COEXISTENCE OF MAGNETIC AND DELOCALIZED ELECTRONS IN HYBRID MOLECULAR MATERIALS - THE SERIES OF ORGANIC-INORGANIC RADICAL SALTS (BEDT-TTF)(8)[XW(12)O(40)](SOLV)(N)(X=2(H+), B-III, SI-IV, CU-II, CO-II, FE-III SOLV=H2O, CH3CN)

The synthesis, crystal structure and physical properties of the new series al and cc:! of radical salts made with bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) and Keggin polyoxoanions are reported. The structure of the alpha(1)-ET(8)[XW(12)O(40)] (X = Co-II, Cu-II, 2(H+) and Fe-III) series (crystal data: alpha(1)-ET(8)[CoW12O40]. 5.5H(2)O (I), monoclinic, space group I2/m, a = 13.971(9) Angstrom, b = 43.117(7) Angstrom, c = 14.042(5) Angstrom, beta = 107.25(3)degrees, V= 8078 Angstrom(3), Z = 2; alpha(1)-ET(8)[FeW12O40]. 9H(2)O (II), monoclinic, space group 12/m, a = 13.955(10) Angstrom, b = 43.221(7) Angstrom, c = 14.049(3) Angstrom, beta = 107.24(4)degrees, V = 8093 Angstrom(3), Z = 2) consists of alternating layers of the organic donor and the Keggin polyoxometalates. The organic layers contain three crystallographically independent molecules that form two different parallel stacks alternating in the [10 $$($) over bar 1] direction. The structure of the alpha(2)-ET(8)[XW(12)O(40)] (X = Co-II, Cu-II, 2(H+), Fe-III and B-III) series (crystal data: alpha(2)-ET(8)[CoW12O40]. 0.5CH(3)CN . 3H(2)O (III), monoclinic, space group 12/m, a = 16.66(2) Angstrom, b = 43.42(2) Angstrom, c = 12.14(1) Angstrom, beta = 111.78(9)degrees, V = 8151 Angstrom(3), Z = 2; alpha(2)-ET(8)[BW12O40]. 2H(2)O (IV), monoclinic, space group 12/m, a = 16.50(1) Angstrom, b = 43.27(2) Angstrom, c = 12.125(3) Angstrom, beta = 111.99(4)degrees, V = 8026 Angstrom(3), Z = 2) is similar to that of the alpha(1) phase but the organic layers contain only two crystallographically independent molecules. In both a phases the Keggin polyanions form closed packed pseudohexagonal layers. Both crystal structures suggest the presence of two types of differently charged stacks: a dimerized one with almost neutral ET molecules, and an eclipsed one formed by almost ionized ET molecules. This inhomogeneous charge distribution is confirmed by Raman spectroscopy. Conductivity measurements show that all compounds are semiconductors, in agreement with the band structure EHT calculations. Magnetic measurements indicate the presence of antiferromagnetic interactions in the organic sublattice with the presence of a strong Curie tail and confirm the electronic distribution in the two kinds of stacks. ESR spectra of the salts with diamagnetic anions complete these results and for the radical salts with paramagnetic anions indicate that both sublattices coexist but do not interact significantly.