STRUCTURAL STUDY ON 1-PHENYL-8-TROPYLIONAPHTALENE AND 1-(2-NAPHTHYL)-8-TROPYLIONAPHTHALENE HEXAFLUOROANTIMONATES

The molecular structures of 1-phenyl- (5) and 1-(2-naphthyl)-8-tropyli onaphthalene (6) hexafluoroantimonates were determined by x-ray crysta llography and compared with those of 1,8-diphenylnaphthalene and relat ed compounds. In these compounds, the two aromatic substituents face e ach other in a nearly parallel conformation with a splayed-out arrange ment. In the cations 5 and 6, the distance between the facing rings is appreciably shorter than that of other 1,8-diarylnaphthalenes, sugges ting the presence of some attractive force. This attraction is ascribe d to an intramolecular charge-transfer interaction, and seems to bring about a slight inward bending of the 2-naphthyl substituent in the ca tion 6. AM1 calculations were carried out for these cations and the re sults are discussed in comparison with the results of x-ray crystallog raphy.