Synthesis and crystal structure of a copper(II) complex of the tripodal tetradentate ligand tris(2-benzimidazolylmethyl)amine

A mononuclear copper complex [Cu(NTB)Cl]Cl·3CH₃CH₂OH (1) (NTB?=?tris(2-benzimidazolylmethyl)amine) was synthesized and its structure was determined by single crystal X-ray diffraction. In this complex, copper(II) is five-coordinate with NTB serving as a neutral tetradentate ligand. Three tertiary nitrogen atoms of benzimidazole groups of NTB formed the base of the trigonal bipyramidal geometry. One axial position was occupied by the apical nitrogen atom of NTB and the other was occupied by chloride. The ESR spectrum of complex 1 in ethanol at 101?K was recorded and the well-defined ESR parameters (g _∥?=?2.02, g _⊥ =?2.16 and A _∥ ^?=?109?G) indicated that the Cu(II) has a distorted trigonal-bipyramidal environment, in good agreement with crystal structure determination for complex 1.