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A family of homodinuclear Ln3+ (Ln3+ = Gd3+, Eu3+) luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] has been developed to study the effect of the β-diketonato and N-oxide ligands on their thermometric properties. The investigated complexes are [Ln2(tta)6(pyrzMO)2] (Ln = Eu (1·C7H8), Gd (5)), [Ln2(dbm)6(pyrzMO)2] (Ln = Eu (2), Gd (6)), [Ln2(bta)6(pyrzMO)2] (Ln = Eu (3), Gd (7)), [Ln2(hfac)6(pyrzMO)3] (Ln = Eu (4), Gd (8)) (pyrzMO = pyrazine N-oxide, Htta = thenoyltrifluoroacetone, Hdbm = dibenzoylmethane, Hbta = benzoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone, C7H8 = toluene), and their 4,4′-bipyridine N-oxide (bipyMO) analogues. Europium complexes emit a bright red light under UV radiation at room temperature, whose intensity displays a strong temperature (T) dependence between 223 and 373 K. This remarkable variation is exploited to develop a series of luminescent thermometers by using the integrated intensity of the 5D0 → 7F2 europium transition as the thermometric parameter (Δ). The effect of different β-diketonato and N-oxide ligands is investigated with particular regard to the shape of thermometer calibration (Δ vs T) and relative thermal sensitivity curves: i.e.. the change in Δ per degree of temperature variation usually indicated as Sr (% K–1). The thermometric properties are determined by the presence of two nonradiative deactivation channels, back energy transfer (BEnT) from Eu3+ to the ligand triplet levels and ligand to metal charge transfer (LMCT). In the complexes bearing tta and dbm ligands, whose triplet energy is ca. 20000 cm–1, both deactivation channels are active in the same temperature range, and both contribute to determine the thermometric properties. Conversely, with bta and hfac ligands the response of the europium luminescence to temperature variation is ruled by LMCT channels since the high triplet energy (>21400 cm–1) makes BEnT ineffective in the investigated temperature range., A family of homodinuclear Eu3+ luminescent complexes with the general formula [Ln2(β-diketonato)6(N-oxide)y] (y = 2, 3) was developed to study the effect of the β-diketonato and N-oxide ligands on the thermometric properties of the complexes. In this way, an effective tuning of the system’s thermometric properties can be achieved.

This paper reports three structurally characterised Ln(III) ternary complexes, [Ln(hfaa)3(Hind)n] {Ln = La (n = 3), Er and Yb (n = 2); hfaa = hexafluoroacetylacetone anion and Hind = indazole}, and their photophysical properties in the pure near infra-red (NIR) region. The hfaa and H-indazole were used as a sensitizer and antenna ligands, respectively, in the complexes. The single crystal XRD and solution NMR studies show that the La complex is nine-coordinate, while the Er and Yb complexes are octa-coordinated. The paramagnetic Er and Yb complexes show very fast longitudinal relaxation rates (ρ = 1/T1), which make them very useful for para-shift relaxation probes used in MRI. Upon UV excitation, erbium and ytterbium exhibit their characteristic luminescence in the pure NIR region (800–1600 nm). These could be very useful in various advanced applications ranging from optical communication to defence. The complexes showed the highest oscillator strength in dichloromethane followed by acetonitrile, and the oscillator strength was lowest in methanol since methanol molecules replaced the Hind ligands and provided a symmetrical ligand field around the Ln ions. The complexes in solid state showed stronger NIR photophysical properties compared to those in solution.

A new samarium complex [Sm(hfaa)3(Py-Im)] (ML) was synthesized by utilizing hexafluoroacetylacetone (hfaa) and 2-(2-pyridyl)benzimidazole (Py-Im) as coordinating ligands. Single crystal X-ray analysis shows that in the solid-state the complex dimerizes through intermolecular hydrogen-bonding with N-H?O (2.127 Å) and N-H?F (2.576 Å) interactions. The complex in the solid-state displayed highly monochromatic brilliant red emission with Commission International de I'Eclairage (CIE) color coordinates of 0.6532; 0.3336, with a remarkably long luminescence lifetime (?exp. ? 204.47 ± 4.043 ?s) and a high intrinsic quantum yield (QSmSm ? 6.60%). Furthermore, the complex in different organic media displayed color tunability from orange (CIE; 0.6071; 0.3568) to violet (CIE; 0.3634; 0.2144) with ?exp. from 105.50 ± 0.143 to 14.27 ± 0.033 ?s. Hybrid and flexible thin films obtained by doping different concentrations (1%, 2%, 4% and 6%) of the complex into the poly(urethane) (PU) polymer matrix also exhibited color tunability from violet (CIE; 0.3380; 0.2162) to light orange (CIE; 0.5666; 0.3408). White light emission from a 1% doped thin film of the complex was realized by changing the excitation wavelength. Thus, the new material could be a potential candidate for the fabrication of full-color display devices and for solid-state lighting (SSL) applications. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. F.279 Engineering and Physical Sciences Research Council: EP/K004956/1 SR/SQU/SCI/CHEM/16/02 MSK acknowledges His Majesty’s Trust Fund for Strategic Research (Grant No. SR/SQU/SCI/CHEM/16/02) for funding. RI thanks the HM’s Trust Fund for a post-doctoral fellowship. The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund). PRR is grateful to the Engineering and Physical Sciences Research Council (EPSRC) for continued support (Grant EP/K004956/1).

A series of electropolymerizable cyclometallated IrIII complexes were synthesized and their electrochemical and photophysical properties studied. The triphenylamine electropolymerizable fragment was introduced by using triphenylamine-2-phenylpyridine and, respectively, triphenylamine-benzothiazole as cyclometalated ligands. The coordination sphere was completed by two differently substituted β-ketoiminate ligands deriving from the condensation of acetylacetone or hexafluoroacetylacetone with para-bromoaniline. The influence of the -CH3 /-CF3 substitution to the electrochemical and photophysical properties was investigated. Both complexes with CH3 substituted β-ketoiminate were emissive in solution and in solid state. Highly stable films were electrodeposited onto ITO coated glass substrates. Their emission was quenched by electron trapping within the polymeric network as proven by electrochemical studies. The -CF3 substitution of the β-ketoiminate leads instead to the quenching of the emission and inhibits electropolymerization.

