New insights into solvolysis and reorganization energy from gas-phase, electrochemical, and theoretical studies of oxo-Tp*Mo(V) molecules.
Molecules of the general form Tp*MoO(OR)(2) [where Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate and (OR)(2) = (OMe)(2), (OEt)(2), and (O(n)Pr)(2) for alkoxide ligands and (OR)(2) = O(CH(2))(3)O, O(CH(2))(4)O, and O[CH(CH(3))CH(2)CH(CH(3))]O for diolato ligands] were studied using gas-phase photoelectron spectroscopy, cyclic voltammetry, and density functional theory (DFT) calculations to examine the effect of increasing ligand size and structure on the oxomolybdenum core. Oxidation potentials and first ionization energies are shown to be sensitive to the character of the diolato and alkoxide ligands. A linear correlation between the solution-phase oxidation potentials and the gas-phase ionization energies resulted in an unexpected slope of greater than unity. DFT calculations indicated that this unique example of a system in which oxidation potentials are more sensitive to substitution than vertical ionization energies is due to the large differences in the cation reorganization energies, which range from 0.2 eV or less for the molecules with diolato ligands to around 0.5 eV for the molecules with alkoxide ligands.
Vannucci
Aaron K
AK
Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721-0041, USA.
Snyder
Rae Ana
RA
Gruhn
Nadine E
NE
Lichtenberger
Dennis L
DL
Enemark
John H
JH
D004563:Electrochemistry; D005740:Gases; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D044367:Phase Transition; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics
D005740:Gases; D008024:Ligands; D009942:Organometallic Compounds; D012997:Solvents; C442339:molybdenum hydrotris-(3,5-dimethyl-1-pyrazolyl)borate; D010100:Oxygen
J Am Chem Soc. 2007 Oct 17;129(41):12521-30
17894491
Chem Rev. 1996 Nov 7;96(7):2757-2816
11848841
Inorg Chem. 2002 May 20;41(10):2642-7
12005487
J Am Chem Soc. 2002 Jul 10;124(27):7918-9
12095333
Inorg Chem. 2004 Nov 15;43(23):7389-95
15530089