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Ariyarathna IR. Ground and excited electronic structures of electride and alkalide units: The cases of Metal-Tren, -Azacryptand, and -TriPip222 complexes. J Comput Chem 2024; 45:655-662. [PMID: 38087935 DOI: 10.1002/jcc.27265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/24/2023] [Accepted: 11/10/2023] [Indexed: 03/02/2024]
Abstract
A systematic electronic structure analysis was conducted for M(L)n molecular electrides and their corresponding alkalide units M(L)n @M' (M/M' = Na, K; L = Tren, Azacryptand, TriPip222; n = 1, 2). All complexes belong to the "superalkali" category due to their low ionization potentials. The saturated molecular electrides display M+ (L)n - form with a greatly diffuse quasispherical electron cloud. They were identified as "superatoms" considering the contours of populating atomic-type molecular orbitals. The observed superatomic Aufbau order of M(Tren)2 is 1S, 1P, 1D, 1F, 2S, 2P, and 1G and it is consistent with those of M(Azacryptand) and M(TriPip222) up to the analyzed 1F level. Their excitation energies decrease gradually moving from M(Tren)2 to M(Azacryptand) and to M(TriPip222). The studied alkalide complexes carry [M(L)n ]+ @M'- ionic structure and their dissociation energies vary in the sequence of K(L)n @Na > Na(L)n @Na > K(L)n @K > Na(L)n @K. Similar to molecular electrides, the anions of alkalide units occupy electrons in diffuse Rydberg-like orbitals. In this work, excited states of [M(L)n @M']0/+/- and their trends are also analyzed.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama, USA
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Ariyarathna IR, Cho Y, Duan C, Kulik HJ. Gas-phase and solid-state electronic structure analysis and DFT benchmarking of HfCO. Phys Chem Chem Phys 2023; 25:26632-26639. [PMID: 37767841 DOI: 10.1039/d3cp03550f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Ab initio multi-reference configuration interaction (MRCI) and coupled cluster singles doubles and perturbative triples [CCSD(T)] levels of theory were used to study ground and excited electronic states of HfCO. We report potential energy curves, dissociation energies (De), excitation energies, harmonic vibrational frequencies, and chemical bonding patterns of HfCO. The 3Σ- ground state of HfCO has an 1σ22σ21π2 electron configuration and a ∼30 kcal mol-1 dissociation energy with respect to its lowest-energy fragments Hf(3F) + CO(X1Σ+). We further evaluated the De of its isovalent HfCX (X = S, Se, Te, Po) series and observed that they increase linearly from the lighter HfCO to the heavier HfCPo with the dipole moment of the CX ligand. The same linear relationship was observed for TiCX and ZrCX. We utilized the CCSD(T) benchmark values of De, excitation energy, and ionization energy (IE) values to evaluate density functional theory (DFT) errors with 23 exchange-correlation functionals spanning GGA, meta-GGA, global GGA hybrid, meta-GGA hybrid, range-separated hybrid, and double-hybrid functional families. The global GGA hybrid B3LYP and range-separated hybrid ωB97X performed well at representing the ground state properties of HfCO (i.e., De and IE). Finally, we extended our DFT analysis to the interaction of a CO molecule with a Hf surface and observed that the surface chemisorption energy and the gas-phase molecular dissociation energy are very similar for some DFAs but not others, suggesting moderate transferability of the benchmarks on these molecules to the solid state.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Yeongsu Cho
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Duan C, Ladera AJ, Liu JCL, Taylor MG, Ariyarathna IR, Kulik HJ. Exploiting Ligand Additivity for Transferable Machine Learning of Multireference Character across Known Transition Metal Complex Ligands. J Chem Theory Comput 2022; 18:4836-4845. [PMID: 35834742 DOI: 10.1021/acs.jctc.2c00468] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Accurate virtual high-throughput screening (VHTS) of transition metal complexes (TMCs) remains challenging due to the possibility of high multireference (MR) character that complicates property evaluation. We compute MR diagnostics for over 5,000 ligands present in previously synthesized octahedral mononuclear transition metal complexes in the Cambridge Structural Database (CSD). To accomplish this task, we introduce an iterative approach for consistent ligand charge assignment for ligands in the CSD. Across this set, we observe that the MR character correlates linearly with the inverse value of the averaged bond order over all bonds in the molecule. We then demonstrate that ligand additivity of the MR character holds in TMCs, which suggests that the TMC MR character can be inferred from the sum of the MR character of the ligands. Encouraged by this observation, we leverage ligand additivity and develop a ligand-derived machine learning representation to train neural networks to predict the MR character of TMCs from properties of the constituent ligands. This approach yields models with excellent performance and superior transferability to unseen ligand chemistry and compositions.
