Michal Sivák

Synthesis, characterization, crystal structure and reactivity of the vanadium(V) monoperoxo complex with tetradentate N-(carbamoylethyl)iminodiacetate as heteroligand

Abstract From water–ethanol solutions of MVO 3 –H 2 O 2 –H 2 ceida, where M is K + or NH 4 + and H 2 ceida is N -(carbamoylethyl)iminodiacetatic acid, the red crystalline complexes of vanadium(V) of composition M[VO(O 2 )ceida] · x H 2 O ( x =2 for M=K + and x =1 for M=NH 4 + ) were prepared. The course of thermal decomposition of the potassium salt enabled us to isolate also the anhydrous K[VO(O 2 )ceida] from the dihydrate. The X-ray structure analysis of K[VO(O 2 )ceida] · 2H 2 O revealed a mononuclear structure of the complex anion with a typical pentagonal bipyramidal arrangement around vanadium. The heteroligand is coordinated as a tetradentate ceida(2−) ion via imino nitrogen, two carboxylic oxygens and oxygen from the carbamoyl group, thus forming two five- and one six-membered chelate rings. The 51 V NMR spectra of aqueous solutions (pH 3.1–4.9) exhibiting a single peak at approx. −580 ppm showed that the complex anion probably maintains its structure in solution upon dissolution. The reactivity of the complex anion in the oxygen transfer reaction from the peroxo ligand to the sulphur in the thiolato complex of Co(III) was studied. The reactivity, thermal stability and the crystal structure are compared with those for other vanadium(V) monoperoxo complexes with heteroligands containing an O 3 N-donor set.

Synthesis, characterization and crystal structure of a stable aqua-dioxo-tetraperoxodivanadate(V) with a cation of macrocyclic tetraamine

Abstract The peroxo complex of vanadium(V) of composition CymH2[V2O2(O2)4H2O] · 2H2O, where Cym is 5,5,7,12,12,14-hexa-methyl,1,4,8,11-tetraazacyclotetradecane, was prepared by crystallization from a water-ethanol solution of vanadium pentoxide, hydrogen peroxide and Cym. The X-ray structure analysis revealed a dinuclear structure of the complex anion with two coordinatively non-equivalent vanadium atoms bridged by a tridentate η2-peroxo ligand. The compound is the thermally most stable peroxo complex of vanadium(V) of this type. After simultaneous release of active oxygen and three water molecules at temperatures up to 90°C, the anhydrous metavanadate CymH2(VO3)2 is formed.

Synthesis and characterization of a new heteroligand vanadium(v) oxo-monoperoxo complex and first crystal structure with coordinated N-(carbamoylmethyl)iminodiacetate

Abstract Formation of a vanadium(V) monoperoxo complex with coordinated N-(carbamoylmethyl)iminodiacetate2− (ada) was observed in the pH range 1.3–8.6. The MI[VO(O2)ada] · xH2O (MI= K+, Cs+; x = 4 for K+ and 1 for Cs+) and Ba[VO(O2) ada]2 · 3H2O complexes were isolated from aqueous solution. K[VO(O)2)ada]·H2O was obtained by thermal decomposition of the crystallohydrate. The crystal structure of K[VO(O2)ada] · 4H2O was determined by X-ray structure analysis. The vanadium atom is seven-coordinated by oxo, η2-peroxo and tetradentate ada2−-N,O1, O2, O3 ligands. The oxygen of the carbamoyl group is in the apical position trans to the VO group.

