Synthesis and structural characterization of copper(II) complexes of pincer ligands derived from benzimidazole

Abstract

A few pincer-type ligands, 1,3-bis(2′-benzimidazolyl)benzene (L1 ), 2,6-bis(2′-benzimidazolyl)pyridine (L2 ), and their N-alkylated derivatives were prepared and characterized by IR and 1H NMR spectroscopy. The N-alkylated benzimidazolyl ligands, 2,6-bis(N-benzylbenzimidazolyl)pyridine (L3 ), 2,6-bis(N-allylbenzimidazolyl)pyridine (L4 ), and 1,3-bis(N-allylbenzimidazolyl)benzene (L5 ) form 1 : 1 complexes with copper nitrate. X-ray diffraction showed that [Cu(NO3)(MeOH)(L4 )](NO3) (7) and [Cu(NO3)2(L3 )] (8) are mononuclear complexes, whereas [Cu(NO3)2(L5 )] · 2DMF (9) exhibits one-dimensional zigzag motif. The chain consists of mutually bridged Cu(NO3)2 and L5 ligand. Crystal data: 7, triclinic, , a = 9.035(3) Å, b = 11.149(4) Å, c = 14.664(5) Å, α = 104.856(5)°, β = 99.635(5)°, γ = 99.409(5)°, V = 1374.2(8) Å3, Z = 2, and R 1 = 0.0666, wR 2 = 0.1753; 8, monoclinic, Cc, a = 12.979(5) Å, b = 14.343(5) Å, c = 16.966(6) Å, β = 109.958(6)°, V = 2968.9(18) Å3, Z = 4, and R 1 = 0.0582, wR 2 = 0.1352; 9, monoclinic, P21/c, a = 17.278(6) Å, b = 15.234(5) Å, c = 16.161(5) Å, β = 111.221(5)°, V = 3965(2) Å3, Z = 4, and R 1 = 0.0658, wR 2 = 0.1612.