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.