Three-Dimensional Open-Framework Neodymium Oxalates with Organic Functional Groups Protruding in 12-Member Channels

Abstract

Two open-framework neodymium oxalates, [NH3CH2CH(NH3)CH3][Nd(C2O4)(2)(HCOO)].H2O (I) and [OC(CH3)NCH2CH(CH3)NH3][Nd(C2O4)(2)].H2O (11), have been synthesized hydrothermally in the presence of 1,2-diaminopropane (1,2-DAP) and formic (1) and acetic (11) acids. The Nd atoms in both these oxalates have 9-fold coordination with respect to the oxygens, with the Nd atom in a distorted monocapped square antiprism coordination in I and in an idealized D-3h triply capped trigonal prism coordination in H. The three-dimensional framework structures of I and II are built up by in-plane linkages between the Nd and the oxalate moieties, forming layers with 12-membered honeycomb-like apertures, pillared by an out-of-plane oxalate unit. The 12-memberd channel in I contains a dangling formate group in addition to the disordered amine molecule, while in II, the channel has N-(2-aminopropyl acetimide) molecules formed by the in situ reaction of 1,2-DAP and acetic acid. The accessibility of the formate and N-(2-aminopropyl acetimide) functional groups in I and II, respectively, uniformly distributed within the channels enables chemical manipulation. Crystal data: 1, monoclinic, space group P2(1)/c (no. 14), M = 459.5, a = 9.0279(4) Angstrom, b = 18.1362(8) Angstrom, c = 8.5631(4) Angstrom, beta = 102.735(10)degrees, V = 1367.56(11) Angstrom(3), Z = 4, R-1 = 0.0229, wR(2) = 0.0599 [1782 observed reflections with I > 2sigma(I)]; II, triclinic, space group P (1) over bar (no. 2), M = 454.5, a 8.6222(9) Angstrom, b = 9.5683(10) Angstrom, c = 9.5712(10) Angstrom, alpha = 109.388(2)degrees, beta = 98.508(10)degrees, gamma = 102.361(12)degrees, V = 706.73(13) Angstrom(3), Z = 2, R-1 = 0.0446, wR(2) = 0.115 [1730 observed reflections with I > 2sigma(I)].