Heteroleptic poly(pyrazol-1-yl)borate derivatives of the lanthanides. The syntheses of picolinate-N-oxide complexes and the X-ray crystal structure of [Tb{HB(C3H3N2)(3)}(2)(ONC5H4CO2-2)]

The new complexes [Ln(Tp)(2)(pnx)] (Ln = Y, Eu, Gd, Tb, Er, Yb or Lu; Tp(-) = hydrotris(pyrazol-1-yl)borate, pnxH = picolinic acid N-oxide) have been synthesised and characterised. The complexes which contain Eu or Tb are emi ssive upon ligand excitation and substantially larger intensities of emissi on are associated with excitation of the pnx(-) ligand than with excitation of the Tp(-) ligand. The solid state structure of [Tb(Tp)(2)(pnx)] shows t he complex to be eight-coordinate and monomeric, containing a pnx(-) co-lig and chelating via one N-oxide oxygen and one carboxylate oxygen. The geomet ry around the Tb3+ ion is distorted square antiprismatic with a steric angl e sum of 0.79. (C) 1999 Elsevier Science S.A. All rights reserved.