Unprecedented Enhancement of Noble GasâNoble Metal Bonding in

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Unprecedented Enhancement of Noble Gas-Noble Metal Bonding in NgAu (Ng = Ar, Kr, and Xe) Ion Through Hydrogen Doping 3+

Ayan Ghosh, and Tapan K. Ghanty J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.6b09631 • Publication Date (Web): 24 Nov 2016 Downloaded from http://pubs.acs.org on November 25, 2016

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The Journal of Physical Chemistry

Unprecedented Enhancement of Noble GasNoble Metal Bonding in NgAu3+ (Ng = Ar, Kr, and Xe) Ion through Hydrogen Doping

Ayan Ghosh†,# and Tapan K. Ghanty‡,#,*

†

Laser and Plasma Technology Division, Beam Technology Development Group, Bhabha Atomic Research Centre, Mumbai 400085, INDIA.

‡

Theoretical Chemistry Section, Chemistry Group, Bhabha Atomic Research Centre, Mumbai 400085, INDIA. #

Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, INDIA.

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ABSTRACT Behavior of gold as hydrogen in certain gold compounds and a very recent experimental report on the noble gas-noble metal interaction in Ar complexes of mixed Au-Ag trimers have motivated us to investigate the effect of hydrogen doping on the Ng-Au (Ng = Ar, Kr and Xe) bonding through various ab initio based techniques. The calculated results show considerable strengthening of the Ng-Au bond in terms of bond length, bond energy, stretching vibrational frequency, and force constant. Particularly, an exceptional enhancement of Ar-Au bonding strength has been observed in ArAuH2+ species as compared to that in ArAu3+ system, as revealed from the CCSD(T) calculated Ar-Au bond energy value of 32 and 72 kJ mol-1 for ArAu3+ and ArAuH2+, respectively. In the calculated IR spectra, the Ar-Au stretching frequency is blue-shifted by 65% in going from ArAu3+ to ArAuH2+ species. Similar trends have been obtained in case of all Ar, Kr, and Xe complexes with Ag and Cu trimers. Among all the NgM3-kHk+ complexes (where k = 0-2), the strongest binding in NgMH2+ complex is attributed to significant enhancement in the covalent characteristics of the Ng-M bond and considerable increase in charge-induced dipole interaction, as shown from the topological analysis. *

Author to whom correspondence should be addressed. Telephone: (+) 91-22-25595089;

Fax: (+) 91-22-25505151; Electronic mail: [email protected].


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1. INTRODUCTION Due to completely filled valence electronic configuration, the noble gas atoms are extremely reluctant to participate in conventional chemical bonding with other atoms through electron density redistribution. Similarly, the coinage metal atoms (Cu, Ag, and Au) are known as noble metals because of their less reactivity. Therefore, the noble gas-noble metal interaction is expected to be extremely unusual from the view point of inert nature of both the noble gas and noble metal atoms. Consequently, it has been a great challenge to the scientists to investigate a chemical bond that exists in between noble gas and noble metal by combining these two very less reactive atoms. Schröder et al. first experimentally identified chemical compounds involving noble gas and noble metal, XeAu+ and XeAuXe+, by mass spectrometry in 1998,1 although they were first conceived by Pyykkö, who predicted the stability of the species theoretically in 1995.2 According to Buckingham and co-workers,3 the origin of the noble metalnoble gas bonding is the long range polarization and dispersion effect, and no significant covalent character persists therein as proposed by Pyykkö.2 In 2000, the experimental detection of solid reddish compound, [AuXe4]2+ containing AuXe bonds by Seidel and Seppelt4,5 as well as the finding of pure rotational spectra of ArAuCl and KrCuCl with the cavity pulsed-jet FTMW spectrometer by Gerry et al.6 open the door of a new era in the chemical sciences. Subsequently, a series of compounds containing NgM bond (Ng = Ar, Kr, and Xe; M = Au, Ag, and Cu), viz., NgMX (X = F, Cl, and Br) have been investigated6-12 both experimentally and theoretically. In the recent past, we have explored the feasibility study of noble gas inserted compounds, MNgF and MNgOH (M = Cu, Ag, and Au; Ng = Ar, Kr, and Xe) using ab initio calculations,13,14 motivated from the work of Räsänen and coworkers on the observation of HArF,15 and exploiting the gold-hydrogen analogy.16-18 Very recently, NeAuF has also been prepared experimentally.19,20 Apart from noble gasnoble metal bonding, interaction of noble gas with other metal atom is also of considerable recent interests.21-25 As mentioned, noble gasnoble metal bonding have been investigated extensively over the years, however, the nature of this kind of bonding has been controversial as pointed out very recently by Fielicke and co-workers.26,27 In fact, they proposed trimeric coinage metal cluster as a prototype system to unravel the nature of ArM bonding (M = Ag, and Au) and showed that the total Ar binding energy in Au3+.Ar3 is considerably higher than that in Ag3+.Ar3 (cf. 0.84 vs 0.45 eV). Moreover, through far IR multiple-photon dissociation Page 3 of 29 ACS Paragon Plus Environment


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spectroscopy it has been demonstrated that Ar atoms in Ag3+.Ar3 complex act merely as messenger while the same participate in conventional ArAu chemical bonding in Au3+.Ar3 complex and thereby modify the IR spectra significantly. Also, the ArM bond energy in ArAg3+ complex (0.16 eV) is found to increase with the replacement of Ag with Au atom, and finally reaches to 0.31 eV in the ArAu3+ complex. The study of this kind of bonding is very important in elucidating the structure of a metal cluster, since the electronic structure and the IR spectra of metal cluster are highly dependent on the nature and strength of noble gas – noble metal interaction.26-29 Apart from the experimental investigations on the interaction of noble gas atom with coinage metal atom trimer cations, very recently, theoretical studies involving similar kind of complexes have been reported in the literature. 30 In this work, we raise a question: Is it possible to further increase the noble gasnoble metal bonding interaction exceptionally as compared to that in the ArAu3+26 system? To answer this question quantitatively, we have considered various noble gas atoms (Ng=Ar, Kr and Xe) and hydrogen doped gold trimers, which is motivated by the goldhydrogen analogy as proposed by Li et al.,17 and subsequently investigated by others for various systems.18,19 Here it may be noted that both hydrogendoped small size gold/silver clusters and H2 adsorbed gold clusters have been shown to behave as a better catalyst in the oxidation of carbon monoxide,31-35 however, the catalytic activity remains almost unchanged when Au20 cluster is doped with hydrogen atom.36 Therefore, it is further interesting to investigate the change in the nature and strength of Ng-Au bonding in NgAu3+ through successive replacement of Au atom(s) with H atom(s) resulting into NgAu2H+ and NgAuH2+ kind of species. To the best of our knowledge NgAu2H+ and NgAuH2+ species have never been reported in the literature. In this connection, it is worthwhile to mention that the hydrogen doped noble metal clusters have been investigated experimentally as well as theoretically.26.27,31,32,37-41 In the present work, all the calculations have been performed by using MP2, DFT with dispersion corrected B97XD functionals, and CCSD(T) methods, details of which are given in the Supporting Information. In order to standardize the appropriate method and basis set, we have carried out extensive theoretical calculations of NgMF (Ng = Ar, Kr, and Xe; M = Cu, Ag, and Au) compounds and evaluated their NgM bond length, bond energy, IR frequency and force constant values to compare with the available experimental results (Supporting Information, Table S1 and S2). We have found that the results obtained from Page 4 of 29 ACS Paragon Plus Environment

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B97XD and MP2 methods with def2TZVPPD (DEF2) basis set agree very well with the experimentally observed values.