Reactions of (NBu4)[MOCl4] complexes (M = Tc or Re) with an excess of hexafluoroacetylacetone (Hhfac) give products with a composition of (NBu4)[MOCl3(hfac)] as bright yellow (Tc) or red (Re) solids. The products are stable as solids but rapidly decompose in solution. A number of related phenylimidorhenium(V) complexes were synthesized starting from [Re(NPhF)Cl3(PPh3)2], where (NPhF)2– is a para-fluorinated phenylimido ligand. Products with compositions of [Re(NPhF)Cl2(PPh3)(acac)], [Re(NPhF)Cl2(PPh3)(hfac)], [Re(NPhF)Cl2(PPh3)(tfac)], [Re(NPhF)Cl2(PPh3)(naphtfac)], and [Re(NPhF)Cl2(PPh3)(tbutfac)] (Hacac = acetylacetone, Htfac = trifluoroacetylacetone, Hnaphtfac = naphthoyltrifluoroacetylmethane, and Htbutfac = tert-butyroyltrifluoroacetylmethane) were isolated from reactions of the quite soluble [Re(NPhF)Cl3(PPh3)2] with the corresponding β-diketones and studied spectroscopically and by X-ray diffraction. The β-diketonates are coordinated in a meridional arrangement with the phenylimide. The formation o...

Previous work has shown that introduction of hexafluoroacetylacetone (Facac) units as nonstructural ligands for the zirconia-like nodes of the eight-connected metal–organic framework (MOF), NU-1000, greatly alters the selectivity of node-supported oxy-nickel clusters for ethylene dimerization vs oligomerization. Here we explore a related concept: tuning of support/catalyst interactions, and therefore, catalyst activity, via parallel installation of organic modifiers on the support itself. As modifiers we focused on para-substituted benzoates (R-BA–; R = −NH2, −OCH3, −CH3, −H, −F, and −NO2) where the substituents were chosen to present similar steric demand, but varying electron-donating or electron-withdrawing properties. R-benzoate-engendered shifts in the node-based aqua O–H stretching frequency for NU-1000, as measured by DRIFTS (diffuse-reflectance infrared Fourier-transform spectroscopy), together with systematic shifts in Ni 2p peak energies, as measured by X-ray photoelectron spectroscopy, show tha...

Hydrolysis of the 4-nuclear [Cu(hfac)(MeO)]4 complex (where hfac is the hexafluoroacetylacetone ion) can be used as a convenient way to obtain the 11-nuclear complex [Cu11(hfac)10(OH)8(O)2] · 2MePh. The structure of the latter is determined using X-ray diffraction.

Four new compounds of formulas [Cu(hfac)2(L)] (1), [Ni(hfac)2(L)] (2), [{Cu(hfac)2}2(µ-L)]·2CH3OH (3) and [{Ni(hfac)2}2(µ-L)]·2CH3CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN2O4 surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χMT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm−1] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm−1] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS1·S2). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties.

This paper presents three crystallographically and solution NMR (one- and two-dimensional) characterised ternary Ln(III) complexes, and their photo-physical and opto-electronic properties in the visible and NIR regions. The single crystal X-ray diffraction analysis indicates that the complexes are nona-coordinate with a chemical composition of [Ln(hfaa)3(Hind)3] (hfaa = anion of hexafluoroacetylacetone, Hind = indazole and Ln = Pr, Nd and Sm). The Ln ions, in the complexes, are coordinated to six O-atoms of three hfaa and three N-atoms of three monodentate Hind ligands, making the coordination polyhedra LnO6N3 with distorted monocapped square antiprismatic geometries, low symmetry structures that promote radiative transitions, suggesting efficient energy transfer from the organic ligands to the metal ion. The NMR analysis confirms the nona-coordinate structures and shows the isostructurality of the complexes in solution. The excitation of the complexes at 310 nm led to the characteristic of both visible and near infrared luminescence of the Pr, Nd and Sm complexes. The samarium complex displayed very strong orange-red luminescence. In contrast to the solution, the PMMA doped samples of the complexes showed an enhancement in the emission lifetime and the quantum yield. A triple layered NIR-emitting OLED, fabricated using the Nd-complex as an emitting layer, showed good optical and electrical performances.

The synthesis, characterization and photoluminescence studies of two new highly photoluminescent complexes, [Sm(hfaa)3(impy)2] and [Eu(hfaa)3(impy)2] (impy is 2-(1H-imidazol-2-yl)pyridine and hfaa is the anion of hexafluoroacetylacetone) are reported. The photoluminescence of these complexes were studied in solid, solution and PMMA thin films. These complexes were incorporated independently into polymer matrix of PMMA with varying amounts. The calculated quantum yield (φ) and experimental life time (τ) in solution for (i) Sm complex are φ = 0.013, τ = 0.036 ms and (ii) Eu complex are φ = 0.36, τ = 0.98 ms. The Judd–Ofelt intensity parameters, radiative parameters, intramolecular energy transfer rates and theoretical quantum efficiency are calculated and discussed. The intramolecular energy transfer rates, in the case of europium complex, suggest that the major energy transfer channels are T1 → 5D1 and T1 → 5D0 and these contribute 55.33% and 44.65%, respectively, to the overall energy transfer process. The emission colour changes with a change in concentration of the complexes in PMMA substrate. This feature may be employed in fabricating 'colour indicator diodes'. The thin hybrid films of these structurally ten-coordinate complexes in PMMA matrix exhibit outstanding photostability upon UV irradiation that defines their robust nature. The efficient photophysical properties of PMMA hybrids of these complexes, may possibly find their applications in optoelectronic devices.

Two neodymium(III) fluorou ternary complexes, [Nd(C5H2F6O2)3(C18H15OP)2] (C5H2F6O2 = hexafluoroacetylacetone, C18H15OP = triphenylphosphine oxide) (1) and [Nd(C5H2F6O2)3(C12H24N3O4P)2] (C5H2F6O2 = hexafluoroacetylacetone, C12H24N3O4P) = tri(4-morphollno) phosphine oxide) (2) have been synthesized by mild condition. The single crystals suitable for X-ray measurement were obtained and the structures of the two complexes were determined by X-ray diffraction in solid states. Single crystal analysis revealed that the two complexes were both eight-coordinated with one central Nd ion and eight O atoms from ligands. They were crystallized in monoclinic symmetry with P21/c and monoclinic symmetry C2/c space group, respectively. The complexes were characterized by IR-spectroscopy, thermogravimetric, elemental analyses and fluorescent. In fluorescence spectra, the two complexes both exhibit characteristic neodymium-centered emission.

