Supramolecular isomerism within three-dimensional 3-connected nets: unusual synthesis and characterization of trimorphic copper(I) 3,5-dimethyl-1,2,4-triazolate

Solvothermal treatments of acetonitrile, aqueous ammonia and copper(II) salts frequently yielded alpha-[Cu(mtz)] (1) (Hmtz = 3,5-dimethyl-1,2,4-triazole) under different reaction conditions. However, two new supramolecular isomers of 1, namely beta-[Cu(mtz)] (2) and gamma-[Cu(mtz)] (3) were successfully isolated upon introducing 4,4'-bipyridine or nitrate as an additive. 1-3 represent the first example of true supramolecular isomerism within 3D 3-connected nets. Besides the 4.8.10 net for the tetragonal phase 1 (P4(2)/n, a = 13.470(2), c = 6.142(2) angstrom), two novel 3-connected nets, 8(2)10-a and 6.10(2), were observed in the new tetragonal phase 2 (I(4) over bar 2d, a = 14.0247(5), c = 5.2884(4) angstrom) and orthorhombic phase 3 (Iba2, a = 8.0423(7), b = 11.5310(10), c = 17.3505(16) angstrom), respectively. The three isomers also displayed distinct physical properties related to their different supramolecular structures.