2. COMPUTATIONAL METHODOLOGY In the present work, all the calculations have been carried out through ab initio molecular orbital and density functional theory based methods using GAMESS42 and MOLPRO 201243 programs. The geometry of the concerned NgM3kHk+ (Ng = Ar, Kr and Xe; M = Cu, Ag and Au; k = 02) complexes have been optimized using the Møller-Plesset second-order perturbation theory (MP2)44, density functional theory (DFT) with dispersion corrected omega separated form of Becke's 1997 hybrid functional with short-range HF exchange (ωB97XD),4546 and coupled cluster theory with the inclusion of single and double substitutions and an estimate of connected triples, (CCSD(T))47 based methods. All the structural parameters have been optimized using planar structure with Cs symmetry on the respective singlet potential energy surface. We have used valence only def2TZVPPD basis set designed by Weigend and Ahlrichs,48 with Stuttgart small core effective core potentials (ECP10MDF for Cu and Kr atoms; ECP28MDF for Ag and Xe atoms; and ECP60MDF for Au atom),49 and the def2TZVPPD basis sets for the H and Ar atoms in the ωB97X-D and MP2 calculations. This combination of basis set has been designated as DEF2. In addition, the augccpVTZ−PP basis set for the same number of core electrons for Cu, Kr, Ag, Xe and Au atoms and augccpVTZ basis sets5051 for the H and Ar atoms have been used for the CCSD(T) calculations, which is abbreviated as AVTZ. The aug−cc-pVDZ−PP basis set for the same number of core electrons for Cu, Kr, Ag, Xe and Au atoms and aug−cc-pVDZ basis sets for the H and Ar atoms have been used for frequency calculations with CCSD(T) method, which is defined as AVDZ. Furthermore, to understand the nature of chemical bonding between noble gas and noble metal atoms quantitatively, the AIM (Atoms-in-Molecule) analysis has been adopted by employing ωB97XD and MP2 methods. The electron density [], Laplacian of the electron density [2], the local energy density [Ed], and the ratio of electron kinetic energy density and electron density [G(r)/] at the NgM bond critical point (BCP) in NgM3kHk+ (k = 02) complexes have been calculated following the footsteps of Bader’s quantum theory of atoms-in-molecule (QTAIM) approach.52 Various topological properties local electron energy density , the electron density, Page 5 of 29 ACS Paragon Plus Environment


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and ratio of local electron energy density and electron density (−Ed/ρ), i.e., bond degree, at the local energy density critical points [(3,+1) HCP] for the NgM bond in NgM3+, NgM2H+ and NgMH2+ species have been computed by employing ωB97XD method with def2TZVPD basis sets using Multiwfn program.53 In the frozen core approximations up to 3d- and 4d- orbitals for silver and gold, respectively, and 2p orbital for both copper and argon atoms, electrons are kept in the core for the ADF calculations, and the corresponding Slater type orbital TZ2P54 basis sets have been used. Zeroth-order regular approximation (ZORA) has been used to take into account the scalar relativistic effects. To obtain the interaction energies between the two fragments (Ng and M3–kHk+) in the NgM3–kHk+ complexes, energy decomposition analysis (EDA)5556 of the total interaction energy has been performed with ADF20135558 software using PBE–D3 (Perdew-Burke-Ernzerhof with dispersion correction) functional. The total interaction energy, Eint can be decomposed into three components, viz., Eint = Eelec + EPauli + Eorb + Edis

(1)

where Eelec and EPauli represent the electrostatic interaction energy and the Pauli repulsive energy, respectively, between the fragments. Eorb is the stabilizing orbital interaction term, which includes polarization term and covalency factor due to the overlap between the noble gas and noble metal orbitals. The term, Edis denotes the dispersion energy. 3. RESULTS AND DISCUSSIONS 3.1. Structural Parameters of NgAuHn+ Ions The precursor ions viz. Au3+, Au2H+, and AuH2+ exhibit nonlinear planar structure for the minima. Now interaction of Ng atom with these ions leads to the formation of strongly bonded NgAu3+, NgAu2H+, and NgAuH2+complexes as depicted in Figure 1. The decrease in the ArAu bond length value from 2.605 Å in ArAu3+ to 2.518 Å in ArAu2H+ and 2.429 Å in ArAuH2+, respectively, as obtained by CCSD(T)/AVTZ level of theory indicates that the NgAu interaction is increased considerably in ArAuH2+ species. It implies that the NgAu bond strength is enhanced drastically with the doping of two hydrogen atoms in pure Autrimer cation. Similar trend is followed in the case of KrAu3+ and XeAu3+ complexes although the change in the NgAu bond length is not that significant. The NgAu bond length values as obtained by various theoretical methods are depicted in Figure 1. In this context it is important to note that the CCSD(T)/AVTZ computed NgAu bond length values Page 6 of 29 ACS Paragon Plus Environment

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in NgAu+ are generally larger (2.537, 2.553 and 2.617 Å in ArAu+, KrAu+ and XeAu+, respectively) than that in the NgAuH2+ complexes, which indicate that the NgAu bond strength is greater in the latter complexes. Further evidences on the enhancement of the NgAu bonding strength in the NgAuH2+ complexes are discussed in the subsequent sections. In the spirit of Gerry and co-workers,7 we have analyzed the NgAu bond length with respect to covalent limit (Rcov) and van der Waals limit (RvdW). The Rcov values obtained from the recently reported literature59 are 2.20, 2.41 and 2.55 Å for ArAu, KrAu and XeAu bond, respectively, and the corresponding RvdW60 values are 4.15, 4.57 and 4.38 Å. It is quite evident from the above data that NgAu bond length values in NgAu3kHk+ (k = 02) are in close proximity with the covalent limits. In fact, a slightly higher value of the NgAu bond distance in the NgAu3kHk+ species implies that both covalent as well as induction and dispersion interactions are likely to coexist in the NgAu bonding. Apart from the NgAu bond distance, it is interesting to analyse the AuH and HH bond distances in the NgAu3kHk+ complexes. The calculated AuH distance of 1.528 Å in the AuH molecule is changed to 1.684, 1.696 and 1.718 Å in the NgAu2H+ complexes, respectively, and the same is changed to 1.712, 1.722 and 1.741 Å in the NgAuH2+ complexes, respectively. The HH bond distance of 0.740 Å in free H2 molecule is changed to 0.855, 0.848

and 0.837 Å in the ArAuH2+, KrAuH2+ and XeAuH2+ complexes, respectively. Therefore, the NgAuH2+ complex can be considered as a non-classical 2-electron, 3-center bond where H2 binds side-on (η2) to the metal center and the bonding electron pair in H2 interacts strongly with the metal center.61 3.2. Energetics and Stability of NgAuHn+ Ions The endothermicity of the 2body dissociation channel, (NgAu3kHk+  Ng + Au3kHk+) illustrates that the predicted species are more stable than the dissociated products by an amount of 31.9, 47.5, 72.0 kJ mol1 in Ar, 50.7, 69.3, 100.7 kJ mol1 in Kr, and 81.2, 102.4, 142.0 kJ mol1 in Xe containing complexes for NgAu3+, NgAu2H+, and NgAuH2+ species, respectively, as obtained by CCSD(T)/AVTZ level of theory (Table 1). The zero point energy (ZPE) and basis set superposition error (BSSE) corrected NgAu binding energies have also been reported in Table 1. Here the NgAu bond dissociation energy has been found to increase significantly with the subsequent addition of H atom in place of Au atom. This trend Page 7 of 29 ACS Paragon Plus Environment


