Upon prolonged thermal exposure under vacuum, a well-defined single-site surface species [(Si–O–)Zr(NEt₂)₃] (1) evolves into an ethylimido complex [(Si–O–)Zr(NEt)NEt₂] (2). Reactions of 2 with an imine substrate result in imido/imine (NR_i, R: Et, Ph) exchange (metathesis) with the formation of [(Si–O–)Zr(NPh)NEt₂] (3). Compounds 2 and 3 effectively catalyze imine/imine cross-metathesis and are thus considered as the first heterogeneous catalysts active for imine metathesis.