Lanthanide(III) Complexes of 4,10‐Bis(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecane‐1,7‐diacetic acid (trans‐H6do2a2p) in Solution and in the Solid State: Structural Studies Along the Series

Complexes trans-H6do2a2p (H6L)with transition metal and lanthanide(III) ions were investigated. Values of stability constants complexes are intermediate in the ligand series as a consequence of this ligand basicity. The solid-state structures of the ligand and nine lanthanide(III) complexes were determined by X-ray diffraction. The formation kinetics and the acid-assisted dissociation of several Ln(III)-H6L complexes were investigated. According to the 1H NMR pseudo-contact shifts for the Ce–Eu and Tb–Yb series, the solution structures of the complexes reflect the structures of the [Ce(HL)(H2O)]2– and [Yb(HL)]2– anions, respectively, found in the solid state. However, these solution NMR studies showed that there is no unambiguous relation between 31P/1H lanthanide induced shift (LIS) values and coordination of water in the complexes.