Structures and Stability of Ir<sub>n</sub>(CO)<sub>m</sub>

Chen, Mingyang; Dyer, Jason; Gates, Bruce C.; Katz, Alexander; Dixon, David A.

doi:10.1080/00268976.2012.703885

Cited by 9 publications

(27 citation statements)

References 24 publications

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“…Ir 2 (PH 3 ) y (CO) z structures, relative energies, and ligand dissociation energies Ir 2 (CO) 8 has three low-energy isomers [51], which we previously optimized, and three fundamental structures of Ir 2 (PH 3 ) y (CO) z are predicted: C 2v (C s ), C 2 , and D 3d (Fig. 3).…”

Section: Resultsmentioning

confidence: 97%

“…Previously, geometry parameters of Ir 4 (CO) 12 with T d symmetry have been obtained from DFT with the SVWN5 exchange-correlation functional, which provides excellent geometry results that are very close to the experimental results, but gives poor relative energies that predict a lower-energy C 3v structure [51]. The CAM-B3LYP functional performs best in calculations of carbonyl dissociation energies for a number of Ir x (CO) y complexes, and the xB97X-D functional gives the best predictions of total dissociation energies [51].…”

Section: Methodsmentioning

confidence: 93%

“…The CAM-B3LYP functional performs best in calculations of carbonyl dissociation energies for a number of Ir x (CO) y complexes, and the xB97X-D functional gives the best predictions of total dissociation energies [51]. In most nucleation reactions, DFT calculations give higher energies than CCSD(T) results, whereas the reverse pertains to the prediction based on the MP2 method.…”

Section: Methodsmentioning

confidence: 99%

“…In most nucleation reactions, DFT calculations give higher energies than CCSD(T) results, whereas the reverse pertains to the prediction based on the MP2 method. Thus, the average of the MP2 and DFT values were considered to be suitable for predicting the carbonyl ligand dissociation energies [51].…”

Section: Methodsmentioning

confidence: 99%

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Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

Zhang

Katz

Gates

et al. 2015

Computational and Theoretical Chemistry

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a b s t r a c tThere is significant interest in the catalytic properties of substituted iridium carbonyl clusters but little thermodynamic information available characterizing them. The low-energy isomers of Ir x (PH 3 ) y (CO) z (x = 1, 2, 4) were investigated with density functional theory and correlated molecular orbital theory at the coupled cluster CCSD(T) level. The relative energies and ligand dissociation energies were calculated. Differences in relative energies are consequences of both electronic and steric effects of the phosphines and carbonyls. The calculations predict three fundamental structural types for Ir 2 (PH 3 ) y (CO) z : C 2v , C 2 , and D 3d . Ten exchange-correlation functionals were used for the ligand dissociation energy calculations in addition to CCSD(T) for the smaller clusters. The xB97X-D functional gave the most consistent ligand dissociation energies as compared with the CCSD(T) benchmark calculations, and, so it was used to predict the dissociation energies for larger clusters when CCSD(T) calculations were infeasible. The dissociation energies characteristic of Ir 4 (PH 3 ) y (CO) z were in the range of $30 to $60 kcal/mol. Dissociation of a bridging ligand often involved a hydrogen atom transfer from a phosphine to a coordinatively unsaturated iridium atom and a phosphine converting from a bridging site to an equatorial site. The products of such reactions are predicted to have lower relative energies than other isomers.Phosphines act as r-electron donors, and there is a trend of an increase in carbonyl ligand dissociation energies as more phosphines are substituted in the small clusters.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Structures, relative energies, and ligand dissociation energies of iridium carbonyl phosphine clusters

Zhang

Katz

Gates

et al. 2015

Computational and Theoretical Chemistry

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show abstract

“…However, DFT results depend strongly on the functional and may not provide good enough energetics [12,13]. Correlated molecular orbital theory at the coupled cluster CCSD(T) (or multi-reference configuration interaction methods) with large enough basis sets can provide the needed chemical accuracy, but they are computationally too expensive with any but simpler models-so here again we see the motivation for synthesizing catalysts to have simple, uniform structures.…”

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confidence: 99%