Reaction of quinoline with HBr and CuBr2 generates a mixture of two compounds, (quinolinium)(2)CuBr4 center dot 2H(2)O (1) and (quinolinium)(2)CuBr4 (2) for which single-crystal X-ray structures have been solved. Compound I crystallizes in the monoclinic space group C2/c as layers of let rab romocup rate ions which are separated by intervening layers of quinolinium ions. Compound 2 crystallizes in the triclinic space group P (1) over bar. 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 Ik(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.