A series of experiments in the UO2(CH3CO2)(2).2H(2)O/H2SO4/1-(2-aminoethyl)piperazine/H2O system were conducted to determine the effects of variation in initial reactant concentrations on the reaction products. Several reaction gels were produced, in which the composition varied from 16:80:4:500 UO2(CH3CO2)(2).2H(2)O/H2SO4/1-(2-aminoethyl)piperazine/H2O to 4:92:4:500 UO2(CH3CO2)(2).2H(2)O/H2SO4/1-(2-aminoethyl)piperazine/H2O. Single crystals of two new organically templated uranium sulfates, [N3C6H18](2)[(UO2)(5)(H2O)(SO4)(8)].5H(2)O and [N3C6H18][(UO2)(2)(H2O)(SO4)(3)(HSO4)].4.5H(2)O, were isolated. Both compounds exhibit structures in which the inorganic frameworks are two-dimensional and the protonated amines reside between layers, participating in extensive hydrogen bonding. The composition and structure of each compound is dependent on the nature of the starting concentrations. Crystal data: for [N3C6H18](2)[(UO2)(5)(H2O)(SO4)(8)].5H(2)O, monoclinic, space group P2(1)/n (No. 14), a = 21.5597(3) Angstrom, b = 10.2901(2) Angstrom, c = 22.8403(3) Angstrom, beta = 96.7436(7)degrees, and Z = 4; for [N3C6H18][(UO2)(2)(H2O)(SO4)(3)(HSO4)].4.5H(2)O, monoclinic, space group P2(1)/a (No. 14), a = 15.7673(4) Angstrom, b = 10.5813(3) Angstrom, c = 16.7710(5) Angstrom, beta = 99.9216(9)degrees, and Z = 4.