3 research outputs found
EfektivnĂ aritmetika eliptickĂ˝ch kĹivek nad koneÄnĂ˝mi tÄlesy
The thesis deals with arithmetics of elliptic curves over finite fields and methods to improve those calculations. In the first part, algebraic geometry helps to define elliptic curves and derive their basic properties including the group law. The second chapter seeks ways to speed up these calculations by means of time-memory tradeoff, i.e. adding redundancy. At last, the third part introduces a wholly new curve form, which is particularly effective for such purposes
Cationic Ir(III) Alkylidenes Are Key Intermediates in CâH Bond Activation and CâC Bond-Forming Reactions
This work describes the chemical reactivity of a cationic
(Ρ<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)ÂIrÂ(III) complex that
contains
a bisÂ(aryl) phosphine ligand, whose metalation determines its unusual
coordination in a Îş<sup>4</sup>-<i>P</i>,<i>C</i>,<i>Câ˛</i>,<i>Câł</i> fashion. The
complex (<b>1</b><sup><b>+</b></sup> in this paper) undergoes
very facile intramolecular CâH bond activation of all benzylic
sites, in all likelihood through an IrÂ(V) hydride intermediate. But
most importantly, it transforms into
a hydride phosphepine species <b>4</b><sup><b>+</b></sup> by means of an also facile, base-catalyzed, intramolecular dehydrogenative
CâC coupling reaction. Mechanistic studies demonstrate the
participation as a key intermediate of an electrophilic cationic IrÂ(III)
alkylidene, which has been characterized by low-temperature NMR spectroscopy
and by isolation of its trimethylphosphonium ylide. DFT calculations
provide theoretical support for these results
Cationic Ir(III) Alkylidenes Are Key Intermediates in CâH Bond Activation and CâC Bond-Forming Reactions
This work describes the chemical reactivity of a cationic
(Ρ<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)ÂIrÂ(III) complex that
contains
a bisÂ(aryl) phosphine ligand, whose metalation determines its unusual
coordination in a Îş<sup>4</sup>-<i>P</i>,<i>C</i>,<i>Câ˛</i>,<i>Câł</i> fashion. The
complex (<b>1</b><sup><b>+</b></sup> in this paper) undergoes
very facile intramolecular CâH bond activation of all benzylic
sites, in all likelihood through an IrÂ(V) hydride intermediate. But
most importantly, it transforms into
a hydride phosphepine species <b>4</b><sup><b>+</b></sup> by means of an also facile, base-catalyzed, intramolecular dehydrogenative
CâC coupling reaction. Mechanistic studies demonstrate the
participation as a key intermediate of an electrophilic cationic IrÂ(III)
alkylidene, which has been characterized by low-temperature NMR spectroscopy
and by isolation of its trimethylphosphonium ylide. DFT calculations
provide theoretical support for these results