Study of temperature dependencies of saturated vapor pressure of ruthenium(III) beta-diketonate derivatives

Complexes of ruthenium(III) with the following beta-diketones: 2,4-pentanedione (Ru(acac)₃), 1,1,1-trifluoro-2,4-pentanedione (Ru(tfac)₃), 2,2,6,6-tetramethyl-3,5-heptanedione (Ru(thd)₃), 2,2,6,6–tetramethyl-4-fluoro-3,5-heptanedione (Ru(tfhd)₃) and 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione (Ru(ptac)₃) were synthesized and identified by means of mass spectrometry. By effusion Knudsen method with mass spectrometric registration of gas phase composition the temperature dependencies of saturated vapor pressure were measured for ruthenium(III) compounds and the thermodynamic characteristics of vaporization processes enthalpy ΔH _T* and entropy $ \Updelta S^{\text{o}}_{T*} $ of this complexes were determined.     

Simple and highly diastereoselective synthesis of trifluoromethyl-containing myosmines via reaction between 2-(aminomethyl)pyridine and 1,1,1,5,5,5-hexafluoro-2,4-pentanedione

The reaction between 1,1,1,5,5,5-hexafluoro-2,4-pentanedione and 2-(aminomethyl)pyridine, or its salts with carboxylic acids, was found to produce a mixture of diastereomeric 2-(2′-pyridyl)-3-hydroxy-3,5-bis-trifluoromethyl-1-pyrrolines with high (up to 85% de) of kinetic (3R*,5S*)-diastereoselectivity. The thermodynamic (3R*,5R*) diastereomer was prepared as a major product (90% de) by epimerization of the kinetic (3R*,5S*) diastereomer with triethylamine.     

Thermodynamic characteristics of phase conversion of structural isomers for volatile complex of ruthenium (III) trifluoroacetylacetonate

The comprehensive analysis of volatile β-diketonate compound—ruthenium(III) trifruoroacetylacetonate (Ru(tfac)₃)—was carried out. By means of flow method in quasi-equilibrium conditions and static method the temperature dependencies of saturated vapor pressure have been measured over solid and liquid cis- and trans-modifications of Ru(tfac)₃ and isomer mixture. The thermodynamic characteristics of sublimation, evaporation, melting, and phase conversion have been calculated for structural isomers. Also by differential-scanning calorimetry the temperature meanings and the thermodynamic characteristics of melting have been determined for individual isomers of Ru(tfac)₃ and their mixtures. By XRD the structures for cis- and trans-modifications have been determined. Both structures consist of neutral molecules arranged in pseudo layers.     

Phenyl bismuth β-diketonate complexes: Synthesis and structural characterization

The first examples of arylbismuth diketonate complexes are reported. Phenylbismuth(III) bis(hexafluoroacetylacetonate), BiPh(hfac)₂ (1) and its adducts [BiPh(hfac)₂(L)] (Hhfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; L = H₂O (1a), Me₂CO (1b), THF (1c), DMA (N,N-dimethylacetamide) (1d), DMSO (1e), PhCN (1f), as well as a mixed hexafluoroacetylacetonate-trifluoroacetate complex, [BiPh(hfac)(O₂CCF₃)]₂ (2), have been synthesized and characterized. Compound 1 is isolated from the reaction of BiPh₃ with 2 equiv. of Hhfac in dry hexanes. Compound 2 can be synthesized using two different routes: one utilizes the reaction between stoichiometric amounts of 1 and CF₃CO₂H, while the second method involves the interaction of the previously described BiPh₂(O₂CCF₃) (3) with Hhfac. Crystallographic analysis of the [BiPh(hfac)₂(L)] adducts reveals a pentagonal pyramidal geometry around the metal center; similarly, the dinuclear [BiPh(hfac)(O₂CCF₃)]₂ complex is composed of two distorted pentagonal pyramids connected into dimers by the bridging carboxylate groups. The effect of replacing the Lewis base in the coordination sphere of Bi(III) on the coordination polyhedron and crystal packing is discussed. The ¹H and ¹⁹F NMR spectra of the title complexes at room temperature indicate single environments for the hfac group and suggest that they are fluxional in solutions on the NMR time scale. Compounds 1 and 2 are promising starting materials in the chemistry of bismuth(III) and as building blocks for the construction of heterometallic species.     

