A new 2D network polyoxometalate constructed from Strandberg-type phosphomolybdates linked through binuclear Ca(II) clusters

Abstract

A polyoxometalate cluster based on Strandberg-type phosphomolybdate [K 3 Ca(H 2 O) 4 (HP 2 Mo 5 O 23 )]·6H 2 O ( 1 ) has been synthesized by the conventional solution method and characterized by IR spectrum, UV spectra, electrochemical measurements, thermogravimetric analysis, ICP techniques and X-ray crystallography. X-ray single crystal diffraction analysis shows that 1 contains a novel polyoxoanion [Ca(H 2 O) 4 (HP 2 Mo 5 O 23 )] 3− ( 1a ) based on a Strandberg-type phosphomolybdate [HP 2 Mo 5 O 23 ] 5− . Notably, it represents the first 2D polymolybdate inorganic structure constructed from Strandberg-type phosphomolybdates linked through alkaline earth metal clusters. Interestingly, the phenomenon that 1a and heteropolyoxoanion {[Ca(H 2 O)] 6 [P 4 Mo 6 O 34 ] 2 } 12− can be mutually transformed when the pH of the solution is adjusted to ca. 4.50 in aqueous solution has been observed. A polyoxometalate cluster based on Strandberg-type phosphomolybdate [K 3 Ca(H 2 O) 4 (HP 2 Mo 5 O 23 )]·6H 2 O has been synthesized by the conventional solution method and characterized by IR spectra, UV spectra, electrochemical measurements, TG analyses and X-ray crystallography. The interesting phenomenon that 1a and heteropolyoxoanion {[Ca(H 2 O)] 6 [P 4 Mo 6 O 34 ] 2 } 12− can be mutually transformed when the pH of the solution is adjusted to ca. 4.50 in aqueous solution has been observed. ► A polyoxometalate cluster based on Strandberg-type phosphomolybdate [K 3 Ca(H 2 O) 4 (HP 2 Mo 5 O 23 )]·6H 2 O has been synthesized by the conventional solution method and characterized by IR spectra, UV spectra, electrochemical measurements, TG analyse and X-ray crystallography. ► The polyoxometalate represents the first inorganic 2D layer Strandberg-type phosphomolybdate. ► The polyoxometalate enriches the structural diversity of Strandberg-type polyoxometalates. ► The heteropolyoxoanions [Ca(H 2 O) 4 (HP 2 Mo 5 O 23 )]3– and {[Ca(H 2 O)] 6 [P 4 Mo 6 O 34 ] 2 } 12– can be mutually transformed when the pH of solution is adjusted to ca . 4.50 in aqueous solution.