Metal–Organic Chemical Vapor Deposition (MOCVD) is a vigorously growing technique for film production. Accurate vapor pressure, as well as sublimation and fusion thermodynamics of the precursor used in MOCVD is paramount for achieving the desired film composition, growth rates, uniformity, and functionality. Herein, we present the results of thermodynamic study of magnesium heteroligand complexes with aromatic neutral ligands Q = bipy (2,2′-bipyridine) or phen (1,10-phenanthroline), and hfac (1,1,1,5,5,5-hexafluoropentane-2,4-dionate anion). The complexes have been synthesized, purified, and identified. Differential scanning calorimetry has been applied to measure the melting temperature and fusion enthalpy. Saturated vapor pressures over the solid compounds were measured by a transpiration method. Thermodynamic characteristics of enthalpy and entropy of the sublimation process have been calculated from the experimental data at average temperature and at 298.15 K; the p(T) equations operating over a wide temperature range have been derived. [Mg(bipy)(hfac)2] was tested as an MOCVD precursor. Thermodynamic simulation has been executed to outline the conditions for film deposition formation in various reactive atmospheres. The critical importance of precise thermodynamic data on sublimation has been highlighted through a set of MOCVD experiments on the production of MgF2 films.

New data on the thermal behavior, sublimation, and melting of (hexafluoroacetylacetonato)(cyclooctadiene-1,5)copper, [Cu(cod)(hfac)], have been obtained. The condensed phase was studied by thermal and differential thermal analysis and differential scanning calorimetry. The temperature, enthalpy, and entropy of melting of the complex were determined. The temperature dependence of the saturated vapor pressure of [Cu(cod)(hfac)] in the temperature range 293–337 K was obtained by the Knudsen effusion method with mass spectrometric recording of the gas phase composition. The thermodynamic characteristics of sublimation were calculated at the average temperature over the experimental range and at 298.15 K: Δ_sublH_m^o (Tav) = 94.8 ± 1.5 kJ mol–1; Δ_sublS_m^o (Tav) = 200.9 ± 3.2 J mol–1 K–1; Δ_sublH_m^o (298.15 K) = 95.8 ± 3.1 kJ mol–1; Δ_sublS_m^o (298.15 K) = 203.5 ± 6.6 J mol–1 K–1. The obtained values are compared with data for a similar iridium(I) compound, [Ir(cod)(hfac)]. The results were used formulate approaches to evaluation of the thermodynamic properties of [M(cod)(hfac)] complexes to determine the optimum conditions for the deposition of metal-containing coatings. These approaches are necessary in those cases when compounds of this type (e.g., [Ag(cod)(hfac)]) are hypersensitive to heating and it is impossible to determine reliable thermodynamic characteristics experimentally.

Single crystals of Fe(dpm)3 (dpm - dipivaloylmethanate) are analyzed by X-ray diffraction in the temperature range of 90-365 K. A new crystal modification is found in the range of 90-100 K (space group P1̅ , Z = 8); a phase transition is confirmed to occur at 230 K (space group P1̅ , Z = 4). In the range of 250-365 K, a relative increase in the monoclinic unit cell parameters (space group C2/c, Z = 8) is Δa/a = 0.67

Разнолигандные комплексы магния со фторированными β-дикетонами и диаминами перспективны в качестве прекурсоров для получения тонких пленок MgF2 методом химического осаждения из газовой фазы (MOCVD). В настоящей работе проведено комплексное исследование наиболее летучего на данный момент представителя этого семейства, [Mg(tmeda)(ofhac)2] (tmeda = (CH3)2NCH2CH2CN(CH3)2, ofhac = C2F5COCHCOCF3–. Методом ДСК определены характеристики процесса плавления (Тпл. = 354.4 ± 0.6 K, ∆пл.Н = 23.3 ± 0.9 кДж/моль) и показано, что комплекс стабилен в конденсированной фазе как минимум до 473 K. Исследована температурная зависимость теплоемкости в интервале 298–403 K. Методом переноса в потоке гелия измерены температурные зависимости давления насыщенного пара над твердым (318–352 K) и жидким (358–393 K) комплексом. Определены термодинамические параметры сублимации и испарения. С помощью квантово-химических расчетов (B3LYP-D3(BJ) / def2-SVP, def2-TZVP и OPBE / TZ2P-J) проведено сравнение возможных изомеров комплекса (по положению C2F5-заместителей).

