N₄H₉Cu₇S₄: A hydrazinium-based salt with a layered Cu₇S₄^- framework

Crystals of a hydrazinium-based copper(I) sulfide salt, N4H 9Cu7S4 (1), have been isolated by an ambient temperature solution-based process. In contrast to previously reported hydrazinium salts of main-group metal chalcogenides, which consist of isolated metal chalcogenide anions, and ACu7S4 (A = NH 4+, Rb+, Tl+, K+), which contains a more three-dimensional Cu7S4- framework with partial Cu-site occupancy, the structure of 1 [P21, a = 6.8621 (4) Å, b = 7.9851(4) Å, c = 10.0983(5) Å, β = 99.360(1)°, Z = 2] is composed of extended two-dimensional Cu 7S4- slabs with full Cu-site occupancy. The Cu7S4- slabs are separated by a mixture of hydrazinium and hydrazine moieties. Thermal decomposition of 1 into copper(I) sulfide proceeds at a significantly lower temperature than that observed for analogous hydrazinium salts of previously considered metal chalcogenides, completing the transition at temperatures as low as 120°C. Solutions of 1 may be used in the solution deposition of a range of Cu-containing chalcogenide films. © 2007 American Chemical Society.