Formation of various polymeric frameworks by dicarboxylate-like ligands: Synthesis and crystal structures of polymeric complexes of sodium perchlorate with flexible double betaines

Abstract

Three crystalline complexes of sodium perchlorate with different flexible double betaines [Na2(L1)(ClO4)(H2O)n](ClO4)n (1), [Na3(L2)(ClO4)3(H2O)2n] (2), and [Na(L3)(CH3OH)n]-(ClO4)n·xnH2O (x=0.25) (3) [−O2CCH2N+Me2−(CH2)n-N+Me2CH2CO2−,n=2 L1;n=3 L2;n=4 L3] have been synthesized and characterized by single-crystal X-ray structure analysis. Complex (1) comprises tetranuclear sodium units consolidated by betaine and aqua ligands, which are bridged by half of the ClO4− anions to form layers matching the (200) planes, the remaining uncoordinated ClO4− anions being accommodated between adjacent layers. Complex (2) possesses a double-layer polymeric structure with the sodium atoms bridged by ligand oxygen atoms to form columns running parallel to thea axis, which are interconnected by double-betaine ligands lying parallel to theac plane. All of the ClO4− groups and water molecules are coordinated to the metal atoms. In complex (3) the chains composed of alternating eight-membered and four-membered metallocycles are cross-linked by the betaine ligands, which lie in the (020) and (01/1) families of planes, to yield a three-dimensional network. All of the ClO4− groups and water molcules fill the resulting infinite channels running parallel to thea axis. Two unusual carboxylate coordination modes are identified, namelyμ3-O andhapto-3-O plushapto-2-O′ in (1) and (2), respectively.