Curtis reactions with Zn complexes derived from 2-(Aminomethyl)Benzimidazole

[1-(1H-benzimidazol-2-yl)-N-(propan-2-ylidene)methanamine-?2,N2,N3]dichloridozinc(II) 1, [N-((1H-benzimidazole-2-yl-?N)methyl)-4-(((1H-benzimidazole-2-yl-?N)methyl)imino-?N)-2-methylpentan-2-amine-?N)]chloridozinc(II) chloride dihydrate 2, and tris [(E)-4-(((1H-benzimidazol-2-yl-?N3)methyl)amino)pent-3-en-2-one]chloridozinc(II) chloride hydrate 3 complexes were synthesized via condensation of ZnII complexes A-C with the corresponding ketone. Whereas compounds 1 and 2 were obtained by condensation of propan-2-one with complexes A-C, pentane-2,4-dione was used in the synthesis of 3. Vibrational and thermogravimetric studies showed that the chelate structure of 2 is stabilized by the presence of hydrogen bonds. Moreover, theoretical and experimental NMR studies confirmed that the metal ion is bonded to the ligand in chelate form. On the other hand, vibrational and crystallographic studies showed that 3 has a helicoidal geometry in which the metal ion is bonded to three ligands that act as blades. In solid state, the complex 3 is stabilized by the presence of weak interactions between each blade of the molecule. Additionally, NMR studies indicated that 3 preserves its C3 symmetry in methanolic solution.