title: Preparation of α1- and α2-isomers of mono-Ru-substituted Dawson-type phosphotungstates with an aqua ligand and comparison of their redox potentials, catalytic activities, and thermal stabilities with Keggin-type derivatives.
abstract: Both the α1- and the α2-isomers of mono-ruthenium (Ru)-substituted Dawson-type phosphotungstates with terminal aqua ligands, [α1-P2W17O61Ru(III)(H2O)](7-) (α1-RuH2O) and [α2-P2W17O61Ru(III)(H2O)](7-) (α2-RuH2O), were prepared in pure form by cleavage of the Ru-S bond of the corresponding DMSO derivatives, [α1-P2W17O61Ru(DMSO)](8-) (α1-RuDMSO) and [α2-P2W17O61Ru(DMSO)](8-) (α2-RuDMSO), respectively. Redox studies indicated that α1-RuH2O and α2-RuH2O show proton-coupled electron transfer (PCET), and the Ru(III)(H2O) species was reversibly reduced to Ru(II)(H2O) species and oxidized to Ru(IV)([double bond, length as m-dash]O) species and further to Ru(V)([double bond, length as m-dash]O) species in aqueous solution depending on the pH. Their redox potentials and thermal stabilities were compared with those of the corresponding α-Keggin-type derivatives ([α-XW11O39Ru(H2O)](n-); X = Si(4+) (n = 5), Ge(4+) (n = 5), or P(5+) (n = 4)). The basic electronic and redox features of Ru(L)-substituted Keggin- and Dawson-type heteropolytungstates (with L = H2O or O(2-)) were analyzed by means of density functional calculations. Similar to the corresponding α-Keggin-type derivatives, both α1-RuH2O and α2-RuH2O show catalytic activity for water oxidation.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Nishiki
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp.
authors.forename: Naoya
authors.initials: N
authors.lastname: Umehara
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kadota
authors.affiliation: Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: López
authors.affiliation: Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Poblet
authors.affiliation: Laboratoire de Chimie-Physique, Université Paris-Sud, UMR 8000 CNRS, Orsay F-91405, France.
authors.forename: Charyle Ayingone
authors.initials: CA
authors.lastname: Mezui
authors.affiliation: Laboratoire de Chimie-Physique, Université Paris-Sud, UMR 8000 CNRS, Orsay F-91405, France.
authors.forename: Anne-Lucie
authors.initials: AL
authors.lastname: Teillout
authors.affiliation: Laboratoire de Chimie-Physique, Université Paris-Sud, UMR 8000 CNRS, Orsay F-91405, France.
authors.forename: Israël M
authors.initials: IM
authors.lastname: Mbomekalle
authors.affiliation: Laboratoire de Chimie-Physique, Université Paris-Sud, UMR 8000 CNRS, Orsay F-91405, France.
authors.forename: Pedro
authors.initials: P
authors.lastname: de Oliveira
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Miyamoto
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp.
authors.forename: Tsuneji
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. sadakane09@hiroshima-u.ac.jp and PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, 332-0012, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sadakane