The hexaphenylethane riddle

The correct quinoid structure for the dimer of triphenylmethyl radicals was proposed in 1904. By 1906 there existed three independent lines of evidence which support this structure: acid-catalyzed aromatization, para-halogen lability, and radical chain autoxidation. Despite this evidence, and the skill and insight of the numerous chemists who studied the system, the incorrect hexaphenylethane structure was assigned to the dimer until 1968. This paper attempts to explain how this could have happened by tracing the evolution of triphenylmethyl theory and of attitudes toward the evidence from 1900 until 1968.