for improved accuracy of the energetic calculations.
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