Two binuclear Ni-inserted polyoxotantalates based on {NiTa10O32} units with catalytic activity

Abstract

Two Ni-inserted polyoxotantalates, K_5.5Na₂H_0.5[Ni(H₂O)₂{NiTa₁₀O₃₀(OH)₂}]·21H₂O (1) and K₆Na₄[Ni(en){NiTa₁₀O₃₂}]·22H₂O (2, en = ethanediamine), were synthesized in this work. Crystallographic data analyses reveal that 1 and 2 have similar configurations. A minor difference between these two structures is that the {Ni(H₂O)₂} unit in 1 is replaced by {Ni(en)} unit in 2. Notably, the other Ni in 1 and 2 is located as a heteroatom at the center of the {Ta₁₀} unit, which is reported in POTas for the first time. Moreover, 2 exhibits excellent catalytic performance in transesterification reactions in a preliminary exploration of the catalytic ability of the synthesized POTas.