Derivative of cyclen with three methylene(phenyl)phosphinic acid pendant arms. Synthesis and crystal structures of its lanthanide complexes

A new macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraylmet hyltrimethylenetris(phenylphosphinic acid) H3L1 was synthesised and its com plexes with lanthanides were prepared. X-Ray analysis of seven Ln complexes (Ln=La, Ce, Nd, Eu, Tb, Er, Yb) shows a formation of dimers [LnL(1)](2) wi th phosphinic acid bridges in the solid state. All complexes are isostructu ral and the coordination polyhedra are formed by four N atoms and four O at oms of phosphinic acid groups. A water molecule is placed near the O-4 base . The Ln-O-w distance is strongly dependent on Ln(III), it varies from 2.81 5(6) Angstrom in the La complex to 4.448(10) Angstrom in the Yb complex. Th e P-31 NMR studies show formation of a rather complex mixture of isomers in solution. The dimer stability in solution is verified by reaction with tri phenylphosphine oxide (tppo) and with pyridine N-oxide and by cyclic voltam metry.