Coordination polymers of d10 metals and N,N′-bis(3-pyridinecarboxamide)-1,2-ethane

Abstract

The ligands N,N′-bis(3-pyridinecarboxamide)-1,2-ethane (L) was designed to form coordination polymers capable of assembling into 2-D network via complementary amide hydrogen bonds. The reactions of L with AgX (X = ClO₄⁻, CF₃SO₃⁻ or NO₃⁻), Zn(ClO₄)₂·6H₂O and Cd(ClO₄)₂·6H₂O produced coordination polymers 1–5,the structures of which were characterized by single crystal X-ray diffraction. The polymer {[AgL][ClO₄]}_∞ crystallized in two polymorphs 1A and 1B which consisted of coordination polymers {[AgL]⁺}_∞ in sine-wave and zigzag conformations, respectively. In addition, the X-ray crystal structures of {[AgL][CF₃SO₃]}_∞ (2) and {[AgL][NO₃](H₂O)_1.25}_∞ (3) showed coordination polymers in zigzag conformation similar to that of 1B. The polymers in compounds 1, 2 and 3 aggregate via complementary amide hydrogen bonds, forming corrugated sheets in the solid state. Furthermore, the compound trans-{[ZnL₂(H₂O)₂][ClO₄]₂·(H₂O)₂·CH₃CN}_∞ (4) was shown to be an infinite chain of [Zn₂L₂] metallacycles. The stacking of the Zn polymer leads to the formation of a channel-like structure. The coordination polymer {[CdL(H₂O)₃][ClO₄]₂}_∞ (5) shows zigzag chains which are linked through hydrogen bonds between the anion, amide groups and coordinated water molecules. In contrast to its isomer L, the ligand N,N′-bis(2-pyridinecarboxamide)-1,2-ethane (L¹) formed segregated Ag(I) coordination polymer (6) in which the Ag ion is four coordinate.