TY - JOUR
T1 - Investigation of metal-dithiolate fold angle effects
T2 - Implications for molybdenum and tungsten enzymes
AU - Joshi, Hemant K.
AU - Cooney, J. Jon A.
AU - Inscore, Frank E.
AU - Gruhn, Nadine E.
AU - Lichtenberger, Dennis L.
AU - Enemark, John H.
PY - 2003/4/1
Y1 - 2003/4/1
N2 - Gas-phase photoelectron spectroscopy and density functional theory have been used to investigate the interactions between the sulfur π-orbitals of arene dithiolates and high-valent transition metals as minimum molecular models of the active site features of pyranopterin Mo/W enzymes. The compounds (Tp*)MoO(bdt) (compound 1), Cp2Mo(bdt) (compound 2), and Cp2Ti(bdt) (compound 3) [where Tp* is hydrotris(3,5-dimethyl-1pyrazolyl)borate, bdt is 1,2-benzenedithiolate, and Cp is η5cyclopentadienyl] provide access to three different electronic configurations of the metal, formally d1, d2, and d0, respectively. The gas-phase photoelectron spectra show that ionizations from occupied metal and sulfur based valence orbitals are more clearly observed in compounds 2 and 3 than in compound 1. The observed ionization energies and characters compare very well with those calculated by density functional theory. A "dithiolate-folding-effect" involving an interaction of the metal in-plane and sulfur-π orbitals is proposed to be a factor in the electron transfer reactions that regenerate the active sites of molybdenum and tungsten enzymes.
AB - Gas-phase photoelectron spectroscopy and density functional theory have been used to investigate the interactions between the sulfur π-orbitals of arene dithiolates and high-valent transition metals as minimum molecular models of the active site features of pyranopterin Mo/W enzymes. The compounds (Tp*)MoO(bdt) (compound 1), Cp2Mo(bdt) (compound 2), and Cp2Ti(bdt) (compound 3) [where Tp* is hydrotris(3,5-dimethyl-1pyrazolyl)borate, bdt is 1,2-benzenedithiolate, and Cp is η5cyclopentadienyl] provide access to three different electronic configurations of the metal, formally d1, d2, and d0, respectively. The gas-phase photoelectron spectra show that ionizations from occupied metal and sulfur based valence orbitals are more clearly observed in compounds 2 and 3 than in compound 1. The observed ionization energies and characters compare very well with those calculated by density functional theory. A "dithiolate-folding-effect" involving an interaction of the metal in-plane and sulfur-π orbitals is proposed to be a factor in the electron transfer reactions that regenerate the active sites of molybdenum and tungsten enzymes.
UR - http://www.scopus.com/inward/record.url?scp=0037383996&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037383996&partnerID=8YFLogxK
U2 - 10.1073/pnas.0636832100
DO - 10.1073/pnas.0636832100
M3 - Article
C2 - 12655066
AN - SCOPUS:0037383996
VL - 100
SP - 3719
EP - 3724
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 7
ER -