Publications by authors named "Bogdan Botar"

The self-assembly of soluble molybdenum blue species from simple molybdate solutions has primarily been associated with giant mixed-valent wheel-shaped cluster anions, derived from the {Mo(V/VI)(154/176)} archetypes, and a {Mo(V/VI)(368)} lemon-shaped cluster. The combined use of Raman spectroscopy and kinetic precipitation as self-assembly monitoring techniques and single-crystal X-ray diffraction is key to mapping the realm of molybdenum blue species by establishing spherical {Mo(V/VI)(102)}-type Keplerates as an important giant molybdenum blue-type species. We additionally rationalize the empirical effect of reducing agent concentration on the formation of all three relevant skeletal types: wheel, lemon and spheres.

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"Out-of-pocket" association of Ag(+) to the tetradentate defect site of mono-vacant Keggin and Wells-Dawson polyoxometalate (POM) cluster-anions is used to direct the formation of water-soluble AgCl nanocubes.

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Acetate-induced demetalation of a {gamma-SiW(10)Fe(2)}-based dimer affords an acetato/hydroxo-bridged triiron cluster stabilized by two isomerically distinct Keggin units.

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The effect of acetate concentration on the formation of {SiW10Fe2}-based complexes is demonstrated by the synthesis of an open-shell diiron tungstosilicate derivative featuring two rotational Keggin isomer units.

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Investigation of the catalytically relevant gamma-diiron(III) Keggin complexes in aqueous acetate buffer leads to a dimeric C(2v)-symmetric polyanion, [{Fe(OH)(OAc)}(4)(gamma-SiW(10)O(36))(2)](12-) (3) and a trimeric C(2)-symmetric polyanion, [{Fe(6)(OH)(9)(H(2)O)(2)(OAc)(2)}(gamma-SiW(10)O(36))(3)](17-) (4). Polyanion 3 incorporates a hydroxo/acetato-bridged tetrairon(III) core, while 4 incorporates a trigonal prismatic hydroxo/acetato-bridged hexairon(III) core. The monomeric building unit of 3 and 4, {gamma-SiW(10)Fe(2)}, adopts the "out-of-pocket" structural motif (with two corner-sharing FeO(6) coordination polyhedra no longer connected to the internal SiO(4) tetrahedron of the Keggin unit) also observed in the {gamma-SiW(10)Fe(2)}(-)type structures isolated from nonbuffered aqueous solutions.

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The complex [gamma(1,2)-SiW(10){Fe(OH(2))}(2)O(38)](6)(-) (1) has been reported to catalyze the much sought reductant-free selective O(2)-based epoxidation of alkenes (Nishiyama, Y.; Nakagawa, Y.; Mizuno, N.

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A controlled, Raman-monitored chemical reduction of a molybdate and vanadate mixture affords a new type of molybdenum-oxide-based cluster showing an unprecedented level of inorganic structural organization. The cluster incorporates two nanosized substructures (a ring and a sphere) in an open clam-like assembly. Multiple methods indicate that the nanoring contains delocalized electrons and the nanosphere contains localized but interacting electrons.

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The role of the central atom X in the structure and reactivity of di-Ru-substituted gamma-Keggin polyoxometalates (POMs), gamma-[(Xn+O4)RuIII2(OH)2(MFM)10O32](8-n)-), where MFM = Mo and W, and X = AlIII, SiIV, PV, and SVI., was computationally investigated. It was shown that for both MFM = Mo and W the nature of X is crucial in determining the lower lying electronic states of the polyoxoanions, which in turn likely significantly impacts their reactivity.

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The self-assembly of molybdate building units in the presence of Fe(II) and V(IV) produces the first mixed-spin heterometal keplerate-type clusters displaying ferrimagnetic interactions.

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Self-assembly of aqueous solutions of molybdate and vanadate under reducing, mildly acidic conditions results in a polyoxomolybdate-based {Mo72V30} cluster compound Na8K16(VO)(H2O)5[K10 subset{(Mo)Mo5O21(H2O)3(SO4)}12(VO)30(H2O)20].150H2O, 1, a quantum spin-based Keplerate structure.

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A new monomeric diiron beta-Keggin derivative, [(CH3)2NH2]5[beta-SiFe2W10O36(OH)2(H2O)Cl].7H2O (1) with non-adjacent substituted sites has been obtained in good yield by reaction of Fe(III) cations with [gamma-SiW10O36]8- in aqueous solution. The use of hydrogen bonding counter-cations produced a disorder-free polyanion.

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The novel spherical cluster-compound K2Na6[K20 [symbol: see text] Mo80-V22O282(SO4)12(H2O)66]. approximately 140H2O 1 has been obtained in a 'one-pot' reaction and exhibits several remarkable structural features: 30 open shell centers, i.e.

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