Six rhenium(I) complexes are structurally compared, with regards to steric and electronic influences induced by the different β-diketone (benzoylacetone – Benzac, trifluoroacetylacetone – Tfaa and hexafluoroacetylacetone – Hfaa) and phosphine ligands (cyclohexyldiphenyl phosphine – PPh2Cy and dicyclohexylphenyl phosphine – PPhCy2). The complexes fac-[Re(Benzac)(CO)3(PPh2Cy)] (2), fac-[Re(Benzac)(CO)3(PPhCy2)] (3), fac-[Re(Tfaa)(CO)3(PPh2Cy)] (5), fac-[Re(Tfaa)(CO)3(PPhCy2)] (6), fac-[Re(Hfaa)(CO)3(PPh2Cy)] (8) and fac-[Re(Hfaa)(CO)3(PPhCy2)] (9) were synthesized by using the ‘2 + 1’ mixed ligand approach and characterized by means of IR, UV–Vis, 1H, 13C and 31P NMR and also X-ray diffraction, clearly showing the increase in the carbonyl stretching frequencies and downfield shifts in the 31P NMR as the fluoro atoms on the ligand backbone increases. The Tolman angles for the coordinated phosphine ligands are: 2 = 134.77°; 3 molecule A = 146.81°; 5 = 134.46°; 6 = 146.05°; 8 = 136.68° and 9 = 146.22°, illustrating the change in steric bulk as the cyclohexyl ligands on the phosphine ligands increase. A direct link is noted between the Re–P distances (2.4906(6) A for 2, 2.5213(17) A for 3 molecule A, 2.4865(16) A for 5, 2.5372(15) A for 6, 2.4906(14) A for 8 and 2.5365(16) A for 9), O,O′-bidentate ligand bite angles, O4–Re–O5, (85.12(6)° for 2, 83.34(13)° for 3 molecule A, 84.91(12)° for 5, 83.53(12)° for 6, 84.54(11)° for 8 and 83.7(2)° for 9) and the calculated dihedral angles (3.677(1)° for 2, 12.521(1)° for 3 molecule A, 1.489(7)° for 5, 12.463(11)° for 6, 2.940(7)° for 8 and 11.747(6)° for 9). The dihedral angle is calculated between the equatorial plane (Re1, C1, O1, C2, O2, O4, C5, C6, C7, O5) and the plane through Re1, O4, C5, C6, C7, O5. Dihedral angles of approximately four times larger are observed in complexes with coordinated PPhCy2 ligands compared to the PPh2Cy containing analogues, indicating the steric effect induced on the bidentate ligand by the extra cyclohexyl substituent on the PPhCy2 ligand.

The photochemistry of gas-phase 1,1,1-trifluoroacetylacetone (TFAA) and 1,1,1,5,5,5-hexafluoroacetylacetone (HFAA) excited with ultraviolet light involves a significant photoelimination channel producing HF and difluoromethylfuranone or pentafluoromethylfuranone, respectively. We report collisional self-quenching of the experimentally-determined relative quantum yield, and determine rate constants of 0.27 ± 0.03 and 0.33 ± 0.04 μs −1 , for HFAA and TFAA respectively. A strong collision model is consistent with the observed quenching. The data suggest that this elimination is the primary photochemical fate at low pressure in both cases. The TFAA rate constant is larger than that for HFAA, in spite of TFAA having half as many fluorine atoms as HFAA.

Abdulrahman H. Basher, Marjan Krstić, Takae Takeuchi, Michiro Isobe, Tomoko Ito, Masato Kiuchi, Kazuhiro Karahashi1, Wolfgang Wenzel, and Satoshi Hamaguchi, Journal of Vacuum Science & Technology A 38:2, (2020); licensed under a Creative Commons Attribution (CC BY) license., Thermal atomic layer etching (ALE) of nickel (Ni) may be performed with a step of thin-layer oxidation of its surface and another step of its removal by gas-phase hexafluoroacetylacetone (hfacH) as an etchant. In this study, adsorption of hfacH and possible formation of volatile nickel hexafluoroacetylacetonate Ni(hfac)2 on a NiO surface were investigated based on the density functional theory (DFT) with more realistic surface material models than those used in the previous study [A. H. Basher et al., J. Vac. Sci. Technol. A 38, 022610 (2020)]. It has been confirmed that an hfacH molecule approaching a NiO surface deprotonates without a potential barrier and adsorbs on the surface exothermically. In addition, stable adsorption of two deprotonated hfacH molecules on a NiO (100) surface was found to occur not on a single Ni atom but over a few Ni atoms instead, which makes the formation of a Ni(hfac)2 complex on the flat surface very unlikely even at elevated temperature. However, if the surface is rough and a Ni atom protrudes from the surrounding atoms, two hexafluoroacetylacetonate anions (hfac-) can bond to the Ni atom stably, which suggests a possibility of desorption of a Ni(hfac)2 complex from the surface at elevated temperature. Given the experimentally observed fact that desorption of Ni(hfac)2 complexes typically takes place on a NiO surface at a temperature of ∼300-400 °C, our DFT calculations indicate that the surface roughness of an oxidized Ni surface facilitates the formation and desorption of organometallic complexes Ni(hfac)2, and therefore, the resulting Ni surface after ALE can be smoother than the initial surface.

Abdulrahman H. Basher, Marjan Krstić, Takae Takeuchi, Michiro Isobe, Tomoko Ito, Masato Kiuchi, Kazuhiro Karahashi, Wolfgang Wenzel, and Satoshi Hamaguchi, Journal of Vacuum Science & Technology A 38:2, (2020); licensed under a Creative Commons Attribution (CC BY) license., Adsorption of enol hexafluoroacetylacetone (hfacH) on nickel oxide (NiO) fcc (100) and metallic Ni fcc (100) surfaces and the stability of the adsorbate was examined using first-principles quantum mechanical simulations. It was shown that an hfacH molecule can be unstable and dissociate on an Ni metal surface. On an NiO surface; however, an hfacH molecule can be deprotonated and form a hexafluoroacetylacetonate anion (hfac-) bonded stably with positively charged Ni atoms of the surface. The results are consistent with observations of the interaction of hfacH with NiO and Ni surfaces in earlier experiments. The results also explain the mechanisms of the adsorption steps in the thermal atomic layer etching of Ni based on the cyclic processes of surface oxidation and formation of volatile organo-nickel complexes.

Tuning the magnetic anisotropy of metal ions remains highly interesting in the design of improved single-molecule magnets (SMMs). We herein report synthetic, structural, magnetic, and computational studies of four mononuclear CoII complexes, namely [Co(hfac)2 (MeCN)2 ] (1), [Co(hfac)2 (Spy)2 ] (2), [Co(hfac)2 (MBIm)2 ] (3), and [Co(hfac)2 (DMF)2 ] (4) (MeCN=acetonitrile, hfac=hexafluoroacetylacetone, Spy=4-styrylpyridine, MbIm=5,6-dimethylbenzimidazole, DMF=N,N-dimethylformamide), with distorted octahedral geometry constructed from hexafluoroacetylacetone (hfac) and various axial ligands. By a building block approach, complexes 2-4 were synthesized by recrystallization of the starting material of 1 from various ligands containing solution. Magnetic and theoretical studies reveal that 1-4 possess large positive D values and relative small E parameters, indicating easy-plane magnetic anisotropy with significant rhombic anisotropy in 1-4. Dynamic alternative current (ac) magnetic susceptibility measurements indicate that these complexes exhibit slow magnetic relaxation under external fields, suggesting field-induced single-ion magnets (SIMs) of 1-4. These results provide a promising platform to achieve fine tuning of magnetic anisotropy through varying the axial ligands based on Co(II) bis(hexafluoroacetylacetonate) complexes.

Two new lanthanide complexes [Ln(hfaa)3(Py-Im)] [hfaa = hexafluoroacetylacetone, Py-Im = 2-(2-pyridyl)benzimidazole and Ln = Eu(III) (1) and Tb(III) (2)] were synthesized and characterized. An X-ra...

The modulation of the environment around the “PtI2” molecular fragment in the Pt(IV) cyclometalated complexes [PtI2(ppy) (facac)](1a) and [PtI2(ppy) (acac)] (1b) (Hfacac = hexafluoroacetylacetone; Hacac = acetylacetone) causes competition between halogens in the formation of leading intermolecular interactions. Particularly, the presence of the “organic fluorine” CF3 induces significant structural changes proving the key role that fluorine plays in crystal engineering in metallorganic systems.

The coordination polymers [ Ln ( β - dik ) 3 bpy ] ∞ 1 ·C7H8 (Ln = Eu, β-dik = dbm, tta, hfac; Ln = Tb; β-dik = dbm; Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac: hexafluoroacetylacetone) were easily assembled in mild conditions and high yields starting from the anhydrous lanthanide β-diketonates as nodes and 4,4′-bipyridine (bpy) as connector. X-ray single crystal studies have shown zigzag extended chains where lanthanide centres are 8-coordinated in a distorted square-antiprismatic geometry. Photoluminescence studies show bright red europium emission and spectral features dependent on the topology of the polymeric chains.

A new cobalt(II) complex, [Co(hfa)2(tmea)], derived from the multifluoro containing ligand hexafluoroacetylacetone (Hhfa) and N,N,N′,N′-tetramethylethane-1,2-diamine (tmea) has been prepared and characterized by elemental analyses, molar conductivity, and single-crystal X-ray crystallographic determination. The crystal of the complex is monoclinic: space group P21/n, a = 13.903(2), b = 10.406(1), c = 17.913(2) A, β = 111.342(2)°, V = 2414.0(5) A3, Z = 4, R1 = 0.0757, wR2 = 0.1575. The Co atom is coordinated by four O atoms from two hfa ligands, and two N atoms from tmea ligand, and generating octahedral coordination. The effects of the complex on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans were studied.

Abdulrahman H. Basher, Ikutaro Hamada, and Satoshi Hamaguchi. Jpn. J. Appl. Phys. 59 090905., In thermal atomic layer etching (ALE) of Ni, a thin oxidized Ni layer is removed by a hexafluoroacetylacetone (hfacH) etchant gas at an elevated surface temperature, and etching ceases when a metallic Ni surface appears (self-limiting step). However, atomistic details of the self-limiting step was not well understood. With periodic density-functional-theory calculations, it is found that hfacH molecules barrierlessly adsorb and tend to decompose on a metallic Ni surface, in contrast to the case of a NiO surface, where they can form volatile Ni(hfac)2. Our results clarify the origin of the self-limiting process in the thermal ALE.

The pressure of saturated and unsaturated vapor over solid and liquid scandium(III) complexes with acetylacetone Sc(acac)3, trifluoroacetylacetone Sc(tfac)3, and hexafluoroacetylacetone Sc(hfac)3 has been measured using a static method with glass membrane-gauge manometers and Knudsen effusion method with mass spectrometric gas phase monitoring. The temperatures and enthalpies of melting were measured for these compounds by differential scanning calorimetry. As a result of this study the thermal stabilities of investigated complexes were established, the temperature dependences of saturated vapor pressure were obtained, the thermodynamic characteristics of processes under study (ΔprH°T, ΔprS°T) were calculated. Thermal properties of these compounds were compared with literature data.

The reaction mechanism of atomic layer etching (ALE) process of Co thin films using Cl2 gas and diketone organic precursor hexafluoroacetylacetone (Hfac) has been investigated. In operando XPS featuring a reaction chamber directly connected to the XPS surface analysis chamber allows the study of the mechanism of ALE process of Co thin films with minimum surface contamination. Chlorine activated Co surfaces were investigated using in operando XPS that confirms the formation of CoCl2 and CoCl3. Hfac reacts with chlorinated Co surfaces to perform thermal etching surface chemical reactions at 140 °C. The chlorine removal rate upon exposure to Hfac follows a first order kinetics at 140 °C. The reaction mechanism elucidated by in operando XPS reveals that Hfac decomposes on chlorine activated Co surfaces suggesting a more complex reaction mechanistic pathway other than a simple adsorbate substitution reaction between chlorine and Hfac on Co surfaces. Moreover, the Co surface becomes smoother during the etching process.

Association of acetylacetone molecules with water was studied by means of infrared absorption spectroscopy aided by matrix isolation technique. The spectra of acetylacetone–water mixtures isolated in low temperature argon and nitrogen matrices revealed additional spectral bands, not observed in the spectra of pure substances, thus confirming the formation of hydrogen bonded complexes. The precise assignment of the spectral bands was performed by varying the sample concentration, performing annealing experiments and DFT B3LYP 6-311++G(3df, 3pd) calculations. Positions of the associated water bands indicate a medium strength hydrogen bond comparable to the one observed in the water trimers. The effect of hydrogen bond formation is rather minimal for the acetylacetone molecule and our experiments confirm no significant influence on an internal hydrogen bond structure or dynamics in the acetylacetone molecule. Similar conclusions are valid in the case of the D2O D2-acetylacetone complex. Different situation is observed when CH3 groups in acetylacetone are replaced with CF3 groups. The calculated energy of the complex is twice as small. This is also confirmed by a very small bounded OH stretch shift. This observation confirms that the electronic structure of the molecular groups even relatively far away from the hydrogen bond accepting atom has a large influence on its possibility to form a hydrogen bond.

A series of novel nona- and octacoordinate highly volatile and luminescent complexes, [Eu(hfaa)3(indazole)3] and [Ln(hfaa)3(indazole)2] (Ln = Tb, Dy, and Lu), were synthesized using a monoanionic bidentate hexafluoroacetylacetone (hfaa(-)) and a neutral monodentate indazole ligand. The X-ray diffraction analyses of their single-crystals indicate that the complexes are mononuclear. The Eu complex is nonacoordinate and has a distorted monocapped square antiprismatic structure whereas the terbium and dysprosium complexes are octacoordinate and possess a trigonal bicapped prism geometry. The indazole units are involved in π-π stacking interaction and N-H···F hydrogen bonding with the fluorine atoms of hfaa(-). The photophysical studies of indazole and the complexes show that the triplet states are at the appropriate positions and make ligand-to-metal energy transfer process efficient. A strong protective shield is provided by the coordination of three hfaa(-) moieties (which have low frequency C-F vibrational oscillators), and two/three ancillary indazole ligands around these metal ions ascribe higher quantum yields and longer radiative life times (ΦEu = 69% ± 10, 989 ± 1 μs, ΦTb = 33% ± 10, 546 ± 1 μs, and ΦDy = 2.5% ± 10, 13.6 ± 1 μs) to these novel compounds. The emission from europium, terbium, and dysprosium are, respectively, red, green, and yellow. Finally, these compounds were used, as emitting layers, to fabricate electroluminescent devices of their respective colors. The best devices are found with the following structure: ITO/CuPc (15 nm)/[Eu complex]:CBP or [Tb complex]:CBP or [Dy complex]:CBP (80 nm)/BCP (25 nm)/AlQ (30 nm)/LiF (1 nm)/Al (100 nm), which indicates an improved EL performance for the Eu device over the Eu devices reported in the literature. The ligand, indazole, is a good sensitizer for trivalent europium, terbium, and dysprosium ions. It together with hfaa(-) plays an important role in fabricating OLEDs, especially, processed at low temperature.

Europium(III) and yttrium(III) complexation processes in the extraction systems with β-diketones and amino acids were studied. The increase in the lanthanide distribution ratios in these systems is caused by the formation of mixed-ligand coordination compounds of lanthanides in these systems. The formation of mixed-ligand coordination compounds of lanthanides with β-diketones and amino acids in the organic phase was confirmed by IR and luminescence spectroscopy and quantum chemical calculations of the formation energies of mixed-ligand yttrium complexes with glycine and acetylacetone or hexafluoroacetylacetone. It was found that amino acid molecules form mixed-ligand compounds with lanthanide β-diketonates by coordinating the lanthanide ion by the oxygen ion of the carboxy group with retention of the betaine structure, while the amino acid NH3+ group is hydrogen-bonded to one oxygen atom of β-diketone. The possibility of effective use of europium tris-dibenzoylmethanate as a glycine receptor is demonstrated.

Summary. Volatile metal complexes of the group 4 elements Zr and Hf with hexafluoroacetylacetonate (hfa) have been studied using short-lived radioisotopes of the metals. The new technique of physical preseparation has been employed where reaction products from heavy-ion induced fusion reactions are isolated in a physical recoil separator – the Berkeley Gas-filled Separator in our work – and made available for chemistry experiments. Formation and decomposition of M(hfa)4 (M = Zr, Hf) has been observed and the interaction strength with a fluorinated ethylene propylene (FEP) Teflon surface has been studied. From the results of isothermal chromatography experiments, an adsorption enthalpy of −ΔHa = (57 ± 3) kJ/mol was deduced. In optimization experiments, the time for formation of the complex and its transport to a counting setup installed outside of the irradiation cave was minimized and values of roughly one minute have been reached. The half-life of 165 Hf , for which conflicting values appear in the literature, was measured to be (73.9 ± 0.8) s. Provided that samples suitable for α-spectroscopy can be prepared, the investigation of rutherfordium (Rf), the transactinide member of group 4, appears possible. In the future, based on the studies presented here, it appears possible to investigate short-lived single atoms produced with low rates (e.g., transactinide isotopes) in completely new chemical systems, e.g., as metal complexes with organic ligands as used here or as organometallic compounds.

The mechanism of thermal dry etching of cobalt films is discussed for a thermal process utilizing sequential exposures to chlorine gas and a diketone [either 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hexafluoroacetylacetone, hfacH) or 2,4-pentanedione (acetylacetone, acacH)]. The process can be optimized experimentally to approach atomic layer etching (ALE); a sequential exposure to Cl(2) and hfacH dry etchants at 140 °C is shown to proceed efficiently. The use of acacH as a diketone does not result in ALE with chlorine even at 180 °C, but the decrease of surface chlorine concentration and chemical reduction of cobalt is noted. However, thermal desorption analysis suggests that the reaction of chlorinated cobalt surface exposed to the ambient conditions (oxidized) with hfacH does produce volatile Co-containing products within the desired temperature range and the products contain Co(3+). The effect of adsorption of ligands on the energy required to remove surface cobalt atoms is evaluated using the density functional theory.

Pt nanoparticles were grown on titanium oxide and tungsten oxide at 200 °C by Pt atomic layer deposition (ALD) using platinum(II) hexafluoroacetylacetonate [Pt(hfac)2] and formalin as the reactants. The Pt ALD surface chemistry and Pt nanoparticles were examined using in situ Fourier transform infrared (FTIR) vibrational spectroscopy and ex situ transmission electron microscopy (TEM). The FTIR spectra identified the surface species after the Pt(hfac)2 and formalin exposures on TiO2. An infrared feature at ~2100 cm–1 in the FTIR spectrum after Pt(hfac)2 and formalin exposures on TiO2 was consistent with CO on Pt, revealing that Pt(hfac)2 and formalin exposures led to the formation of Pt nanoparticles. The FTIR spectrum of Pt(hfac)2 on TiO2 was very similar to the FTIR spectrum of hexafluoroacetylacetone (hfacH) on TiO2. The FTIR spectra also revealed that hfacH blocked the adsorption of Pt(hfac)2 on TiO2. The coverage of the Pt nanoparticles could be reduced by preadsorbing hfacH on TiO2 prior to Pt(hfac)2 adsorption. Time-dependent FTIR spectra showed that the coverage of hfacH and its adsorption products were reduced versus time following hfacH exposure. Pt ALD on WOx at 200 °C led to the growth of Pt nanoparticles that were fairly similar to the Pt nanoparticles from Pt ALD on TiO2. The TEM images revealed that the size of the Pt nanoparticles on WOx could be adjusted by varying the number of Pt ALD cycles. Because of site-blocking by the hfac ligands, the Pt(hfac)2 and formalin reactants required many more ALD cycles for nucleation and growth compared with other Pt ALD surface chemistries.

