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)A), two novel 3-connected nets, 8(2)10-a and 6.10(2), were observed in the new tetragonal phase 2 (I42d, a= 14.0247(5), c= 5.2884(4)A) and orthorhombic phase 3 (Iba2, a= 8.0423(7), b= 11.5310(10), c= 17.3505(16)A), respectively. The three isomers also displayed distinct physical properties related to their different supramolecular structures.