STUDIES ON ORGANOLANTHANIDE COMPLEXES .47. SYNTHESES OF BIS(2-METHOXYETHYLCYCLOPENTADIENYL)LANTHANIDE TETRAHYDROBORATES (LN=LA, PR, ND, SM OR GD) - CRYSTAL-STRUCTURES OF BIS(2-METHOXYETHYLCYCLOPENTADIENYL) PRASEODYMIUM AND NEODYMIUM TETRAHYDROBORATES

Five new complexes, bis(2-methoxyethylcyclopentadienyl) lanthanide tet rahydroborates (Ln = La (1), Pr (2), Nd (3), Sm (4) or Gd (5)) have be en synthesized with good yields by the reaction of bis(2-methoxyethylc yclopentadienyl)lanth chlorides with sodium borohydride in THF at room temperature. These complexes have been characterized by elemental ana lyses, MS, H-1 NMR and IR spectra. The X-ray structure analyses of 2 a nd 3 show both to be orthorhombic, with space group P2(1)2(1)2(1), a = 11.081(3) Angstrom, b = 13.145(5) Angstrom, c = 12.080(3) Angstrom, D -calc = 1.518 g cm(-3) and Z = 4 for 2, and space group Pna2(1), a = 1 2.753(2) Angstrom, b = 11.207(2) Angstrom, c = 12.042(2) Angstrom, D-c alc = 1.565 g cm(-3) and Z = 4 for 3. The structures were solved from 2982 observed reflections with F-o greater than or equal to 4 sigma(F- o) to a final R factor of 0.0610 for 2 and from 1149 observed reflecti ons with F-o greater than or equal to 4 sigma(F-o) to a final R factor of 0.0607 for 3. The molecular structures show that they are monomers , and intramolecular coordination bonds between lanthanide metal and o xygen atom on ligand in the above tetrahydroborate complexes exist. Th e average Pr-O and Nd-O bond lengths are 2.605 Angstrom and 2.560 Angs trom respectively. The X-ray crystal structures also reveal that the P r...B distance is 2.757(18)Angstrom and the Nd...B distance is 2.664(2 5) Angstrom and suggest the tridentate mode of BH4- bonding.