Theoretical Prediction on [5] Radialene Sandwich Complexes (CpM) 2

Jan 12, 2017 - Kawai, Takahashi, Ito, Pawlak, Meier, Spijker, Canova, Tracey, Nozaki, Foster, and Meyer. 2017 11 (8), pp 8122–8130. Abstract: Accord...
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Theoretical Prediction on [5]Radialene Sandwich Complexes (CpM)2(C10H10) (Cp = η5‑C5H5; M = Fe, Co, Ni): Geometry, Spin States, and Bonding Nan-nan Liu,*,† Ying-ying Xue,‡ and Yi-hong Ding*,‡ †

Chemistry Center, College of Food Engineering, Harbin University of Commerce, Harbin 150076, China Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China

‡

S Supporting Information *

ABSTRACT: [5]Radialene, the missing link for synthesis of radialene family, has been finally obtained via the preparation and decomplexation of the [5]radialene−bis-Fe(CO)3 complex. The stability of [5]radialene complex benefits from the coordination with Fe(CO)3 by losing free 1,3-butadiene structures to avoid polymerization. In light of the similar coordination ability of half-sandwiches CpM(Cp = η5-C5H5; M = Fe, Co, Ni), there is a great possibility that the sandwiched complexes of [5]radialene with CpM are available. Herein, we present the first theoretical prediction on the geometry, spin states and bonding of (CpM)(C10H10) and (CpM)2(C10H10). For M = Fe, Co, Ni, the ground states of (CpM)(C10H10) and (CpM)2(C10H10) are doublet and triplet, singlet and singlet, and doublet and triplet states, where each Fe, Co, and Ni adopts 17, 18, and 19 electron-configuration, respectively. In particular, (CpFe)2(C10H10) and (CpNi)2(C10H10) have considerable open-shell singlet features. Generally the trans isomers of (CpM)2(C10H10) with two CpM fragments on the opposite sides of the [5]radialene plane are apparently more stable than the cis ones with CpM fragments on the same side. However, for the singlet and triplet isomers of (CpNi)2(C10H10) (both cis and trans isomers), the energy differences are relatively small, indicating that these isomers all have the opportunity to exist. Besides, the easy Diels−Alder (DA) dimerization between the [3]dendralene-like fragments of (CpM)(C10H10) suggests the great difficulty in isolating the (CpM)(C10H10) monomer.

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INTRODUCTION

stable due to even lacking a free 1,3-butadiene structure to initiate Diels−Alder dimerization.8 Apparently, two exocyclic bonds of radialene are favored as π donors to coordinate with one electron-deficient Fe(CO)3 according to the 18-electron rule. The metal−alkene interactions in [5]radialene coordinated complexes could result in radialene losing some free 1,3-butadiene structure and preventing from polymerization. For the same reason, except for metal carbonyls, we believe the coordination of some other metal cyclopentadienyl ligands may also show the same benefits on stability of [5]radialene from being polymerized, for example, half-sandwiches CpM (Cp = η5-C5H5; M = Fe, Co, Ni). These half-sandwiches of iron group are also common building block in organometallic chemistry. There are many complexes, such as [CpFe(CO)2(C2H4)][BF4], CpCo(C4H6), CpCo(η2,2-C8H8), CpNi(CH3)(C2H4), etc., containing alkene or dienes coordinated to the metal center of the halfsandwiches.15−18 These references indicate that the coordination between half-sandwiches CpM and alkene or dienes are generally feasible in the fields of organometallic chemistry. It is

