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Solid-State Coordination Chemistry of the Cu/Triazolate/X System (X = F-, Cl-, Br-, I-, OH-, and SO42-)

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posted on 2006-11-13, 00:00 authored by Wayne Ouellette, Andrey V. Prosvirin, Vincent Chieffo, Kim R. Dunbar, Bruce Hudson, Jon Zubieta
Hydrothermal reactions of 1,2,4-triazole with the appropriate copper salt have provided eight structurally unique members of the Cu/triazolate/X system, with X = F-, Cl-, Br-, I-, OH-, and SO42-. The anionic components X of [Cu3(trz)4(H2O)3]F2 (1) and [Cu6(trz)4Br]Cu4Br4(OH) (4) do not participate in the framework connectivity, acting as isolated charge-compensating counterions. In contrast, the anionic subunits X of [CuIICuI(trz)Cl2] (2), [Cu6(trz)4Br2] (3), [CuIICuI(trz)Br2] (5), [Cu3(trz)I2] (6), [Cu6IICu2I(trz)6(SO4)3(OH)2(H2O)] (8), and [Cu4(trz)3]OH·7.5H2O (9·7.5H2O) are intimately involved in the three-dimensional connectivities. The structure of [CuIICuI(trz)2][Cu3II4] (7) is constructed from two independent substructures:  a three-dimensional cationic {Cu2(trz)2}nn+ component and {Cu3I4}nn- chains. Curiously, four of the structures are mixed-valence CuI/CuII materials:  2, 5, 7, and 8. The only CuII species is 1, while 3, 4, 6, and 9·7.5H2O exhibit exclusively CuI sites. The magnetic properties of the CuII species 1 and of the mixed-valence materials 5, 7, 8, and the previously reported [Cu3(trz)3OH][Cu2Br4] have been studied. The temperature-dependent magnetic susceptibility of 1 conforms to a simple isotropic model above 13 K, while below this temperature, there is weak ferromagnetic ordering due to spin canting of the antiferromagnetically coupled trimer units. Compounds 5 and 7 exhibit magnetic properties consistent with a one-dimensional chain model. The magnetic data for 8 were fit over the temperature range 2−300 K using the molecular field approximation with J = 204 cm-1, g = 2.25, and zJ‘ = −38 cm-1. The magnetic properties of [Cu3(trz)3OH][Cu2Br4] are similar to those of 8, as anticipated from the presence of similar triangular {Cu3(trz)33-OH)}2+ building blocks. The CuI species 3, 4, 6, and 9 as well as the previously reported [Cu5(trz)3Cl2] exhibit luminescence thermochromism. The spectra are characterized by broad emissions, long lifetimes, and significant Stokes' shifts, characteristic of phosphorescence.