Molecular, supramolecular and solution structures of peroxovanadium complexes with ON and O3N donor set ligands: two new types of cationic–anionic peroxovanadium(V) peroxovanadates(V)

The complexes, [VO(O(2))(pa)(2)]ClO(4).3H(2)O (1), [VO(O(2))(pa)(2)][VO(O(2))(2)(pa)].3H(2)O (2), [VO(O(2))(pa)(2)][VO(O(2))(ada)].2H(2)O (3) and [VO(O(2))(pa)(pca)].H(2)O (4)[pa = picolinamide, ada = carbamoylmethyliminodiacetate(2-) and pca = 2-pyrazinecarboxylate(1-)], were synthesized. 2 and 3 are new types of peroxovanadium complexes: monoperoxovanadium diperoxovanadate (2) and monoperoxovanadium monoperoxovanadate (3). The complexes were characterized by chemical analysis and IR spectroscopy, and 1, 3 and 4 also by X-ray analysis. The structure of 1 is disordered, with alternating positions of the oxo and peroxo ligands. The peroxo oxygen atoms, O(p), in 1 are involved in weak hydrogen bonds with water molecules and close intramolecular C-HO...(p) bonds [d(HO(p)) approximately 2.0 A]. The supramolecular structure of 1 is formed by a network of hydrogen bonds and strong attractive intermolecular pi-pi interactions between the pyridine rings. The supramolecular architecture in 4 is constructed by (N,O)-H...O hydrogen bonds between the neutral complex molecules and water of crystallization. The peroxo oxygen atoms in 4 form intramolecular C-H...O(p) bonds [d(H...O(p))= 2.303 A]. The pa and pca ligands are ON coordinated via the oxygen atoms of the C(NH(2))=O and COO(-) groups, respectively, and nitrogen atoms of the heterocyclic rings, and ada as a tetradentate O(3)N ligand. The thermal analysis of 4 showed that the loss of water of crystallization and the active oxygen release (T(min)/ degrees C 82, T(max)/degrees C 165) are, under given conditions, individual processes separated by the temperature interval 90-132 degrees C. The solution structures and stability were studied by UV-VIS and (51)V NMR spectroscopies.

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.

Hexakis[3-(aminocarbonyl)pyridinium] decavanadate(V) dihydrate.

The structure of the title compound, (C(6)H(7)N(2)O)(6)[V(10)O(28)].2H2O, at 120 (2) K has monoclinic (C2/c) symmetry. The asymmetric unit consists of one half-decavanadate anion of Ci symmetry, three cations and one water molecule. Each water molecule is hydrogen bonded to two decavanadate anions, thus forming a one-dimensional chain of anions. The three-dimensional supramolecular structure is formed by a network of N-H...O, O-H...O and C-H...O hydrogen bonds, in which the cations, anions and water molecules are involved, and by nonparallel-displaced pi-stacking interactions between pyridine rings. As a result of hydrogen bonding, the carboxamide groups of the cations are somewhat twisted from the pyridine ring plane.

Experimental and computational evidence of solid-state anion–π and π–π interactions in [VO(O2)(L)(pa)]·xH2O complexes (L = picolinate, pyrazinate or quinolinate; pa = picolinamide)

Two new neutral monoperoxidovanadium(V) complexes [VO(O2)(L)(pa)]·xH2O have been synthesized: [VO(O2)(pic)(pa)]·H2O (1) and [VO(O2)(Hquin)(pa)]·2H2O (2) [pic: pyridine-2-carboxylato(1–) or picolinato(1–), Hquin: pyridine-2,3-dicarboxylato(1–) or quinolinato(1–), and pa: picolinamide]. The solid state structures of 1 and 2 feature a typical distorted pentagonal bipyramid coordination polyhedron around the central vanadium atoms. The bidentate anionic ligands are coordinated in two equatorial positions, while the bidentate picolinamide molecule is bound via the aromatic nitrogen and the carboxamide oxygen in one equatorial and one apical position. The experimental geometric parameters were used for a detailed study of intermolecular interactions between the pic–pic and pa–pa aromatic rings in 1. Interestingly, no π–π interactions were observed between the pyridine rings of Hquin or pa in 2, however, the less common anion–π solid-state interactions were found between the pic ligands in 1 and pca [pca = pyrazinecarboxylato(1–)] ligands in the already published structure of the related complex [VO(O2)(pca)(pa)]·H2O (3). The presence of anion–π and π–π interactions in 1 and 3 was confirmed by DFT computations performed on their solid-state structures. Computational results suggested a direct analogy between anion–π and π–π interactions, both being of predominantly electrostatic character.

Synthesis, characterization, and crystal and molecular structures of caesium N-(carbamoylethyl)iminodiacetatooxoperoxovanadate(V) monohydrate

A new monoperoxo complex of vanadium(V) of composition Cs[VO(O2)(CEIDA)]·H2O [where H2CEIDA is N-(carbamoylethyl)iminodiacetic acid] was prepared and characterized by IR, UV-VIS and 51V NMR spectroscopies. Thermal analysis showed that after crystal water release the anhydrous Cs[VO(O2)(CEIDA)] is formed, which is stable over a relatively large temperature interval and can be isolated by interruption of the dynamic heating in that interval. The X-ray structure analysis of Cs[VO(O2)(CEIDA)]·H2O revealed a mononuclear structure of the complex anion with a typical distorted pentagonal bipyramidal arrangement around vanadium formed by two peroxo oxygens bound in an η2-fashion, two oxygens from the deprotonated carboxylic groups and a nitrogen in the equatorial plane, and an oxo ligand and an oxygen from the carbamoyl group in the apical positions. The heteroligand is thus bound as a tetradentate CEIDA(2-)-N,O,O,O ligand to form one six-membered and two glycinate rings.

METAVANADATES AND DIHYDROGENDECAVANADATES WITH CATIONS OF MACROCYCLIC TETRAAMINES

SummaryFrom the reaction systemsCyclam/Mecyclam-KVO3-H2O-HCl-EtOH (Cyclam=1,4,8,11-tetraazacyclotetradecane; Mecyclam=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane), the first polyvanadates with cations of macrocyclic amines were isolated: (CyclamH2)2-H2V10O28·2H2O, (MecyclamH2)2H2V10O28·6H2O, (CyclamH2)(VO3)2·3H2O, (CyclamH2)(VO3)2·2H2O, and (MecyclamH2)(VO3)2·H2O. The metavanadates with theCyclamH22+ cation differ markedly in their IR spectra, obviously due to the different structure of the polyanion. The interruption of dynamic heating at the thermal analysis of the crystallohydrates of dihydrogendecavanadates resulted in the formation of corresponding anhydrous dihydrogendecavanadates.ZusammenfassungAus demCyclam/Mecyclam-KVO3-H2O-HCl-EtOH Reaktionssystem (Cyclam=1,4,8,11-tetraazacyclotetradecane;Mecyclam=5,5,7,12,12,14-hexamethyl-1,4,8,11-tetrazacyclotetradecane) wurden die ersten Polyvanadate mit cyclischen Aminen als Kationen isoliert: (CyclamH2)2V10O28·H2O, (MecyclamH2)2H2V10O28·6H2O, (CyclamH2)(VO3)2·3H2O, (CyclamH2)(VO3)2·2H2O und (MecyclamH2)(VO3)2·H2O. Die zwei Metavanadate mit dem KationCyclamH22+ unterscheiden sich wesentlich in ihren Infrarotspektren, was auf unterschiedliche Polyanionstruktur der Metavanadate hinweist. Durch Unterbrechen der dynamischen Erhitzung bei der thermischen Analyse von Kristallhydraten der Dihydrogendekavanadate wurden entsprechende Verbindungen ohne Kristallwasser gewonnen.

Thermal decomposition of potassium fluorooxodiperoxovanadate(V)

Abstract The thermal decomposition of K 2 [VFO(O 2 ) 2 ], proceeding isothermally at 114 and 175°C in a self-generated atmosphere or under dynamic conditions up to 240°C, is a multi-step process. The unstable intermediate formed in the first stage of the decomposition reacts to form a mixture of KVO 3 , KF, K 3 VF 4 O 2 and K 4 [V 2 O 6 (O 2 )]. The final decomposition product is a mixture of K 4 V 2 O 7 , KVO 3 , K 3 VF 4 O 2 and KF.