In this journal, Moses Gomberg's 1900 revelation, "An Instance of Trivalent Carbon: Triphenylmethyl", lauded on a centennial National Historic Chemical Landmark for challenging the "prevailing belief that carbon can only have four bonds", shifts its place in our imaginations as the facts given here are accommodated. In 1898 Gomberg presumed that he had made a molecular complex of bromotriphenylmethane and two neutral I2 molecules. But he was mistaken. Instead, Gomberg produced a mixture of three persistent single crystals of the triphenylmethyl cation before he published his aforementioned, controversial paper. Trigonal carbon coordination was the crack in the valency rules that had organized chemistry prior to the invention of quantum mechanics. Gomberg did not recognize the wealth of trivalent carbon compounds he had in hand before the proposition of the radical and corresponding cation thereafter. This work alludes to a counterfactual history.
Grainger et al. (Fri,) studied this question.