4-(3-Azaniumylpropyl)morpholin-4-ium chloride hydrogen oxalate: an unusual example of a dication with different counter-anions.

Abstract

The mixed organic-inorganic title salt, C7H18N2O(2+)·C2HO4(-)·Cl(-), forms an assembly of ionic components which are stabilized through a series of hydrogen bonds and charge-assisted intermolecular interactions. The title assembly crystallizes in the monoclinic C2/c space group with Z = 8. The asymmetric unit consists of a 4-(3-azaniumylpropyl)morpholin-4-ium dication, a hydrogen oxalate counter-anion and an inorganic chloride counter-anion. The organic cations and anions are connected through a network of N-H···O, O-H···O and C-H···O hydrogen bonds, forming several intermolecular rings that can be described by the graph-set notations R3(3)(13), R2(1)(5), R1(2)(5), R2(1)(6), R2(3)(6), R2(2)(8) and R3(3)(9). The 4-(3-azaniumylpropyl)morpholin-4-ium dications are interconnected through N-H···O hydrogen bonds, forming C(9) chains that run diagonally along the ab face. Furthermore, the hydrogen oxalate anions are interconnected via O-H···O hydrogen bonds, forming head-to-tail C(5) chains along the crystallographic b axis. The two types of chains are linked through additional N-H···O and O-H···O hydrogen bonds, and the hydrogen oxalate chains are sandwiched by the 4-(3-azaniumylpropyl)morpholin-4-ium chains, forming organic layers that are separated by the chloride anions. Finally, the layered three-dimensional structure is stabilized via intermolecular N-H···Cl and C-H···Cl interactions.