Radialenes (C2nH2n) are cyclic hydrocarbons containing n ring atoms and n cross-conjugated exocyclic double bonds formed by sp2-hybridized carbons.1−4 The unique structures make radialenes of particular interest on their characteristics, such as aromaticity and conjugation.5−12 Radialenes are also useful molecules with potential applications as building blocks for polymers, organic conductors, and ferromagnets materials.1,13,14 Although [3]-, [4]-, and [6]radialenes were prepared several decades ago,2−4 the synthetic approaches for radialenes are still the research focuses even now. [5]Radialene, which remained the missing link for synthesis, has been finally obtained via the preparation and decomplexation of the [5]radialene−bisFe(CO)3 complex very recently.8 The difficulty for synthesis of [5]radialene monomer was proposed to be its high reactivity for dimerization or polymerization. Compared to the other radialenes, [5]radialene has relatively small magnitude of distortion energy for dimerization, which enhances its reactivity. Besides, the narrow HOMO−LUMO energy gap for [5]radialene is another reason for its high reactivity. The mono-Fe(CO)3 complex of [5]radialene was calculated to be much less reactive toward dimerization or polymerization, and the bis-Fe(CO)3 complex of [5]radialene was suggested to be © XXXX American Chemical Society

Received: November 3, 2016 Revised: January 12, 2017 Published: January 12, 2017 A

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Figure 1. Relative energies (in kcal/mol) and bond distances (in Å) of (CpFe)(C10H10) and (CpFe)2(C10H10) isomers obtained at PBEPBE/TZVP (left) and BP86/TZVP (right in italics) levels. Single-point energies calculated with aug-cc-PVDZ basis set listed in brackets. Hydrogen atoms are abbreviated.

Figure 2. Selected NLMOs of the ground states of (CpFe)(C10H10) and (CpFe)2(C10H10) obtained at PBEPBE/TZVP level. The visual cubes are produced by associating with the Multiwfn and Visual Molecular Dynamics programs.26,27

triplet, and quintet isomers of (CpCo)2(C10H10) are considered. The reactivity of (CpM)(C10H10) to undergo Diels− Alder (DA) reaction with ethylene and [3]dendralene are also calculated. The details are reported as follows.

logical that half-sandwiches CpM could also coordinate with the free 1,3-butadiene structure and stabilize [5]radialene. It is also reasonable to believe that the CpM complexes of [5]radialene might also be obtained by experiments in the future, just like their Fe(CO)3 complex of [5]radialene cousins. As the potential CpM complexes of [5]radialene remain to be discovered yet, their configuration, spin multiplicity, and coordination mode are surely of much interest. Herein we present the first theoretical study on CpMcomplexed [5]radialene, i.e., (CpM)(C 1 0 H 1 0 ) and (CpM)2(C10H10) (Cp = η5-C5H5; M = Fe, Co, Ni). The geometry, spin states, and bonding are studied in great detail. The singlet, triplet, quintet, and septet isomers of (CpFe)2(C10H10) and (CpNi)2(C10H10), as well as the singlet,

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COMPUTATIONAL METHODS All the (CpM)(C10H10) and (CpM)2(C10H10) (Cp = η5-C5H5; M = Fe, Co, Ni) isomers are fully optimized using the density functional theory (DFT) at PBEPBE/TZVP and BP86/TZVP level.19−22 For geometry optimization, several candidate structures (shown in Figure S1 of Supporting Information) are considered as initial input, and only the minima are described in the following section. Harmonic vibrational frequencies are calculated to ensure the correct minima. The B

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Figure 3. Relative energies (in kcal/mol) and bond distances (in Å) of (CpCo)(C10H10) and (CpCo)2(C10H10) isomers obtained at PBEPBE/TZVP (left) and BP86/TZVP (right in italics) levels. Single-point energies using aug-cc-PVDZ basis set listed in brackets.