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Affiliation(s)
- Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Adriana J Ladera
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Julian C-L Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael G Taylor
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Isuru R Ariyarathna
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Ariyarathna IR, Duan C, Kulik HJ. Understanding the chemical bonding of ground and excited states of HfO and HfB with correlated wavefunction theory and density functional approximations. J Chem Phys 2022; 156:184113. [PMID: 35568536 DOI: 10.1063/5.0090128] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Knowledge of the chemical bonding of HfO and HfB ground and low-lying electronic states provides essential insights into a range of catalysts and materials that contain Hf-O or Hf-B moieties. Here, we carry out high-level multi-reference configuration interaction theory and coupled cluster quantum chemical calculations on these systems. We compute full potential energy curves, excitation energies, ionization energies, electronic configurations, and spectroscopic parameters with large quadruple-ζ and quintuple-ζ quality correlation consistent basis sets. We also investigate equilibrium chemical bonding patterns and effects of correlating core electrons on property predictions. Differences in the ground state electron configuration of HfB(X4Σ-) and HfO(X1Σ+) lead to a significantly stronger bond in HfO than HfB, as judged by both dissociation energies and equilibrium bond distances. We extend our analysis to the chemical bonding patterns of the isovalent HfX (X = O, S, Se, Te, and Po) series and observe similar trends. We also note a linear trend between the decreasing value of the dissociation energy (De) from HfO to HfPo and the singlet-triplet energy gap (ΔES-T) of the molecule. Finally, we compare these benchmark results to those obtained using density functional theory (DFT) with 23 exchange-correlation functionals spanning multiple rungs of "Jacob's ladder." When comparing DFT errors to coupled cluster reference values on dissociation energies, excitation energies, and ionization energies of HfB and HfO, we observe semi-local generalized gradient approximations to significantly outperform more complex and high-cost functionals.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Liu G, Ariyarathna IR, Zhu Z, Ciborowski SM, Miliordos E, Bowen KH. Molecular-level electrocatalytic CO 2 reduction reaction mediated by single platinum atoms. Phys Chem Chem Phys 2022; 24:4226-4231. [PMID: 35132978 DOI: 10.1039/d1cp05189j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The activation and transformation of H2O and CO2 mediated by electrons and single Pt atoms is demonstrated at the molecular level. The reaction mechanism is revealed by the synergy of mass spectrometry, photoelectron spectroscopy, and quantum chemical calculations. Specifically, a Pt atom captures an electron and activates H2O to form a H-Pt-OH- complex. This complex reacts with CO2via two different pathways to form formate, where CO2 is hydrogenated, or to form bicarbonate, where CO2 is carbonated. The overall formula of this reaction is identical to a typical electrochemical CO2 reduction reaction on a Pt electrode. Since the reactants are electrons and isolated, single atoms and molecules, we term this reaction a molecular-level electrochemical CO2 reduction reaction. Mechanistic analysis reveals that the negative charge distribution on the Pt-H and the -OH moieties in H-Pt-OH- is critical for the hydrogenation and carbonation of CO2. The realization of the molecular-level CO2 reduction reaction provides insights into the design of novel catalysts for the electrochemical conversion of CO2.
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Affiliation(s)
- Gaoxiang Liu
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA.
| | - Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Zhaoguo Zhu
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA.
| | - Sandra M Ciborowski
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA.
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Kit H Bowen
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, MD 21218, USA.
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Abstract
Ab initio coupled-cluster, electron propagator, and Møller-Plesset second-order perturbation theory calculations are utilized to analyze the low-lying electronic states of several metal-doped B20. In the ground state, the presently focused AB20/EB20 (A = Li, Na, and K; E = Mg and Ca) consist of charge-separated A+B20-/E2+B202- frameworks. The excited electronic states of AB20 and EB20+ were analyzed by computing the vertical electron attachment energies (VEAEs) of AB20+ and EB202+. In several excited states, the radical electron is predominantly localized on the B20 frames, which are counterparts of the low-lying states of bare B20-. A variety of basis sets were tested on obtaining VEAEs, and the aug-cc-pVDZ/A,E d-aug-cc-pVDZ/B combination provided the best accuracy-efficiency compromise on them. Furthermore, this work analyzes the Rydberg-like excited states of AB20 and EB20+ and will serve as a guide for future studies on similar metal-doped boron systems.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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Abstract
Li, Na, and Mg+-coordinated hexaaza-18-crown-6 ([18]aneN6) and 1,4,7-triazacyclononane ([9]aneN3), Li[1.1.1]cryptand, and Na[2.2.2]cryptand species possess a diffuse electron in a quasispherical s-type orbital. They populate expanded p-, d-, f-, and g-shape orbitals in low-lying excited states and hence are identified as "superatoms". By means of quantum calculations, their superatomic shell models are revealed. The observed orbital series of M([9]aneN3)2 and M[18]aneN6 (M = Li, Na, Mg+) are identical to the 1s, 1p, 1d, 1f, 2s, and 2p. The electronic spectra of Li[1.1.1]cryptand and Na[2.2.2]cryptand were analyzed up to the 1f1 configuration, and their transitions were found to occur at lower energies compared to their aza-crown ethers. The introduced superatomic shell models in this work closely resemble the Aufbau principle of "solvated electrons precursors". All reported alkali metal complexes bear lower ionization potentials than any atom in the periodic table; thus, they can also be recognized as "superalkalis".
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Ariyarathna IR, Miliordos E. Ground and excited states analysis of alkali metal ethylenediamine and crown ether complexes. Phys Chem Chem Phys 2021; 23:20298-20306. [PMID: 34486608 DOI: 10.1039/d1cp02552j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-level electronic structure calculations are carried out to obtain optimized geometries and excitation energies of neutral lithium, sodium, and potassium complexes with two ethylenediamine and one or two crown ether molecules. Three different sizes of crowns are employed (12-crown-4, 15-crown-5, 18-crown-6). The ground state of all complexes contains an electron in an s-type orbital. For the mono-crown ether complexes, this orbital is the polarized valence s-orbital of the metal, but for the other systems this orbital is a peripheral diffuse orbital. The nature of the low-lying electronic states is found to be different for each of these species. Specifically, the metal ethylenediamine complexes follow the previously discovered shell model of metal ammonia complexes (1s, 1p, 1d, 2s, 1f), but both mono- and sandwich di-crown ether complexes bear a different shell model partially due to their lower (cylindrical) symmetry and the stabilization of the 2s-type orbital. Li(15-crown-5) is the only complex with the metal in the middle of the crown ether and adopts closely the shell model of metal ammonia complexes. Our findings suggest that the electronic band structure of electrides (metal crown ether sandwich aggregates) and expanded metals (metal ammonia aggregates) should be different despite the similar nature of these systems (bearing diffuse electrons around a metal complex).
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
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Ariyarathna IR. Ground and excited electronic structures of metal encapsulated nanocages: the cases of endohedral M@C 20H 20 (M = K, Rb, Ca, Sr) and M@C 36H 36 (M = Na, K, Rb). Phys Chem Chem Phys 2021; 23:18588-18594. [PMID: 34612395 DOI: 10.1039/d1cp03146e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
High-level electronic structure calculations were performed to analyze ground and excited states of neutral and cationic endohedral M@C20H20 (M = K, Rb, Ca, Sr) and M@C36H36 (M = Na, K, Rb). In their ground states, one or two electrons occupy a diffuse atomic s-type orbital, thus 1s1 and 1s2 superatomic electronic configurations are assigned for M = Na, K, Rb and M = Ca, Sr cases, respectively. These species populate 1p-, 1d-, 1f-superatomic orbitals in electronically excited states. The specific superatomic Aufbau model introduced for M@C20H20 (M = K, Rb) is 1s, 1p, 1d, 2s, 1f, 2p, 2d, 1g, 2f. On the other hand, excited electronic spectra of M@C20H20 (M = Ca, Sr) are rich in multireference characters. Excited states of bigger M@C36H36 molecules were investigated up to the 1d level and the transitions were found to require slightly higher energies compared to M@C20H20. These superatoms possess lower ionization potentials, hence can also be categorized as superalkalis.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
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Hiti EA, Wilkinson GR, Ariyarathna IR, Tutson CD, Hardy EE, Maynard BA, Miliordos E, Gorden AEV. Comparing coordination uranyl(vi) complexes with 2-(1H-imidazo[4,5-b]phenazin-2-yl)phenol and derivatives. Dalton Trans 2021; 50:11113-11122. [PMID: 34323252 DOI: 10.1039/d1dt02359d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four derivatives of 2-(1H-imidazo[4,5-b]phenazin-2-yl)phenol have been synthesized and characterized structurally using X-ray crystallography. Coordination complexes with uranyl (UO22+) and copper (Cu2+) were prepared and absorption/emission spectra detailed. We observed increased fluorescence upon uranyl binding, in stark contrast to rapid quenching observed with the addition of copper. These phenomena have been further examined by DFT computational methods.
