... Journal of Catalysis. ... fragments such as [W 2 O 3 (O 2 ) 4 (H 2 O) 2 ] 2− and [SiO 4 {WO(O 2 ) 2 } 4 ] 4− were not formed during the catalysis by I ... 4 ] 3− and [W 2 O 3 (O 2 ) 4 (H 2 O) 2 ] 2− . Reaction conditions are the same as those in Table 1. TON=products (mol)/catalyst used (mol ...