Peter Schwendt

A new coordination mode for the tartrato ligand. Synthesis of vanadium(V) oxo peroxo tartrato complexes and the X-ray crystal structure of K2[{VO(O2)(L-tartH2)}2(μ-H2O]5H2O

Abstract Vanadium(V) oxo peroxo tartrato complexes M2[{VO(O2)(L-tartH2}2(μ-H2O)]. 5H2O (M = K+, NH4+; tart4− = C4O6H24− have been prepared from aqueous-ethanolic medium and characterized by elemental analysis and IR spectroscopy. The X-ray crystal structure of K2[{VO(O2) (L-tartH2)}2(μ-H2O)]. 5H2O, as the first crystal structure of a vanadium(V) tartrato complex has been determined. The dinuclear anion exhibits two pentagonal bipyramidal polyhedra about vanadium atoms which are joined to each other by sharing two oxygen atoms of hydroxyl groups and oxygen atom from water molecule. The tartrate group is bonded to the vanadium atom in a bidentate way via oxygen atoms of neighbouring carboxylic and hydroxyl groups. The coordinated hydroxyl oxygen atom is bonded also to the second vanadium atom, but in a monodentate way. This type of bonding of tartrate group was not observed so far.

Stereospecific formation of α-hydroxycarboxylato oxo peroxo complexes of vanadium(V). Crystal structure of (NBu4)2[V2O2(O2)2(l-lact)2]·2H2O and (NBu4)2[V2O2(O2)2(d-lact)(l-lact)]·2H2O

An overview of structurally characterized α-hydroxycarboxylatodioxo- and α-hydroxycarboxylatooxoperoxovanadates(V) is presented and the geometric parameters of the V2O2 bridging core are discussed. The first case of a stereospecific formation of oxoperoxovanadates(V) is reported: The crystal structures of the isomeric compounds (NBu4)2[V2O2(O2)2(l-lact)2]·2H2O and (NBu4)2[V2O2(O2)2(d-lact)(l-lact)]·2H2O (lact=C3H4O32−, the anion of the lactic acid) differ mainly in the arrangement of the V2O2 core and in mutual orientation of the VO bonds. The complexes with achiral ligands adopt the same structural type as the complexes formed from a racemic mixture of a chiral ligand, while the structure obtained using an enantiopure l,l-hydroxycarboxylate is different.

Correlation between stretching mode absorptions and asymmetry of the V(O2) group in peroxo complexes of vanadium (V)

Abstract Stretching vibration wavenumbers have been estimated for (NH4)2[VO(O2)2F] and (NH4)3[VO(O2)2F2] based on normal coordinate calculations employing a valence force field derived from bond length—force constant correlations. The results bear out the recently suggested re-assignment of the vanadium—ligand stretching vibrations. The effect of ligands on the asymmetry of the group is discussed using structural data for 19 vanadium (V) peroxo complexes. The asymmetry of the group is different in compounds with different coordination numbers. This difference is accompanied by characteristic shifts of the vanadium—peroxo oxygen stretching mode absorptions.

The first tetranuclear vanadium(V) peroxo complex: Preparation, vibrational spectra and X-ray crystal structure of K6[V4O4(O2)8(PO4)]·9H2O

Abstract The vanadium(V) peroxo phosphato complex K 7 [V 4 O 4 (O 2 ) 8 (PO 4 )]·9H 2 O has been obtained from the KVO 3 KH 2 PO 4 KOHH 2 O 2 H 2 OC 2 H 5 OH system. The X-ray structural analysis revealed a tetranuclear anionic structure in which two dinuclear [V 2 O 2 (O) 2 ) 2 ( μ - η 1 : η 2 -O 2 ) 2 ] units are connected by the μ 4 -PO 4 group.

