Bonding Insights from Structural and Spectroscopic Comparisons of {SnW5} and {TiW5} Alkoxido‐ and Aryloxido‐Substituted Lindqvist Polyoxometalates. Issue 11 (29th January 2018)

• Record Type: Journal Article
• Authors: Kandasamy, Balamurugan; Bruce, Peter G.; Clegg, William; Harrington, Ross W.; Rodríguez‐Fortea, Antonio; Pascual‐Borrás, Magda; Errington, R. John
• Is Part Of: Chemistry. Volume 24:Issue 11(2018)
• Page Start: 2750
• Page End: 2757
• Publication Date: 2018-01-29
• Subjects: bonding -- density functional calculations -- multinuclear NMR spectroscopy -- polyoxometalate synthesis -- tin alkoxides; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201705547
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Incorporation of {MX} n + groups into polyoxometalates (POMs) provides the means not only to introduce reactivity and functionality but also to tune the electronic properties of the oxide framework by varying M, X and n . In order to elucidate the factors responsible for differences in reactivity between {TiW5 } and {SnW5 } Lindqvist‐type hexametalates, a series of alkoxido‐ and aryloxido‐tin substituted POMs ( n Bu4 N)3 [(RO)SnW5 O18 ] (R=Me, Et, i Pr and t Bu) and ( n Bu4 N)3 [(ArO)SnW5 O18 ] (Ar=C6 H5, 4‐MeC6 H5, 4‐ t BuC6 H5, 4‐HOC6 H4, 3‐HOC6 H4 and 2‐CHOC6 H4 ) has been structurally characterised and studied by multinuclear NMR ( 1 H, 13 C, 17 O, 119 Sn and 183 W) and FTIR spectroscopy. Spectroscopic and structural parameters were compared with those of titanium‐substituted homologues and, when coupled with theoretical studies, indicated that Sn−OR and Sn−OAr bonds are ionic with little π‐contribution, whereas Ti−OR and Ti−OAr bonds are more covalent with π‐bonding that is more prevalent for Ti−OR than Ti−OAr. This experimental and theoretical analysis of bonding in a homologous series of reactive POMs is the most extensive and detailed to date, and reveals factors which account for significant differences in reactivity between tin and titanium congeners. Abstract : Sn versus Ti : The effects of metal substitution on the bonding within a homologous series of [(RO)MW5 O18 ] 3− polyoxometalates have been studied by combined structural, spectroscopic and theoretical studies of Ti and Sn derivatives, highlighting the influence of M−OR π‐bonding on the distributed electronic effects within the oxide framework.