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)]

Abstract 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 emissive upon ligand excitation and substantially larger intensities of emission 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 the complex to be eight-coordinate and monomeric, containing a pnx − co-ligand chelating via one N -oxide oxygen and one carboxylate oxygen. The geometry around the Tb 3+ ion is distorted square antiprismatic with a steric angle sum of 0.79.