Volatility and thermal stability of vanadyl β-diketonate complexes

Thermal behavior and thermodynamic characteristics of vanadyl β-diketonates—acetylacetonate VO(acac)₂, dipivaloylmethanate VO(thd)₂, and tris-hexafluoroacetylacetonate VO(hfa)₂ (Hacac, 2,4-pentanedione; Hthd, 2,2,6,6-tetramethyl-3,5-heptanedione; Hhfa, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione)—have been studied by thermal analysis and the Knudsen effusion mass spectrometry study of gas phase composition. The compounds have been shown to undergo congruent sublimation. Saturated vapor over the complexes has been shown to comprise monomeric VOL₂ molecules. Absolute values of partial pressures and sublimation enthalpies of these compounds have been determined.     

Sulfanylamide-containing coordination compounds of 3d-elements with 2,4-pentanedione bis-thiosemicarbazone and bis-4-phenylthiosemicarbazone

Thiosemicarbazide and 4-phenylthiosemicarbazide react in ethanol with 2,4-pentanedione in the presence of manganese, cobalt, nickel, copper, and zinc acetates hydrates and streptamin (Sf¹), sulfaethidole (Sf²), and sulfadimidine (Sf³) to form coordination compounds of the composition M(Sf^1–3)(L^1–2) · nH₂O (M = Mn, Co, Ni, Cu, Zn; H₂L¹ is 2,4-pentanedione bis-thiosemicarbazone, H₂L² is 2,4-pentanedione bis-4-phenylthiosemicarbazone; n = 0–6). All the complexes synthesized are monomeric. Thiosemicarbazones (H₂L¹ and H₂L²) behave as twice deprotonated S,N,N,S-tetradentate ligands, while sulfanylamides (Sf^1–3) act as monodentate ones. Thermolysis of these substances proceeds through the stages of dehydration (65–95°C) and complete thermal decomposition (430–560°C). It is found that the complex [Cu(Sf²)(L¹)] · 4H₂O in the concentration 10^?5 M inhibits the growth and fission of 100% cancer cells of the human myeloid leukemia (HL-60).     

Investigation of thermal properties of ruthenium(III) Β-diketonate precursors for preparation of RuO2 films by CVD

By means of a tensimetric flow method and a static method with a silica-membrane zero gauge, the dependence of vapour pressure on temperature was obtained for tris(2,4-pentanedionato)ruthenium(III), Ru(aa)₃, and tris(1,1,1-trifluoropentane-2,4-dionato)ruthenium(III), Ru(tfa)₃. The thermodynamic characteristics of vaporization and sublimation of these complexes were determined. The processes of thermal decomposition of the vapour of the compounds in vacuum, hydrogen and oxygen were investigated by using mass spectrometry in the temperature range 170–550C for Ru(aa)₃ and 150–620C for Ru(tfa)₃. The threshold temperatures of the stability of the vapour of the complexes and the rate constants of the thermolysis processes were determined. The main gaseous products of the thermal decomposition and the dependences of their composition on the presence of hydrogen and oxygen were established.     

Acid–base equilibria of the aqua adducts of Ru(II) arene complexes with functionalised pyridines

Acid?Cbase equilibria of the aqua adducts of Ru(II) arene complexes, general formulae [(??⁶-p-cymene)Ru (L^1?3)Cl₂] where L¹?=?3-acetylpyridine (1), L²?=?4-acetylpyridine (2) and L³?=?2-amino-5-chloropyridine (3), then [(??⁶-p-cymene)Ru(HL⁴)Cl₂] with HL⁴?=?isonicotinic acid (4); [(??⁶-p-cymene)Ru(HL^5?8)Cl] where H₂L⁵?=?2,3-pyridine dicarboxylic acid (5), H₂L⁶?=?2,4-pyridine dicarboxylic acid (6), H₂L⁷?=?2,5-pyridine dicarboxylic acid (7) and H₂L⁸?=?2,6-pyridine dicarboxylic acid (8) have been studied. pK _a values were determined by potentiometry at 25?°C and constant ionic strength of 0.1?M NaNO₃. The assumed equilibria were confirmed by UV and ¹H-NMR spectroscopy.     

