Planar and Pyramidal Tetracoordinate Carbon in Organoboron Compounds
2005-08-19T00:00:00Z (GMT) by
Using previously proposed C(BH)2(CH)2 (16, 17) and C(CH)2B2 (22) systems with a central planar tetracoordinate carbon (ptC) atom linking two three-membered rings as building blocks, a series of stable structures containing two and three ptC centers within a molecule have been designed and computationally studied with the DFT (B3LYP/6-311+G**) method. Inclusion of a carbon atom ligated with π-accepting and σ-donating boron centers into at least one aromatic ring is critical for stabilization of a planar structure. A square pyramidal configuration at tetracoordinate carbon may be achieved in appropriately strained molecules such as [22.214.171.124]tetraborafenestrane 45 and others by surrounding the carbon with boron-centered ligands.
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