Abstract
The object of this work was to investigate the structures of some monocyclic polycarbonyl compounds and their condensation products. Methods employed in this study include infrared, ultraviolet-visible, 'H and 14N magnetic resonance spectroscopy and mass spectrometry. The electronic spectra of tetrahydroxy-p-benzoquinone, rhodizonic acid, croconic acid and squaric acid are interpreted on the basis of Pariser-Parr-Pople LCAO-SCF-MO calculations. The mass spectral fragmentation of the oxocarbons is characterised by the elimination of carbon monoxide followed by ring closure to yield the next lower member of the series. These measurements also indicate a gem-diol structure for rhodizonic acid dihydrate. The isolation and both the spectroscopic and mass spectrometric studies of some oxocarbon condensation products is reported. These studies confirm the structural features of the compounds 1,2,3,4-tetrahydroxy-phenazines, 2,3-dihydroxy-phenazine-1,4-quinones, phenazine-1,2,3,4-tetrones and polycondensation products. Pariser-Parr-Pople LCAO-SCF-MO calculations on 1,2,3,4-tetrahydroxy-phenazine and 2,3-dihydroxy-phenazine-1,4-quinone provide a satisfactory basis for the interpretation of their electronic spectra. Squaric acid condensation products have been isolated and studied. These compounds are shown to have the 1,2,3,8-tetrahydro-1,2-dioxo-cyclobuta-(b)-quinoxaline structure. Squaric acid also gives a salt with o-phenylenediamine from which octahedral copper and nickel complexes have been isolated and characterized.