title: Triazolyl-based copper-molybdate hybrids: from composition space diagram to magnetism and catalytic performance.
abstract: The multicomponent mixed-metal Cu(II)/Mo(VI) oxides/1,3-bis(1,2,4-triazol-4-yl)adamantane (tr2ad) system was thoroughly studied employing a compositional diagram approach. The concept allowed us to prepare three layered copper-molybdate hybrid solids [Cu(II)2(tr2ad)4](Mo8O26) (1), [Cu4(II)(μ4-O)(tr2ad)2(MoO4)3]·7.5H2O (2), and [Cu(I)2(tr2ad)2](Mo2O7)·H2O (3), and to elucidate the relationship between initial reagent concentration/stoichiometry and the stability of the resultant structural motifs. Compounds 1 and 2 were found to dominate throughout a wide crystallization range of the concentration triangle, whereas compound 3 was formed by redox processes in the narrow crystallization area having a high excess of Cu(OAc)2·H2O. Independent experiments carried out with Cu(OAc)2 and (NH4)6Mo7O24 in the absence of tr2ad, under the same conditions, revealed the formation of low-valent and bimetallic oxides, including Cu2O, MoO2, Cu(Mo3O10)·H2O, and Cu3(MoO4)2(OH)2. Compounds 1 and 2 show high thermal and chemical stability as examined as catalysts in the epoxidation of cis-cyclooctene and the oxidation of benzyl alcohol (BzOH) with different types of oxidants. The oxidation reaction of BzOH using tert-butyl hydroperoxide (TBHP) as the oxidant, in the presence of 1 or 2, led to benzaldehyde and benzoic acid (PhCO2H), with the latter being formed in up to 90% yield at 24 h. The results suggest that 1 and 2 may be favorable heterogeneous catalysts for the synthesis of PhCO2H. Whereas compound 1 only reveals a weak ferromagnetic coupling between neighboring Cu(II) centers (J = 0.41 cm(-1)), compound 2 shows distinct intracluster antiferromagnetic exchange interactions (J = -29.9 cm(-1), J' = -25.7 cm(-1)), which consequently results in a diamagnetic ground state.
authors.affiliation: Inorganic Chemistry Department, Taras Shevchenko National University of Kyiv , Volodimirska Str. 64, Kyiv 01033, Ukraine.
authors.forename: Ganna A
authors.initials: GA
authors.lastname: Senchyk
authors.forename: Andrey B
authors.initials: AB
authors.lastname: Lysenko
authors.forename: Artem A
authors.initials: AA
authors.lastname: Babaryk
authors.forename: Eduard B
authors.initials: EB
authors.lastname: Rusanov
authors.forename: Harald
authors.initials: H
authors.lastname: Krautscheid
authors.forename: Patrícia
authors.initials: P
authors.lastname: Neves
authors.forename: Anabela A
authors.initials: AA
authors.lastname: Valente
authors.forename: Isabel S
authors.initials: IS
authors.lastname: Gonçalves
authors.forename: Karl W
authors.initials: KW
authors.lastname: Krämer
authors.forename: Shi-Xia
authors.initials: SX
authors.lastname: Liu
authors.forename: Silvio
authors.initials: S
authors.lastname: Decurtins
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Domasevitch