MOLECULAR AND CRYSTAL-STRUCTURES OF COMPLEXES OF STABLE FREE-RADICAL BDPA WITH BENZENE AND ACETONE

The crystal structures of two complexes of the 9-(9H-fluoren-9-ylidenephenylmethyl)-9H-fluoren-9-yl stable radical with benzene (BDPA-Bz) and acetone (BDPA-Ac) have been determined by X-ray diffraction at room temperature. They are an isostructure of a monoclinic system with a space group of P2(1)/n. For BDPA-Bz, a = 9.502(2), b = 14.632(2), c = 19.452(2) Angstrom, beta = 93.64(1)degrees, V = 2699(1) Angstrom(3), Z = 4, D-x = 1.220 g cm(-3). For BDPA-Ac, a = 9.657(1), b = 14.675(2), c = 18.812(2) Angstrom, beta =95.388(9)degrees, V = 2854.4(6) Angstrom(3), Z = 4, D-x = 1.190 g cm(-3). The final R values are 0.043 and 0.062 for 5.47 and 3.93 ratio of the observed reflections Versus the parameters for BDPA-Bz and BDPA-Ac, respectively. The BDPA molecules in both crystals have the same propeller shape with an approximated C-2 symmetry. The molecular packing of these crystals does not show a one-dimensional stacking, in spite of the magnetic one-dimensionality elucidated by the magnetic susceptibilites. The exchange pathways are discussed based on the McConnell's spin-density Hamiltonian.