Abstract
Traditional Pariser-Parr-Pople and variable electronegativity calculations have been carried out on C6H5B(OR)2 and p-CH3OC6H4B(OR)2, and the results compared with calculations for C6H5BR2. It is concluded that the VE-SCF method offers a real advantage over the simple PPP method for predicting percent charge transfer and transition intensity in cases where excited states possess substantial C.T. character. The restriction that empirically chosen parameters fit the observed transition energies and intensities of both triarylboranes and ArB(OR)2 requires the choice of a boron VSIP greater than 2.0 eV in the fixed parameter procedure of the usual PPP-SCF-CI method for these molecules. Observed transitions in C6H5B(OR)2 correlate with 1 L b, 1 L a, 1 B b, whereas the first absorption maximum of (C6H5)3B is assigned to C.T. (1 A 1→1 A 1) local C 2v symmetry.
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