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is found to be consistent with the structural parameters. The NgAu binding energy in NgAuF and NgAu+ have been calculated to be 46.0, 44.1 kJ mol1 in Ar, 64.4, 73.5 kJ mol1 in Kr, and 92.4, 121.6 kJ mol1 in Xe containing complexes, respectively, at the same level. All these results clearly indicate that the NgAu bonding strength is not only greatly enhanced with the hydrogen doping in pure Autrimers but also is found to be greater than that in the NgAuF and NgAu+ species. As far as binding energy is concerned, the NgAu bonding interaction has been found to be increased by 2.26 times for Ar, 1.99 times for Kr, and 1.75 times for Xecomplexes in going from NgAu3+ to NgAuH2+ complex as predicted by CCSD(T) method. Therefore, it is quite obvious that the enhancement in the NgAu bond strength is more pronounced in case of Ar containing H doped Autrimers in comparison with the corresponding Kr and Xecomplexes. It has also been found that the predicted NgAu3kHk+ species are stable with respect to all other 2body dissociations and all possible 3body dissociations (Table S3 in the supporting information). Here it is interesting to note that the ArH binding energy in ArH3+ complex,62 where all the Au atoms are replaced with H atoms, has been found to be much smaller (CCSD(T)/AVTZ values ~2632 kJ mol1) as compared to that in the ArAuH2+ species (CCSD(T)/AVTZ values 72 kJ mol1). From all these results it is evident that the H doping in pure noble metal trimers increases the noble gasnoble metal bonding significantly. 3.3. Harmonic Vibrational Analysis of NgAuHn+ Ions Subsequently, we have calculated the NgAu stretching vibrational frequency along with the force constant values with B97XD/DEF2, MP2/DEF2, and CCSD(T)/AVDZ level of theory and reported in Table 2. For the present NgAu systems, the MP2/DEF2 computed NgAu stretching vibrational frequency values changes from 142.1 to 223.2 cm-1 in Ar, 108.1 to 183.0 cm-1 in Kr, and 101.9 to 166.2 cm-1 in Xe containing complexes on going from NgAu3+ to NgAuH2+ species, respectively, and the corresponding force constant values are changed from 39.4 to 97.8 N m1 in Ar, 60.3 to 115.2 N m1 in Kr, and 81.0 to 125.3 N m1 in Xe containing complexes (Table 2).


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3.4. Molecular Orbitals and HOMOLUMO Energies of NgAuHn+ Ions The relevant molecular orbitals depicting the ArAu bonding represented in Figure S1 (Supporting Information) reveal that the  orbitals from both Ar and Au are involved in the bonding. Moreover, the nature of ArAu interaction in ArAu3+, ArAu2H+ and ArAuH2+ ions is found to be almost the same, at least qualitatively. However, the ArAu bonding orbitals for the ArAuH2+ ion is found to be associated with lowest eigenvalue. Moreover, significant differences in various bonding parameters (as discussed above) clearly indicate that magnitude of bonding interaction differs remarkably. Therefore, it is interesting to analyze the enhancement of NgAu binding energy, and we have explained this aspect in terms of the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy of the precursor species and their complexes (Table 3). The ArAu bond energy has been shown to correlate very well with the LUMO energy of the precursor ion (Figure S2). The B97XD/DEF2 computed LUMO energy for Au3+, Au2H+, and AuH2+ species have been found to be 6.66, 7.27, and 8.12 eV, respectively, whereas the HOMO energy for Ar, Kr, and Xe are 13.93, 12.71, and 11.34 eV, respectively. Thus, through successive replacement of Au atom(s) by the H atom(s) in pure Autrimer, the LUMO of Au3kHk+ species has been stabilized more and more, resulting into decreases in the energy gap between the HOMO of Ng and LUMO of AuH2+, which leads to the formation of most stable NgAu bond in NgAuH2+ complexes, among all the complexes considered here. This is one of the factors for the enhancement of NgAu bonding interaction on doping with hydrogen atom in pure Autrimer. The HOMOLUMO energy gaps of 7.88, 8.92, and 11.11 eV in Ar, 7.86, 8.97, and 11.23 eV in Kr, 7.81, 9.00, and 11.20 eV in Xe containing complexes in the NgAu3+, NgAu2H+, and NgAuH2+ species, respectively, are also found to be higher as compared to that for the respective precursor, Au3+, Au2H+, and AuH2+. Moreover, this increase of HOMOLUMO gap is the maximum for the AuH2+ ion, in agreement with the highest stability of the NgAuH2+ complex. Here it may be noted that ArAu+ bonding is not as strong as ArAuH2+ interaction, although LUMO of Au+ (9.73 eV) is more stabilized. It is due to limited scope of charge reorganization in ArAu+ ion as compared to that in ArAuH2+ ion. As a result the HOMOLUMO gap of Au+ ion (9.12 eV) remains almost the same as in the ArAu+ ion (9.02 eV). Here it may be noted that many DFT functionals are not able to predict the correct HOMO-LUMO gap of chemical systems.63 Among various Page 9 of 29 ACS Paragon Plus Environment


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functionals, the performance of ωB97XD functional in predicting the HOMO-LUMO gap is very good as compared to that of the other density functionals. Therefore, we have used

