In 1960, Linnett originated a modification to the
octet rule, originally proposed by
Lewis, concerning
valence electrons. He proposed that the octet should be considered as a double quartet of electrons rather than as four pairs, and hence the theory became known as "
Linnett double-quartet theory". Using this method, he was able to explain the stability of 'odd electron' molecules such as nitric oxide and oxygen. This theory was set out in a book "The Electronic Structure of Molecules: A New Approach", published by Methuen & Co Ltd, London, 1964. His general book "Wave Mechanics and Valency" also published by Methuen & Co Ltd, London, appeared in 1960. ==Death==