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Title: A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN 3

Abstract

We report here the results of a combined experimental and computational study of the negative ion photoelectron spectroscopy (NIPES) of the recently synthesized, planar, aromatic, HCPN3– ion. The adiabatic electron detachment energy of HCPN3– (electron affinity of HCPN3•) was measured to be 3.555 ± 0.010 eV, a value that is intermediate between the electron detachment energies of the closely related (CH)2N3– and P2N3– ions. High level electronic structure calculations and Franck–Condon factor (FCF) simulations reveal that transitions from the ground state of the anion to two nearly degenerate, low-lying, electronic states, of the neutral HCPN3• radical are responsible for the congested peaks at low binding energies in the NIPE spectrum. The best fit of the simulated NIPE spectrum to the experimental spectrum indicates that the ground state of HCPN3• is a 5π-electron 2A" π radical state, with a 6π-electron, 2A', σ radical state being at most ~1.0 kcal/mol higher in energy. This assignment contrasts with our recent finding that the ground state of P2N3• is a 6π-electron σ radical state

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1340802
Report Number(s):
PNNL-SA-118787
Journal ID: ISSN 1089-5639; 49062; KC0301050
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory; Journal Volume: 120; Journal Issue: 31
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Hou, Gao-Lei, Chen, Bo, Transue, Wesley J., Hrovat, David A., Cummins, Christopher C., Borden, Weston Thatcher, and Wang, Xue-Bin. A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN 3 –. United States: N. p., 2016. Web. doi:10.1021/acs.jpca.6b06343.
Hou, Gao-Lei, Chen, Bo, Transue, Wesley J., Hrovat, David A., Cummins, Christopher C., Borden, Weston Thatcher, & Wang, Xue-Bin. A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN 3 –. United States. doi:10.1021/acs.jpca.6b06343.
Hou, Gao-Lei, Chen, Bo, Transue, Wesley J., Hrovat, David A., Cummins, Christopher C., Borden, Weston Thatcher, and Wang, Xue-Bin. Thu . "A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN 3 –". United States. doi:10.1021/acs.jpca.6b06343.
@article{osti_1340802,
title = {A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN 3 –},
author = {Hou, Gao-Lei and Chen, Bo and Transue, Wesley J. and Hrovat, David A. and Cummins, Christopher C. and Borden, Weston Thatcher and Wang, Xue-Bin},
abstractNote = {We report here the results of a combined experimental and computational study of the negative ion photoelectron spectroscopy (NIPES) of the recently synthesized, planar, aromatic, HCPN3– ion. The adiabatic electron detachment energy of HCPN3– (electron affinity of HCPN3•) was measured to be 3.555 ± 0.010 eV, a value that is intermediate between the electron detachment energies of the closely related (CH)2N3– and P2N3– ions. High level electronic structure calculations and Franck–Condon factor (FCF) simulations reveal that transitions from the ground state of the anion to two nearly degenerate, low-lying, electronic states, of the neutral HCPN3• radical are responsible for the congested peaks at low binding energies in the NIPE spectrum. The best fit of the simulated NIPE spectrum to the experimental spectrum indicates that the ground state of HCPN3• is a 5π-electron 2A" π radical state, with a 6π-electron, 2A', σ radical state being at most ~1.0 kcal/mol higher in energy. This assignment contrasts with our recent finding that the ground state of P2N3• is a 6π-electron σ radical state},
doi = {10.1021/acs.jpca.6b06343},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 31,
volume = 120,
place = {United States},
year = {Thu Aug 11 00:00:00 EDT 2016},
month = {Thu Aug 11 00:00:00 EDT 2016}
}
  • Negative Ion Photoelectron (NIPE) spectra of the radical anion of cyclopropane-1,2,3-trione, (CO)3•-, have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show broadened bands, due to the short lifetimes of both the singlet and triplet states of (CO)3. The smaller intensity of the band with the lower electron binding energy suggests that the singlet is the ground state of (CO)3. From the NIPE spectra, the electron affinity (EA) and the singlet-triplet energy gap of (CO)3 are estimated to be, respectively, EA = 3.1 ± 0.1 eV and ΔEST = -14 ±more » 3 kcal/mol. High-level, (U)CCSD(T)/aug-cc-pVQZ//(U)CCSD(T)/aug-cc-pVTZ, calcu-lations give EA = 3.04 eV for the 1A1´ ground state of (CO)3 and ΔEST = -13.8 kcal/mol for the energy gap between the 1A1´ and 3A2 states, in excellent agreement with values from the NIPE spectra. In addition, simulations of the vibrational structures for formation of these states of (CO)3 from the 2A2'' state of (CO)3•- provide a good fit to the shapes of broad bands in the 266 nm NIPE spectrum. The NIPE spectrum of (CO)3•- and the analysis of the spectrum by high-quality electronic structure calculations demonstrate that NIPES can not only access and provide information about transition structures, but NIPES can also access and provide information about hilltops on potential energy surfaces.« less
