Accessing yttrium–polyoxometalate–carboxylate hybrids from a versatile arsenotungstate(III) precursor

Exploration of the reactivity of the versatile polyoxometalate precursor [As2W19O67(H2O)]14− with yttrium salts and organic proligands derived from 2-picolinic acid: 2,5-pyridinedicarboxylic acid (pdcH2) and 5-(methoxycarbonyl)-2-pyridinecarboxylic acid (mcpcH), has afforded the three new hybrid complexes [Y{AsW8O30}2(AsO)2{WO2(pdc)}2]13− (1) and [{Y(H2O)3}2{As2W19O68}{WO2(L)}2]8− (L− = pdcH− (2) or mcpc− (3)). The structurally-related and organic ligand free species [{Y(H2O)3}4{Y(H2O)6}2{As2W19O68}2{WO3(H2O)}4(AsO)2]20− (4) was also obtained. Structural characterization of the mixed salts of the four complexes, K8H5[1]·9H2O, K2.5H5.5[2]·37H2O, K2.5H5.5[3]·34H2O and K6Na2H4[4]·30H2O, has revealed that five membered N,O-chelated {WO2(L)} units play a key structural role in complexes 1–3. With no picolinate-based ligand present in 4, additional arsenite fragments bind to the analogous tungsten coordination sites.

Four new yttrium–arsenotungstate hybrid complexes have been synthesized from [As2W19O67(H2O)]14− and structurally characterized, three of which incorporate organic ligands derived from 2-picolinate that chelate some of the tungsten centers.Figure optionsDownload as PowerPoint slideHighlights
► First systematic exploration of generation of hybrid organic/polyoxometalates by N,O-chelation of tungsten centers.
► Synthesis and structural characterization of four new rare-earth/organic/polyoxometalate hybrid complexes.
► Observation of rare square-faced bicapped trigonal prismatic coordination geometry for an yttrium center.