Krebs-Type {M₂(WO₂)₂[B-β-SbW₉O₃₃]₂}ⁿ⁻ (M = Sb^III, (WO₃)) Tungstoantimonate Possessing Unique Pseudo-Seesaw Sb–O Structure

Defect {(WVIO7)WVI4} and Full {(WVIO7)WVI5} Pentagonal Units as Synthons for the Generation of Nanosized Main Group V Heteropolyoxotungstates

“…The turnover frequency values (TOF) were calculated based on the substrate conversion determined from the absorption at 420 nm after 180 min. The TOF is 1.19 h –1 for {Sb 3 W 43 } , which is comparable to other previously reported tungstoantimonates such as (H 2 en) 7 [(WO 2 ) 2 (WO 3 ) 2 ( B -β-SbW 9 O 33 ) 2 ]·12H 2 O (en = ethylenediamine) (TOF = 1.64 h –1 ) under similar reaction conditions, 12 while TOF is 0.89 h –1 for {Bi 3 W 43 } . The lower catalytic performance of {Bi 3 W 43 } compared to that of {Sb 3 W 43 } can be explained by the change of the primary heteroatom in the otherwise isostructural polyanion leading to a change of the overall redox properties of the polyanion, which has been previously observed for other POM-based catalysts.…”

“…Slow evaporation of the reaction mixture at 20 °C resulted in rhombohedral crystals of {Sb 3 W 43 } (CCDC 2070328) in a 20% yield based on tungsten after 4 days (Scheme 1). To explore the role of L-malic acid, synthesis studies lacking the carboxylic acid were conducted, resulting in a Krebs-POT K 12 11 It should be mentioned that a one-pot synthesis approach by mixing WO 4 2− , Sb 3+ , and L-malic acid in the corresponding stoichiometric ratios exclusively resulted in the formation of Krebs POM or uncharacterizable, inhomogeneous precipitates, respectively. {Co 3 Sb 3 W 42 } was prepared in a consecutive reaction step by addition of {Sb 3 W 43 } to a solution of CoCl 2 (4 eq.…”

“… 11 Since then, much attention has been paid to the catalytic properties of the Krebs archetype with recent focus on the use of tungstoantimonates as electron-transfer catalysts for the reductive conversion of pollutants such as K 3 [Fe III (CN) 6 ] to K 4 [Fe II (CN) 6 ]. 12 Herein, we report on the synthesis and characterization of K 20 Na 7 [H 2 (Bi III W VI 9 O 33 )(W 5 O 12 )(Bi III 2 W VI 29 O 103 )]·68H 2 O {Bi 3 W 43 } , K 11 Na 16 [H 2 (Sb III W VI 9 O 33 )(W 5 O 12 )(Sb III 2 W VI 29 O 103 )]·115.5H 2 O {Sb 3 W 43 } , and K 8 Na 15 [H 16 (Co II (H 2 O) 2 ) 0.9 (Co II (H 2 O) 3 ) 2 (W VI 3.1 O 14 )(Sb III W VI 9 O 33 )(Sb III 2 W VI 30 O 106 )(H 2 O)]·53H 2 O {Co 3 Sb 3 W 42 } , which were synthesized using a one-pot procedure and a stepwise approach, respectively. Being the first main group V heteropolyoxotungstates that incorporate a defect pentagonal {(W VI O 7 )W VI 4 } unit, {Bi 3 W 43 } and {Sb 3 W 43 } represent the largest unsubstituted tungstobismuthates and -antimonates reported so far ( Table S2 ).…”

“…7 In polyoxotungstate (POT) chemistry, architectural control can be achieved at the fragment level by carefully selecting the heteroanion template. Among the variety of primary heteroatoms grafted into heteropolyoxotungstates, main group V and VI representatives such as As III , Sb III , Bi III , Se IV , and Te IV are of synthetic interest as their lone pair prevents the formation of a closed Keggin {XW 12 O 40 } sphere resulting in a structure-directing effect of the heteroanion. Using Se IV and Te IV as central atoms in anionic templates, a series of nanosized tungstoselenates and tellurates has been synthesized and characterized (Table S1).…”

Recent Advances in Electrochemical Monitoring of Chromium

“…Nowadays, great efforts have been provided to the utilization of polyoxometalates (POMs) as functional catalysts in several applications among them catalysis [86][87][88], energy conversion [89][90][91] electronics and biosensors [92][93][94][95][96][97]. Recently, Zhangang Han et al [39] have published two papers about the elaboration of POMs based sensors for Cr(VI) detection.…”