Lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands were synthesized conveniently and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated. The reaction of 1 equivalent of 2,5-bis(pyrrolidinomethyl)pyrrole {C 4 H 2 NH(2,5-CH 2 NC 4 H 8 ) 2 } with n-BuLi generated [Li{C 4 H 2 N(2,5-CH 2 NC 4 H 8 ) 2 }] 2 (1) in diethyl ether. Treatment of 2 equivalents of C 4 H 2 NH(2,5-CH 2 NC 4 H 8 ) 2 with MgBu 2 or ZnEt 2 in THF afforded [Mg(THF){C 4 H 2 N(2,5-CH 2 NC 4 H 8 ) 2 } 2 ] (2) or [Zn{C 4 H 2 N(2,5-CH 2 NC 4 H 8 ) 2 } 2 ] (3) in high yield, respectively. Compounds 1, 2 and 3 were characterized by 1 H and 13 C NMR spectra and their molecular structures were determined by single crystal X-ray diffraction. Furthermore, compounds 1, 2 and 3 were proved to be moderate to good initiators for cyclotrimerization of isocyanate to the corresponding isocyanurate in diethyl ether.