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 P21/n. For BDPA–Bz, a = 9.502(2), b = 14.632(2), c = 19.452(2) Å, β = 93.64(1)°, V = 2699(1) Å3, Z = 4, Dx = 1.220 g cm−3. For BDPA-Ac, a = 9.657 (1), b = 14.675(2), c = 18.812(2) Å, β = 95.388(9)°, V = 2654.4(6) Å3, Z = 4, Dx = 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 C2 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.