THE CRYSTAL AND MOLECULAR-STRUCTURES OF THE N,N'-DIISOPROPYLBUTYRAMIDE (DIPIBA) AND N,N-DICYCLOHEXYLACETAMIDE (DCA) COMPLEXES [TH(NCS)4(DIPIBA)3] AND [TH(NCS)2CL2(DCA)3]

The X-ray crystal structures of [Th(NCS)4(DIPIBA)3] (1) [DIPIBA = Me2CH CON(CHMe2)2] and [Th(NCS)2Cl2(DCA)3](2) [DCA = MeCON(cycloC6H11)2] have been determined from three-dimensional X-ray diffraction data. The different steric constraints of the ligand are not sufficient for different coordination geometries. In 1 and 2 the coordination polyhedron about the seven-coordinate thorium atom is a pentagonal bipyramid geometry which is becoming rather common for thorium(IV) compounds. In these compounds two chlorine (2) and two thiocyanate (1) anions are in axial positions with a significant shortening of the axial Th-NCS bonds with respect to the equatorial ones, while in the equatorial plane a neutral ligand lies between two anionic ligands, the remaining coordination positions being occupied by two other neutral ligands. The average bonding distances are Th-O = 2.34(1) angstrom, Th-N(ax) = 2.42(1) and Th-N(eq) = 2.46(1) angstrom in 1, and Th-O = 2.357(5), Th-N(eq) = 2.479(6) and Th-Cl(ax) = 2.695(3) angstrom in 2.