Oxo Peroxo Glycolato Complexesof Vanadium (V). Crystal Structureof (NBu4)2[V2O2(O2)2(C2H2O3)2]ċH2O

Summary. Oxo peroxo glycolato complexes of vanadium(V) (M2[V2O2(O2)2(C2H2O3)2]ċnH2O (n=0, 1; M=NBu4+ (1), K+ (2), NH4+ (3), Cs+ (4), NPr4+ (5)) as well as (NBu4)2[V2O4(C2H2O3)2]ċ H2O (6) have been prepared and characterized by spectroscopic methods. X-Ray structure analysis of 1 revealed the presence of dinuclear [V2O2(O2)2(C2H2O3)2]2− anions with a (chemical structure) bridging core and six coordinated vanadium(V) atoms in a distorted pentagonal pyramidal array.

Nitrilotriacetato-monoperoxo complexes of vanadium(V): formation in aqueous solution, synthesis and structure

SummaryM2[VO(nta)(O2)]·xH2O, where M+ is NHinf4♪p+, K+ or Rb+ and nta is nitrilotriacetate, and Sr[VO(nta)(O2)]·2H2O were synthesized. The electronic spectra of aqueous KVO3-H2O2-H3nta-HClO4(KOH) solutions (pH 1.45–5.62) and the thermal decomposition of K2[VO(nta)(O2)]· 2H2O with active oxygen release at 275° C showed that the nta-monoperoxo complex is the most stable vanadium(V) peroxo complex so far investigated. The anhydrous potassium salt was prepared on heating the crystallohydrate under dynamic conditions. The i.r. spectra indicate the same anion structure in solution and in the solid state where nta is coordinated as a tetradentate ligand.

Thermal decomposition of potassium hydrogentetrafluorodioxotriperoxodivanadate(V) dihydrate, K3[HV2O2(O2)3F4]·2 H2O

Abstract Products of the isothermal and non-isothermal decompositions of K3[HV2O2(O2)3 F4] · 2 H2O have been studied by means of vibrational spectroscopy and X-ray phase analysis. A new peroxo complex of vanadium(V), K6[V4O4(O2)6F6], is formed as the reaction intermediate. The final products of thermal decomposition, both isothermally at 51°C and non-isothermally up to 400°C, are KVO3 and K2[VO2F3].

Tetradecanuclear lanthanide-vanadium “nanochocolates”: catalytically-active cationic heteropolyoxovanadium clusters

The synthesis, structural characterization, magnetic and catalytic properties of a new class of lanthanide-containing cationic heteropolyoxovanadium clusters with a nanochocolate-like structure are reported. The title compounds were characterized by single-crystal and powder X-ray diffraction, IR and 51V-NMR spectroscopies and magnetic susceptibility measurements.

Fluorooxoperoxo complexes of vanadium(V)

Abstract Substances crystallizing under various conditions from the MVO 3 (MF, HF)H 2 O 2 H 2 O (M = NH 4 , K) systems have been characterized by elemental analysis, infrared and Raman spectra and X-ray powder patterns. Besides the known M 2 [VO(O 2 ) 2 F] complexes, complexes of two new types have been obtained: M 3 [HV 2 O 2 (O 2 ) 3 F 4 ·2H 2 O and (NH 4 ) 3 [V 2 O 2 (O 2 ) 4 F]· n H 2 O ( n ≈2). Vibrational spectra of new complexes are consistent with the presence of dimeric anions containing V(μ 2 O 2 )V and VFV bridges, respectively.

Ethylenediaminetetraacetato-monoperoxo complexes of vanadium(V)

SummaryThe monoperoxo complexes, M2[VO(HEDTA)(O2)]· 4H2O, where M is K+ or NH4+ and H4EDTA is ethylene-diaminetetraacetic acid, were prepared and characterized by Raman and i.r. spectra in the solid state and in aqueous solution. The single crystal X-ray study revealed a pentagonal bipyramidal anion structure with a tetradentate HEDTA(3—) ligand. The decomposition of complexes in aqueous solution to blue vanadium(IV) complexes as end products proceeds via a nonperoxo complex of vanadium.