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Title: Negative Ion Photoelectron Spectroscopy Reveals Remarkable Noninnocence of Ligands in Nickel Bis(dithiolene) Complexes [Ni(dddt) 2 ] - and [Ni(edo) 2 ] -

Abstract

[Ni(dddt)2] (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) and [Ni(edo)2] (edo = 5,6-dihydro-1,4-dioxine-2,3-dithiolate) are two donor-type nickel bis(dithiolene) complexes, with the tendency of donating low binding energy electrons. These two structurally similar complexes differ only with respect to the outer atoms in the ligand framework where the former has four S atoms while the latter has four O atoms. Herein, we report a negative ion photoelectron spectroscopy (NIPES) study on these two complexes to probe electronic structures of the anions and their corresponding neutrals. The NIPE spectra exhibit the adiabatic electron detachment energy (ADE) or, equivalently, the electron affinity (EA) of the neutral [Ni(L)2]0 to be relatively low for this type complexes, 2.780 and 2.375 eV for L = dddt and edo, respectively. The 0.4 eV difference in ADEs shows significant substitution effect for sulfur in dddt by oxygen in edo, i.e., noninnocence of the ligands, which has decreased the electronic stability of [Ni(edo)2] by lowering its electron binding energy by ~0.4 eV. The observed substitution effect on gas-phase EA values correlates well with the measured redox potentials for [Ni(dddt)2]–/0 and [Ni(edo)2]–/0 in solutions. The singlet-triplet splitting (ΔEST) of [Ni(dddt)2]0 and [Ni(edo)2]0 is also determined from the spectra to be 0.57 and 0.53 eV,more » respectively. Accompanying DFT calculations and molecular orbital (MO) composition analyses show significant ligand contributions to the redox MOs and allow the components of the orbitals involved in each electronic transition and spectral assignments to be identified.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1327116
Report Number(s):
PNNL-SA-116711
Journal ID: ISSN 1089-5639; 48584; KC0301050
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 120; Journal Issue: 18; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Negative ion photoelectron spectroscopy; nickel bis(dithiolene) complexes; noninnocent ligands; redox chemistry; Environmental Molecular Sciences Laboratory

Citation Formats

Liu, Xing, Hou, Gao-Lei, Wang, Xuefeng, and Wang, Xue-Bin. Negative Ion Photoelectron Spectroscopy Reveals Remarkable Noninnocence of Ligands in Nickel Bis(dithiolene) Complexes [Ni(dddt) 2 ] - and [Ni(edo) 2 ] -. United States: N. p., 2016. Web. doi:10.1021/acs.jpca.6b02711.
Liu, Xing, Hou, Gao-Lei, Wang, Xuefeng, & Wang, Xue-Bin. Negative Ion Photoelectron Spectroscopy Reveals Remarkable Noninnocence of Ligands in Nickel Bis(dithiolene) Complexes [Ni(dddt) 2 ] - and [Ni(edo) 2 ] -. United States. https://doi.org/10.1021/acs.jpca.6b02711
Liu, Xing, Hou, Gao-Lei, Wang, Xuefeng, and Wang, Xue-Bin. 2016. "Negative Ion Photoelectron Spectroscopy Reveals Remarkable Noninnocence of Ligands in Nickel Bis(dithiolene) Complexes [Ni(dddt) 2 ] - and [Ni(edo) 2 ] -". United States. https://doi.org/10.1021/acs.jpca.6b02711.
@article{osti_1327116,
title = {Negative Ion Photoelectron Spectroscopy Reveals Remarkable Noninnocence of Ligands in Nickel Bis(dithiolene) Complexes [Ni(dddt) 2 ] - and [Ni(edo) 2 ] -},
author = {Liu, Xing and Hou, Gao-Lei and Wang, Xuefeng and Wang, Xue-Bin},
abstractNote = {[Ni(dddt)2]– (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) and [Ni(edo)2]– (edo = 5,6-dihydro-1,4-dioxine-2,3-dithiolate) are two donor-type nickel bis(dithiolene) complexes, with the tendency of donating low binding energy electrons. These two structurally similar complexes differ only with respect to the outer atoms in the ligand framework where the former has four S atoms while the latter has four O atoms. Herein, we report a negative ion photoelectron spectroscopy (NIPES) study on these two complexes to probe electronic structures of the anions and their corresponding neutrals. The NIPE spectra exhibit the adiabatic electron detachment energy (ADE) or, equivalently, the electron affinity (EA) of the neutral [Ni(L)2]0 to be relatively low for this type complexes, 2.780 and 2.375 eV for L = dddt and edo, respectively. The 0.4 eV difference in ADEs shows significant substitution effect for sulfur in dddt by oxygen in edo, i.e., noninnocence of the ligands, which has decreased the electronic stability of [Ni(edo)2]– by lowering its electron binding energy by ~0.4 eV. The observed substitution effect on gas-phase EA values correlates well with the measured redox potentials for [Ni(dddt)2]–/0 and [Ni(edo)2]–/0 in solutions. The singlet-triplet splitting (ΔEST) of [Ni(dddt)2]0 and [Ni(edo)2]0 is also determined from the spectra to be 0.57 and 0.53 eV, respectively. Accompanying DFT calculations and molecular orbital (MO) composition analyses show significant ligand contributions to the redox MOs and allow the components of the orbitals involved in each electronic transition and spectral assignments to be identified.},
doi = {10.1021/acs.jpca.6b02711},
url = {https://www.osti.gov/biblio/1327116}, journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
issn = {1089-5639},
number = 18,
volume = 120,
place = {United States},
year = {Thu Apr 21 00:00:00 EDT 2016},
month = {Thu Apr 21 00:00:00 EDT 2016}
}