Mixed-ligand complexes of magnesium with fluorinated β-diketones and diamines are promising as precursors for the preparation of thin MgF2 films by metal-organic chemical vapor deposition (MOCVD). The currently most volatile representative of this family, [Mg(tmeda)(ofhac)2] (tmeda = (CH3)2NCH2CH2CN(CH3)2, ofhac = C2F5COCHCOCF _3^ - ), was studied. The melting process was characterized by DSC (Tm = 354.4 ± 0.6 K, ∆mH = 23.3 ± 0.9 kJ/mol). The complex was shown to be stable in the condensed phase up to at least 473 K. The temperature dependence of the heat capacity was studied in the range 298–403 K (DSC, using sapphire as a standard). The temperature dependences of the saturated vapor pressure over the solid (318–352 K) and liquid (358–393 K) complex were measured by transport in a helium flow. The thermodynamic parameters of sublimation and vaporization were determined. The possible isomers of the complex (based on the position of the C2F5 substituents) were compared using quantum-chemical calculations (B3LYP-D3(BJ)/def2-SVP, def2-TZVP, and OPBE/TZ2P-J).

An approach is proposed to design new lithium MOCVD precursors by minor ligand modification. It has been shown that β-ketoiminate ligand can significantly improve the properties of volatile lithium complexes compared to β-diketonate analogues. For this purpose, the structure and properties of two volatile lithium complexes with similar bulky ligands are compared: for β-diketonate Li(tmhd) (1) (tmhd=2,2,6,6-tetramethyl-heptane-3,5-dionate or dipivaloylmethanate, tBu-CO-CH-CO-tBu, where tBu=C(CH3)3) and β-ketoiminate Li(tmha) (2) (tmha= 2,2,6,6-tetramethyl-heptane-3-imino-5-onate, tBu-CO-CH-C(NH)-tBu). Compound 2 is new, and is formally derived from 1 by substitution of oxygen donor atom by NH-group. The compounds were prepared by the same technique and were studied by X-ray diffraction and IR and Raman spectroscopy. Molecular structure of these complexes is similar, built of tetrameric aggregates [LiL]4 with cubane-like Li4O4 core. Both 1 and 2 crystallize in C2/c space group with Z = 4 and Z’ = 0.5 but with different packing motif. According to DSC data, only 2 experiences a crystal-to-crystal phase transition at 384K, which manifests itself as a shift of molecular rows along the a axis, while geometry of [Li(tmha)]4and crystal space group remain unchanged. Analysis of intermolecular contacts using Hirshfeld surface analysis showed that [Li(tmha)]4 molecules are less densely packed compared to [Li(tmhd)]4. This explains the greater volatility of 2 compared to 1, due to the lower value of the lattice energy.

The reaction of [RuNO(Py)2Cl2OH] with bipyridine in water–ethanol media results in trans-(NO, OH)-[RuNO(Py)(Bpy)ClOH]+ with an acceptable yield (60–70%) as hexafluorophosphate salt. Further treatment of the hydroxy-complex with concentrated HF quantitatively leads to trans-(NO, F)-[RuNO(Py)(Bpy)ClF]+. Despite the chirality of both coordination spheres, the hexafluorophosphate salts crystallized as racemates. A NO-linkage isomerism study of the obtained complexes was performed at 80 K with different excitation wavelengths (405, 450, 488 nm). The most favorable wavelengths for the MS1 isomer (Ru-ON) formation were 405 and 450 nm, where the linkage isomer populations were 17% and 1% for [RuNO(Py)(Bpy)ClOH]PF6 and [RuNO(Py)(Bpy)ClF]PF6. The shift of the excitation wavelength to the green (488 nm) sharply decreased the MS1 population. The IR-spectral signatures of MS1 were registered. Reverse-transformation Ru-ON (MS1)-Ru-NO (GS) was investigated for [RuNO(Py)(Bpy)ClOH]PF6 using IR and DSC techniques that made it possible to determine the kinetic parameters (Ea and k0) and decay temperature.

