Different oxidation states of copper(I, I/II, II) thiocyanate complexes containing 1,2,4-triazole as a bridging ligand: syntheses, crystal structures, and magnetic properties of 2-D polymer Cu I(admtrz)SCN, linear trinuclear [CuI2CuII(admtrz)6(SCN)2](ClO4)2, and triangular trinuclear [CuII3(admtrz)4(SCN)3(mu3-OH)(H2O)](ClO4)2.H2O (admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole).

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Copper thiocyanate compounds with three different oxidation states, Cu(I)(admtrz)SCN (1), [Cu(I)(2)Cu(II)(admtrz)(6)(SCN)(2)](ClO(4))(2) (2), and [Cu(II)(3)(admtrz)(4)(SCN)(3)(mu(3)-OH)(H(2)O)](ClO(4))(2).H(2)O (3), have been synthesized and characterized (admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole). Compounds 1 and 3 crystallize in the space group Pbca of the orthorhombic system with eight formula units in cells of dimensions a = 8.0221(2) A, b = 32.3844(1) A, c = 13.5659(3) A, R1/wR2 = 0.0595/0.1674 for compound 1 and a = 21.501(3) A, b = 18.382(2) A, c = 21.526(2) A, R1/wR2 = 0.0638/0.1519 for compound 3. Compound 2 crystallizes in the space group C2/c of the monoclinic system with four formula units in cells of dimensions a = 18.772(4) A, b = 11.739(2) A, c = 22.838(5) A, beta = 91.11(3) degrees, R1/wR2 = 0.0482/0.1265. The layered-type structure of 1 can be regarded as constructed from the tetranuclear copper units double bridged by one of the two unique thiocyanate and admtrz ligands, which are bridged by the other unique thiocyanate ligands to form a two-dimensional layered structure along the a and b directions. The linear trinuclear copper cation in mixed-valence compound 2 consists of one two-valence copper and two one-valence copper atoms which are bridged by admtrz ligands, and the external copper(I) atoms are coordinated by terminal thiocyanate. The EPR spectra of 2 show the existence of localized mixed-valence copper ions. The triangle trinuclear copper cation in compound 3 has its Cu(3) triangle capped by one apical mu(3)-OH group, each edge bridged by a bridging admtrz ligand and each Cu atom coordinated by a N atom from the terminal thiocyanate, while one of the three edges is further bridged by another admtrz ligand and the opposite Cu1 atom is coordinated by a water molecule. The EPR and magnetic susceptibility of compound 3 were studied, showing antiferromagnetic behavior.