ωB97XD calculated HOMO-LUMO gap for our analysis.64 3.5. Charge Distribution in NgAuHn+ Ions The MP2/DEF2 calculated NBO charges (Table 4) reveal that the positive charge on the metal atom is increased considerably in going from Au3+ to AuH2+ ion, which enhances the electron density transfer from HOMO of Ng atom to the LUMO of AuH2+ species leading to the formation of stronger NgAu bond. Moreover, the NBO charge on Au atom in Au3kHk+ is decreased on complexation with Ng and the extent of decrease is the maximum in AuH2+ ion (from 0.925 to 0.716, 0.634, 0.545 in ArAuH2+, KrAuH2+, and XeAuH2+, respectively) among all the Au containing trimers because of the lowest LUMO energy of AuH2+ ion. Consequently, charge transfer from the Ng atom to the trimer cation is also found to be the maximum in case of NgAuH2+ complex. It implies that charge reorganization in AuH2+ is the maximum after complexation, indicating an increase in the charge-induced dipole interaction in the series, NgAu3+ < NgAu2H+ < NgAuH2+. Moreover, calculated charge values clearly indicate that the close shell6567 nature of Au is more pronounced in the AuH2+ trimer. Thus, the charge distribution analysis also emphasizes the strongest NgAu bonding in NgAuH2+ species as revealed from the structure, bonding and vibrational frequency analysis. 3.6. Analysis of Topological Properties of NgAuHn+ Ions Following Bader’s quantum theory of atomsinmolecules (QTAIM),68 we have reported the electron density () based topological properties in Table 5. The calculated values of electron density [], Laplacian of the electron density [2], the local energy density [Ed], and the ratio of electron kinetic energy density and electron density [G(r)/] at the NgAu bond critical point (BCP) in NgAu3kHk+ (k = 02) complexes strongly indicate that the bonding between Ng and Au atoms are of “Wc type” covalent bonding.69 Therefore, we can emphasize that the bonding between the Ng and Au atoms bear a partial covalent character, which is also evident from the NgAu bond length values that is even smaller than the covalent limit as discussed in the structural part. Moreover, the variation of all these computed BCP


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parameters (, 2, Ed, and [G(r)/]) clearly indicate that the NgAu bonding in NgAuH2+ complexes possesses highest degree of covalency. Following, the work of Grandinetti and co-workers,70 we have calculated the critical point corresponding to the distributions of the total energy density (HCP) and found that the bond degree parameter, (Ed(r)/(r)) for the NgAu bond at HCP, reported in Table 6, is increased monotonically from 0.085, 0.158, 0.219 in NgAu3+ to 0.140, 0.190, 0.239 and 0.214, 0.243, 0.289 in NgAu2H+ and NgAuH2+ (MP2/DEF2 level of theory) along the ArKrXe series, respectively, evidently indicating an increasing trend in the NgAu covalent bonding in NgAu3+ with the successive replacement of Au atom(s) by the H atom(s). Increase in both covalent characteristics and chargeinduced dipole interaction through successive replacement of Au atom with H atom in NgAu3+ complex is further supported by the calculated values of various energy components (reported in Table 7), which reveal that there has been increase of both electrostatic and orbital components in going from NgAu3+ to NgAuH2+ species. It is also very important to note that the extent of increase in orbital component is significantly higher, particularly for the ArAu3+ complex. 3.7. Comparison of Results of NgAuHn+ Ions with NgAgHn+ and NgCuHn+ Ions For the purpose of comparison, we have reported the optimized NgM bond lengths (Figure S3 and Figure S4) and the bond dissociation energy (Table S4), the NgM stretching frequency and the corresponding force constant values (Table S5) in the supporting information for NgM3kHk+ (k = 02) complexes, which show that the similar trends has been observed in case of Ag and Cu complexes as observed by Au complexes. Table S6 and Table S7 in the supporting information list all the HOMOLUMO energy values and the NBO charges, respectively, of the concerned M3kHk+ and NgM3kHk+ complexes, which strongly indicate that the decrease in the energy gap between the HOMO of Ng and LUMO of MH2+, and considerable increase of positive charge on the metal atom in MH2+ ion enhance the electron density transfer from HOMO of Ng atom to the LUMO of MH2+ species leading to the formation of stronger NgM bonding in case of all NgM3kHk+ complexes. The BCP and HCP parameters for all the NgM3kHk+ complexes as reported in Table S8 and Table S9, respectively, clearly indicate that the NgAg and NgCu bonds are associated with higher degree of covalency in NgAgH2+ and NgCuH2+ complexes as it is observed in case of NgAuH2+ complexes. Various energy components for all the NgMH2+ complexes have been Page 11 of 29 ACS Paragon Plus Environment


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reported in Table S10 in the supporting information, which clearly reveal that the electrostatic and orbital components of bonding energy play the key role for the formation of strong NgM bond in NgMH2+ complexes. It is worthwhile to mention that the NgAg3kHk+ and NgCu3kHk+ complexes follow the similar trends in chemical properties while going from pure metal trimers to hydrogen doped metal trimers as it is observed in case of NgAu3kHk+ complexes. However, all these effects are more pronounced in NgAu3kHk+ complexes due to the presence of strong relativistic effects in gold.65 4. CONCLUSION In summary, the unprecedented strengthening of the NgAu bonding has been observed with successive replacement of Au atom by the H atom in pure Autrimers. The concept of goldhydrogen analogy makes it possible to evolve this pronounced effect of hydrogen doping in Autrimers leading to the strongest NgAu bond in NgAuH2+ species, as revealed from the calculated values of NgAu bond length, bond energy, vibrational frequency and force constant. Similar trends have been found in case of NgAg and NgCu complexes. The enhancement of NgM bonding interaction in NgMH2+ (Ng = Ar, Kr, and Xe; M = Cu, Ag, and Au) as compared to that in NgM3+ can be attributed to considerable increase in the NgM covalency as revealed from the electron density based topological properties and energy decomposition analysis. Calculated values of HOMO and LUMO energies, and partial atomic charges further indicate that an enhancement in the chargeinduced dipole interaction is also responsible for the surprisingly high NgM bonding interaction in NgMH2+ species. All the theoretical results reported in the present work and earlier experimental existence of AgH2+,38 AuxH2+29 and NgMX (Ng = Ar, Kr, Xe; M = Cu, Ag, Au; X = F, Cl)6,7 species along with very recent experimental identification of Ar complexes of mixed noble metal clusters, ArkAunAgm+ (n+m = 3; k = 0-3) by Fielicke and co-workers26,27 strongly suggest that the predicted NgMH2+ species would be observed experimentally. Supporting Information Structural parameters (bond length, bond dissociation energies), energetics, harmonic vibrational frequencies, intrinsic force constants corresponding to individual internal coordinates, HOMOLUMO energy values, NBO charges, AIM properties of BCPs and HCPs, and the EDA values of NgM3+, NgM2H+, and NgMH2+ (Ng = Ar, Kr, and Xe; M = Page 12 of 29 ACS Paragon Plus Environment

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Cu, Ag, and Au) complexes are included (Tables S1-S10). The degenerate molecular orbitals depicting the ArAu bonding in ArM3kHk+ (k = 02) is given in Figure S1. The variation of ArAu bond energy vs the LUMO energy has been depicted in Figure S2. The optimized structural parameters have been depicted in Figure S3 and Figure S4 for NgAgHn+ and NgCuHn+, respectively. This material is available free of charge via the Internet at http://pubs.acs.org.

