Crown ether alkali metal TCNQ complexes revisited - the impact of smaller cation complexes on their solid-state architecture and properties

The solid-state behaviour of four alkali metal TCNQ complexes: (15-crown-5)LiTCNQ ( 1 ), (15-crown-5)NaTCNQ ( 2 ), (15-crown-5)Li(TCNQ) 2 ·H 2 O ( 3 · H 2 O ) and (15-crown-5)Na(TCNQ) 2 ·H 2 O ( 4 · H 2 O ) has been explored by single crystal X-ray diffraction, infrared (IR), Raman and electron paramagnetic resonance (EPR) measurements. The presence of a small cation and ionophore leads to subtle changes in behaviour compared with their larger alkali metal analogues and in the hydrated salts water bridges form links between the crown-encapsulated cations and neighbouring TCNQ stacks. Water molecules play a key structure-organising role in the crystallisation of 15-crown-5 complexes of lithium and sodium TCNQ in the presence of excess TCNQ 0 .