New silver complexes [Ag(bipy)(CH3COCHCOR)]x with 2,2′-bipyridine (bipy) and β-diketonate ligands (tfac: R = CF3, x = 2; hfbac: R = C3F7, x = 1) are prepared as part of the search for precursors for the vapor deposition of films and silver nanoparticles. The compounds are characterized by elemental analysis, IR and 1H NMR spectroscopy; their crystal structures are determined by XRD. Both complex are molecular due to the bidentate-cyclic coordination of both ligands. The [Ag(bipy)(hfbac)] molecules are mononuclear due to the steric effect of the extended perfluoroalkyl chain. For L = tfac, a binuclear complex is formed due to the coordination of the methine carbon atom. Thermal properties of the new complexes are studied by TGA and DSC and compared with those of the known hexafluoroacetylacetonate analog [Ag(bipy)(hfac)]2. The temperatures and thermodynamic parameters of melting are determined for all the studied compounds.

Синтезирован первый пример комплекса Zr(IV) с ароматическим карбоксиамидатным лигандом, Zr(mba)4 (mba = N-метоксибензамидат). Установлено его строение в растворе (1H, 13C{1H} ЯМР) и кристаллической фазе (РСА) в сравнении с исходным N-метоксибензамидом Hmba. При комплексообразовании лиганды mba- проявляют бидентатно-циклическую функцию за счет атомов кислорода. Координационный полиэдр металла – искаженная квадратная антипризма, длины связей Zr-O с карбонильной и метоксигруппой лежат в интервалах 2.08-2.09 Å и 2.29-2.33 Å соответственно. Несмотря на наличие доступных фенильных колец, в кристаллах Zr(mba)4 и Hmba отсутствуют межмолекулярные π-π-взаимодействия, а проявляются C-H…π и N-H…O контакты соответственно. По данным ДСК, Hmba не проявляет фазовых превращений от 130 K до плавления (335.0 ± 0.5 K, ∆H = 15.1 ± 0.1 кДж/моль, ∆S = 45.2 ± 0.2 Дж/(моль·K)), тогда как для Zr(mba)4 обнаружено обратимое твердофазное превращение (Tonset = 177.4 ± 0.5K, ΔH = 0.68 ± 0.20 кДж/моль, ΔS = 3.8 ± 0.1 Дж/(моль·K)). Исследование кристаллов Zr(mba)4 при 150 и 200 K показало, что этот переход не сопровождается их деформацией и, по-видимому, обусловлен поворотом фенильных групп лигандов. При этом пространственная группа изменяется от P21/c до P21/n, один из параметров ячейки возрастает в 3 раза.

The crystal structure of new isostructural complex Tb(thd)3 (1), Ho(thd)3 (2) (sp. gr. Pmn21) and Tb(thd)3 (3), Dy (thd)3 (4), Er(thd)3 (5), Yb(thd)3 (6) (sp. gr. Pna21) are determined. The crystal structures of 1-6 are molecular and consist of discrete monomeric Ln(thd)3 molecules (Ln = Tb, Ho, Dy, Er, Yb). The samples of Ln(thd)3 in the solid state have been investigated over the temperature range from 120 to 300 K using differential scanning calorimetry. DSC curves Ln(thd)3 exhibit a single endothermic peak of the crystal-to-crystal reversible phase transition. First-order phase transition is accompanied by an abrupt change in the volume of the unit cell. The quantum chemical calculations allow one to conclude that the electronic structures of the three modifications for Tb tris-2,2,6,6-tetramethylheptane-2,4-dionates are some different. It has been shown that for Tb(III) complexes with thd-ligands the modification I is energetically more stable.

