Two binuclear Ni-inserted polyoxotantalates based on {NiTa 10 O 32 } units with catalytic activity.

Two Ni-inserted polyoxotantalates, K 5.5 Na 2 H 0.5 [Ni(H 2 O) 2 {NiTa 10 O 30 (OH) 2 }]·21H 2 O (1) and K 6 Na 4 [Ni(en){NiTa 10 O 32 }]·22H 2 O (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(H 2 O) 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 {Ta 10 } 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.