The reaction of titanacyclobutene–silacyclobutene fused-ring complexes with nitriles was investigated. Formal insertion of the C–N triple bond of nitriles into the silacyclobutene ring was observed, affording their corresponding titanacyclobutene and six-membered azasilacycle fused-ring complexes. This reaction pattern with nitriles is totally different from that of their analogous zirconacyclobutene–silacyclobutene fused-ring complexes. The size effect of the central metals (Ti vs Zr) is considered as the major reason for the different reaction patterns.