It is presumed that each Fe atom has a single-electron in (CpFe)2(C10H10)-1-triplet. The electron configuration of (CpFe)(C10H10)-doublet and (CpFe)2(C10H10)-1-triplet are studied by NLMOs.24 NLMOs are semilocalized molecular orbitals that could provide a more intuitive isovalue surface on the donor−acceptor interactions for coordinated complex than molecular orbital (MO) and natural bond orbital (NBO). As shown in Figure 2, for (CpFe)(C10H10)-doublet, NLMO-1−3 represent the Fe-Cp coordination, NLMO-4−6 are three noncoordinated exocyclic π-bond of [5]radialene, NLMO-7−9 represent the Fe-[5]radialene interaction, NLMO-10−11 are two lone pairs of delectrons on Fe atom, and NLMO-12 is a single d-electron located on Fe atom. Therefore, Fe atom adopts 17 electronconfiguration in (CpFe)(C10H10)-doublet. For (CpFe)2(C10H10)-1-triplet, NLMO-7 is the free exocyclic π-bond of [5]radialene. NLMO-1−3, NLMO-8−10, NLMO14−15, and NLMO-18 represent Fe1-[5]radialene coordination, Fe1-Cp coordination, two lone pairs of d-electrons, and a single d-electron on Fe1 atom, respectively, while NLMO-4−6, NLMO-11−13, NLMO-16−17, and NLMO-19 represent Fe2[5]radialene coordination, Fe2-Cp coordination, two lone pairs of d-electrons, and a single d-electron on Fe2 atom, respectively. Fe1 and Fe2 atoms all adopt 17 electronconfiguration. It can be seen from the shape of NLMOs that the electron-configuration of Fe atom in (CpFe)2(C10H10)-1triplet is very similar to that in (CpFe)(C10H10)-doublet. In the second lowest energic η4,4-coordinated cis (CpFe)2(C10H10)-2triplet, where the two (CpFe) fragments are on the same side of [5]radialene plane, each Fe also possesses a single-electron and adopts 17 electron-configuration (shown in Figure S2 of supplement information). Besides, the coefficients and secondorder perturbative stabilization energy ΔE(2) of the main parent NBOs of the NLMOs related to the M-C10H10 interaction in (CpM)(C10H10) and (CpM)2(C10H10) ground states (M = Fe, Co and Ni) are shown in Figures S4−S9 of the Supporting Information.

single-point energies are performed at the aug-cc-PVDZPBEPBE and BP86 levels based on the optimized geometries at TZVP/PBEPBE and BP86/TZVP, respectively. Besides, the Diels−Alder transition states of (CpM)(C10H10) with ethylene and [3]denlralene are calculated at PBEPBE/TZVP. The above calculations are performed using the Gaussian 09 program package.23 To investigate the coordination between metal atom and radialene ligand, the natural localized molecular orbitals (NLMOs)24 of selected molecules are obtained by using NBO5.0 program.25

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RESULTS AND DISCUSSION 1. (CpFe)(C10H10) and (CpFe)2(C10H10) Complexes. As shown in Figure 1, the relative energies of (CpFe)(C10H10) and (CpFe)2(C10H10) isomers calculated by PBEPBE and BP86 methods are very close. Generally the single-point energies obtained with aug-cc-PVDZ basis set show similar trend with the results obtained with TZVP basis set. To be concise, the following discussions are mainly based on the PBEPBE/TZVP results. For (CpFe)(C10H10), the ground state is doublet state, which is 25.1 kcal/mol lower in energy than the quartet state. [5]Radialene ligand are all η4-coordinated in the doublet and quartet states. For (CpFe)2(C10H10), the ground state is 1triplet, which is 16.1, 23.5, 53.1, 22.8, 9.4, 27.7, and 48.9 kcal/ mol lower in energy than 1-singlet, 1-quintet, 1-septet, 2-singlet, 2-triplet, 2-quintet, and 2-septet, respectively. The ground state 1-triplet, where [5]radialene is η4,4-coordinated, is C2symmetric along the axis of C9−C10 bond. It is a trans structure with the two (CpFe) fragments on the opposite sides of [5]radialene plane. The bond distances 2.051, 2.048, 2.049, and 2.054 Å for Fe1−C1, Fe1−C2, Fe1−C3, and Fe1−C4 of (CpFe)2(C10H10)-1-triplet are nearly the same as Fe2−C7, Fe2−C5, Fe2−C8, and Fe2−C6, and meanwhile, those values are also very close to 2.049, 2.047, 2.050, and 2.045 Å for Fe− C1, Fe−C2, Fe−C3, and Fe−C4 of (CpFe)(C10H10)-doublet. C

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Figure 4. Selected NLMOs of the ground states of (CpCo)(C10H10) and (CpCo)2(C10H10) obtained at PBEPBE/TZVP level.

