A MONOCLINIC POLYMORPH OF TRIS(1,3-DIPHENYLPROPANE-1,3-DIONATO)-COBALT(III)

There is essential stereochemical difference between the molecules of the monoclinic and triclinic polymorph of tris (1,3-diphenylpropane-1, 3-dionato)-cobalt(III), C45H33CoO6. The monoclinic form crystallizes w ith the space group P2(1)/c. The crystal data are: a = 17.257(4) Angst rom, b = 9.951(2) Angstrom, c = 20.786(5) Angstrom, beta = 92.73(2)deg rees, V = 3565(1) Angstrom(3), Z = 4, lambda(MoKalpha) = 0.7107 Angstr om, mu(MoKalpha) = 0.53 mm(-1), D-x = 1.358 g cm(-3). The structure wa s solved by the heavy-atom method. The structure was refined by full-m atrix least-squares technique with terminal phenyl rings taken as idea l hexagons to R = 0.050 for 3652 unique reflections. Only very weak in termolecular attraction forces keep the individual molecules together and the contacts between neighboring molecules correspond to the norma l van der Waals interactions. The cobalt environment is a distorted oc tahedron with Co-O bond lengths ranging from 1.872(3) Angstrom to 1.89 7(3) Angstrom. The rotation of the terminal phenyl rings in relation t o the chelate plane depends on the intramolecular steric hindrances an d the tendency of the ligand to achieve planarity as a delocalized pi- electron system.