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The anisotropic and isotropic spin-Hamiltonian parameters (g factors and hyperfine structure constants) of tetragonal Cu(H(2)O)(6)(2+) clusters due, respectively, to the static and dynamic Jahn-Teller effects for Cu(2+) in trigonal A(2)Mg(3)(NO(3))(12)center dot 24H(2)O (A = La, Bi) crystals are calculated from the high-order perturbation formulas based on the cluster approach. In the approach, the admixture between the d orbitals of 3d(n) ion and the p orbitals of ligand ion via covalence effect is considered. All of the calculated results are in agreement with the experimental values. The tetragonal elongations (characterized by Delta R=R(parallel to)-R(perpendicular to)) of Cu(H(2)O)(6)(2+) cluster due to the Jahn-Teller effect in A(2)Mg(3)(NO(3))(12)center dot 24H(2)O crystals are acquired from the calculations. The results are discussed. (C) 2009 Elsevier B.V. All rights reserved.