Synthesis and Characterization of [(1-benzylpyrazole) [N,N-bis(2-aminoethyl)-1,2-ethanediamine]copper(II)] Diperchlorate, a Structure with a Sterically Strained, Distorted-Trigonal-Bipyramidal Cation

Abstract

The synthesis, characterization, and molecular structure of the title compound, [(1-benzylpyrazole)[N,N-bis(2-aminoethyl)-1,2-ethanediamine]copper(II)] diperchlorate, [(nbp)(tren)Cu(II)](ClO₄)₂, 2  · 2ClO₄, is reported. The salt crystallized in the monoclinic space group P2₁/n with a = 10.1453(5) Å, b = 17.5250(8) Å, c = 13.6021(6) Å, β = 100.737(19)° and V = 2376.06(19) ų with Z = 4. The structure contains copper(II) (nbp)(tren) cations, each with a distorted-trigonal-bipyramidal CuN₅ coordination geometry, separated by perchlorate anions. The cations exhibit steric strain associated primarily with close contacts between the methylene protons of the nbp ligand and one of the amine groups of the tren ligand. The strain has a noticeable effect on the coordination geometry and certain physical properties of the complex.

Graphical Abstract

In the title structure, steric strain in the (nbp)(tren)Cu(II) cations, associated with close contacts between protons of the nbp ligand and two of the amine groups of the tren ligand (dashed lines in the figure below) affects certain physical properties of the cation and is consistent with an anomalously long Cu(II)–N(pyrazole) distance (Cu–N41) and an unusually large axial–equatorial angle, N41–Cu–N12.