Four tri-spin lanthanide–nitronyl nitroxide (LnIII = GdIII,DyIII, ErIII,and HoIII) complexes: syntheses,structures, and magnetic properties

Four radical–Ln(III)–radical complexes, [Ln(hfac)₃(NITPhSCH₃)₂] (Ln?=?Gd (1), Dy (2), Er (3), Ho (4); hfac?=?hexafluoroacetylacetonate; NITPhSCH₃?=?4′-thiomethylphenyl-4,4,5,5tetramethyl-imidazoline-1-oxyl-3-oxide), have been synthesized, and structurally and magnetically characterized. The X-ray crystal structures show that the structures of the four complexes are similar, consisting of isolated molecules in which Ln(III) ions are coordinated by six oxygen atoms from three hfac and two oxygen atoms from nitronyl radicals. The temperature dependencies of magnetic susceptibilities for the four complexes show that in the Gd(III) complex, ferromagnetic interactions between Gd(III)–radical and antiferromagnetic interactions between the radicals coexist with J _Rad–Gd?=?1.09?cm^?1, J _Rad–Rad?=??1.85?cm^?1.     

Synthesis and study of Cu<Superscript>II</Superscript> complex with nitroxide,a jumping crystal analog

We synthesized 1-ethylimidazolyl-substituted nitronyl nitroxides, i.e., 2-(1-ethylimidazol-4-yl)- (L^4Et) and 2-(1-ethylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide-1-oxyl (L^5Et). The stable radical L^5Et is an ethyl analog of 2-(1-methylimidazol-5-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole 3-oxide-1-oxyl (L^5Me) described earlier, the reaction of which with Cu(hfac)₂ (hfac is 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) leads to the formation of the [Cu(hfac)₂(L^5Me)₂] jumping crystals. The reaction of Cu(hfac)₂ with L^5Et with reagent ratios 1: 2 and 1: 1 yields heterospin complexes [Cu(hfac)₂(L^5Et)₂] and [Cu(hfac)₂L^5Et]₂, respectively. X-ray diffraction study of the mononuclear complex [Cu(hfac)₂(L^5Et)₂] determined that the compound has a packing similar to that of jumping crystals studied earlier, with the only difference being that the O...O contacts between neigh- boring nitroxide groups were found to be 0.3—0.5 Å longer than in [Cu(hfac)₂(L^5Me)₂]. As a result of the lengthening of these contacts, [Cu(hfac)₂(L^5Et)₂] crystals lack chemomechanical activi- ty. We found that when cooling crystals of binuclear complex [Cu(hfac)₂L^5Et]₂ below 50 K, the antiferromagnetic exchange between unpaired electrons of the >N—?O groups of neighboring molecules leads to the full spin-pairing of the nitroxides, with only the Cu²⁺ ions contributing to the residual paramagnetism of the compound.     

Reactions of [Cp*Ru(H2O)(NBD)]+ with alkynes

Formal [2 + 2 + 2] addition reactions of [Cp*Ru(H₂O)(NBD)]BF₄ (NBD = norbornadiene) with PhC?CR (R = H, COOEt) give [Cp*Ru(η⁶‐C₆H₅? C₉H₈R)] BF₄ (1a, R = H; 2a, R = COOEt). Treatment of [Cp*Ru(H₂O)(NBD)]BF₄ with PhC?C? C?CPh does not give [2 + 2 + 2] addition product, but [Cp*Ru(η⁶‐C₆H₅? C?C? C?CPh)] BF₄(3a). Treatment of 1a, 2a, 3a with NaBPh₄ affords [Cp*Ru(η⁶‐C₆H₅? C₉H₈R)] BPh₄ (1b, R = H; 2b, R = COOEt) and [Cp*Ru(η⁶‐C₆H₅? C?C? C?CPh)] BPh₄(3b). The structures of 1b, 2b and 3b were determined by X‐ray crystallography. Copyright © 2007 John Wiley & Sons, Ltd.     

Syntheses,crystal structures,and electrochemical properties of transition metal complexes with new tetrathiafulvalene-derivatized acetylacetonate ligands

Two new tetrathiafulvalene (TTF) derivatives of acetylacetone, namely, 3-[{6,7-benzo-2-(methylthio)-TTF-3-yl}-thio]-2,4-pentanedione (L₁) and 3-[{6,7-(ethylenedithio)-2-(methylthio)-TTF-3-yl}-thio]-2,4-pentanedione (L₂), have been synthesized. Four transition metal(II) complexes of these ligands, of general formulae [Zn(L₁)₂(THF)₂] and [M(L₂)₂(THF)₂] (M = Zn, Mn, and Ni), have been prepared and structurally characterized. The redox properties of both the ligands and their complexes were investigated by cyclic voltammetry. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Peng Zheng and Yun-Jun Guo contributed equally to this work.     

