Two new sandwich-type tungstobismuthates constructed from trivacant Keggin units, estertin and transition metals

Two new sandwich-type tungstobismuthates containing carboxyethyltin groups and transition metals, Na8K2[{Co(H2O)3}2{Sn(CH2)2COO}2·(B-β-BiW9O33)2]·25H2O (1) and K10[{Mn(H2O)3}2{Sn(CH2)2COO}2·(B-β-BiW9O33)2]·30H2O (2) have been synthesized in the aqueous solutions and characterized by IR, TG, NMR and XRD. Single crystal X-ray diffraction analysis reveals that two 3d-transition metal (TM) cations and two organometallic (OM) groups in the central belt of the two complexes are all sandwiched by two B-β-[BiW9O33]9− units. The two compounds represent the first transition metal and carboxyethyltin-decorated polyoxometalate complexes. Structural analyses reveal that the reaction processes involving the α → β isomerization of [BiW9O33]9− unit and the hydrolysis of ester group. Both compounds have high thermal stabilities.