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Affiliation(s)
- E A Hiti
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA
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Ariyarathna IR, Miliordos E. Radical abstraction vs. oxidative addition mechanisms for the activation of the S -H, O -H, and C -H bonds using early transition metal oxides. Phys Chem Chem Phys 2021; 23:1437-1442. [PMID: 33393944 DOI: 10.1039/d0cp05513a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Quantum chemical calculations are performed to study the S-H, O-H, and C-H bond activation of H2S, H2O, and CH4 by bare and ligated ZrO+ and NbO+ units. These representative oxides bear low energy oxo and higher energy oxyl units. S-H and C-H bonds are readily activated by metal oxyl states (radical mechanism), but the O-H bond is harder to activate with either the oxyl or oxo states. Our results suggest that known practices for the C-H bond activation can be applied to S-H, but not to O-H bonds. The identified trends are rationalized in terms of the HS-H, HO-H, and H3C-H dissociation energies to the homolytic or heterolytic fragments. We also found that these dissociation energies drop to about half after coordination of H2S or H2O to the metal oxide unit. In addition, chlorine ligands are shown to stabilize the higher energy oxyl states of the transition metal oxygen unit enhancing the reactivity of the formed complexes.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
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Abstract
High-level coupled-cluster, electron propagator, and multi-reference ab initio methods are employed to study the ground and excited electronic states of the XM4 (X = N, P and M = Li, Na) series. All XM4 species bear lower ionization potentials and can be classified as superalkalis. In the ground state each possesses a diffuse electron in the periphery. This expanded electron cloud of tetrahedral NLi4, NNa4, and PNa4 molecules is spherical (similar to an s-orbital) and evenly distributed around the XM4+ core. The outer electron is promoted to higher-angular momentum p-, d-, 2s-type orbitals in excited states. Singly occupied molecular orbitals of excited PLi4 are deformed due to its lower C1 symmetry. The aug-cc-pVQZ basis set was found to describe the excited states of XM4 accurately and efficiently. The bound singlet and triplet electronic states of XM4- that possess two peripheral electrons are also analyzed.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
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Liu G, Ariyarathna IR, Ciborowski SM, Zhu Z, Miliordos E, Bowen KH. Simultaneous Functionalization of Methane and Carbon Dioxide Mediated by Single Platinum Atomic Anions. J Am Chem Soc 2020; 142:21556-21561. [PMID: 33307694 DOI: 10.1021/jacs.0c11112] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mass spectrometric analysis of the anionic products of interaction among Pt-, methane, and carbon dioxide shows that the methane activation complex, H3C-Pt-H-, reacts with CO2 to form [H3C-Pt-H(CO2)]-. Two hydrogenation and one C-C bond coupling products are identified as isomers of [H3C-Pt-H(CO2)]- by a synergy between anion photoelectron spectroscopy and quantum chemical calculations. Mechanistic study reveals that both CH4 and CO2 are activated by the anionic Pt atom and that the successive depletion of the negative charge on Pt drives the CO2 insertion into the Pt-H and Pt-C bonds of H3C-Pt-H-. This study represents the first example of the simultaneous functionalization of CH4 and CO2 mediated by single atomic anions.
