σ-Aromaticity in dinuclear copper(ii) complexes: Novel interaction between perchlorate anion and σ-aromatic [Cu2X2] (X = N or O) core†
Abstract
Two dinuclear Cu(II) complexes [Cu2(3,5-dimethyl-pyrazole)4(1,1-N3)2(ClO4)2] (1) and [Cu2(3,5-dimethyl-pyrazole)2(N-hydroxymethyl-3,5-dimethyl-pyrazole)2(ClO4)2] (2) with rhombus [Cu2X2] cores exhibit σ-aromaticity that unprecedentedly interact with two closely disposed coordinated perchlorate ions with interaction energies, −53 and −47 kJ mol−1 respectively.