  • Negative ion photoelectron (NIPE) spectra of the radical anion of meta-benzoquinone (MBQ, m-OC6H4O) have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show well-resolved peaks and complex spectral patterns. The electron affinity of MBQ is determined from the first resolved peak to be 2.875 ±17 0.010 eV. Single-point, CASPT2/aug-cc-pVTZ//CASPT2/ aug-cc-pVDZ calculations predict accurately the positions of the 0-0 bands in the NIPE spectrum for formation of the four lowest electronic states of neutral MBQ from the 2A2 state of MBQ•-. In addition, the Franck-Condon factors that are computed from the CASPT2/aug-cc-pVDZmore » optimized geometries,vibrational frequencies, and normal mode vectors, successfully simulate the intensities and frequencies of the vibrational peaks in the NIPE spectrum that are associated with each of these electronic states. The successful simulation of the NIPE spectrum of MBQ•- allows the assignment of 3B2 as the ground state of MBQ, followed by the 1B2 and 1A1 electronic states, respectively 9.0 ± 0.2 and 16.6 ± 0.2 kcal/mol higher in energy than the triplet. These experimental energy differences are in good agreement with the calculated values of 9.7 and 15.7 kcal/mol. The relative energies of these two singlet states in MBQ confirm the previous prediction that their relative energies would be reversed from those in meta-benzoquinodimethane (MBQDM, m-CH2C6H4CH2).« less
  • Cyclobutane-1,2,3,4-tetrathione, (CS)4, has recently been calculated to have a singlet ground state, 1A1g, in which the highest b2g MO is doubly occupied and the lowest a2u MO is empty. Thus, (CS)4 is predicted to have a different ground state than its lighter congener, (CO)4, which has a triplet ground state, 3B1u, in which these two MOs are each singly occupied. Here we report the results of a negative ion photoelectron spectroscopy (NIPES) study of the radical anion (CS)4∙-, designed to test the prediction that (CS)4 has a singlet ground state. The NIPE spectrum reveals that (CS)4 does, indeed, have amore » singlet ground state with electron affinity (EA) = 3.75 eV. The lowest triplet state is found to lie 0.31 eV higher in energy than the ground state, and the open-shell singlet is 0.14 eV higher in energy than the triplet state. Calculations at the (U)CCSD(T)/aug-cc-pVTZ//(U)B3LYP/6-311+G(2df) level support the spectral assignments, giving EA = 3.71 eV, EST = 0.44 eV. These calculated values are, respectively, 0.04 eV (0.9 kcal/mol) smaller, and 0.13 eV (3.0 kcal/mol) larger than the corresponding experimental values. In addition, RASPT2 calculations with various active spaces converge on a 1B1u-3B1u energy gap of 0.137 eV, in excellent agreement with the 0.14 eV energy difference obtained from the NIPE spectrum. Finally, calculations of the Franck-Condon factors for transitions from the ground state of (CS)4∙- to the ground (1A1g) and two excited states (3B1u, 1B1u) of (CS)4 account for all of the major spectral peaks, and nicely reproduce vibrational structure observed in each electronic transition. The close correspondence between the calculated and the observed features in the NIPE spectrum of (CS)4∙- provides unequivocal proof that (CS)4, unlike (CO)4, has a singlet ground state.« less
  • The recent successful synthesis of P 2N 3 , a planar all-inorganic aromatic molecule, represents a breakthrough in inorganic chemistry, because, like its isolobal counterparts C 5H 5– and cyclo-P 5 , P 2N 3 has potential to serve as a new ligand for transition metals and a building block in solid-state molecular architectures. In light of its importance, we report here a negative ion photoelectron spectroscopy (NIPES) and ab initio study of P 2N 3 , to investigate the electronic structures of P 2N 3 and its neutral P 2N 3• radical. The adiabatic detachment energy ofmore » P 2N 3 (electron affinity of P 2N 3•) was determined to be 3.765 ± 0.010 eV, indicating high stability for the P 2N 3 anion. Ab initio electronic structure calculations reveal five low-lying electronic states in the neutral P 2N 3• radical. Calculation of the Franck-Condon factors (FCFs) for each anion-to-neutral electronic transition and comparison of the resulting simulated NIPE spectrum with the vibrational structure in the observed spectrum allows the first four excited states of P 2N 3• to be determined to lie 6.2, 6.7, 11.5, and 22.8 kcal/mol -1 above the ground state of the radical, which is found to be a 6π-electron, 2A 1, σ state.« less
  • Here, a structural characterization of the hydrated form of the brownmillerite-type phase Ba 2In 2O 5, Ba 2In 2O 4(OH) 2, is reported using experimental multinuclear NMR spectroscopy and density functional theory (DFT) energy and GIPAW NMR calculations. When the oxygen ions from H 2O fill the inherent O vacancies of the brownmillerite structure, one of the water protons remains in the same layer (O3) while the second proton is located in the neighboring layer (O2) in sites with partial occupancies, as previously demonstrated by Jayaraman et al. (Solid State Ionics 2004, 170, 25–32) using X-ray and neutron studies. Calculationsmore » of possible proton arrangements within the partially occupied layer of Ba 2In 2O 4(OH) 2 yield a set of low energy structures; GIPAW NMR calculations on these configurations yield 1H and 17O chemical shifts and peak intensity ratios, which are then used to help assign the experimental MAS NMR spectra. Three distinct 1H resonances in a 2:1:1 ratio are obtained experimentally, the most intense resonance being assigned to the proton in the O3 layer. The two weaker signals are due to O2 layer protons, one set hydrogen bonding to the O3 layer and the other hydrogen bonding alternately toward the O3 and O1 layers. 1H magnetization exchange experiments reveal that all three resonances originate from protons in the same crystallographic phase, the protons exchanging with each other above approximately 150 °C. Three distinct types of oxygen atoms are evident from the DFT GIPAW calculations bare oxygens (O), oxygens directly bonded to a proton (H-donor O), and oxygen ions that are hydrogen bonded to a proton (H-acceptor O). The 17O calculated shifts and quadrupolar parameters are used to assign the experimental spectra, the assignments being confirmed by 1H– 17O double resonance experiments.« less