The dielectric permittivity (epsilon') of the organic complexes of the general formula (CH2)(n)(NH3)(2)Mn1-xLaxCl4, n = 5, 6, 7 and 0.1 less than or equal to x less than or equal to 0.9 was studied at different temperatures as a function of the applied frequency. The obtained results contain more than one phase transition depending on the La3+ ion concentration as well as the applied frequency. The appeared transitions were of thermochromic type (change in crystal symmetry) because it gives a reversible color change with temperature. Varying the layer spacing by varying the number of carbon atom (n) will change drastically the permittivity of the sample, due to varying the superexchange interaction through the intervening of the organic group. The AC conductivity for the investigated samples was measured in the same range of temperature and frequency as that of permittivity measurements. The calculated values of the activation energy indicate the semiconducting behavior of these complexes. More than one conduction mechanisms were obtained as indicated from the existence of more than one straight line. Hopping mechanism was the most predominant one that interprets the conductivity in the low temperature region. In the moderate region of temperature the holes play a role. In the high temperature region we expect some ionic conduction which was clear from the high values of activation energy. (C) 2003 Kluwer Academic Publishers.