Low-temperature thermodynamic properties of Ir(C5H7O2)3: Connection of entropy with the molecule volume for tris-acetylacetonates of metals

Universal Interaction of Thermodynamical and Structural Characteristics in Molecular Crystals of Metal β-Diketonates

“…Among the properties of metal β-diketonates, an important place is occupied by those properties that can be obtained from data on a low-temperature heat capacity. The experimental data are now the main source of information about thermodynamic properties of such complex objects as metal β-diketonates. − Regular interrelations can be observed in this direction when studying the behavior of the various properties of these objects. Research in this direction is an important task of physical chemistry, because it can help in forecasting the properties of unstudied objects.…”

Low-Temperature Heat Capacity and Thermodynamic Functions of Tetrameric Cobalt(II) Acetylacetonate

“…We analyzed our heat capacity data in comparison with the data for previously studied metal acetylacetonates M­(C 5 H 7 O 2 ) n (M is Al, Cu, Cr, Fe, Ru, Ir, or Pt) (Figure ). The heat capacity data C p , m ( T ) for Fe­(C 5 H 7 O 2 ) 3 , Cr­(C 5 H 7 O 2 ) 3 , Ir­(C 5 H 7 O 2 ) 3 , Al­(C 5 H 7 O 2 ) 3 , Ru­(C 5 H 7 O 2 ) 3 , Pt­(C 5 H 7 O 2 ) 2 , and Cu­(C 5 H 7 O 2 ) 2 at low temperatures were obtained by the adiabatic method.…”

“…Heat capacity for metal acetylacetonates. Purple – our data for [Co­(C 5 H 7 O 2 ) 2 ] 4 , pink – Fe­(C 5 H 7 O 2 ) 3 , blue – Cr­(C 5 H 7 O 2 ) 3 , orange – Ir­(C 5 H 7 O 2 ) 3 , green – Al­(C 5 H 7 O 2 ) 3 , gray – Ru­(C 5 H 7 O 2 ) 3 , black – Pt­(C 5 H 7 O 2 ) 2 , and red – Cu­(C 5 H 7 O 2 ) 2 …”

“…Relative deviations (Δ C = C p , m – C s Fe ) of the experimental heat capacity C p , m of metal tris-acetylacetonates from the smoothed curve for iron tris-acetylacetonate ( C s Fe ). Pink – Fe­(C 5 H 7 O 2 ) 3 , blue – Cr­(C 5 H 7 O 2 ) 3 , orange – Ir­(C 5 H 7 O 2 ) 3 , green – Al­(C 5 H 7 O 2 ) 3 , and gray – Ru­(C 5 H 7 O 2 ) 3 …”

“…Intermolecular vibrational modes have the lowest frequency and are completely excited in the range from 0 to 130 K. ,, Therefore, the intermolecular component C v ,ex makes a constant contribution ( C v ,ex ≈ 6 R ) to the heat capacity C v , f at temperatures above 130 K. Most of the intramolecular vibrational modes are not excited at T = 310 K. Only a part of the intramolecular vibrational modes associated with the ligand and with weakly bound groups inside the ligand are excited at room temperature. , The considered complexes have the same ligand structure; therefore, the contribution of the intramolecular component ( C v ,in ) to the phonon heat capacity ( C v , f ) will be proportional to the number of ligands ( N L ) in the molecule.…”