Claus diagonal formula

Claus, Armstrong and Baeyer.—Still other formulas have been suggested on account of this difficulty, each endeavoring to avoid the necessity of oscillation in order to satisfy the four valencies of carbon. One of these was suggested by Claus and called the diagonal formula and another by Armstrong and Baeyer and known as the centric formula. 

Kekule s benzene formula was published in 1865 (see p. 555) and alternative formulae soon began to appear. Dewar and Wislicenus proposed a diagonal formula I. Claus proposed other diagonal formulae II and III, in which each carbon atom is linked by single bonds with three others. He preferred formula II ... 

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