Crystals of the CuII complex with nitronyl nitroxide and imino nitroxide exhibiting mechanical activity

As part of continuing studies of multispin compounds capable of exhibiting chemomechanical activity, a series of heterospin solids of the composition [Cu(hfac)₂L _x L′_2?x ], [Cu(hfac)₂L′], [Cu₂(Piv)₄L′₂]·0.5C₆H₁₄, and [Cu₂(hfac)₂(Piv)₂L′2], where hfac is the hexafluoroacetylacetonate anion, L is 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, L′ is the imino nitroxide analog of L, viz., 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazole-1-oxyl, and Piv is the 2,2-dimethylpropionate anion, were synthesized and characterized. The packing of the synthesized crystals of the solid solutions [Cu(hfac)₂L _x L′_2-x ], where L predominates, is similar to that for [Cu(hfac)₂L₂], and these crystals are able to undergo chemomechanical motion. On the contrary, the crystals of [Cu(hfac)₂L _x L′_2?x ], where L′ predominates, have structural parameters similar to those of [Cu(hfac)₂L′₂] and do not exhibit thermally activated or photoactivated chemomechanical activity.     

Elucidating Interactions between DMSO and Chelate‐Based Ionic Liquids

The C?D bond stretching vibrations of deuterated dimethyl sulfoxide ([D₆]DMSO) and the C₂?H bond stretching vibrations of 1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione (hfac) ligand in anion are chosen as probes to elucidate the solvent–solute interaction between chelate‐based ionic liquids (ILs) and DMSO by vibrational spectroscopic studies. The indirect effect from the interaction of the adjacent S=O functional group of DMSO with the cation [C₁₀mim]⁺ and anion [Mn(hfac)₃]^? of the ILs leads to the blue‐shift of the C?D stretching vibrations of DMSO. The C₂?H bond stretching vibrations in hfac ligand is closely related to the ionic hydrogen bond strength between the cation and anion of chelate‐based ILs. EPR studies reveal that the crystal field of the central metal is kept when the chelate‐based ILs are in different microstructure environment in the solution.     

Ferro- and antiferromagnetic interactions in polymeric and molecular complexes of Cu(hfac)2 with 1-oxoazin-2-yl-substituted nitronyl nitroxides

Solid heterospin compounds based on Cu(hfac)₂ complexes with a new group of nitronyl nitroxides bearing different azine-N-oxide substituents at position 2 of the 2-imidazoline ring (Lⁿ) were studied. The major factor responsible for the change in the magnetic characteristics of the [Cu(hfac)₂L¹] complex with triazine nitronyl nitroxide with temperature was shown to be the specific pairwise packing of heterospin molecules with the dominant antiferromagnetic exchange between the radical fragments of adjacent molecules. For complexes of Cu(hfac)₂ with 1-oxoazin-2-yl-substituted nitronyl nitroxides L² and L⁴, 7-membered metallocycles were obtained, although they form rarely. It was shown that polymer chains formed in the solid complex with spin-labeled pyrazine-N-oxide [(Cu(hfac)₂)₃(L³)₂] due to the cross-linking of {(Cu(hfac)₂)₂(L³)₂} binuclear fragments via the bridging [Cu(hfac)₂].     

Adsorption properties of GaAs-CdS system

The adsorption properties of GaAs-CdS solid solutions and the constituent binary systems with respect to CO and NH₃ were studies by piezoquartz microweighing, temperature-programmed desorption, and IR spectroscopy. On the basis of an analysis of the measured α _p = f(T), α _T = f(p), and α _T = f(t) dependences, the thermodynamic and kinetic characteristics of adsorption, earlier obtained acid-base and other physicochemical characteristics of adsorbents, and the electronic properties of the adsorbate molecules, the mechanism and regularities of the adsorption processes at various conditions and compositions of the system were established. A comparison of the adsorption properties of the GaAs and CdS individual binary compounds with their (GaAs)_x(CdS)_1?x solutions, multicomponent systems, revealed common and distinctive features. Optimal compositions of adsorbents suitable for manufacturing primary transducers in sensors for medical and environmental purposes were determined.     