ACKNOWLEDGMENTS The authors gratefully acknowledge the generous support provided by their host institution, Bhabha Atomic Research Centre, Mumbai. The authors would like to thank the Computer Division, Bhabha Atomic Research Centre for providing computational facilities. We would like to thank Dr. A. K. Nayak, Shri R. K. Rajawat and Dr. B. N. Jagatap for their continuous encouragements. REFERENCES 1. Schröder, D.; Schwarz, H.; Hrušák, J.; Pyykkö, P. Cationic Gold(I) Complexes of Xenon and of Ligands Containing the Donor Atoms Oxygen, Nitrogen, Phosphorus, and Sulfur. Inorg. Chem. 1998, 37, 624632. 2. Pyykkö, P. Predicted Chemical Bonds between Rare Gases and Au+. J. Am. Chem. Soc. 1995, 117, 20672070. 3. Read, J. P.; Buckingham, A. D. Covalency in ArAu+ and Related Species? J. Am. Chem. Soc. 1997, 119, 90109013. 4. Seidel, S.; Seppelt, K. Xenon as a Complex Ligand: The Tetra Xenono Gold(II) Cation in AuXe42+(Sb2F11)2. Science 2000, 290, 117118. 5. Drews, T.; Seidel, S.; Seppelt, K. GoldXenon Complexes. Angew. Chem. Int. Ed. 2002, 41, 454456. 6. Evans, C. J.; Lesarri, A.; Gerry, M. C. L. Noble GasMetal Chemical Bonds. Microwave Spectra, Geometries, and Nuclear Quadrupole Coupling Constants of ArAuCl and KrAuCl. J. Am. Chem. Soc. 2000, 122, 61006105. 7. Michaud, J. M.; Gerry, M. C. L. XeCu Covalent Bonding in XeCuF and XeCuCl, Characterized by Fourier Transform Microwave Spectroscopy Supported by Quantum



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 29

Chemical Calculations. J. Am. Chem. Soc. 2006, 128, 76137621, and references therein. 8. Kurzydlowski, D.; Grochala, W. Xenon as a Mediator of Chemical Reactions? Case of Elusive Gold Monofluoride, AuF, and its Adduct with Xenon, XeAuF. Anorg. Allg. Chem. 2008, 634, 10821086. 9. Belpassi, L.; Infante, I.; Tarantelli, F.; Visscher, L. The Chemical Bond between Au(I) and the noble Gases. Comparative Study of NgAuF and NgAu+ (Ng = Ar, Kr, Xe) by Density Functional and Coupled Cluster Methods. J. Am. Chem. Soc. 2008, 130, 10481060. 10. Evans, C. J.; Wright, T. G.; Gardner, A. M. Geometries and Bond Energies of the HeMX, NeMX, and ArMX (M = Cu, Ag, Au; X = F, Cl) Complexes. J. Phys. Chem A 2010, 114, 44464454. 11. Pan, S.; Gupta, A.; Saha, R.; Merino, G.; Chattaraj, P. K. A CoupledCluster Study on the Noble Gas Binding Ability of Metal Cyanides Versus Metal Halides (Metal = Cu, Ag, Au). J. Comput. Chem. 2015, 36, 21682176. 12. Chakraborty, D.; Chattaraj, P. K. In Quest of a Superhalogen Supported Covalent Bond Involving a Noble Gas Atom. J. Phys. Chem. A 2015, 119, 30643074. 13. Ghanty, T. K. Insertion of NobleGas Atom (Kr and Xe) into NobleMetal Molecules (AuF and AuOH): Are They Stable? J. Chem. Phys. 2005, 123, 074323. 14. Ghanty, T. K. How Strong is the Interaction between a Noble Gas Atom and a Noble Metal Atom in the Insertion Compounds MNgF (M = Cu and Ag, and Ng = Ar, Kr, and Xe)?. J. Chem. Phys. 2006, 124, 124304. 15. Khriachtchev, L.; Pettersson, M.; Runeberg, N.; Lundell, J.; Räsänen, M. A Stable Argon Compound. Nature (London) 2000, 406, 874876. 16. Kiran, B.; Li, X.; Zhai, H. J.; Cui, L. F.; Wang, L. S. [SiAu4]: Aurosilane. Angew. Chem. Int. Ed. 2004, 43, 21252129. 17. Li, X.; Kiran, B.; Wang, L. S. Gold as Hydrogen. An Experimental and Theoretical Study of the Structures and Bonding in Disilicon Gold Clusters Si2Aun and Si2Aun (n = 2 and 4) and Comparisons to Si2H2 and Si2H4. J. Phys. Chem. A 2005, 109, 43664374.


Page 15 of 29


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

18. Ghanty, T. K. Gold Behaves as Hydrogen: Prediction on the Existence of a New Class of Boron Containing Radicals, AuBX (X = F, Cl, Br). J. Chem. Phys. 2005, 123, 241101. 19. Wang, X.; Andrews, L.; Willmann, K.; Brosi, F.; Riedel, S. Investigation of Gold Fluorides and Noble Gas Complexes by MatrixIsolation Spectroscopy and QuantumChemical Calculations. Angew. Chem. Int. Ed. 2012, 51, 1062810632. 20. Wang, X.; Andrews, L.; Brosi, F.; Riedel, S. Matrix Infrared Spectroscopy and QuantumChemical Calculations for the CoinageMetal Fluorides: Comparisons of ArAuF, NeAuF, and Molecules MF2 and MF3. Chem. Eur. J. 2013, 19, 13971409. 21. Li, J.; Bursten, B. E.; Liang, B.; Andrews, L. Noble GasActinide Compounds: Complexation of the CUO Molecule by Ar, Kr, and Xe Atoms in Noble Gas Matrices. Science 2002, 295, 22422245. 22. Mück, L. A.; Timoshkin, A. Y.; Hopffgarten, M. V.; Frenking, G. Donor Acceptor Complexes of Noble Gases. J. Am. Chem. Soc. 2009, 131, 39423949. 23. Infante, I.; Andrews, L.; Wang, X.; Gagliardi, L. Noble Gas Matrices May Change the Electronic Structure of Trapped Molecules: The UO2(Ng)4 [Ng = Ne, Ar] Case. Chem. Eur. J. 2010, 16, 1280412807. 24. Zhang, Q.; Chen, M.; Zhou, M.; Andrada, D. M.; Frenking, G. Experimental and Theoretical Studies of the Infrared Spectra and Bonding Properties of NgBeCO3 and a Comparison with NgBeO (Ng He, Ne, Ar, Kr, Xe). J. Phys. Chem. A 2015, 119, 25432552. 25. Andrejeva, A.; Breckenridge, W.H.; Wright, T. G. A Surprisingly Simple Electrostatic Model Explains Bent Versus Linear Structures in M+RG2 Species (M = Group 1 Metal. LiFr; RG = Rare Gas, HeRn). J. Phys. Chem. A 2015, 119, 1095910970 and references there in. 26. Shayeghi, A.; Johnston, R. L.; Rayner, D. M.; Schäfer, R.; Fielicke, A. The Nature of Bonding between Argon and Mixed GoldSilver Trimers. Angew. Chem. Int. Ed. 2015, 54, 1067510680. 27. Shayeghi, A.; Schäfer, R.; Rayner, D. M.; Johnston, R. L.; Fielicke, A. ChargeInduced Dipole vs. Relativistically Enhanced Covalent Interactions in ArTagged AuAg Tetramers and Pentamers. J. Chem. Phys. 2015, 143, 024310. Page 15 of 29 ACS Paragon Plus Environment


