Bisorganophosphonyl and ‐Organoarsenyl Derivatives of Heteropolytungstates as Hard Ligands for Early‐Transition‐Metal and Lanthanide Cations

Abstract

Keywords: Polyoxometalates / Organic-inorganic hybrids / Coordination chemistry / Transition metals / Tungsten / Titanium / Vanadium / Lanthanides / CalciumThe coordination properties of bisorganophosphonyl and bisorganoarsenyl derivatives of heteropolytungstates towards lanthanides and early-transition-metal cations were studied in organic medium. This new class of vacant polyoxometalate (POM) hybrids proved to conserve coordination sites after the grafting of the {RP=O} 2+ or {RAs=O} 2+ groups onto the trivacant A,α-[PW 9 O 34 ] 9and B,α-[AsW 9 O 33 ] 9platforms. The consequence of the presence of free {P=O} or {As=O} groups is an increase of the hardness of the coordination sites in these anions (according to Pearson's HSAB theory). Although soft [a]

Efficiency of Polyoxometalate-Based Mesoporous Hybrids as Covalently Anchored Catalysts

“…In addition, the dispersion has then been tentatively correlated with the catalytic efficiency of the supported POMs in the cyclooctene and cyclohexene epoxidation by H 2 O 2 , used here as convenient model reactions. 24 25,26 TBA 4 H(POM-NH 2 ), were prepared as previously described.…”

Selective Formation of Epoxylimonene Catalyzed by Phosphonyl/Arsonyl Derivatives of Trivacant Polyoxotungstates at Low Temperature

“…Consequently, the two free O atoms of the lacuna are strongly nucleophilic. Furthermore, the two O atoms from the {RP=O} functions present nucleophilic properties, as shown before , . For this reason, we have considered that the Na + cation was located inside the lacuna and linked to these four O atoms, a location which was found as a minimum (Figure ) by DFT calculations (see Computational details).…”

“…For this reason, we have considered that the Na + cation was located inside the lacuna and linked to these four O atoms, a location which was found as a minimum (Figure ) by DFT calculations (see Computational details). Despite the absence of X‐ray diffraction structural determination available for the family of compounds ( n Bu 4 N) 3 [NaHAsW 9 O 33 {P(O)R} 2 ], the coordination of Na + is in line with the partial structure determined by X‐ray crystallography obtained on ( n Bu 4 N) 3 [NaHPW 9 O 34 {As(O) p ‐C 6 H 4 NH 2 } 2 ] ( 3 ) . In contrast, in the absence of experimental elements, the position of the H + counterion had to be determined computationally.…”

“…Furthermore, the two O atoms from the {RP=O} functions present nucleophilic properties, as shown before. [11,16] For this reason, we have considered that the Na + cation was located inside the lacuna and linked to these four O atoms, a location which was found as a minimum ( Figure 3) by DFT calculations (see Computational details). Despite the absence of X-ray diffraction structural determination available for the family of compounds (nBu 4 N) 3 [NaHAsW 9 O 33 {P(O)R} 2 ], [17] the coordination of Na + is in line with the partial structure determined by X-ray crystallography obtained on (nBu 4 N) 3 [NaHPW 9 O 34 {As(O)p-C 6 H 4 NH 2 } 2 ] (3).…”

“…Despite the absence of X-ray diffraction structural determination available for the family of compounds (nBu 4 N) 3 [NaHAsW 9 O 33 {P(O)R} 2 ], [17] the coordination of Na + is in line with the partial structure determined by X-ray crystallography obtained on (nBu 4 N) 3 [NaHPW 9 O 34 {As(O)p-C 6 H 4 NH 2 } 2 ] (3). [16] In contrast, in the absence of experimental elements, the position of the H + counterion had to be determined computationally. This was carried out through geometry optimization of the regioisomers differing from the proton position (see Figure S1 for complete results).…”