Kristallstruktur eines aromatischen Tetraboran(4)-Dianions, ein nichtklassisches Triboracyclobutan und ein Borylboratiren mit sehr starker C-B-Hyperkonjugation
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Philipps-Universität Marburg
Abstract
So far unknown two-electron aromatics with
classical and nonclassical sigma skeletons are acquired
experimentally in this dissertation (PhD thesis). By synthesis
and X-ray structural analysis of the first dianion of a
tetraboracyclobutane (tetaraborane(4)), the series of puckered
four membered two-electron aromatics with classical sigma
skeletons was completed. Prerequisite for this was the
development (design) of perparative route to the precursor,
which was accessible only in very low yields (0.5%) before. A
new planar two-electron aromatic tetraboracyclobutane with a
nonclassical sigma sekeleton was obtained by reacting the
dianion with a dichloroborane. A highly reactive derivative of
the so far unknown triboracyclobutane was fully characterized
by NMR spectroscopy at ?100°C. Its double aromatic
electronic structure is definitely established by its 11B
chemical shifts as compared to computed shifts for model
compounds. Nonclassical triboracylobutane is thus shown to be
the homo form of the double aromatic triboracyclopropane known
only from computations.So far unknown two-electron aromatics with
classical and nonclassical sigma skeletons are acquired
experimentally in this dissertation (PhD thesis). By synthesis
and X-ray structural analysis of the first dianion of a
tetraboracyclobutane (tetaraborane(4)), the series of puckered
four membered two-electron aromatics with classical sigma
skeletons was completed. Prerequisite for this was the
development (design) of perparative route to the precursor,
which was accessible only in very low yields (0.5%) before. A
new planar two-electron aromatic tetraboracyclobutane with a
nonclassical sigma sekeleton was obtained by reacting the
dianion with a dichloroborane. A highly reactive derivative of
the so far unknown triboracyclobutane was fully characterized
by NMR spectroscopy at ?100°C. Its double aromatic
electronic structure is definitely established by its 11B
chemical shifts as compared to computed shifts for model
compounds. Nonclassical triboracylobutane is thus shown to be
the homo form of the double aromatic triboracyclopropane known
only from computations.
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This item has been published with the following license: In Copyright