The reaction of the N-heterocyclic-carbenestabilized disilicon(0) complex [IPr -> Si=Si <- IPr] (1; IPr = :C{N(Ar)CH}(2) and Ar = 2,6-iPr(2)C(6)H(3)) with ArN3 afforded the N-heterocyclic-carbene-stabilized siladiimide [ArNSi((IPr)NAr] (2). X-ray crystallography and theoretical studies show that the N Si N skeleton in compound 2 possesses considerable double-bond character and the Si atom is stabilized by the N-heterocyclic carbene.