Anion-Dependent Assembly of Cyclic Structure

Five Keggin-based metal complexes, [Ag 3 (2,4‘-bipy) 3 PMo 12 O 40 ] ( 1 ), [Ag 4 (2,4‘-bipy) 4 SiW 12 O 40 ] ( 2 ), [Ag 3 (2,4‘-bipy) 4 PW 12 O 40 ] ( 3 ), [Cu 4 (2,4‘-bipy) 4 SiW 12 O 40 ] ( 4 ), and [Cu 3 (2,4‘-bipy) 4 PW 12 O 40 ] ( 5 ) (2,4‘-bipy = 2,4‘-bipyridine), were synthesized and structurally characterized. Among them, complexes 1, 2, and 4 show a cyclic structure, while complexes 3 and 5 exhibit a one-dimensional (1D) chain structure. Investigation of their structural differences reveals that anions play a key role in the formation of a cyclic structure.