Reaction of quinoline with HBr and CuBr(2) generates a mixture of two compounds, (quinolinium)(2)CuBr(4).2H(2)O (1) and (quinolinium)(2)CuBr(4) (2) for which single-crystal X-ray structures have been solved. Compound 1 crystallizes in the monoclinic space group C2/c as layers of tetrabromocuprate ions which are separated by intervening layers of quinolinium ions. Compound 2 crystallizes in the triclinic space group P1. Magnetic data analysis reveals that 1 behaves as a 2D-quantum Heisenberg antiferromagnet with 2J/k(B) = -6.17(3) K within the layers. High field magnetization data at low temperatures suggests that T(N) must be less than 1.8 K for 1, yielding a figure of merit |k(B)T(N)/2J| < 0.29, which indicates excellent isolation between the layers. Magnetic exchange in compound 2 was much weaker and was fit to a linear chain antiferromagnet with 2J/k(B) = -1.59(3) K.
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