Synthesis, crystal structure, and characterization of two-dimensional coordination polymers of three heavy rare-earth elements: [RE(5-Nip)(5-HNip)(H2O)2](H2O)2 (RE = Y, Ho, Er)

Abstract

Three new coordination polymers, [RE(5-Nip)(5-HNip)(H2O)2)] · 2H2O (RE = Y (I), Ho (II), and Er (III)) were synthesized by hydrothermal reactions of lanthanide nitrates with 5-nitroisophthalic acid (H2Nip) and characterized by IR spectra, elemental analysis, and single-crystal X-ray diffraction. X-ray diffraction studies suggest that all the two-dimensional 5-nitroisophthalic complexes crystallize in the P % MathType!MTEF!2!1!+- % feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBqj3BWbIqubWexLMBb50ujbqegm0B % 1jxALjharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqr % Ffpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0F % irpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaa % GcbaGabGymayaaraaaaa!3A3A! $$ \bar 1 $$ space group and are isomorphic. The two-dimensional layer-like structures are constructed by the lanthanide ions bridged by 5-Nip2− ligands, and the layers further packed into 3D complexes through hydrogen bonds and two kinds of π-π stacking interactions. These complexes exhibit high stabilities up to 465 (1), 518 (2), and 528°C (3), respectively. According to the effective ionic radii of eight-coordinate lanthanide, Y(III) should be arranged before Ho(III) and Er(III), and we obtain a series of lines (except for the RE-OW bonds) in the corresponding RE-O against their ionic radii. In these complexes the yttrium complex could be located before the other two complexes according to the position of its ionic radius, and the ionic radii become a key factor in the formation of these complexes.