LONG-RANGE ELECTRONIC TRANSMISSION IN CONFORMATIONALLY RIGID ALPHA-DIKETONES

The conformationally rigid α-diketones 4-7 have been synthesized and their photoelectron (PE), absorption, and emission spectra recorded. Assignment of the first bands in the PE spectra is based upon correlation with related molecules and substantiated by MINDO/3 results. The first band (π+ ∗@r@n← n+) in the electronic spectra of 4-6 shows a hypsochromic shift through the series. This finding is explained in terms of interaction involving the π∗@r@n+ orbital of the C2O2 fragment and the π orbital of the olefinic moiety in 4 and 5. This interpretation is supported by CNDO/S calculations. © 1978, American Chemical Society. All rights reserved.