Homoscorpionates (hydridotris(1-pyrazolyl)borato complexes) of the trivalent 4f ions. The crystal and molecular structure of [(HB(N2C3H3)(3)](3)Ln(III) (Ln=Pr, Nd)

The compounds [(eta(3)-HB(N2C3H3)(3)](3)M of scandium, yttrium, lanthanum and of the trivalent lanthanides from cerium to lutetium (with the exception of promethium) have been synthesized by the reaction of MCl(3) with K[HB(N2C3H3)(3)] in tetrahydrofuran or in water. The crystal and molecular structures of the Pr and Nd compounds were determined by single-crystal X-ray diffraction. The crystal structure corresponds to the structure of the praseodymium trichloride (LaCl3-type). The Pr3+ is nine-coordinate to the N atoms of the three Tp ligands. One N atom of each of the three Tp ligands and the Pr ion are almost coplanar with a Pr-N distance of 278.3 pm, while all other six N atoms are at a distance of 260.9 pm in a tricapped trigonal prismatic arrangement. The M-N distances in the Nd compound are 280.4 (3x) and 259.9 (6x) pm. IR spectroscopic studies have shown that the metal ion in the LnTp(3) compounds from La to Dy is nine-coordinate, while in the compounds of the heavier lanthanides from Ho to Lu, of Sc, and Y, the central ion is eight-coordinate. Copyright (C) 1997 Elsevier Science Ltd.