Co-crystallization of Keggin type polyoxometalates [HL]3[PW12O40] and [Ln(DMF)8][PW12O40] (Ln = La, Dy, Yb) (L = N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine): Syntheses, structures and magnetic properties

Four new Keggin type polyoxometalate clusters [HL]3[PW12O40]·5MeOH (1) and [Ln(DMF)8][PW12O40] {Ln = La (2), Dy (3), Yb (4)} (L = N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine) have been synthesized. Co-crystallization of complex 1 with each of the three complexes 2–4 takes place when the Schiff base ligand is treated with hydrated phosphotungstic acid, H3[PW12O40]·xH2O, hydrated lanthanide nitrate, Ln(NO3)3·6H2O in the presence of Ni(NO3)2·6H2O. The Schiff base ligand is protonated in complex 1 and thus it is neutralizing the charge of the polyoxotungstate anion, [PW12O40]3−. A dimethylformamide (DMF) coordinated trivalent lanthanide ion balances the negative charge of the polyoxoanion in 2–4. All complexes are characterized by several standard analytical techniques. Solid state molecular structures of 1–4 were confirmed by single crystal X-ray diffraction analyses. The magnetic properties of complexes 3 and 4 confirm the presence of monomeric Dy(III) and Yb(III) complexes with a thermal depopulation of the highest energy Stark levels as the temperature is decreased.

Graphical abstractFour new Keggin type polyoxometalate clusters [HL]3[PW12O40]·5MeOH (1) and [Ln(DMF)8][PW12O40] {Ln = La (2), Dy (3), Yb (4)} (L = N-(2-hydroxyphenyl)-3-methoxy-salicylideneamine) have been synthesized. All complexes are characterized by standard analytical techniques and their magnetic properties have been investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide