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Abstract
Predissociation thresholds corresponding to dissociation at ground state separated atom limits (SALs) have been recorded in this group for more than 100 d- and f-block metal-containing molecules. The metal atom electronic degeneracies in these molecules generate a dense manifold of electronic states that allow high-lying vibronic levels to couple to pathways leading to dissociation. However, CrN, CuB, and AuB fail to dissociate at their ground SAL. Instead, the molecules remain bound at energies that far surpass their bond dissociation energies (BDEs), and their bonds break only when excited at or above an excited SAL. Sharp predissociation thresholds at excited SALs nevertheless allowed BDEs to be derived: D0(CrN): 3.941(22) eV; D0(CuB): 2.26(15) eV; D0(Au11B): 3.724(3) eV. A previous measurement of D0(AlCr) is re-evaluated as dissociating to a higher energy limit, giving a revised value of D0(AlCr) = 1.32(2) eV. A discussion of this physical behavior is presented.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Merriles DM, Knapp AS, Barrera-Casas Y, Sevy A, Sorensen JJ, Morse MD. Bond dissociation energies of diatomic transition metal nitrides. J Chem Phys 2023; 158:084308. [PMID: 36859107 DOI: 10.1063/5.0141182] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
Resonant two-photon ionization (R2PI) spectroscopy has been used to measure the bond dissociation energies (BDEs) of the diatomic transition metal nitrides ScN, TiN, YN, MoN, RuN, RhN, HfN, OsN, and IrN. Of these, the BDEs of only TiN and HfN had been previously measured. Due to the many ways electrons can be distributed among the d orbitals, these molecules possess an extremely high density of electronic states near the ground separated atom limit. Spin-orbit and nonadiabatic interactions couple these states quite effectively, so that the molecules readily find a path to dissociation when excited above the ground separated atom limit. The result is a sharp drop in ion signal in the R2PI spectrum when the molecule is excited above this limit, allowing the BDE to be readily measured. Using this method, the values D0(ScN) = 3.905(29) eV, D0(TiN) = 5.000(19) eV, D0(YN) = 4.125(24) eV, D0(MoN) = 5.220(4) eV, D0(RuN) = 4.905(3) eV, D0(RhN) = 3.659(32) eV, D0(HfN) = 5.374(4) eV, D0(OsN) = 5.732(3) eV, and D0(IrN) = 5.115(4) eV are obtained. To support the experimental findings, ab initio coupled-cluster calculations extrapolated to the complete basis set limit (CBS) were performed. With a semiempirical correction for spin-orbit effects, these coupled-cluster single double triple-CBS calculations give a mean absolute deviation from the experimental BDE values of 0.20 eV. A discussion of the periodic trends, summaries of previous work, and comparisons to isoelectronic species is also provided.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Annie S Knapp
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | | | - Andrew Sevy
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Jason J Sorensen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Armentrout PB. Thermochemistry and mechanisms of the Pt + + SO 2 reaction from guided ion beam tandem mass spectrometry and theory. J Chem Phys 2022; 156:194301. [PMID: 35597638 DOI: 10.1063/5.0091510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The kinetic energy dependences of the reactions of Pt+ (2D5/2) with SO2 were studied using a guided ion beam tandem mass spectrometer and theory. The observed cationic products are PtO+ and PtSO+, with small amounts of PtS+, all formed in endothermic reactions. Modeling the kinetic energy dependent product cross sections allows determination of the product bond dissociation energies (BDEs): D0(Pt+-O) = 3.14 ± 0.11 eV, D0(Pt+-S) = 3.68 ± 0.31 eV, and D0(Pt+-SO) = 3.03 ± 0.12 eV. The oxide BDE agrees well with more precise literature values, whereas the latter two results are the first such measurements. Quantum mechanical calculations were performed for PtO+, PtS+, PtO2 +, and PtSO+ at the B3LYP and coupled-cluster with single, double, and perturbative triple [CCSD(T)] levels of theory using the def2-XZVPPD (X = T, Q) and aug-cc-pVXZ (X = T, Q, 5) basis sets and complete basis set extrapolations. These theoretical BDEs agree well with the experimental values. After including empirical spin-orbit corrections, the product ground states are determined as PtO+ (4Σ3/2), PtS+ (4Σ3/2), PtO2 + (2Σg +), and PtSO+ (2A'). Potential energy profiles including intermediates and transition states for each reaction were also calculated at the B3LYP/def2-TZVPPD level. Periodic trends in the thermochemistry of the group 9 metal chalcogenide cations are compared, and the formation of PtO+ from the Pt+ + SO2 reaction is compared with those from the Pt+ + O2, CO2, CO, and NO reactions.