Scandium complexes with beta-diketonate ligands are valuable precursors for the metal-organic chemical vapour deposition (MOCVD) of scandia based materials. The technology has been constantly developing and demanding novel precursors with accurately defined thermal properties, which could be used in MOCVD as well as related gas phase processes. Two new complexes with 1,1-difluoroacetylacetone (dfac) and 5,5,6,6,6-pentafluorohexane-2,4-dione (5Fac) have been synthesized, isolated, and characterized. The volatility and condensed phase behaviour including thermal stability and phase transitions of the obtained compounds have been studied; the saturated vapour pressures over crystalline Sc(dfac)(3) and liquid Sc(5Fac)(3) complexes have been measured. As a result, the standard molar thermodynamic characteristics of melting, sublimation, and vaporization processes have been calculated. Thermal properties of these compounds have been compared with literature data on scandium(III) beta-diketonates already used as MOCVD precursor. These new compounds can be successfully used as precursors in the gas-phase deposition processes, and the set of obtained thermodynamic data can help in choosing the optimal deposition conditions.

First example of a Zr(IV) complex with an aromatic carboxyamidate ligand, Zr(mba)4 (mba = N-methoxybenzamidate), is prepared. Its structures in the solution (1H, 13C1H NMR) and in the crystal phase (single-crystal XRD) are determined and compared with those of the initial N-methoxybenzamide Hmba. During the complexation, mba– ligands exhibit a bidentate cyclic function through oxygen atoms. The coordination polyhedron of the metal atom is a distorted square antiprism, the lengths of Zr–O bonds with carbonyl and methoxy groups fall within 2.08-2.09 Å and 2.29-2.33 Å, respectively. Despite the presence of available phenyl rings, the Zr(mba)4 and Hmba crystals contain no intermolecular π–π-interactions, but exhibit C–H⋯π and N–H⋯O contacts, respectively. According to the DSC data, Hmba undergoes no phase transitions from 130 K up to the melting point (335.0±0.5 K, ΔH = 15.1±0.1 kJ/mol, ΔS = 45.2±0.2 J/(mol·K)), while Zr(mba)4 exhibits a reversible solid-phase transition (Tonset = 177.4±0.5 K, ΔH = 0.68±0.20 kJ/mol, ΔS = 3.8±0.1 J/(mol·K)). Studying the Zr(mba)4 crystals at 150 K and 200 K shows that this transition is not accompanied by the crystal deformation and is apparently caused by the rotation of phenyl groups. Due to this conversation, the space group changes from P21/c to P21/n, and one of the unit cell parameters increases by 3 times.

For the first time, the kinetics of decomposition of a metastable Ni 0.50 Ru 0.50 solid solution was studied under isothermal conditions using in situ powder XRD.

Предложена новая методика синтеза этилендиаминового комплекса [RuNO(en)2OH]J2 из K2[RuNOCl5], позволяющая увеличить выход целевого продукта до 76 %. Последующая обработка нитратной соли [RuNO(en)2OH](NO3)2 концентрированной HF с осаждением HClO4 приводит к получению [RuNO(en)2F](СlO4)2 с количественным выходом. По данным РСтА в катионном фрагменте [RuNO(en)2F]2+ нитрозо- и фторо-лиганды находятся в транс-положении друг к другу, а экваториальная плоскость в координационном окружении рутения образована четырьмя атомами азота этилендиаминовых лигандов. Облучение комплекса [RuNO(en)2F](СlO4)2 светом с длиной волны 450 нм при 80 К приводит к образованию метастабильного связевого изомера MS1 c координацией нитрозогруппы через кислород. По данным ИК спектроскопии достигаемая заселенность MS1 составляет около 1 % , а соответствующая полоса колебаний исчезает при нагреве в температурном интервале 280-310 К. Активационные параметры перехода MS1-GS (основное состояние) по данным ДСК равны Ea = 107.1±6.8 кДж/моль, lnk0 = 36.1±2.6.

Проведено рентгеноструктурное исследование монокристаллов Fe(dpm)3 (dpm – дипивалоилметанат) в интервале температур 90-365 K. Обнаружена новая кристаллическая модификация в интервале 90-100 K (пр. гр. Р, Z = 8), подтвержден фазовый переход при 230 K (пр. гр. Р, Z = 4). В диапазоне 250-365 K относительное увеличение параметров моноклинной ячейки (пр. гр. C2/c, Z = 8) составило Δa/a = 0.67, Δb/b = 1.16 и Δc/c = 0.47 %, угол  уменьшился на 3,3 %. В интервале 90-365 K относительное увеличение объема, приходящегося на одну молекулу, составило 6.65 %, причем средние значения расстояний Fe-O и хелатных углов O-Fe-O практически не изменились. Построены поверхности Хиршвельда для структур при температурах: 90, 130, 250 и 365 K. Изучены слои Fe(dpm)3, полученные напылением в вакууме (PVD) и кристаллизацией раствора при центрифугировании (spin coating) на разных неорганических подложках, установлена ориентация и проведен анализ особенностей структуры в направлениях [100] и [001].

