Metathesis cleavage of an N[double bond, length as m-dash]N bond in benzo[c]cinnolines and azobenzenes by triply-bonded ditungsten complexes

A metathesis reaction of a W[triple bond, length as m-dash]W bond and an N[double bond, length as m-dash]N bond was observed by reacting a W-W triply-bonded W(iii)2 complex, (tBuO)3W[triple bond, length as m-dash]W(OtBu)3 (1), with benzo[c]cinnoline derivatives to form biphenyl-linked dinuclear (imido)tungsten complexes 2-4. When azobenzene was used as the substrate, a trans to cis isomerization induced by blue-LED light was essential prior to the metathesis cleavage of the N[double bond, length as m-dash]N bond by the W[triple bond, length as m-dash]W bond of (Me2N)2(TfO)W[triple bond, length as m-dash]W(OTf)(NMe2)2 (6), affording the corresponding imido-bridged dinuclear tungsten complexes 7-9.