Metal complexes of backbone diimino-functionalised imidazolidines: synthesis, structural characterizations and application for Suzuki–Miyaura coupling

The backbone diimino-functionalized imidazolidine (1) was introduced by condensation of N,N′-bis(2,4,6-trimethylphenyl)form-amidine and bis-phenylimidoyl chloride in the presence of potassium carbonate. The coordination properties of proligand 1 with various metal ions [M = Pd(2), Sn(3), Fe(4), Zn(5), Hg (6)], and the attempts made to cyclise the backbone diimino nitrogen centers of 1 were explored with Vilsmeier reagent. Although the expected chelation occurred using the nitrogen atoms of diimine units to the metal ions, the final structures show different isomeric s-cis type proligand configurations depending upon the type of metal ions. During these reactions an isomeric derivative, 4,5-bis(mesitylimino)-1,3-diphenylimidazolidin-2-ol (8), was isolated. Further, the reaction of 8 with palladium dichloride afforded the expected chelated product 9. This paper discusses the overall syntheses (1–9) and Suzuki–Miyaura coupling using 2 as a catalyst with electron-withdrawing and donating substrates in DMF or water as a reaction medium.