Six lanthanide coordination compounds with two isomeric carboxylic acids, nicotinic acid (HL1) and isonicotinic acid (HL2), [(L 1)3Ln(H2O)2]2 (Ln = Eu, 1; Gd, 2; Tb, 3) and [(L2)2Ln(H2O) 4][NO3] (Ln = Eu, 4; Gd, 5; Tb, 6), have been synthesized and structurally characterized by single-crystal X-ray diffraction. Complexes 1-3 are dimeric whereas 4-6 are polymeric, all with 8-coordination of Ln 3+. The distinction between these lanthanide complexes is readily accomplished from the 10 K high resolution electronic emission spectra. Spectral interpretation is given for the Eu3+ complexes 1, 4, whereas the spectra of 3 and 6 are more complex. The relationships between spectroscopic and crystallographic site symmetries are discussed. The calculated second rank crystal field strengths of Eu3+ in 1 and 4 are intermediate in magnitude.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry