Volatile Heterobimetallic Complexes from PdIIand CuIIβ-Diketonates: Structure, Magnetic Anisotropy, and Thermal Properties Related to the Chemical Vapor Deposition of Cu-Pd Thin Films

A novel approach for preparing volatile heterometallic complexes for use as precursors for the chemical vapor deposition of various materials is reported. New Cu¢Pd complexes based on b-diketonate units were prepared, and their structures and compositions were determined. [PdL2*CuL2] (1) and [PdL2*Cu(tmhd)2] (2) (L=2-methoxy-2,6,6-trimethylheptane-3,5-dionate; tmhd=2,2,6,6- tetramethylheptane-3,5-dionate) are 1D coordination polymers with alternating metal complexes, which are connected through weak interactions between the Cu atoms and the OCH3 groups from the ligand of the Pd complexes. The volatility and thermal stability were studied using thermogravimetric and differential thermal analyses and mass spectrometry. Compound 1 vaporizes without decomposition into monometallic complexes. It exhibits magnetic anisotropy, which was revealed from the angular variations in the EPR spectrum of a single crystal. The vapor thermolysis process for 1 was investigated using mass spectrometry, allowing the process to be framed within the temperature range of 200–3508C. The experimental data, supported by QTAIM calculations of the allowed intermolecular interactions, suggest that 1 likely exists in the gas phase as bimetallic molecules. Compound 1 proved to be suitable as a single-source precursor for the efficient preparation of Cu¢Pd alloy films with tunable Cu/Pd ratio. A possible mechanism for the film growth is proposed based on the reported data

MONITORING COMPOSITION AND STRUCTURE OF MOCVD ZrO2-BASED MULTICOMPONENT FILMS BY INNOVATIVE MIXED METAL-ORGANIC PRECURSORS

Three volatile mixed-metal precursors [ZrL4Pb(hfa)2] (1), [ZrL4PbL2] (2), and [ZrL4La(dpm)3] (3) (L = 2-methoxy-2,6,6-trimethyl-3,5-heptanedionate; dpm = 2,2,6,6-tetramethyl-3,5-heptanedionate; hfa = 1,1,1,5,5,5-hexafluore-2,4-pentanedionate) are used to prepare ZrO2-based multicomponent films by metalorganic chemical vapor deposition (MOCVD). The deposition experiments are carried out in a hot-wall reactor at 600-750 °C on silicon substrates under 20 Torr in the presence of oxygen. According to X-ray powder diffraction, the main crystal phases in the films prepared from precursors 1 and 2 are solid solutions based on tetragonal and cubic ZrO2. Lead does not form separate crystal phases but is dissolved in the oxide form within the ZrO2 matrix, as is indicated by X-ray photoelectron spectroscopy data. La2Zr2O7 films are prepared from 3 using two ways of precursor supply: evaporation in argon and by direct liquid injection (DLI). It is shown that the composition and structure of obtained films are determined by the precursor composition. The results obtained for thermal behavior of precursors in condensed and gas phases are discussed

Volatile iridium(I) complexes with β-diketones and cyclooctadiene: syntheses, structures and thermal properties

<p>A series of volatile mixed-ligand iridium(I) complexes [Ir(cod)(L)] (cod = cyclooctadiene-1,5, L = R¹C(O)CHC(O)R², R¹ = CF₃, R² = CF₃ – hfac <b>1</b>, Me – tfac <b>2</b>; ^<i>t</i>Bu – ptac <b>3</b>, Ph – btfac <b>4</b>, R¹ = R² = Me – acac <b>5</b>; ^<i>t</i>Bu – thd <b>6</b>) was synthesized and investigated in terms of usage in metal-organic chemical vapor deposition processes. Compounds <b>3</b> and <b>4</b> were obtained for the first time. All compounds were investigated by elemental analysis, NMR spectroscopy, thermogravimetry, and mass spectrometry. Crystal structures of <b>2</b>–<b>4</b> and <b>6</b> were determined by single-crystal XRD. The influence of β-diketonate ligand on the thermal properties of complexes in condensed and gas phase was revealed. The following volatility order was arranged: L = hfac <b>1</b> > tfac <b>2</b> ≈ ptac <b>3</b> > acac <b>5</b> > thd <b>6</b> > btfac <b>4</b>. Complexes <b>1</b> and <b>6</b> vapors demonstrated the lowest and the highest thermostability, respectively.</p

Volatile Pd–Pb and Cu–Pb heterometallic complexes: structure, properties, and <i>trans</i>-to-<i>cis</i> isomerization under cocrystallization of Pd and Cu β-diketonates with Pb hexafluoroacetylacetonate

<div><p>Preparation of volatile heterometallic precursors is a significant step on the way to advanced multicomponent materials. Study of molecular transformations in solution upon precursor synthesis is of importance to optimize the preparation of the stable solid product of desired composition. Two new volatile heterobimetallic complexes, <i>cis</i>-PdL₂*Pb(hfa)₂ and <i>cis</i>-CuL₂*Pb(hfa)₂, were obtained (L = 2-methoxy-2,6,6-trimethylheptane-3,5-dionate, hfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) under cocrystallization of <i>trans</i>-bis-beta-diketonates of Pd(II) and Cu(II) with Pb(hfa)₂ from organic solvents. Crystals of these compounds are built of discrete bimetallic molecules where transition metal complex isomerized from <i>trans</i>-to-<i>cis</i> form. Complexation followed by isomerization was studied by solution NMR. The bimetallic molecular species were formed early in solution. Enthalpy and activation energy of isomerization were estimated to be 49 and 93 kJ mol⁻¹, respectively. A new synthesis technique of Pd(II) beta-diketonates which is distinguished by simplicity and selectivity as well as the crystal structure of <i>trans</i>-PdL₂ is described. Volatility of all obtained compounds was confirmed by thermogravimetric analysis and fractional sublimation in vacuum; Pd-containing heterobimetallic complex appeared to be more volatile than both the initial monometallic complexes and Cu-containing complex.</p></div