In the present study the interaction of lanthanide β-diketonate complexes with polyvinylpyrrolidone (PVP) has been systematically investigated using fluorescence spectroscopy. The emission of terbium complexes with hexafluoroacetylacetone (hfa) ligands is almost completely quenched by PVP in the absence of H(+) ions, while it is enhanced by more than 30 times in the presence of H(+) ions. Conversely, the H(+) ions increase the quenching efficiency of terbium complex with acetylacetone ligands. The strikingly different behavior of complexes with fluorinated and nonfluorinated β-diketonates is accounted for by the interaction mechanism, in which the important role of hydrogen bonds is indicated. The proposed mechanism includes ion-dipol Coulombic interactions between negative charge localized on ligands O-C-CH2-C-O group and positive charge induced in N atom of PVP pyrrolidone group, as well as interactions through hydrogen bonds formed between ligand C-O groups and PVP, occurring directly or through solvent molecules. Additional stabilizing effect, significantly influencing the binding strength of ligands with PVP, results from hydrogen bonds formed by terminal (CF3 or CH3) substituents of ligands with C-O group of PVP. Importantly, the quenching and enhancement of luminescence of terbium complexes with hfa ligands in PVP solution is a reversible process. This enables one to obtain the emission switch-OFF-ON system triggered externally by H(+) ions, which can find possible application in the development of molecule-based devices.

Four complexes based on rare earth biradicals [Ln(hfac)3(NITPhmbis)2]2 {Ln = La (1), Nd (2), Gd (3), Tb (4); hfac = hexafluoroacetylacetone; NITPhmbis = [1,3-bis(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4,5-hydro-1H-imidazol-2-yl)benzene]} were successfully synthesized under appropriate conditions. Single-crystal structures show that 1 is a mononuclear two spin complex and 2–4 are mononuclear three spin complexes, in which a NITPhmbis molecule acts as a bidentate ligand with one coordinated lanthanide ion. The four complexes are isomorphous, the coordination number around the lanthanide ion is eight, and the polyhedron is a 4,4-bicappped trigonal prism. For lanthanum(III) complex 1, the temperature dependence of the magnetic susceptibility indicates that weakly antiferromagnetically coupled radicals exist (Jrad–rad = –1.2 cm–1). In the case of neodymium(III) complex 2, its magnetic behavior gives antiferromagnetic NdIII–radical interactions, whereas for complexes 3 and 4, static magnetic properties show that the GdIII and TbIII ions interact ferromagnetically with the radical. The dynamic magnetic properties of 4 were also measured, and 4 was found to exhibit slow relaxation of the magnetization at low temperature.

The synthesis and X-ray single crystal study of two mixed-ligand Cu(II) complexes are performed: (CH3C(NCH3)CHC(O)CH3)(CF3C(O)CHC(O)CF3)Cu (1) (space group P21/c, a = 7.0848(12) A, b = 17.854(3) A, c = 11.837(2) A, β = 100.495(6)°, V = 1472.4(4) A3, Z = 4), (CH3C(NC6H5)CHC(O)CH3)· (CF3C(O)CHC(O)CF3)Cu (2) (space group P-1, a = 9.1119(4) A, b = 9.6954(4) A, c = 11.1447(6) A, α = 113.784(2)°, β = 92.383(2)°, γ = 95.402(2)°, V = 893.52(7) A3, Z = 2). The structures are molecular, formed from neutral mixed-ligand copper complexes. The central copper atom has the (3O+N) coordination environment with average Cu-O distances of 1.948 A and Cu-N of 1.932 A; the chelate O-Cu-N angle (average) is 94.0°. In the structures, the complexes are linked into dimeric associates with Cu…Cu distances of 3.197 A (for 1) and 3.246 A (for 2). The volatility of mixed-ligand complexes 1 and 2 is in between of that of the starting homo-ligand complexes.

The luminescent Pt(II) complex [Pt(4,4′-tBu2-bipy){CC-(5-pyrimidinyl)}2] (1) was prepared by coupling of [Pt(4,4′-tBu2-bipy)Cl2] with 5-ethynyl-pyrimidine, and contains two pyrimidinyl units pendant from a Pt(II) bipyridyl diacetylide core; it shows luminescence at 520 nm which is typical of Pt(II) luminophores of this type. Reaction with [Ln(hfac)3(H2O)2] (hfac = anion of hexafluoroacetylacetone) affords as crystalline solids the compounds [1 · {Ln(hfac)3(H2O)}{Ln(hfac)3(H2O)2}] (Ln = Nd, Gd, Er, Yb), in which the {Ln(hfac)3(H2O)} unit is coordinated to one pyrimidine ring via an N atom, whereas the {Ln(hfac)3(H2O)2} unit is associated with two N atoms, one from each pyrimidine ring of 1, via N⋯HOH hydrogen-bonding interactions involving the coordinated water ligands on the lanthanide centre. Solution spectroscopic studies show that the luminescence of 1 is partly quenched on addition of [Ln(hfac)3(H2O)2] (Ln = Er, Nd) by formation of Pt(II)/Ln(III) adducts in which Pt(II)→Ln(III) photoinduced energy-transfer occurs to the low-lying f-f levels of the Ln(III) centre. Significant quenching occurs with both Er(III) and Nd(III) because both have several f-f states which match well the 3MLCT emission energy of 1. Time-resolved luminescence studies show that Pt(II)→Er(III) energy-transfer (7.0 × 107 M-1) is around three times faster than Pt(II)→Nd(III) energy-transfer (≈2 × 107 M-1) over the same distance because the luminescence spectrum of 1 overlaps better with the absorption spectrum of Er(III) than with Nd(III). In contrast Yb(III) causes no significant quenching of 1 because it has only a single f-f excited level which is a poor energy match for the Pt(II)-based excited state. © 2008 Elsevier Ltd. All rights reserved.