Figure 5. Relative energies (in kcal/mol) and bond distances (in Å) of (CpNi)(C10H10) and (CpNi)2(C10H10) isomers obtained at PBEPBE/TZVP (left) and BP86/TZVP (right in italics) levels. Single-point energies using aug-cc-PVDZ basis set listed in brackets.

state is 1-singlet with η4,4-coordinated [5]radialene. 1-Singlet is 22.2, 45.7, 8.0, 29.5, and 50.0 kcal/mol lower in energy than 1triplet, 1-quintet, 2-singlet, 2-triplet, and 2-quintet, respectively. 1-Singlet is also C2-symmetric along the axis of C9−C10 bond, and the trans structure has two (CpCo) fragments on the opposite sides of [5]radialene plane. The bond distances of 1.999, 2.035, 1.997, and 2.042 Å for Co1−C1, Co1−C2, Co1− C3, and Co1−C4 of (CpCo)2(C10H10)-1-singlet are also very close to 1.998, 2.038, 1.997, and 2.039 Å for Co1−C1, Co1− C2, Co1−C3, and Co1−C4 of (CpCo)(C10H10)-singlet. From the NLMOs (Figure 4), the coordinations of Co-Cp and Co-[5]radialene are similar to the case of Fe-Cp and Fe[5]radialene. For (CpCo)(C10H10)-singlet, NLMO-10−12 are three lone pairs of d-electrons on Co atom, which adopts 18 electron-configuration. For (CpCo) 2 (C 10 H 10 )-1-singlet, NLMO-14−16 and NLMO-17−19 are three lone pairs of delectrons on Co1 and Co2, respectively. Therefore, Co1 and Co2 atoms all adopt 18 electron-configuration. Besides, in the η4,4-coordinated cis (CpCo)2(C10H10)-2-singlet, the two

The open-shell singlet state of (CpFe)2(C10H10) is calculated with Gaussian 09’s fragment guess feature28 based on the (CpFe)2(C10H10)-1-triplet wave function as input, and the stability is checked with keyword stable = opt. The open-shell antiferromagnetic singlet state is 0.06 kcal/mol lower in energy than 1-triplet at PBEPBE/TZVP level. The energy difference between the open-shell singlet state and triplet state is also calculated by the single-point energies at MP2/TZVP// PBEPBE/TZVP level. The open-shell singlet state is 0.5 kcal/ mol lower by HF and 2.6 kcal/mol lower by MP2 than (CpFe)2(C10H10)-1-triplet. Since the results obtained by HF, MP2, and PBE methods all indicate the open-shell singlet state is slightly lower in energy than the triplet state, we think the open-shell singlet would be available as the triplet. Thus, the open-shell singlet state of (CpFe)2(C10H10) might be obtained and isolated from 1-triplet in the future experiments. 2. (CpCo)(C10H10) and (CpCo)2(C10H10) Complexes. As shown in Figure 3, for (CpCo)(C10H10), the ground state is the η4-coordinated singlet state, which is 23.9 kcal/mol lower in energy than the triplet state. For (CpCo)2(C10H10), the ground D

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Figure 6. Selected NLMOs of the ground states of (CpNi)(C10H10) and (CpNi)2(C10H10) obtained at PBEPBE/TZVP level.

