Hexanuclear Cu(3)O–3Cu triazole-based units as novel core motifs for high nuclearity copper(ii) frameworks

The asymmetric 3,5-disubstituted 1,2,4-triazole ligand H(2)V (5-amino-3-picolinamido-1,2,4-triazole) by reaction with an excess of Cu(ii) perchlorate (Cu : H(2)V being 12 : 1) has produced a novel hexanuclear {Cu(6)(μ(3)-O/H)(HV/V)(3)} fragment, with one triangular Cu(3)(μ(3)-O/H) group connected to three peripheral single Cu(ii) ions through a cis–cis–trans bridging mode of the ligand, which is the building block of the three structures described here: one hexanuclear, [Cu(6)(μ(3)-O)(HV)(3)(ClO(4))(7)(H(2)O)(9)]·8H(2)O (1), one dodecanuclear, [Cu(12)(μ(3)-O)(2)(V)(6)(ClO(4))(5)(H(2)O)(18)](ClO(4))(3)·6H(2)O (2), and one tetradecanuclear 1D-polymer, {[Cu(14)(μ(3)-OH)(2)(V)(6)(HV)(ClO(4))(11)(H(2)O)(20)](ClO(4))(2)·14H(2)O}(n) (3), the last two containing hexanuclear subunits linked by perchlorato bridges. The Cu–Cu av. intra-triangle distance is 3.352(2) Å and the Cu(central)–Cu(bridged external) av. distance is 5.338(3) Å. The magnetic properties of the hexanuclear “Cu(3)O–3Cu” cluster have been studied, resulting as best fit parameters: g = 2.18(1), J(intra-triangle) = −247.0(1) cm(−1) and j(central Cu(II) – external Cu(II)) = −5.15(2) cm(−1).