The performance of the density functional theory (DFT) methods with different gradient corrections as an approach for the computation of transition metal complexes has been evaluated As a test, the structures, binding energies, and vibrational frequencies of a series of binary transition metal carbonyl complexes were calculated Comparison with previous studies shows that the gradient correction significantly improves the performance of the DFT schemes, and that the results obtained generally match the quality of the data obtained from coupled cluster and pair functional methods

Binding energies, molecular structures, and vibrational frequencies of transition metal carbonyls using density functional theory with gradient corrections

Thermochemical studies of organo-transition metal carbonyls and related compounds

Ab initio calculations have been performed for Cr(CO)6 and Fe(CO)n, n = 1,5 Basis sets of better than double zeta quality are used, and correlation is included using the modified coupler-pair functional method The computed geometries and force constants are in reasonable agreement with experiment The sequential bond dissociation energies of CO from Fe(CO)5 are estimated to be: 39, 31, 25, 22, and greater than 5 kcal/mol It is noted that the first bond dissociation energy is relative to the singlet ground state of Fe(CO)5 and the lowest singlet state of Fe(CO)4, whereas the second is relative to the ground triplet states of Fe(CO)4 and Fe(CO)3 In addition, the binding energy for Fe-CO would be modified to 18 kcal/mol if dissociation occurred to the Fe(5F) excited state asymptote The CO binding energies for Fe and Cr are found to be in poorer agreement with experiment than those found in a previous study on Ni(CO)4 The origins of this difference are discussed

An ab initio study of Fe(CO)n, n = 1,5, and Cr(CO)6

The DMol methodology is reviewed with special emphasis on recent developments such as gradient dependent, or so-called nonlocal, density functionals. Applications to crystalline silicon structures in the nanometer size imply a discussion of excited states. This is also a first application using periodic boundary conditions. The application to carbonyl complexes is a case study of the effect of some recent gradient dependent density functionals on the energy surface.

DMol, a standard tool for density functional calculations: Review and advances

The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11–C192 reported over the period 1880–2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid–solid transitions or behave ani...

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Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds and Ionic Liquids. Sublimation, Vaporization, and Fusion Enthalpies from 1880 to 2015. Part 2. C11–C192

Measurements of the energy of combustion of tungsten hexacarbonyl in oxygen gas at 298 K by static bomb calorimetry are reported. Independent measurements of the enthalpy of thermal decomposition of the hexacarbonyl have also been made, using a “hot-zone” reaction calorimeter. The values of the standard enthalpy of formation, at 298 K, of crystalline tungsten hexacarbonyl, as derived from the two independent thermochemical studies, agree with one another within the combined error limits; the mean value was: ΔH 0 f [ W ( CO ) 6 , c ] = − 229.5 ± 0.7 kcal mol −1 , ≡ −960.3 ± 2.9 kJ mol −1 .

The enthalpy of formation of tungsten hexacarbonyl

Measurements of the enthalpy of thermal decomposition of chromium hexacarbonyl have been made using a “hot-zone” reaction calorimeter. Independent measurements of the energy of combustion of the hexacarbonyl in oxygen at 298 K by static bomb calorimetry lead to an enthalpy of formation in accord with that derived from the thermal decomposition measurements. From consideration of all the reported measurements of the enthalpy of formation of chromium hexacarbonyl, a mean selected value is proposed: ΔH o f [Cr(CO) 6 , c] = −234.2 ± 0.4 kcal mol −1 ,  − 979.9 ± 1.7 kJmor −1 .

The enthalpy of formation of chromium hexacarbonyl

New measurements of the heat of combustion of Mo(CO) 6 in oxygen have been made by bomb calorimetry. Independent measurements of the heat of thermal decomposition of Mo(CO) 6 have also been made with a “hot-zone” reaction calorimeter of novel design. Measurements are also reported of the heat of reaction of Mo(CO) 6 with iodine vapour at high temperatures by using a Calvet High Temperature microcalorimeter, from which the heat of formation of molybdenum triiodide is calculated.

D. Todd

Papers

The enthalpy of formation of tungsten hexacarbonyl

The enthalpy of formation of chromium hexacarbonyl

Thermochemistry of molybdenum hexacarbonyl and molybdenum triiodide