Syntheses, structural determination, and binding studies of nine-coordinate multinuclear (mnH)2[EuIII(egta)]2·6H2O and binuclear (mnH)4[EuIII2(dtpa)2]·6H2O

Abstract

Two lanthanide complexes, (mnH)2[EuIII(egta)]2·6H2O (1) (H4egta = ethyleneglycol-bis-(2aminoethylether)-N,N,N′,N′-tetraacetic acid) and (mnH)4[EuIII2(dtpa)2]·6H2O (2) (H5dtpa = diethylenetriamine-N,N,N′,N″,N″-pentaacetic acid), have been synthesized and characterized by FT-IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray diffraction reveals that 1 is multinuclear nine-coordinate and crystallizes in the monoclinic crystal system with space group C2/c. The obtained cell dimensions are a = 38.513(3) Å, b = 13.5877(8) Å, c = 8.7051(5) Å, β = 99.6780(10)°, and 4490.6(5) Å3. Each methylamine (mnH+) cation in 1, through hydrogen bonds, connects three adjacent [EuIII(egta)]− anions. The [EuIII(egta)]− anions connect one another forming a 1-D multinuclear zigzag chain structure along the c-axis. Complex 2 is nine-coordinate binuclear structure with tricapped trigonal prismatic conformation and crystallizing in the monoclinic crystal system, but with space group P21/n. The obtained cell dimensions are a = 9.9132(8) Å, b = 24.1027(18) Å, c = 10.7120(10) Å, β = 109.1220(10)°, and 2418.2(3) Å3. For 2, there are two kinds of methylamine cations (mnH+) connecting [EuIII2(dtpa)2]4− complex anions and lattice waters through hydrogen bonds, leading to formation of a 2-D ladder-like layer structure.