Abstract
Photoirradiation of organosillicon compounds bearing a 2-(phenylazo)phenyl group as intramolecularly coordination site is expected to cause not only isomerization of the azo groups, but also reversible switching of the coordination states of silicon between a usual tetracoordinate state and a highly reactive pentacoordinate state. We report here the photocontrol of reactivities of a highly coordinate disiloxane and allylsilane without changing other conditions by taking advantage of the coordination state change. (E,E)-Tetrafluorobis[2-(phenylazo)phenyl]disiloxane (E,E)-2 decomposed very slowly in the solution to give trifluorosilane (E)-1. On the other hand, photoirradiation of (E,E)-2 gave a mixture of (Z)-1 and (Z,Z)-2, both of which were converted to (E)-1 fast at room temperature. Photoirradiation accelerated the decomposition of (E,E)-2 to (E)-1. Addition of fluoride ion also accelerated the formation of (E)-1. Formation mechanism of (E)-1 as well as the reaction control of allyldifluorosilane (E)-5 will also be discussed.
