The reactivity of thorium–phosphido and thorium–arsenido bonds was probed using tert-butyl isocyanide, tBuNC. Reaction of (C5Me5)2Th[E(H)R]2, E = P, As; R = 2,4,6-iPr3C6H2, 2,4,6-Me3C6H2 with tBuNC affords the first phosphaazaallene and arsaazaallene moieties with an f-element.
