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Graphical abstract Highlights • Three volatile iridium (I) complexes with cyclooctadiene and acetylacetonate derivatives were synthesized and characterized. • Two complexes contained beta-ketoiminate ligand were obtained for the first time. • Thermal properties of complexes were studied by TG, DSC and tensiometry (transpiration method). • Sublimation and melting enthalpies and entropies were derived. • Effect of donor atom changing (O vs. N) in chelating ligand on volatility and thermal stability of complexes was established. Abstract Three hetero-ligand volatile iridium (I) complexes with β-diketonate derivatives [Ir(cod)(L)] (cod = 1,5-cyclooctadiene, L = CH 3 C(O)CHC(X)CH 3 , X = O (acac) 1 , N–H (i -acac) 2 , N–CH 3 (Me i -acac) 3) have been synthesized, purified and characterized in order to investigate the influence of (O,O) and (O,N) coordination sites in chelate ligand on the thermochemical properties of this type compounds. β-Ketoiminate complexes (L = i -acac, Me i -acac) were prepared for the first time. Thermal behavior of iridium complexes in condensed phase has been studied by differential scanning calorimetry and thermodynamic parameters of melting processes (Δ melt. H m.p. , Δ melt. S ° m.p.) have been determined for the first time. The temperature dependencies of saturated vapor pressures over the solid complexes have been measured by flow (transpiration) method (temperature intervals (363–423) K, (383–431) K and (383–420) K for compounds 1 , 2 and 3 , respectively). Using these data, the thermodynamic parameters of sublimation processes (Δ sub H T , Δ sub S ° T) have been calculated. It has been found that although the ligand modification has a minor effect on the vaporization characteristics of this type complexes, the volatility unexpectedly decreases in the following sequence: L = acac > i -acac > Me i -acac. However, the vapor pressure values in the above-mentioned temperature interval are sufficient to all complexes studied be used as effective volatile precursors to obtain iridium-containing coatings by chemical vapor-phase deposition methods. [ABSTRACT FROM AUTHOR]

Highlights: [•] The volatile complexes of MI[Y(β-diketonato)4] (MI =Cs, Na, K) were the objects of this investigation. [•] Thermal behaviour was studied by TG and DSC, vapour pressures were measured by transpiration and Knudsend’s effusion methods. [•] The thermodynamic parameters of phase transitions and equilibriums were calculated. [•] The ways of thermodecomposition of one Cs-containing complex’s vapour in vacuum and oxygen presence were proposed. [•] Using thermochemical data Cs2O-containing films were obtained by Metal–Organic Chemical Vapour Deposition for the first time. [Copyright &y& Elsevier]