Nikolay B. Kompankov

Cyclic tungstoselenites based on {Se2W12} units.

The reaction of Na2WO4 and SeO2 under moderately acidic conditions yielded a novel 39-tungsto-6-selenite, [(Se2W12O46(WO(H2O))3](24-) (1), isolated as Na24[H6Se6W39O144]·74H2O. The macrocyclic polyanion consists of three {Se2W12} fragments connected via three trans-{WO(H2O)}(4+) groups. The same {Se2W12} building block is present in the structure of [(Se2W12O46)2{Mn2Cl(H2O)2}{Mn(H2O)2}2(SeO)2](13-) (2), which was obtained from the same reagents in the presence of MnCl2. The compounds were characterized by single-crystal X-ray diffraction, (77)Se NMR, Fourier transform infrared, and Raman spectroscopy.

New {RuNO} Polyoxometalate [PW11O39RuII(NO)]4-: Synthesis and Reactivity

New Ru-containing polyoxometalate [PW11O39Ru(II)(NO)](4-) (1(4-)) was obtained in high yield by reaction of [Ru(NO)Cl5](2-) with [PW11O39](7-) and characterized by multinuclear NMR, cyclic voltammetry, IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The intrinsic reactivity of the {RuNO} site in 1(4-) toward various reagents has been studied using a versatile and simple ESI tandem mass spectrometric methodology for identification of the L attached at the Ru site; this approach relies on the preferential liberation of the L ligands attached at the Ru sites upon mass-selecting desired intermediates and subsequent promotion of their fragmentation. Reactions with both hydrazine and hydroxylamine lead to elimination of the nitroso group and quantitative formation of [PW11O39Ru(III)(H2O)](4-) (2(4-)) in aqueous solution. In the reaction with hydroxylamine, an intermediate with coordinated dinitrogen has been detected. An easy access to the NH3-coordinated [PW11O39RuNH3](4-) (3(4-)) complex was achieved upon reduction of 1(4-) with Sn(2+) in water.

Synthesis and Characterization of [(OH)TeNb5O18]6– in Water Solution, Comparison with [Nb6O19]8–

Reaction of [Nb6O19](8-) with H6TeO6 in water gives telluropentaniobate [(OH)TeNb5O18](6-) (1) as single product, which was isolated as Na(+) and mixed Na(+)/K(+) salts. Crystal structures were determined for Na6[(OH)TeNb5O18]·15H2O (Na6-1) and K6Na[Nb(5.5){Te(OH)}(0.5)O(18.5)]·26H2O (K6Na-1). Formation of 1 was monitored with electrospray ionization mass spectrometry (ESI-MS) and (125)Te NMR techniques. Capillary electrophoresis was used to calculate electrophoretic mobilities and radii of the anionic species in solutions of [(OH)TeNb5O18](6-) and [Nb6O19](8-) in borate buffer. No condensation or degradation products were detected. Reactions of 1 with {Cp*Rh}(2+) sources gives 1:1 and 2:1 hybrid polyoxometalate, which are present in solution as a mixture of isomers, as detected by (125)Te NMR. The isomerism is related to various possibilities of coordination of {Cp*Rh}(2+) to different {M3O3} faces, relative to the unique Te atom. According to ESI-MS experiments in water and methanol, rapid redistribution of the organometallic fragments between the 1:1 and 2:1 complexes takes place. The 1:1 complexes are more stable in water, while 2:1 complexes dominate in methanol. X-ray structural analysis of the crystals isolated from 2:1 reaction mixture allowed identification of Na3[{Cp*Rh}2TeNb5O19]·24H2O (Cp*2Rh2-1) with two {Cp*Rh}(2+) fragments capping the opposing faces of the Lindqvist anion.

Facile Substitution of Bridging SO22– Ligands in Re12 Bioctahedral Cluster Complexes

Selective substitution of μ-SO22- groups by either O2- or Se2- ions occurs upon heating the bioctahedral rhenium cluster complex K6[Re12CS14(μ-SO2)3(CN)6] in air atmosphere or in the presence of a Se source, respectively, manifesting the remarkable lability of SO22- ligands bound to a transition-metal cluster. A series of compounds based on the new mixed-ligand anions, [Re12CS14(μ-O)3(CN)6]6-, [Re12CS14(μ-Se)3(CN)6]6-, and [Re12CS14(μ-O)3(OH)6]6-, were isolated and their solid-state structures were elucidated by single-crystal X-ray diffraction analysis. Along with the previously reported μ-sulfide clusters, the new species constitute a series of rhenium anionic complexes with the common formula [Re12CS14(μ-Q)3L6]6- (Q = O, S, Se, L = CN-; Q = O, S, L = OH-), within which the total charge and number of cluster valence electrons (CVEs) are constant. The article presents insights into the mechanistic and synthetic aspects of the substitution process, and it comprehensively discusses the influence of inner ligand environment on the structure, spectroscopic characteristics, and electrochemical behavior of the novel compounds.

Influence of Magnetic Field on the Mobility of Aromatic Chiral Molecules

The influence of magnetic fields on the properties of chiral molecules is of great interest nowadays. This work presents an (1)H NMR study of the mobility of 1-phenylethanol and 1-phenyl-1-propanol molecules in pure forms and in chirally polarized mixtures in external magnetic fields. Molecular mobility is shown to be dependent on the strength of the external magnetic field and chiral mixing. It could be assumed that the mobility changes are caused by rotational and magnetic interactions between induced magnetic moments of the aromatic molecules and the external magnetic field; intermolecular interactions are also essential. The results are important for the tasks related to enantiomer separation.

Na4[trans-{Cp*Rh}2Ta6O19] · 24H2O: Synthesis, structure, solution studies

Reaction of [Cp*RhCl2]2 (Cp* = η5-C5(CH3)5) with Na8[Ta6O19] · 24.5H2O, taken in {Cp*Rh}2+/[Ta6O19]8– 2: 1 molar ratio, in water leads to a new noble-metal-POM complex Na4[trans-{Cp*Rh}2Ta6O19] · 24H2O (I), which was isolated and characterized by XRD (CIF file CCDC no. 1416810), elemental analysis, NMR and IR spectroscopy.

Polyoxoanions assembled by the condensation of vanadate, tungstate and selenite: solution studies and crystal structures of the mixed metal derivatives (NMe4)2Na2[WVI4VV2O19]·8H2O and (NMe4)4.83[(SeIV WVI4.57VV4.43O33)2(WVI(O)(H2O))(VVO)2.6]·10.57H2O

The reaction of acidified aqueous solutions of Na2WO4, NaVO3 and SeO2 in a 16 : 4 : 3 molar ratio gives a complex mixture of polyoxometalates (POMs) with both WVI and VV addenda, formulated as [(SeIVWVIxVV9−xO33)2(WVIO(H2O))(VO)m]n− with x = 4, 5, 6; m = 2 or 3. In solution, the sandwich-type complexes [(SeIVWVIxVV9−xO33)2(WVIO(H2O))(VO)m]n− slowly lose Se and convert into [WVI4VV2O19]4− and further to [WVI5VVO19]3− with a Lindqvist-type structure. These transformations were monitored with 51V and 77Se NMR, electrospray mass-spectrometry and capillary electrophoresis. Crystals of (NMe4)2Na2[(W4V2)O19]·8H2O (1) and (NMe4)4.83[(SeW4.57V4.43O33)2(W(O)(H2O))(VO)2.6]·10.57H2O (2) were isolated and structurally characterized.

Preparation and crystal structure of [Ru2(μ-Cl)3(P(CH2OH)3)6]Cl

A new water-soluble phosphine Ru complex, [Ru2(μ-Cl)3(P(CH2OH)3)6]Cl, has been prepared from [Ru(PPh3)3Cl2] and P(CH2OH)3 in methanol. The complex was characterized by X-ray analysis. The crystal system is triclinic, space group

Combined HPLC-ICP-AES technique as an informative tool for the study of heteropolyniobates

P\bar 1

Hemilability of phosphine-thioether ligands coordinated to trinuclear Mo3S4 clusters and its effect on hydrogenation catalysis

, a = 9.3659(1) Å, b = 13.0976(2) Å, c = 16.791(3) Å, α = 105.620(5)°, β = 91.114(6)°, γ = 110.193(3)°, V = 1847.3(5) Å3, Z = 2. It contains [Ru2(μ-Cl)3(P(CH2OH)3)6]+ and Cl− ions, bound together by hydrogen bonds. Ru has octahedral coordination, with Ru-Cl and Ru-P bond lengths of 2.4815(17)–2.5034(15) and 2.2738(18)–2.2772(18) Å, respectively. The RuïRu distance is nonbonding, 3.350(2) Å, which is atypical of Ru(II) complexes.