Figure 7. Spin density plots of (CpFe)2(C10H10)-1-triplet, (CpNi)2(C10H10)-1-triplet, and their open-shell singlet isomers obtained at PBEPBE/ TZVP level. The visual surface are produced by associating with the Multiwfn and Visual Molecular Dynamics programs.26,27

and Ni2, respectively. Therefore, Ni1 and Ni2 atoms all adopt 19 electron-configuration. The cases of 1-singlet, 2-singlet, and 2-triplet of (CpNi)2(C10H10) are shown in Figure S3 of Supporting Information. 1-Singlet has η4,4-coordinated [5]radialene, where C4−C3−C5−C6 forms a four-center six-electron πbond, and Ni atoms adopt 18 electron-configuration. In the η3,3-coordinated 2-singlet, C5−C6 in the cyclic ring becomes double bond, whereas exocyclic C3−C4 and C5−C6 bonds become single bond, Ni atoms also adopt 18 electronconfiguration. The case of the η4,4-coordinated 2-triplet is similar to 1-triplet, where each Ni possesses a single-electron and adopts 19 electron-configuration. The open-shell singlet state of (CpNi)2(C10H10) based on the (CpNi)2(C10H10)-1-triplet wave function is 0.2 kcal/mol lower in energy than 1-triplet at PBEPBE/TZVP level. The single-point energies of the open-shell singlet state and triplet state are also calculated at MP2/TZVP//PBEPBE/TZVP level. The open-shell singlet state is 1.3 kcal/mol higher by HF and 19.0 kcal/mol lower by MP2 than the triplet. Although the relative energy of the open-shell singlet state is apparently higher than the triplet state by MP2 method, its existence possibility is supported by HF and PBE functions. Thus, we could not easily deny the existence possibility of the open-shell singlet state of (CpNi)2(C10H10). Figure 7 shows the spin density plots of (CpFe)2(C10H10)-1triplet, (CpNi)2(C10H10)-1-triplet, and their open-shell singlet isomers. It is very obvious that the single-electrons in triplet states are spin-parallel and in open-shell singlet states are spinopposite. No matter in open-shell singlet or triplet states, the

(CpCo) fragments are on the same side, and Co atoms also adopt 18 electron-configuration (in Figure S2). 3. (CpNi)(C10H10) and (CpNi)2(C10H10) Complexes. As shown in Figure 5, the ground state of (CpNi)(C10H10) is the η4-coordinated doublet state, which is 27.2 kcal/mol lower in energy than the quartet state. For (CpNi)2(C10H10), the ground state is the η4,4-coordinated 1-triplet, which is 5.7, 28.4, 68.2, 5.7, 7.5, 31.7, and 70.7 kcal/mol lower in energy than 1singlet, 1-quintet, 1-septet, 2-singlet, 2-triplet, 2-quintet, and 2septet, respectively. The energy differences between the ground state 1-triplet, 1-singlet, 2-singlet, and 2-triplet are not so obvious as in the case of (CpFe)2(C10H10). 1-Triplet and 1singlet are trans structures with the two (CpNi) fragments on the opposite sides of [5]radialene plane, while 2-singlet and 2triplet are cis structures with the two (CpNi) fragments on the same side. 1-Triplet is C1-symmetric, the bond distances 2.060, 2.150, 2.072, and 2.213 for Ni1−C1, Ni1−C2, Ni1−C3, and Ni1−C4 are slightly different with 2.086, 2.170, 2.065, and 2.219 Å for Ni1−C7, Ni1−C8, Ni1−C5, and Ni1−C6. However, these values are also close to 2.059, 2.179, 2.063, and 2.156 Å for Ni1−C1, Ni1−C2, Ni1−C3, and Ni1−C4 of (CpNi)(C10H10)doublet. NLMOs (Figure 6) also indicate that each Ni atom possesses a single-electron. For (CpNi)(C10H10)-doublet, NLMO-10−12 and NLMO-13 are three lone pairs of d-electrons and a singleelectron on Ni atom, so that it adopts 19 electronconfiguration. For (CpNi)2(C10H10)-1-triplet, NLMO-14−16 and NLMO-17−19 are three lone pairs of d-electrons on Ni1 and Ni2; NLMO-20 and NLMO-21 are single-electrons on Ni1 E