A series of organic–inorganic hybrids are prepared with magnetic mesoporous silica nanosphere supported europium(III) tetrakis(β-diketonate) complexes with ionic liquid compounds as linker {denoted as MMS·Im+·[Eu(β-diketonate)4]–}. Firstly, Fe3O4 nanoparticles were synthesized through the coprecipitation of ferrous and ferric ion solutions and were incorporated into mesoporous silica nanospheres. Secondly, europium(III) tetrakis(β-diketonate) complexes [β-diketonate = 2-thenoyltrifluoroacetonate (TTA), 4,4,4-trifluoro-1-phenyl-1,3-butanedionate (BTA), trifluoroacetylacetonate (TAA), acetylacetone (ACAC), hexafluoroacetylacetone (HFACAC)] and the ionic liquid 1-methyl-3-[3-(trimethoxysilyl)propyl]imidazolium chloride (Im+Cl–) were prepared. The ionic liquid was then covalently attached to the magnetic mesoporous silica nanospheres through the Si–O network. Finally, europium(III) tetrakis (β-diketonate) complexes were attached by an anion exchange reaction. The physical characterization, magnetic, and especially luminescent properties are discussed in detail. These results reveal that the resultant nanocomposites possess high surface area and superparamagnetic properties at 300 K. Additionally, the MMS·Im+·[Eu(TTA)4]– and MMS·Im+·[Eu(BTA)4]– hybrids exhibit high luminescent quantum efficiencies.

The paper reports the syntheses, 1 H NMR spectral and luminescence spectral studies of eight-coordinate Sm, Eu, Tb, Dy and Tm complexes of the type [Ln(hfaa) 3 (phen)] (hfaa = hexafluoropentanedione and phen = 1,10-phenanthroline). These complexes have been synthesized in high yields by modifying a method reported in literature for synthesizing similar complexes. Large up field and downfield shifts were observed in their 1 H NMR spectra. The lanthanide induced chemical shifts in these paramagnetic complexes are dipolar in nature. The H(2) and H(4) proton resonances of phen of the thulium complex have been shifted to highfields which is unusual. Inter- and intra-molecular chemical shift ratios are similar for Sm and Eu complexes as these are isostructural in solution. The quantum yields ( Φ = 46% for Eu, 32% for Tb, 2.7% for Sm and 2.1% for Dy) of the complexes indicate that energy transfer from ligands (hfaa and phen) to Ln(III) is efficient. The luminescence in the Dy(III) complex is the least intense due to poor intramolecular energy transfer match as compared to rest of the complexes. The lanthanide ions in these complexes have low symmetry sites.

A highly volatile air and moisture stable eight-coordinate samarium complex, [Sm(hfaa)3(pz)2] (hfaa = anion of hexafluoroacetylacetone and pz = pyrazole), has been synthesized and structurally characterized by single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c and the coordination polyhedron around the samarium ion is best describable as a distorted square antiprism. The NMR spectrum reveals that both the pz units remain coordinated to the samarium in solution. The quantum yield of the complex is determined to be 0.012 in solution. The lifetime of the complex is found to be 0.039 ms (χ2 = 1.071). The experimental intensity parameter (ηSm) is calculated for the complex.

The new complexes [Os11(bpy)2L](PF6) [bpy = 2,2′-bipyridine; HL = acetylacetone (Hacac), trifluoroacetylacetone (Htfacac), hexafluoroacetylacetone, dibenzoylmethane or tropolone] have been prepared and the chemical oxidation of the [OsII(bpy)2L]+ species (L = acac or tfacac) by aqueous S 2 O 8 2 - solution in the presence of (NH4)PF6 gave the reddish brown complexes [OsIII(bpy)2L](PF6)2. These complexes were characterized by spectroscopic measurements and also investigated by cyclic voltammetry. The X-ray crystal structure of [Os(bpy)2(acac)](PF6) (1) has been determined and showed that the complex has a distorted octahedral geometry in an environment of N4O2 donors. The reactivity toward oxidation of benzyl alcohol by complex (1) using H2O2 or other co-oxidants has been studied and compared with that of the related ruthenium(II) complexes.

A new biradical di(4-(1′-oxyl-3′-oxido-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)phenyl) ether (1) and its copper complex 2 were synthesized and characterized structurally. The X-ray structure determination revealed that, the complex is in the triclinic P-1 space group and displays a ladder-like structure. Each copper atom is surrounded by four oxygen atoms from hexafluoroacetylacetone and two oxygen atoms from biradical. The magnetic measurements show that biradical 1 exhibits a weak intramolecular nitroxide-nitroxide antiferromagnetic coupling and copper complex 2 possesses weak ferromagnetic coupling (J=5.09 cm−1) between CuII and radical, which attributed to interaction between copper spin and the axially coordinated nitronyl nitroxide spin.

Dynamic nuclear polarization experiments were performed to study the solutions of the stable free radical alpha,gamma-Bisdiphenylene-beta-phenyl allyl complex with benzene (1:1) in some highly fluorinated aliphatic and aromatic solvents. In solutions examined in this study, the Overhauser effect, which normally arises due to both dipolar and scalar interactions between the unpaired electrons of the free radical molecules and fluorine nuclei of solvent molecules occurs mainly. 1-Iodotridecafluorohexane, 2,2,3,4,4,4-Hexafluoro-1-butanol, N-methyl-bis-trifluoroacetamide, hexafluoroacetylacetone, octafluorotoluene, and hexafluorobenzene were used as the solvents. The experiments were performed at a low field double resonance NMR spectrometer, which operates at 1.53 mT. The NMR enhancements depend on competition between intermolecular magnetic interactions. The measurements were performed at four different temperatures to test the dipolar and the scalar part of the coupling between the fluorine nucleus (F-19) and the unpaired electron. It was found that the dipolar interactions are more effective for the aliphatic solvents, while the scalar interactions are more effective for the aromatics. The nuclear-electron coupling parameter varies between 0.018 and 0.157 in all aliphatic solvents and between -0.063 and -0.035 in aromatic solvents.

