Synthesis and characterization of Al and Si substituted polyoxometalates

Polyoxometalates with different transition-metals substituting the main framework element have recently been applied as promising catalysts. In comparison, polyoxometalates, featuring main-group elements in their framework are extremely rare. In this work, we present two main-group element substituted Keggin-type phosphotungstates containing Al or Si, and their characterization using spectroscopic and crystallographic methods. Al substituted POMs are rare examples, which means that the investigation of such systems deserves special attention. Guided by electronic-structure calculations, the reactivity of the Al substituted cluster with the electrophile benzyl bromide was investigated. This reactivity study together with the results of computational simulations illustrate new reaction behaviour for main-group element substituted polyoxometalates, setting the stage for future applications.