The century-old inverted Keggin ion has been revisited, in an effort to unearth its potential in the structural engineering and functional development of polyoxomolybdates (POMos). Over the past hundred years, attempts to program the metal-oxo scaffold of inverted Keggin have been conducted continually but without any success. In this work, the structurally inert, inverted Keggin-type POMo finally agreed to be trimmed by means of a binary heterogroup-templated approach, resulting in the successful isolation of two lacunary species. Of these, their local structure and charge distribution are both adjustable, hence serving as available building blocks for the subsequent assembly of CeIII-incorporated derivative in a controlled manner. From plenary to lacunary, the enclosed structure of inverted Keggin has been opened up significantly with less steric hindrance, along with the transition from electron neutral to negatively charged. Thanks to these, the emerging defected polyanions behaved outstanding Lewis acid-base catalytic activity in the production of pyrazoles with high efficiency.

This article is Open Access

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