The structure of the hexanuclear copper(II) β-diketonate complex with gfa (hexafluoroacetylacetone) and dpm (dipivalylmethanate) ligands was studied by low-temperature (T = 100 K) X-ray diffraction. Crystal data for Cu6(gfa)4(dpm)4(OH)4 [C64H84Cu6F24O20]: a = 28.2364(7) A, b = 12.8072(3) A, c = 24.7199(7) A, β= 115.900(1)°, V = 8041.5(4) A3, space group C2/m, Z = 4, d calc 1.661 g/cm3. The coordination polyhedra of the copper atoms — squares and octahedra — are formed by the oxygen atoms of the gfa and dpm ligands and groups. In all cases, the Cu-O distances vary from 1.89 A to 2.13 A. The complexes follow the sites of the rhombohedral sublattice with the parameters a c ≈ 14.4 A and a c ≈ 61.5°.

We have examined the solute–solvent interactions by measuring Raman spectra of CO2 in neat supercritical CO2 (sc-CO2), and sc-CO2 containing β-diketones (acetylacetone, trifluoroacetylacetone, and hexafluoroacetylacetone) and uranyl β-diketonato complex [UO2(hfacac)2DMSO] (hfacac: hexafluoroacetylacetone, DMSO: dimethyl sulfoxide). As a result, it was found that the Raman bands of sc-CO2 containing β-diketones are shifted to lower wavenumber compared with those of neat sc-CO2 and that such a red-shift is not observed in sc-CO2 containing UO2(hfacac)2DMSO. From these results, it was suggested that the Lewis acid–Lewis base (LA–LB) interactions between carbonyl oxygens of β-diketones and CO2 carbon, and the hydrogen bondings between OH of β-diketones and CO2 oxygen are formed in sc-CO2 containing β-diketones, and that the shifts in Raman bonds of sc-CO2 can be used as the measure of CO2-philicity of solutes in sc-CO2. On the basis of such results, we measured Raman spectra of CO2 in sc-CO2 containing compounds with different donicity. As a result, we found out that the wavenumbers (νl) of Raman bands of CO2 correlate with the donor number (DN) of compounds, i.e., νl = 1281.24–0.0109 DN at 25.0 MPa and 40 °C.

Two mononuclear Dy(III) complexes, [Dy(III)(hfac)3(tmphen)] (1) and [Dy(III)(acac)3(tmphen)]·2H2O (2) (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline, hfac = hexafluoroacetylacetone, acac = acetylacetone) have been synthesized and structurally characterized by single crystal X-ray diffraction. Magnetic properties indicate that both of the complexes exhibit SMM behavior, and complex 1 is the first typical derivative of phenanthroline containing D2d-Dy(III) based mononuclear single molecule magnets. The energy barrier (Ueff/kB) of complex 2 (130.42 K) is much higher than that of complex 1 (35.09 K), indicating that the local symmetry of Dy(III) ions (D2d for 1, D4d for 2) plays an important role in magnetic behaviors.

The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE–β-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants ( β s,1 ) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE–β-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE–β-diketone chelates and the cobalt(III) chelates.

Hexafluoroacetylacetonate hafnium(IV) complex has been synthesized and studied by X-ray structural analysis. Crystal data for C30H8F36Hf2O14 are: a = 12.957(3) A, b = 16.687(3) A, c = 12.398(3) A, β = 108.97°, space group P21/c, Z = 2, dcalc = 2.137 g/cm3, R = 0.047. The molecular structure is built from discrete binuclear molecules of Hf2(OH)2(hfac)6 composition; the Hf...Hf distance in dimer is 3.533 A. The structural units are connected by van der Waals interactions in the crystal.

Copper was etched from a silicon surface using the chelator hexafluoroacetylacetone (hfacH) dissolved in supercritical carbon dioxide (scCO2) at 40−60 °C and 100−250 atm. Copper was deposited on Si(100) using doped HF solutions in the form of 10−90 nm Cu islands, as shown by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) indicated the islands were composed of Cu(I)2O due to air exposure before etching was attempted. Oxidation of the Cu(I) was performed using aqueous 30% H2O2 or a UV−Cl2 gas phase, forming shells of Cu(II)O or Cu(II)Cl2, respectively, surrounding cores of Cu(I)2O. SEM images showed that the Cu(II)O had a flake morphology. The Cu(II) shells were removed selectively to the Cu(I)2O cores by processing with pure scCO2 and rapidly releasing the system pressure (300 atm/min). Mechanical failure of the Cu(II)O and Cu(II)Cl2 when CO2 in stress corrosion cracks quickly expanded delaminated these layers, leaving only Cu(I)2O on the surface. Etching of both Cu(II) and Cu(I...

Precious metals including copper, gold, and palladium can be dissolved in supercritical CO2 by oxidation with HNO3 and subsequent chelation with hexafluoroacetylacetone to form CO2-soluble metal β-...

Ultrasonic irradiation with the frequency of 20–22 kHz and absorbed acoustic power about 0.4 W ml–1 causes degradation of An(IV) tetrakis-β-diketonates, AnL4, where An(IV) is Th(IV), Np(IV), and Pu(IV), and HL is hexafluoroacetylacetone (HFAA) and dibenzoylmethane (HDBM), in hexadecane solutions in the presence of argon. The rate of the sonochemical process corresponds to a first-order kinetic law with respect to metal β-diketonate concentrations. The first-order rate constant of sonolysis increases with the increase in the volatility of the metal complexes. Solid sonication products consisted of a mixture of actinide carbides and partial degradation products, PDP, of initial metal β-diketonates. It is assumed that metal carbides are formed within the cavitating bubbles as a result of high-temperature process with participation of actinide(IV) β-diketonates and solvent vapours. PDP formation is attributed to the thermolysis of the complexes in a liquid reaction zone surrounding the cavitating bubble. To cite this article: S.I. Nikitenko et al., C. R. Chimie 7 (2004).

This work proposes a simple and inexpensive method to prepare a new series of β-diketonate-tantalum complexes. The method is based on the use of a [TaF7](2-) solution, as the tantalum precursor, thenoyltrifluoroacetone (TTA), hexafluoroacetylacetone (HFA), and benzoyltrifluoroacetylacetone (BFA) in basic medium; basic pH is achieved by adding urea to the reaction medium. Elemental analysis, H(1)-NMR spectroscopy, potentiometric measurements conducted with a fluorine-selective electrode, conductivity measurements, vibrational spectroscopy based on quantum chemistry calculations, and electronic spectroscopy helped in determining the molecular structure of the complexes. At room temperature in the solid state and in solution upon irradiation with UV light, the complexes exhibited blue emission, probably as a result of the heavy atom effect. On the basis of the structures, luminescence properties at room temperature, and solvent-dependent changes in the electronic properties of the complexes, these β-diketonates are potentially applicable as optical ethanol or humidity sensors and are promising materials for the development of luminescent devices.