Abstract
The homolytic bond dissociation energies of a series of five- and six-coordinate mono- and dihydride complexes of the type HM(diphosphine)2 and [H2M(diphosphine)2]+ (where M = Co, Rh, and Ir) are calculated and compared with experimental values. This work probes the relationship between the homolytic bond dissociation energies (HMBDEs) of these complexes in these two different coordination environments and formal oxidation states. The results of these calculations and previous experimental observations suggest that for M = Rh the HMBDE of the five-coordinate HM(diphosphine)2 species are 0-2 kcal/mol larger than the HMBDE of the corresponding six-coordinate [H2M(diphosphine)2]+ species. For M = Ir the bond energies of the five- and six-coordinate complexes are nearly the same and for M = Co the six-coordinate species are 1-5 kcal/mol less than the corresponding five-coordinate species. Simplified models of large and complicated ligands seem to capture the essential trends and give very good estimates of these thermodynamic properties compared with experimentally available data that are difficult to obtain. (Chemical Equation Presented).
| Original language | English |
|---|---|
| Pages (from-to) | 1993-2000 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry A |
| Volume | 121 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 9 2017 |
| Externally published | Yes |
Funding
This paper is dedicated to Professor Mark S. Gordon and represents a small contribution to his legacy as one of the most respected scientists in the field of quantum chemistry. V.-A.G. will always be grateful for having been one of his students. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences under grant KC0301050-47319 and computer time was provided through a NERSC computer allocation. PNNL is a multiprogram national laboratory operated for DOE by Battelle.