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Page 16 of 29

28. Gruene, P.; Rayner, D. M.; Redlich, B.; van der Meer, A. F.; Lyon, J. T.; Meijer, G.; Fielicke, A. Structures of Neutral Au7, Au19, and Au20 Clusters in the Gas Phase. Science 2008, 321, 674676. 29. Ghiringhelli, L. M.; Gruene, P.; Lyon, J. T.; Rayner, D. M.; Meijer, G.; Fielicke, A.; Scheffler, M. Not So Loosely Bound Rare Gas Atoms: FiniteTemperature Vibrational Fingerprints of Neutral GoldCluster Complexes. New J. Phys. 2013, 15, 083003 and references there in. 30. Pan, S.; Saha, R.; Mandal, S.; Chattaraj, P. K. Aromatic Cyclic M3+ (M = Cu, Ag, Au) Clusters and Their Complexation with Dimethyl imidazol2ylidene, Pyridine, Isoxazole, Furan, Noble Gases and Carbon Monoxide. Phys. Chem. Chem Phys. 2016, 18, 1166111676. 31. Buckart, S.; Ganteför, G.; Kim, Y. D.; Jena, P. Anomalous Behavior of Atomic Hydrogen Interacting with Gold Clusters. J. Am. Chem. Soc. 2003, 125, 1420514209. 32. Lang, S. M.; Bernhardt, T. M.; Barnett, R. N.; Yoon, B.; Landman, U. HydrogenPromoted Oxygen Activation by Free Gold Cluster Cations. J. Am. Chem. Soc. 2009, 131, 89398951. 33. Jena, N. K.; Chandrakumar, K. R. S.; Ghosh, S. K. Beyond the GoldHydrogen Analogy: Doping Gold Cluster with HAtomO2 Activation and Reduction of the Reaction Barrier for CO Oxidation. J. Phys. Chem. Lett. 2011, 2, 14761480. 34. Manzoor, D.; Pal, S. Hydrogen Atom Chemisorbed Gold Clusters as Highly Active Catalysts for Oxygen Activation and CO Oxidation. J. Phys. Chem. C 2014, 118, 3005730062. 35. Manzoor, D.; Pal, S. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters. J. Phys. Chem. A 2015, 119, 61626170. 36. Mondal, K.; Agrawal, S.; Manna, D.; Banerjee, A.; Ghanty, T. K. Effect of Hydrogen Atom Doping on the Structure and Electronic Properties of 20-Atom Gold Cluster. J. Phys. Chem. C 2016, 120, 1858818594. 37. Zhai, H. J.; Kiran, B.; Wang, L. S. Observation of Au2H Impurity in Pure Gold Clusters and Implications for the Anomalous AuAu Distances in Gold Nanowires. J. Chem. Phys. 2004, 121, 8231. Page 16 of 29 ACS Paragon Plus Environment

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38. Khairallah, G. N.; O’Hair, R. A. J. Gas Phase Synthesis and Reactivity of Agn+ and Agn1H+ Cluster Cations. Dalton Trans. 2005, 27022712. 39. Liu, H. T.; Wang, Y. L.; Xiong, X. G.; Dau, P. D.; Piazza, Z. A.; Huang, D. L.; Xu, C. Q.; Li, J.; Wang, L. S. The Electronic Structure and Chemical Bonding in Gold Dihydride: AuH2 and AuH2. Chem. Sci. 2012, 3, 32863295. 40. Xie, H.; Xing, X.; Liu, Z. Cong, R.; Qin, Z.; Wu, X.; Tang, Z.; Fan, H. Photoelectron Imaging and Theoretical Calculations of GoldSilver Hydrides: Comparing the Characteristics of Au, Ag and H in Small Clusters. Phys. Chem. Chem. Phys. 2012, 14, 1166611672. 41. Vetter, K.; Proch, S.; Ganteför, G. F.; Behera, S.; Jena, P. Hydrogen Mimicking the Properties of Coinage metal Atoms in Cu and Ag Monohydride Clusters. Phys. Chem. Chem. Phys. 2013, 15, 2100721015. 42. Schmidt, M. W.; Baldridge, K. K.; Boatz, J. A.; Elbert, S. T.; Gordon, M. S.; Jensen, J. H.; Koseki, S.; Matsunaga, N.; Nguyen, K. A.; Su, S. et al. General Atomic and Molecular Electronic Structure System. J. Comput. Chem. 1993, 14, 1347−1363. 43. Werner, H. -J.; Knowles, P. J.; Knizia, G.; Manby, F. R.; Schützet, M.; Celani, P.; Korona, T.; Lindh, R.; Mitrushenkov, A.; Rauhut, G. et al. MOLPRO, version 2012.1, a Package of ab initio Programs, 2012; see http://www.molpro.net. 44. Frisch, M. J.; Head-Gordon, M.; Pople, J. A. A Direct MP2 Gradient Method. Chem. Phys. Lett. 1990, 166, 275−280. 45. Chai, J. −D.; Head-Gordon, M. Systematic Optimization of Long−Range Corrected Hybrid Density Functionals. J. Chem. Phys. 2008, 128, 084106. 46. Chai, J. −D.; Head-Gordon, M. Long−Range Corrected Hybrid Density Functionals with damped Atom−Atom Dispersion Corrections. Phys. Chem. Chem. Phys. 2008, 10, 6615−6620. 47. Hampel, C.; Peterson, K.; Werner, H. -J. A Comparison of the Efficiency and Accuracy of the Quadratic Configuration Interaction (QCISD), Coupled Cluster (CCSD) and Brueckner Couple Cluster (BCCD) Methods. Chem. Phys. Lett. 1992, 190, 1−12. 48. Weigend, F.; Ahlrichs, R. Balanced Basis Sets of Split Valence, Triple Zeta Valence and Quadruple Zeta Valence Quality for H to Rn: Design and Assessment of Accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297−3305. Page 17 of 29 ACS Paragon Plus Environment