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Affiliation(s)
- P B Armentrout
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, Utah 84112, USA
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4
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Merriles DM, Tomchak KH, Nielson C, Morse MD. Early Transition Metals Strengthen the B 2 Bond in MB 2 Complexes. J Am Chem Soc 2022; 144:7557-7561. [PMID: 35439416 DOI: 10.1021/jacs.1c13709] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bond dissociation energies of early transition metal diborides (M-B2, M = Sc, Ti, V, Y, Mo) have been measured by observation of the sharp onset of predissociation in a highly congested spectrum. Density functional and CCSD(T) ab initio calculations, extrapolated to the complete basis set limit, have been used to examine the electronic structure of these species. The computations demonstrate the formation of bonding orbitals between the metal d orbitals and the 1πu bonding orbitals of B2, leading to the transfer of metallic electron density into the bonding 1πu orbitals, strengthening both the M-B and B-B bonds in the molecule. This runs counter to most metal-ligand π interactions, where electron density is generally transferred into π antibonding orbitals of the ligand.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Kimberly H Tomchak
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christopher Nielson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Lachowicz A, Perez EH, Shuman NS, Ard SG, Viggiano AA, Armentrout PB, Goings JJ, Sharma P, Li X, Johnson MA. Determination of the SmO + bond energy by threshold photodissociation of the cryogenically cooled ion. J Chem Phys 2021; 155:174303. [PMID: 34742201 DOI: 10.1063/5.0068734] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The SmO+ bond energy has been measured by monitoring the threshold for photodissociation of the cryogenically cooled ion. The action spectrum features a very sharp onset, indicating a bond energy of 5.596 ± 0.004 eV. This value, when combined with the literature value of the samarium ionization energy, indicates that the chemi-ionization reaction of atomic Sm with atomic oxygen is endothermic by 0.048 ± 0.004 eV, which has important implications on the reactivity of Sm atoms released into the upper atmosphere. The SmO+ ion was prepared by electrospray ionization followed by collisional breakup of two different precursors and characterized by the vibrational spectrum of the He-tagged ion. The UV photodissociation threshold is similar for the 10 K bare ion and the He tagged ion, which rules out the possible role of metastable electronically excited states. Reanalysis and remeasurement of previous reaction kinetics experiments that are dependent on D0(SmO+) are included, bringing all experimental results in accord.
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Affiliation(s)
- Anton Lachowicz
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Evan H Perez
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Nicholas S Shuman
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - Shaun G Ard
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - Albert A Viggiano
- Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, Albuquerque, New Mexico 87117, USA
| | - P B Armentrout
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Joshua J Goings
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Prachi Sharma
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Mark A Johnson
- Sterling Chemistry Laboratory, Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA
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Merriles DM, Tomchak KH, Ewigleben JC, Morse MD. Predissociation measurements of the bond dissociation energies of EuO, TmO, and YbO. J Chem Phys 2021; 155:144303. [PMID: 34654298 DOI: 10.1063/5.0068543] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The observation of a sharp predissociation threshold in the resonant two-photon ionization spectra of EuO, TmO, and YbO has been used to measure the bond dissociation energies of these species. The resulting values, D0(EuO) = 4.922(3) eV, D0(TmO) = 5.242(6) eV, and D0(YbO) = 4.083(3) eV, are in good agreement with previous values but are much more precise. In addition, the ionization energy of TmO was measured by the observation of a threshold for one-color two-photon ionization of this species, resulting in IE(TmO) = 6.56(2) eV. The observation of a sharp predissociation threshold for EuO was initially surprising because the half-filled 4f7 subshell of Eu in its ground state generates fewer potential energy curves than in the other molecules we have studied by this method. The observation of a sharp predissociation threshold in YbO was even more surprising, given that the ground state of Yb is nondegenerate (4f146s2, 1Sg) and the lowest excited state of Yb is over 2 eV higher in energy. It is suggested that these molecules possess a high density of electronic states at the energy of the ground separated atom limit because ion-pair states drop below the ground limit, providing a sufficient electronic state density to allow predissociation to set in at the thermochemical threshold.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Kimberly H Tomchak
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Joshua C Ewigleben
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Merriles DM, Nielson C, Tieu E, Morse MD. Chemical Bonding and Electronic Structure of the Early Transition Metal Borides: ScB, TiB, VB, YB, ZrB, NbB, LaB, HfB, TaB, and WB. J Phys Chem A 2021; 125:4420-4434. [PMID: 34003640 DOI: 10.1021/acs.jpca.1c02886] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The predissociation thresholds of the early transition metal boride diatomics (MB, M = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta, W) have been measured using resonant two-photon ionization (R2PI) spectroscopy, allowing for a precise assignment of the bond dissociation energy (BDE). No previous experimental measurements of the BDE exist in the literature for these species. Owing to the high density of electronic states arising from the ground and low-lying separated atom limits in these open d-subshell species, a congested spectrum of vibronic transitions is observed as the energy of the ground separated atom limit is approached. Nonadiabatic and spin-orbit interactions among these states, however, provide a pathway for rapid predissociation as soon as the ground separated atom limit is reached, leading to a sharp decrease in signal to background levels when this limit is reached. Accordingly, the BDEs of the early transition metal borides have been assigned as D0(ScB) 1.72(6) eV, D0(TiB) 1.956(16) eV, D0(VB) 2.150(16) eV, D0(YB) 2.057(3) eV, D0(ZrB) 2.573(5) eV, D0(NbB) 2.989(12) eV, D0(LaB) 2.086(18) eV, D0(HfB) 2.593(3) eV, D0(TaB) 2.700(3) eV, and D0(WB) 2.730(4) eV. Additional insight into the chemical bonding and electronic structures of these species has been achieved by quantum chemical calculations.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christopher Nielson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Erick Tieu
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Sorensen JJ, Tieu E, Morse MD. Bond dissociation energies of lanthanide sulfides and selenides. J Chem Phys 2021; 154:124307. [PMID: 33810674 DOI: 10.1063/5.0042695] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Resonant two-photon ionization spectroscopy has been employed to observe sharp predissociation thresholds in the spectra of the lanthanide sulfides and selenides for the 4f metals Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Lu. As these molecules possess a large density of electronic states near the ground separated atom limit, these predissociation thresholds are argued to coincide with the true 0 K bond dissociation energies (BDEs). This is because spin-orbit and nonadiabatic couplings among these states allow the molecules to predissociate rapidly when the BDE is reached or exceeded. The measured BDEs, in eV, are as follows: 5.230(3) (PrS), 4.820(3) (NdS), 4.011(17) (SmS), 3.811(8) (EuS), 5.282(5) (GdS), 5.292(3) (TbS), 4.298(3) (DyS), 4.251(3) (HoS), 4.262(3) (ErS), 5.189(3) (LuS), 4.496(3) (PrSe), 4.099(3) (NdSe), 3.495(17) (SmSe), 3.319(3) (EuSe), 4.606(3) (GdSe), 4.600(6) (TbSe), 3.602(3) (DySe), 3.562(3) (HoSe), 3.587(3) (ErSe), and 4.599(6) (LuSe). Through the use of thermochemical cycles, the 0 K gaseous heat of formation, ΔfH0K ○, is reported for each molecule. A threshold corresponding to the onset of two-photon ionization in EuSe was also observed, providing the ionization energy of EuSe as 6.483(10) eV. Through a thermochemical cycle and the above reported BDE of the neutral EuSe molecule, the BDE for the Eu+-Se cation was also determined as D0(Eu+-Se) = 2.506(10) eV. Bonding trends of the lanthanide sulfides and selenides are discussed. Our previous observation that the transition metal sulfides are 15.6% more strongly bound than the corresponding selenides continues to hold true for the lanthanides as well.
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Affiliation(s)
- Jason J Sorensen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Erick Tieu
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Sorensen JJ, Tieu E, Sevy A, Merriles DM, Nielson C, Ewigleben JC, Morse MD. Bond dissociation energies of transition metal oxides: CrO, MoO, RuO, and RhO. J Chem Phys 2020; 153:074303. [PMID: 32828096 DOI: 10.1063/5.0021052] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Through the use of resonant two-photon ionization spectroscopy, sharp predissociation thresholds have been identified in the spectra of CrO, MoO, RuO, and RhO. Similar thresholds have previously been used to measure the bond dissociation energies (BDEs) of many molecules that have a high density of vibronic states at the ground separated atom limit. A high density of states allows precise measurement of the BDE by facilitating prompt dissociation to ground state atoms when the BDE is exceeded. However, the number of states required for prompt predissociation at the thermochemical threshold is not well defined and undoubtedly varies from molecule to molecule. The ground separated atom limit generates 315 states for RuO, 252 states for RhO, and 63 states for CrO and MoO. Although comparatively few states derive from this limit for CrO and MoO, the observation of sharp predissociation thresholds for all four molecules nevertheless allows BDEs to be assigned as 4.863(3) eV (RuO), 4.121(3) eV (RhO), 4.649(5) eV (CrO), and 5.414(19) eV (MoO). Thermochemical cycles are used to derive the enthalpies of formation of the gaseous metal oxides and to obtain IE(RuO) = 8.41(5) eV, IE(RhO) = 8.56(6) eV, D0(Ru-O-) = 4.24(2) eV, D0(Cr-O-) = 4.409(8) eV, and D0(Mo-O-) = 5.243(20) eV. The mechanisms leading to prompt predissociation at threshold in the cases of CrO and MoO are discussed. Also presented is a discussion of the bonding trends for the transition metal oxides, which are compared to the previously measured transition metal sulfides.
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Affiliation(s)
- Jason J Sorensen
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Erick Tieu
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Andrew Sevy
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Christopher Nielson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Joshua C Ewigleben
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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Kim J, Armentrout PB. Guided Ion Beam Tandem Mass Spectrometry and Theoretical Study of SO 2 Activated by Os . J Phys Chem A 2020; 124:6629-6644. [PMID: 32702982 DOI: 10.1021/acs.jpca.0c05757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetic-energy dependence of SO2 activated by Os+ was studied by guided ion beam tandem mass spectrometry. Species observed in endothermic reactions were OsO+, OsO2+ or OsS+, and OOsS+. The kinetic energy-dependent cross sections were modeled to yield 0 K bond dissociation energies (BDEs) of 5.01 ± 0.06 eV (Os+-O), 5.15 ± 0.07 eV (Os+-O2), 4.50 ± 0.17 eV (Os+-S), and 4.22 ± 0.11 eV (Os+-SO). Among these BDE values, the values for OsO+ and OsO2+ agree with literature values and those for OsS+ and OOsS+ are novel measurements. Theoretical calculations were performed at a B3LYP/def2-TZVPPD level for all products, and additional calculations were performed for OsS+, OsO2+, and OsSO+ using the CCSD(T) level of theory, extrapolated to the complete basis set (CBS) limit, and def2-QZVPPD and aug-cc-pVxZ (x = T, Q, and 5) basis sets. These calculations indicate that the ground states of the products are 4Π5/2 (OsO+), 2B1 (OsO2+), 4Π5/2 (OsS+), and 2A″ (OOsS+) after including empirical spin-orbit corrections. The potential energy surfaces (PESs) for OsSO2+ intermediates, transition states, and all products were also investigated at the B3LYP/def2-TZVPPD level. The PESs show that none of the reactions have barriers in excess of the product endothermicities. Cross sections for OsO+ formation are compared to those from previous guided ion beam studies of related systems (Os+ + O2 and CO and Re+ + SO2) to evaluate their relative behaviors.
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Affiliation(s)
- JungSoo Kim
- Department of Chemistry, University of Utah, 315 S. 1400 E., Rm. 2020, Salt Lake City, Utah 84112, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 S. 1400 E., Rm. 2020, Salt Lake City, Utah 84112, United States
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Merriles DM, Sevy A, Nielson C, Morse MD. The bond dissociation energy of VO measured by resonant three-photon ionization spectroscopy. J Chem Phys 2020; 153:024303. [PMID: 32668947 DOI: 10.1063/5.0014006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The predissociation threshold of VO has been measured using resonant three-photon ionization (R3PI) spectroscopy. Given the high density of electronic states in the molecule, it is argued that the molecule dissociates rapidly as soon as the thermochemical bond dissociation energy (BDE) is exceeded, allowing the measured predissociation threshold to be assigned as the BDE. This is the first time a BDE has been measured using the R3PI method. The first photon is provided by an optical parametric oscillator (OPO) laser that promotes VO into a high-energy, discrete vibronic state. A tunable dye laser then excites the molecule further to a resonant state close to the dissociation limit where there is a quasi-continuum of states. A second photon from the same dye laser pulse ionizes the molecule, generating VO+ ions. The dye laser is then scanned to higher energies, and when the energy of one OPO photon plus one dye photon exceeds the BDE, the molecule dissociates before another dye photon can be absorbed to induce ionization. The combined photon energy at the sharp drop in the ion signal is assigned as the BDE. The experiment has been repeated using four different intermediate states, all yielding the same BDE, D0(VO) = 6.545(2) eV. Using thermochemical cycles, a revised value for the BDE of cationic VO is obtained, D0(V+-O) = 6.053(2) eV. The 0 K enthalpy of formation for VO(g) is also derived as ΔfH0K 0VO(g) = 128.6(1.0) kJ mol-1. Previous spectroscopic and thermochemical studies of VO are reviewed.
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Affiliation(s)
- Dakota M Merriles
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Andrew Sevy
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Christopher Nielson
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Michael D Morse
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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