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Affiliation(s)
- Gaoxiang Liu
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, Maryland 21218,United States
| | - Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Sandra M Ciborowski
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, Maryland 21218,United States
| | - Zhaoguo Zhu
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, Maryland 21218,United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Kit H Bowen
- Department of Chemistry, Johns Hopkins University, 3400 N Charles St, Baltimore, Maryland 21218,United States
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Affiliation(s)
- Isuru R. Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Ariyarathna IR, Almeida NMS, Miliordos E. Ab initio investigation of the ground and excited states of RuO +,0,- and their reaction with water. Phys Chem Chem Phys 2020; 22:16072-16079. [PMID: 32638768 DOI: 10.1039/d0cp02468f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-level quantum chemical calculations on RuO0,± elucidate the electronic structure of their low-lying electronic states. For thirty-two states, we report the electronic configurations, bond lengths, vibrational frequencies, spin-orbit splittings, and excitation energies. The electronic states of RuO can be generated from those of RuO+ by adding one electron to the σ non-bonding orbital closely resembling the 5s atomic orbital of Ru. The ground states for RuO and RuO- are clearly identified as 5Δ and 4Δ, but the two states (4Δ and 2Π) compete for RuO+. The difficulty of calculations is revealed by our small binding energies compared to the experimental values. In addition, we studied the reaction of the three species with water in their ground and selected low-lying electronic states. We found a consistent decrease of the activation energy barriers and higher exothermicity as we add electrons to the system. RuO- is found to facilitate the reaction for both kinetic and thermodynamic reasons.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Nuno M S Almeida
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
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Ariyarathna IR, Miliordos E. Geometric and electronic structure analysis of calcium water complexes with one and two solvation shells. Phys Chem Chem Phys 2020; 22:22426-22435. [DOI: 10.1039/d0cp04309e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The stability of calcium water complexes is investigated quantum mechanically. Ground and excited electronic states are studied for hexa-, octa-, and octakaideca-coordinated complexes, where calcium valence electrons move to outer diffuse orbitals.
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Abstract
Multi-reference configuration interaction (MRCI) and single reference coupled cluster calculations are performed for the ThCO and OThC isomers. Scalar and spin-orbit relativistic effects are considered through a relativistic pseudopotential and the coupling of MRCI wavefunctions via the Breit-Pauli spin-orbit Hamiltonian. Optimized geometries, excitation energies, and vibrational frequencies are reported for both isomers. Full potential energy profiles are constructed for the Th+CO reaction and the conversion of the produced ThCO to OThC. Linear ThCO was found to be more stable than the highly ionic bent OThC system by about 4 kcal mol-1. The interconversion barrier is estimated to be around 30 kcal mol-1. Our results are in agreement with earlier experimental data for the two isomers. The lowest lying states of Th do not populate f-orbitals and resemble the electronic structure of Ti. Therefore, the ability of the two atoms to activate the C[triple bond, length as m-dash]O bond is compared. OTiC is found to be about 40 kcal mol-1 less stable than TiCO revealing the efficiency of Th and possibly other f-block elements to activate multiple chemical bonds as opposed to d-block metals.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
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Almeida NMS, Ariyarathna IR, Miliordos E. O-H and C-H Bond Activations of Water and Methane by RuO 2+ and (NH 3)RuO 2+: Ground and Excited States. J Phys Chem A 2019; 123:9336-9344. [PMID: 31580075 DOI: 10.1021/acs.jpca.9b05910] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Investigation of the ground and excited states of RuO2+ is carried out using multireference quantum chemical methodologies. The electronic structure is explored in detail, and accurate spectroscopic constants for 12 states are reported. Although ruthenium belongs to the same group as iron, the ground state of RuO2+ is 1Σ+ with a strong oxo character as opposed to the 3Δ of FeO2+ with primarily oxyl character. To see the effect of the different electronic structure of RuO2+ on the O-H and C-H bond activation processes, we studied its reaction with one water or methane molecule. Reaction energies and activation barriers are given for six low-lying electronic states of singlet, triplet, and quintet spin multiplicities. It is found that the higher-energy quintet state (5Σ+) provides the lowest activation energies and is the same state responsible for the C-H activation for FeO2+ complexes. The reason is attributed to its weaker metal-oxygen bond (longer bond length), which is "prepared" to be activated at the same time with the O-H and C-H bonds. The effect of an ammonia ligand in the chemical activity is also discussed.
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Affiliation(s)
- Nuno M S Almeida
- Department of Chemistry and Biochemistry , Auburn University , Auburn , Alabama 36849-5312 , United States
| | - Isuru R Ariyarathna
- Department of Chemistry and Biochemistry , Auburn University , Auburn , Alabama 36849-5312 , United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry , Auburn University , Auburn , Alabama 36849-5312 , United States
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Ariyarathna IR, Pawłowski F, Ortiz JV, Miliordos E. Aufbau Principle for Diffuse Electrons of Double-Shell Metal Ammonia Complexes: The Case of M(NH3)4@12NH3, M = Li, Be+, B2+. J Phys Chem A 2019; 124:505-512. [DOI: 10.1021/acs.jpca.9b07734] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isuru R. Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Filip Pawłowski
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Joseph Vincent Ortiz
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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Ariyarathna IR, Almeida NMS, Miliordos E. Stability and Electronic Features of Calcium Hexa-, Hepta-, and Octa-Coordinated Ammonia Complexes: A First-Principles Study. J Phys Chem A 2019; 123:6744-6750. [DOI: 10.1021/acs.jpca.9b04966] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Isuru R. Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Nuno M. S. Almeida
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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Ariyarathna IR, Miliordos E. Electronic and geometric structure analysis of neutral and anionic alkali metal complexes of the CX series (X = O, S, Se, Te, Po): The case of M(CX) n = 1-4 (M = Li, Na) and their dimers. J Comput Chem 2019; 40:1344-1351. [PMID: 30747451 DOI: 10.1002/jcc.25791] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/21/2018] [Accepted: 01/06/2019] [Indexed: 11/10/2022]
Abstract
Bonding mechanisms, potential energy curves, accurate structures, energetics, and electron affinities are obtained for all M(CX)1-3 species with M = Li, Na, and X = O, S, Se, Te, and Po, at the coupled-cluster level with triple-ζ quality basis sets. We discuss and rationalize the trends within different molecular groups. For example, we found larger binding energies for M = Li, for CX = CPo, and for the tri-coordinated (n = 3) complexes. All three facts are explained by the fact that the global minimum of the titled complexes originate from the first excited 2 P (2p1 for Li or 3p1 for Na) state of the metal, with each ligand forming a dative bond with the metal. All of the complexes, except Na(CO)3 , have stable anions, and their electron affinity increases as MCX < M(CX)3 < M(CX)2 . This sequence is attributed to the binding modes of these complexes. The Li(CO)3 and Li(CS)3 complexes are able to accommodate a fourth ligand, which is attached to the system electrostatically. Finally, two Li(CO)3 molecules can bind together covalently to make the ethane analog. The staggered conformer was found lower in energy and unlike ethane the CO ligands bend toward the neighboring Li(CO)3 moiety. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama, 36849-5312
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama, 36849-5312
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Liu G, Zhu Z, Ciborowski SM, Ariyarathna IR, Miliordos E, Bowen KH. Selective Activation of the C-H Bond in Methane by Single Platinum Atomic Anions. Angew Chem Int Ed Engl 2019; 58:7773-7777. [PMID: 30968506 DOI: 10.1002/anie.201903252] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Indexed: 01/21/2023]
Abstract
Mass spectrometric analysis of the anionic products of interaction between platinum atomic anions, Pt- , and methane, CH4 and CD4 , in a collision cell shows the preferred generation of [PtCH4 ]- and [PtCD4 ]- complexes and a low tendency toward dehydrogenation. [PtCH4 ]- is shown to be H-Pt-CH3 - by a synergy between anion photoelectron spectroscopy and quantum chemical calculations, implying the rupture of a single C-H bond. The calculated reaction pathway accounts for the observed selective activation of methane by Pt- . This study presents the first example of methane activation by a single atomic anion.
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Affiliation(s)
- Gaoxiang Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Zhaoguo Zhu
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Sandra M Ciborowski
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, 36849, USA
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, 36849, USA
| | - Kit H Bowen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
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Ariyarathna IR, Miliordos E. Electronic and geometric structure analysis of neutral and anionic metal nitric chalcogens: The case of MNX series (M=Li, Na, Be and X=O, S, Se, Te). J Comput Chem 2019; 40:1740-1751. [PMID: 30920017 DOI: 10.1002/jcc.25829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 02/15/2019] [Accepted: 03/12/2019] [Indexed: 11/11/2022]
Abstract
Coupled cluster and multireference configuration approaches are employed to study the electronic and geometric structures of mono-coordinated complexes of lithium, sodium, and beryllium with nitric oxide and its isovalent NS, NSe, and NTe species. Ground and low-lying excited states were examined for both linear-bonded and side-bonded isomers. We show that the ionic M+ NX- (M=Li, Na, Be and X=O, S, Se, Te) picture is a more natural representation and can account for the symmetry of the low-lying electronic states as Σ- , Δ, and Σ+ , the smaller excitation energies and the larger binding energies for heavier X. An additional electron binds to the positively charged Li and Na terminal creating stable anions. The electron affinity (EA) of LiNX and NaNX species is in the 0.5-0.8 eV range. Despite the negative EA of beryllium and the very small EA of NO, the BeNO molecule has an EA of ~1.0 eV, which is increased to ~1.5 eV for the heavier BeNX species. This is attributed to the fact that the additional electron goes to the beryllium end for BeNO but to a π(MN)π*(NX) orbital of the rest species. Our accurate results contradict previous findings and serve as a guide for future experimental studies. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312
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Ariyarathna IR, Miliordos E. Superatomic nature of alkaline earth metal–water complexes: the cases of Be(H2O)0,+4 and Mg(H2O)0,+6. Phys Chem Chem Phys 2019; 21:15861-15870. [DOI: 10.1039/c9cp01897b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Beryllium– and magnesium–water complexes are shown to accommodate peripheral electrons around their Be2+(H2O)4 and Mg2+(H2O)6 cores in hydrogenic type orbitals.
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Ariyarathna IR, Khan SN, Pawłowski F, Ortiz JV, Miliordos E. Aufbau Rules for Solvated Electron Precursors: Be(NH 3) 40,± Complexes and Beyond. J Phys Chem Lett 2018; 9:84-88. [PMID: 29232138 DOI: 10.1021/acs.jpclett.7b03000] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Tetra-amino beryllium complexes and ions, Be(NH3)40,±, have a tetrahedral Be(NH3)42+ core with one, two, or three outer electrons orbiting its periphery. Our calculations reveal a new class of molecular entities, solvated electron precursors, with Aufbau rules (1s, 1p, 1d, 2s, 1f, 2p, 2d) that differ from their familiar hydrogenic counterparts and resemble those of jellium or nuclear-shell models. The core's radial electrostatic potential suffices to reproduce the chief features of the ab initio results. Wave function and electron-propagator methods combined with diffuse basis sets are employed to calculate accurate geometries, ionization energies, electron affinities, and excitation energies.
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Affiliation(s)
- Isuru R Ariyarathna
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849-5312, United States
| | - Shahriar N Khan
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849-5312, United States
| | - Filip Pawłowski
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849-5312, United States
| | - Joseph Vincent Ortiz
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849-5312, United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849-5312, United States
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Ariyarathna IR, Miliordos E. Ab initio investigation of the ground and excited states of MoO+,2+,− and their catalytic strength on water activation. Phys Chem Chem Phys 2018; 20:12278-12287. [DOI: 10.1039/c8cp01676c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ground and excited states of the titled molybdenum oxides and their reaction with water were studied with high level quantum chemical methodologies.
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Ariyarathna IR, Pawłowski F, Ortiz JV, Miliordos E. Molecules mimicking atoms: monomers and dimers of alkali metal solvated electron precursors. Phys Chem Chem Phys 2018; 20:24186-24191. [DOI: 10.1039/c8cp05497e] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tetra-amino lithium and sodium complexes M(NH3)0,−4 (M = Li, Na) have one or two electrons that occupy diffuse hydrogenic type orbitals distributed chiefly outside the M(NH3)4+ core. Two such neutral species can bind to form a dimer which can be seen as the analogue of molecular hydrogen.
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Affiliation(s)
| | - Filip Pawłowski
- Department of Chemistry and Biochemistry
- Auburn University
- Auburn
- USA
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Almeida NMS, Ariyarathna IR, Miliordos E. Ab initio calculations on the ground and excited electronic states of neutral and charged palladium monoxide, PdO0,+,−. Phys Chem Chem Phys 2018; 20:14578-14586. [DOI: 10.1039/c8cp01251b] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multi-reference configuration interaction and coupled cluster calculations were carried out for the ground and several low-lying excited electronic states for PdO, PdO+, and PdO−. The photoelectron spectrum peaks of PdO were assigned.
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Affiliation(s)
- Isuru R. Ariyarathna
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Evangelos Miliordos
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Ariyarathna IR, Nedra Karunaratne D. Use of chickpea protein for encapsulation of folate to enhance nutritional potency and stability. Food and Bioproducts Processing 2015. [DOI: 10.1016/j.fbp.2015.04.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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