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49. Peterson, K. A.; Figgen, D.; Goll, E.; Stoll, H.; Dolg, M. Systematically Convergent Basis Sets with Relativistic Pseudopotentials. II. Small−Core Pseudopotentials and Correlation Consistent Basis Sets for the Post−d Group 16−18 Elements. J. Chem. Phys., 2003, 119, 11113–11123. 50. Kendall, R. A.; Dunning, T. H., Jr.; Harrison, R. J. Electron Affinities of the FirstRow Atoms Revisited. Systematic Basis Sets and Wave Functions. J. Chem. Phys. 1992, 96, 67966806. 51. Woon, D. E.; Dunning, T. H., Jr. Gaussian Basis Sets for use in Correlated Molecular Calculations. III. The Atoms Aluminum through Argon. J. Chem. Phys. 1993, 98, 13581371. 52. Bader, R. F. W. Atoms in Molecules−A Quantum Theory; Oxford University Press: Oxford, U.K., 1990. 53. Lu, T.; Chen, F. W. Multiwfn: A Multifunctional Wavefunction Analyzer. J. Comput. Chem. 2012, 33, 580–592. 54. van Lenthe, E.; Baerends, E. J. Optimized Slater Type Basis Sets for the Elements 1– 118. J. Comput. Chem. 2003, 24, 1142−1156. 55. Ziegler, T.; Rauk, A. On the Calculations of Bonding Energies by the Hartree Fock Slater Method. I. The Transition State Method. Theor. Chim. Acta 1977, 46, 1–10. 56. Bickelhaupt, F. M.; Baerends E. J. In Reviews on Computational Chemistry; Lipkowitz, K. B., Boyd, D. B., Eds.; Wiley-VCH: New York, 2000; Vol. 15, pp 1–86. 57. te Velde, G.; Bickelhaupt, F. M.; van Gisbergen, S. J. A.; Fonseca-Guerra, C.; Baerends, E. J.; Snijders, J. G.; Ziegler, T. Chemistry with ADF. J. Comput. Chem. 2001, 22, 931−967. 58. Baerends, E. J. ADF2013.01, SCM, Theoretical Chemistry; Vrije Universiteit: Armsterdam, The Netherlands, 2013. 59. Pyykkö, P. Additive Covalent Radii for Single, Double, and Triple Bonded Molecules and Tetrahedrally Bonded Crystals: A Summary. J. Phys. Chem. A 2015, 119, 23262337. 60. Vogt, J.; Alvarez, S. van der Waals Radii of Noble Gases. Inorg. Chem. 2014, 53, 92609266. 61. Kubas, G. J. Dihydrogen Complexes as Prototypes for the Coordination Chemistry of Saturated Molecules. Proc. Natl. Acad. Sci. (USA) 2007, 104, 6901– 6907 Page 18 of 29 ACS Paragon Plus Environment

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62. Pauzat, F.; Ellinger, Y. H3+ as a Trap for noble Gases2: Structure and Energetics of XH3+ Complexes from X = Neon to Xenon. J. Chem. Phys. 2007, 127, 014308. 63. Zhang, G.; Musgrave, C. B. Comparison of DFT Methods for Molecular Orbital Eigenvalue Calculations. J. Phys. Chem. A 2007, 111, 15541561. 64. Tsai, C. W.; Su, Y. C.; Li, G. –D.; Chai, J. D. Assessment of Density Functional Methods with Correct Asymptotic Behaviour. Phys. Chem. Chem. Phys. 2013, 15, 83528361. 65. Pyykkö, P. Theoretical Chemistry of Gold. Angew. Chem. Int. Ed. 2004, 43, 44124456. 66. Wesendrup, R.; Schwerdtfeger, P. Extremely Strong s2s2 ClosedShell Interactions. Angew. Chem. Int. Ed. 2000, 39, 907910. 67. Pyykkö, P. Relativity, Gold, ClosedShell Interactions, and CsAuNH3. Angew. Chem. Int. Ed. 2002, 41, 35733578. 68. Bader, R. F. W. Atoms in MoleculesA Quantum Theory; Oxford University Press: Oxford, U. K., 1990. 69. Zou, W.; NoriShargh, D.; Boggs, J. On the Covalent Character of Rare Gas Bonding Interactions: A New Kind of Weak Interaction. J. Phys. Chem. A 2013, 117, 207212. 70. Borocci, S.; Giordani, M.; Grandinetti, F. Bonding Motifs of NobleGas Compounds As Described by the Local Electron Energy Density. J. Phys. Chem. A 2015, 119, 65286541.



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FIGURE CAPTION Figure1. Optimized geometrical parameters in graphical format for planar structures of NgAu3+ (a, b, c), NgAu2H+ (d, e, f) and NgAuH2+ (g, h, i) (Ng = Ar, Kr, Xe) where the bond lengths are in angstroms and bond angles are in degrees. The values in green, red, and blue are computed at the B97XD/DEF2, MP2/DEF2, and CCSD(T)/AVTZ levels of theory, respectively.


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(a)

(d)

(g)

(b)

(e)

(h)

(c)

(f)

(i)

Figure1. Optimized geometrical parameters in graphical format for planar structures of NgAu3+ (a, b, c), NgAu2H+ (d, e, f) and NgAuH2+ (g, h, i) (Ng = Ar, Kr, Xe) where the bond lengths are in angstroms and bond angles are in degrees. The values in green, red, and blue are computed at the B97XD/DEF2, MP2/DEF2, and CCSD(T)/AVTZ levels of theory, respectively.



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Table 1. Calculated Values of NgM Bond Dissociation Energy (BE, in kJ mol1) for NgAu3+, NgAu2H+, and NgAuH2+ (Ng = Ar, Kr, and Xe) Species as obtained Using ωB97XD, MP2 Methods with DEF2 Basis Set, and CCSD(T) Method with AVTZ Basis Set. Species ArAu3+ ArAu2H+ ArAuH2+ KrAu3+ KrAu2H+ KrAuH2+ XeAu3+ XeAu2H+ XeAuH2+ a The zero point energy

BE(NgAu) BE(NgAu)a ωB97XD MP2 CCSD(T) MP2 CCSD(T) 26.4 33.3 31.9 27.2 27.8 40.8 49.7 47.5 41.3 41.3 64.6 75.2 72.0 64.1 63.1 42.8 54.1 50.7 47.3 46.1 60.5 73.2 69.3 64.6 62.8 91.1 105.4 100.7 93.8 91.3 69.5 84.3 81.2 76.5 74.4 90.0 105.1 102.4 95.8 93.9 129.0 145.0 142.0 132.7 130.4 (ZPE) and basis set superposition error (BSSE) corrected bond dissociation

energy values.


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Table 2. Calculated Values of NgM Stretching Frequency (NgM) (in cm1) and Force Constant (k in N m1) for NgM3+, NgM2H+, and NgMH2+ (Ng = Ar, Kr, and Xe; M = Au, Ag, and Cu) Species as obtained using ωB97XD and MP2 Methods with DEF2 Basis Set and CCSD(T) Method with AVDZ Basis Set. The IR Intensity (in km mol1) of the Corresponding Frequency are Given in the Parenthesis. (NgAu)

Species ArAu3

+

ArAu2H+ ArAuH2 KrAu3

+

+ +

KrAu2H

KrAuH2 XeAu3

+

+ +

XeAu2H

+

a

k(NgAu)

ωB97XD 136.7 (6.2)

MP2 142.1 (7.5)

CCSD(T) 122.5

196.7 (3.1)

188.9 (3.4)

163.6 a

ωB97XD 35.7

MP2 39.4

70.5

63.4

225.0 (2.3)

223.2 (2.8)

193.1 [211.3]

99.0

97.8

105.0 (0.7)

108.1 (1.0)

93.3

58.4

60.3

178.1 (1.4)

175.7 (1.5)

155.8

89.1

81.1

a

192.6 (1.8)

183.0 (2.1)

163.2 [173.1]

127.2

115.2

101.1 (0.1)

101.9 (0.4)

91.6

89.8

81.0

117.9 (0.6)

116.4 (0.9)

105.4

104.9

95.6

a

174.7 (0.9) 166.2 (1.2) 153.6 [160.5] 138.4 125.3 XeAuH2 The Values in the Square Brackets represents the Frequency as obtained by CCSD(T) Methods with

AVTZ Basis Set.



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Table 3. Calculated HOMO-LUMO Energy Values and HOMO-LUMO gaps (EGap) (in +

+

+

+

+

+

eV) for Ng, Au3 , Au2H , AuH2 , NgAu3 , NgAu2H , and NgAuH2 (Ng = Ar, Kr, and Xe)

Species as obtained Using ωB97XD Method with DEF2 Basis Set. Species Ng=Ar

Ng=Kr

Ng=Xe

HOMO

Ng -13.926

Au3+ -14.560

Au2H+ -15.839

AuH2+ -17.893

NgAu3+ -14.274

NgAu2H+ -15.488

NgAuH2+ -17.110

LUMO

3.154

-6.658

-7.271

-8.116

-6.400

-6.566

-6.000

EGap

17.080

7.902

8.568

9.777

7.875

8.922

11.110

HOMO

-12.707

-14.560

-15.839

-17.893

-14.155

-15.363

-16.859

LUMO

2.446

-6.658

-7.271

-8.116

-6.299

-6.394

-5.630

EGap

15.153

7.902

8.568

9.777

7.856

8.968

11.230

HOMO

-11.338

-14.560

-15.839

-17.893

-13.975

-15.175

-16.487

LUMO

1.826

-6.658

-7.271

-8.116

-6.169

-6.179

-5.287

EGap

13.164

7.902

8.568

9.777

7.807

8.996

11.200

Energy


Page 25 of 29

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Table 4. MP2 Calculated Values of the NBO Charges in Au3+, Au2H+, AuH2+, NgAu3+, NgAu2H+, and NgAuH2+ (Ng = Ar, Kr, and Xe) Species Using AVTZ Basis Set with MOLPRO Program. Charge Corresponding to the Au Atom Bonded with the Ng atom is Represented in Boldface. Species Au3+ / NgAu3+

Au2H+ / NgAu2H+

AuH2+ / NgAuH2+

Atoms Ng Au1 Au2 Au3 Ng Au1 Au2 H Ng Au H1 H2

Cation … 0.333 0.333 0.333 … 0.627 0.627 -0.254 … 0.925 0.037 0.037

Ng = Ar 0.076 0.291 0.317 0.317 0.107 0.513 0.619 -0.240 0.145 0.716 0.070 0.070

Ng = Kr 0.123 0.264 0.306 0.306 0.174 0.445 0.603 -0.222 0.219 0.634 0.073 0.073

Ng = Xe 0.202 0.215 0.291 0.291 0.259 0.376 0.580 -0.215 0.315 0.545 0.070 0.070



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Table 5. Calculated Values of NgAu Bond Critical Point Electron Density (ρ in e a0-3), Laplacian (2ρ in e a0-5), the Local Electron Energy Density (Ed in au), and Ratio of Local Electron Kinetic Energy Density and Electron Density (G/ρ in au) in NgAu3+, NgAu2H+, and NgAuH2+ (Ng = Ar, Kr, and Xe) Species as Obtained Using ωB97XD and MP2 Methods with DEF2 Basis Set. Species ArAu3+ ArAu2H+ ArAuH2+ KrAu3+ KrAu2H+ KrAuH2+ XeAu3+ XeAu2H+ XeAuH2+

 ωB97X-D 0.046 0.057 0.070 0.058 0.065 0.076 0.067 0.071 0.079

MP2 0.047 0.056 0.070 0.057 0.063 0.074 0.064 0.067 0.076

2 ωB97X-D 0.174 0.212 0.247 0.179 0.195 0.211 0.148 0.147 0.143

MP2 0.202 0.237 0.275 0.198 0.212 0.229 0.163 0.162 0.159

Ed ωB97X-D -0.004 -0.009 -0.016 -0.009 -0.013 -0.019 -0.016 -0.018 -0.024

MP2 -0.004 -0.008 -0.015 -0.009 -0.012 -0.018 -0.014 -0.016 -0.022

G(r)/ ωB97X-D 1.039 1.090 1.102 0.934 0.951 0.942 0.787 0.779 0.752

MP2 1.160 1.199 1.205 1.026 1.034 1.021 0.861 0.847 0.815


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Table 6. Various Topological Properties [Local Electron Energy Density (Ed in au), the Electron Density (ρ in e a0-3), and Ratio of Local Electron Energy Density and Electron Density (−Ed/ρ in au)] at the Local Energy Density Critical Points [(3,+1) HCP] for the NgAu bond in NgAu3+, NgAu2H+, and NgAuH2+ (Ng = Ar, Kr, and Xe) Species as Obtained Using ωB97XD and MP2 Methods with DEF2 Basis Set. Species +

ArAu3 ArAu2H+ ArAuH2+ KrAu3+ KrAu2H+ KrAuH2+ XeAu3+ XeAu2H+ XeAuH2+

Ed ωB97X-D -0.004 -0.009 -0.016 -0.009 -0.013 -0.019 -0.016 -0.018 -0.024

 MP2 -0.004 -0.008 -0.015 -0.009 -0.012 -0.018 -0.014 -0.016 -0.022

ωB97X-D 0.046 0.057 0.071 0.058 0.065 0.077 0.067 0.071 0.079

MP2 0.047 0.057 0.070 0.057 0.063 0.074 0.064 0.067 0.076

Ed/ ωB97X-D 0.090 0.152 0.224 0.155 0.200 0.247 0.239 0.254 0.304

MP2 0.085 0.140 0.214 0.158 0.190 0.243 0.219 0.239 0.289



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 29

Table 7. Calculated Values of Energy Decomposition Analysis for NgAu3+, NgAu2H+, and NgAuH2+ (Ng = Ar, Kr, and Xe) Species as Obtained Using PBE-D3 Method with TZ2P Basis Set by Employing ADF Packages and Taking MP2 Optimized Geometry. Complexes

ArAu3+ ArAu2H+ ArAuH2+ KrAu3+ KrAu2H+ KrAuH2+ XeAu3+ XeAu2H+ XeAuH2+

Pauli Repulsion Energy 112.33 132.91 144.14 169.73 177.37 179.63 242.26 233.96 224.74

Electrostatic Energy -67.31 -77.56 -85.47 -109.27 -111.67 -115.21 -165.37 -156.88 -154.33

Orbital Interaction Energy -77.88 -102.11 -142.82 -114.45 -136.69 -180.49 -162.74 -182.44 -229.03

Dispersion Energy -2.16 -1.49 -0.83 -2.86 -1.92 -1.05 -3.77 -2.44 -1.27

Total Bonding Energy -35.02 -48.25 -84.99 -56.84 -72.92 -117.12 -89.62 -107.80 -159.89


Page 29 of 29


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

75 60

Ar-AuH+2

240 210

45

Ar-Au2H+

180

30

Ar-Au+3

150

15

120

 (Ng-Au) (cm-1)

BE (Ng-Au) (kJ mol-1)

TOC GRAPHICS


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