BIS(CYCLOPENTADIENYL) ACTINIDE(IV) COMPOUNDS .1. THE STRUCTURE OF DICHLOROBIS(PENTAMETHYL-ETA-5-CYCLOPENTADIENYL)URANIUM(IV) AND DICHLOROBIS(PENTAMETHYL-ETA-5-CYCLOPENTADIENYL)THORIUM(IV)

[UCl2(C10H15)2], M(r) = 579.40, orthorhombic, Fmm2, a = 14.913 (3), b = 17.348 (3), c = 8.168 (2) angstrom, V= 2113 (1) angstrom3, Z = 4, D(x) = 1.821 Mg m-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 7.5385 mm-1, F(000) = 1104, T = 295 (1) K, R = 0.049 for 436 observed reflections [I > 3sigma(I)]. [ThCl2(C10H15)2], M(r) = 573.41, orthorhombic, Fmm2, a = 14.939 (4), b = 17.535 (5), c = 8.201 (2) angstrom, V = 2148 (2) angstrom3, Z = 4, D(x) = 1. 773 Mg m-3, lambda(Mo Kalpha) = 0. 71073 angstrom, mu = 7.4334 mm-1, F(000) = 1096, T = 295 (1) K, R = 0.045 for 548 observed reflections [I > 3sigma(I)]. The two complexes are isostructural. The coordination geometry about the actinide atom is that of a distorted tetrahedron of symmetry C2v, formed by the two Cl atoms and the centroids of the two cyclopentadienyl ligands. The corresponding bond angles in the two molecules are remarkably alike. The molecular geometry appears to be heavily influenced by intramolecular non-bonded interactions.