Получены новые данные о термическом поведении и процессах сублимации и плавления (гексафторацетилацетонато)(циклооктадиен-1,5)меди, [Cu(cod)(hfac)]. Конденсированная фаза исследована методами термического и дифференциального термического анализа и дифференциальной сканирующей калориметрии: определены температура, энтальпия и энтропия плавления комплекса. Эффузионным методом Кнудсена с масс-спектрометрической регистрацией состава газовой фазы получена температурная зависимость давления насыщенного пара [Cu(cod)(hfac)] в интервале температур 293–337 K, рассчитаны термодинамические характеристики процесса сублимации при средней температуре экспериментального интервала и 298.15 K: ΔсублH0m (Tср) = 94.8 ± 1.5 кДж моль-1, ΔсублS0m (Tср) = 200.9 ± 3.2 Дж моль-1 K-1; ΔсублH0m (298.15 K) = 95.8 ± 3.1 кДж моль-1, ΔсублS0m (298.15 K) = 203.5 ± 6.6 Дж моль-1 K-1. Полученные величины сопоставлены с данными по аналогичному соединению иридия(I), [Ir(cod)(hfac)]. Результаты формируют подходы для оценки термодинамических свойств комплексов состава [M(cod)(hfac)] с целью определения оптимальных условий осаждения металлсодержащих покрытий. Подходы необходимы, когда соединения такого типа (например, [Ag(cod)(hfac)]) являются сверхчувствительными к процессу нагревания и отсутствует возможность определения надежных термодинамических характеристик экспериментальным путем.

В рамках поиска прекурсоров, пригодных для осаждения пленок и наночастиц серебра газофазными методами, синтезированы новые комплексы серебра [Ag(bipy)(CH3COCHCOR)]x c 2,2’-бипиридином (bipy) и β-дикетонатными лигандами (tfac: R = CF3, x = 2; hfbac: R = C3F7, x = 1). Соединения охарактеризованы с помощью элементного анализа, ИК- и 1H-ЯМР-спектроскопии, их кристаллическое строение установлено методом РСА. Оба комплекса являются молекулярными за счет бидентатно-циклической координации обоих лигандов. Молекулы [Ag(bipy)(hfbac)] вследствие стерического влияния удлиненной перфторалкильной цепи моноядерные, тогда как с L = tfac образуется биядерный комплекс за счет координации метинового атома углерода. Термические свойства новых комплексов исследованы с помощью ТГА и ДСК в сравнении с известным гексафторацетилацетонатным аналогом [Ag(bipy)(hfac)]2. Определены температуры и термодинамические параметры плавления всех соединений.

A new method is proposed to synthesize ethylenediamine complex [RuNO(en)2OH]I2 from K2[RuNOCl5], which increases the target product yield to 76

New data are obtained on the thermal behavior and processes of vaporization and melting of (hexafluoroacetylacetonato)(cyclooctadiene-1,5)silver, [Ag(cod)(hfac)]n (n = 1, 2). The dimeric form of the complex is synthesized and characterized. The condensed phase is studied via differential scanning calorimetry plus thermogravimetric and differential thermal analysis. The thermal stability and qualitative volatility are assessed, and the temperature, enthalpy, and entropy of melting are determined for the complex. It is shown that the compound is highly sensitive to heating, preventing the experimental determination of reliable thermodynamic characteristics. Thermodynamic characteristics of the evaporation of these chelates are calculated using standardized values of enthalpies and entropies of the sublimation and melting of similar heteroligand complexes of copper(I) and iridium(I). The data are used to construct structure–volatility correlations that allow estimates of the required phase transitions of the target silver complex. An approach to evaluating the thermodynamic properties of complexes of the composition [M(cod)(β-dik)]n is proposed to determine the optimum conditions for depositing coatings that contain metal.