Synthesis and structural determination of 2D ladder-like mononuclear nine-coordinate (EnH2)[NdIII(Egta)H2O]2 · 6H2O and ten-coordinate (EnH2)1.5[NdIII(Ttha)] · 5H2O

Abstract

Two novel lanthanide complexes, (EnH₂)[Nd^III(Egta)H₂O]₂ · 6H₂O (I) and (EnH₂)_1.5[Nd^III(Ttha)] · 5H₂O (II), where En = ethylenediamine, H₄Egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N'-tetraacetic acid and H6Ttha = triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, have been successfully synthesized through direct heating reflux and their molecular and crystal structures were determined by FT-IR spectroscopy, thermal analysis and single crystal X-ray diffraction (CIF files CCDC nos. 1436598 (I) and 1433221 (II)). X-ray diffraction reveals that I has a nine-coordinate mononuclear structure with pseudo-monocapped square antiprismatic conformation. Complex I crystallizes in a monoclinic system with P2₁/c space group; a = 13.0919(12), b = 12.6840(11), c = 16.9751(14) Å, β = 122.069(3)° and V = 2388.7(4) ų. Complex II takes ten-coordinated structure with a distorted bicapped square antiprismaticprism belong to triclinic crystal system with P1 space group; a = 9.9376(10), b = 12.2178(12), c = 15.2671(16), β = 100.2480(10)° and V = 1609.5(3) ų. Each EnH₂²⁺ cation in I connects four adjacent [Nd^III(Egta)H₂O]^– anions through hydrogen bonds. In II crystal cell, there are two types of cations, which form hydrogen bonds with the neighboring [Nd^III(Ttha)]^3– anions, leading to the formation of a 2D ladder-like layer structure. The results showed that the change of ligands can lead to change of the structure of the complexes, coordination numbers and coordination geometries. Thus, it can be concluded that the shape of ligands play a crucial role on the coordinate structure of complexes, coordination numbers and coordination geometries.