Structures and magnetic properties of copper(II) complexes containing tetrakis(2-pyridyl)methane

We designed spiro-fused dinculear complexes using tetrakis(2-pyridyl)methane (py₄C) for the development of ground high-spin molecules. We attempted to prepare a dinuclear copper(II) complex [{Cu(hfac)₂}₂(py₄C)], where hfac stands for 1,1,1,5,5,5-hexafluoropentane-2,4-dionate, but we obtained [Cu(hfac)₂(py₄C)] and [Cu(hfac)(py₄C) · Cu(hfac)₃]. These molecular structures were determined by the X-ray crystal structure analysis.     

Chronoamperometric study and X-ray analysis of Ru(II)-pdto (1,8-bis-(2-pyridyl)-3,6-dithiaoctane) complexes with substituted 1,10-phenanthrolines

This work presents cyclic voltammetry and double potential step chronoamperometry experiments corresponding to the electrochemical reduction of the substituted 1,10-phenanthroline ligands in the coordination compounds [Ru(pdto)(1,10-phenanthroline)]Cl₂ (1), [Ru(pdto)(5,6-dimethyl-1,10-phenanthroline)]Cl₂ (2), [Ru(pdto)(4,7-diphenyl-1,10-phenanthroline)]Cl₂ (3), [Ru(pdto)(4,7-dimethyl-1,10-phenanthroline)]Cl₂ (4) and [Ru(pdto)(3,4,7,8-tetramethyl-1,10-phenanthroline)]Cl₂ (5). These studies were performed in order to evaluate the stability of the electrogenerated chemical species. An EC_i mechanism for all the complexes was proposed and the rate constant value (k₁) for the chemical coupled reaction was estimated. The stability is discussed in terms of the rate constant value (k₁) and the π*-acceptor properties.     

An investigation of decomposition stages of a ruthenium polypridyl complex by non-isothermal methods

Thermal properties of [cis-(dithiocyanato)(4,5-diazafluoren-9-one)(4,4??-dicarboxy-2,2??-bipyridyl)ruthenium(II)], [Ru(L ₁)(L ₂)(NCS)₂] (where the ligands L ₁?=?4,5-diazafluoren-9-one, L ₂?=?4,4??-dicarboxy-2,2??-bipyridyl) have been investigated by DTA/TG/DTG measurements under inert atmosphere in the temperature range of 30?C1155?°C. The mass spectroscopy technique has been used to identify the products during pyrolytic decomposition. The pyrolytic final products have been analyzed by X-ray powder diffraction technique. A decomposition mechanism has been also suggested for the cis-[Ru(L ₁)(L ₂)(NCS)₂] complex based on the results of thermogravimetrical and mass analysis. The values of the activation energy, E* have been obtained by using model-free Kissenger?CAkahira?CSunose and Flyn?CWall?COzawa non-isothermal methods for all decomposition stages. Thirteen kinetic model equations have been tested for selecting the best reaction models. The best model equations have been determined as A2, A3, D1, and D2 which correspond to nucleation and growth mechanism for A2 and A3 and diffusion mechanism for D1 and D2. The optimized average values of E* are 31.35, 58.48, 120.85, and 120.56?kJ?mol^?1 calculated by using the best model equations for four decomposition stages, respectively. Also, the average Arrhenius factor, A, has been obtained as 2.21, 2.61, 2.52, and 2.21?kJ?mol^?1 using the best model equation for four decomposition stages, respectively. The ??H*, ??S*, and ??G* functions have been calculated using the optimized values.     

LAMMA mass spectra of β-diketone,bis(benzoylacetone)ethylenediimine and bis(salicylidene)ethylenediimine complexes of some transition metals

Complexes of 2,4-pentanedione (acetylacetone, acac), [Cu(acac)₂], [VO(acac)₂] and [CO(acac)₃], and the chromium(III) derivative of 3-methyl-2,4-pentanedione (methylacetylacetone, meac), [Cr(meac)₃], the ligands bis(benzoylacetone)ethylenediimine and bis(salicylidene)ethylenediimine, and their cobalt(II), nickel(II) and copper(II) chelates were analysed by laser desorption mass spectrometry (LAMMA) and compared to electron impact (EI) results. The positive ion LAMMA spectra generally reveal mostly small fragments, although metal cationization peaks are seen for most complexes. Negative ion LAMMA produce carbon clusters and some structurally important fragments.