Abstract:The syntheses and crystal structures of six new complexes containing the UO 2 2+ cation, m-or p-halobenzoic acid ligands (where halogens are Cl and I), and the chelating Ndonors 1,10-phenanthroline (phen) (1, 3, 4, and 6) or 2,2′:6′,2′′-terpyridine (terpy) (7 and 9) are described and compared to UO 2 -m-bromo-and p-bromobenzoic analogues (2, 5, and 8) that have been reported previously. The spectroscopic properties (both vibrational and luminescence) for all nine complexes along with stretching and interaction force constants are reported and redshifts are noted as the electron-donating ability of the chelating N-donors increases. Single crystal X-ray diffraction analysis of these complexes shows that whereas inclusion of a chelating ligand (i.e. phen or terpy) in the uranyl first coor-