Abstract: The photochemistry of methylpentaphenyldisilane (1) and pentamethylphenyldisilane (7) has been investigated using nanosecond laser flash photolysis techniques. Flash photolysis of 1 with 248-nm light in acetonitrile or isooctane solution gives rise to a complex mixture of transient species. A strongly-absorbing transient with k,-= 490 nm and TQ 1.7 ps (in acetonitrile) has been assigned a 1, 3, 5-(l-sila) triene ...