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The Journal of Physical Chemistry A single-electrons have relatively independent spin centers on the opposite sides of [5]radialene ligand. The Mulliken atomic spin densities on the Fe atoms of (CpFe)2(C10H10)-1-triplet are both 1.08, on the Fe atoms of the open-shell singlet state are 1.10 and −1.10, respectively. These values on the Ni atoms of triplet (CpNi)2(C10H10)-1-triplet are both 0.58, on the Ni atoms of the open-shell singlet state are 0.58 and −0.58, respectively. The Mulliken atomic spin densities indicate that the single-electrons are dominantly located on the Fe atoms of the triplet and open-shell singlet states of (CpFe)2(C10H10), while the single-electrons are delocalized to some extent in the triplet and open-shell singlet states of (CpNi)2(C10H10) in spite of they also mainly locate on the Ni atoms. 4. Diels−Alder Reaction of (CpM)(C10H10) (M = Fe, Co, Ni) Complexes with Ethene and [3]Dendralene. Similar to the case of bis-Fe(CO)3 complex of [5]radialene, the (CpM)2(C10H10) complexes also lack a free 1,3-butadiene structure to initiate Diels−Alder reaction. Since (CpM)(C10H10) has similar fragment with ethene and [3]dendralene, the DA reaction of (CpM)(C10H10) with ethene and [3]dendralene are calculated to estimate the reactivity of [5]radialene for dimerization. The transition states of (CpCo)(C10H10) with ethene and [3]dendralene are shown in Figure 8. (CpFe)(C10H10) and (CpNi)(C10H10) have similar transition states.

a conjugated diene and an alkene. For half-sandwich (CpM)(C10H10), two of five CC double bonds of C10H10 are coordinated with one CpM, there are three free CC double bonds left for further Diels−Alder reaction. Therefore, similar to the free [5]radialene, (CpM)(C10H10) monomer is hard to exist because of it still having the free conjugated diene to proceed DA reaction. For (CpM)2(C10H10), four of five CC double bonds of C10H10 are coordinated with two CpM in (CpM)2(C10H10); there is only one free CC double bond left. Lacking free conjugated diene structure for both trans and cis (CpM)2(C10H10), Diels−Alder dimerization is hard to initiate between two (CpM)2(C10H10) monomers.

Figure 8. DA reaction transition states of (CpCo)(C10H10) with ethene and [3]dendralene obtained at PBEPBE/TZVP level. Bond distances are in Å.

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CONCLUSION The ground states of (CpM)(C10H10) for Fe, Co, and Ni are doublet, singlet, and doublet states, in which [5]radialene is η4coordinated to the metal atom. Fe, Co, and Ni adopts 17, 18, and 19 electron-configuration in ground states, respectively. The coordination with CpM slightly reduces the reactivity of [5]radialene, but the DA dimerization of (CpM)(C10H10) is still easy to occur between the [3]dendralene-like fragments of [5]radialene. Thus, (CpM)(C10H10) monomer is hard to exist. For (CpM)2(C10H10), generally the trans isomers with the two CpM fragments on the opposite sides of [5]radialene plane are more stable than the cis ones on the same side. The ground states are the trans (CpFe)2(C10H10)-1-triplet, (CpCo)2(C10H10)-1-singlet, and (CpNi)2(C10H10)-1-triplet with two (CpM) fragments on the opposite sides of η4,4[5]radialene plane. Each Fe, Co, and Ni adopts 17, 18, and 19 electron-configuration, respectively. In (CpFe)2(C10H10)-1triplet and (CpNi)2(C10H10)-1-triplet, each Fe and Ni atom possesses a single-electron. The relative energies of open-shell antiferromagnetic singlet states of (CpFe)2(C10H10) and (CpNi)2(C10H10) based on the triplet wave function are slightly lower (less than 0.2 kcal/mol at PBEPBE/TZVP level) compared with the triplet ground state. The open-shell singlet states might also exist like the triplet states. Besides, the energy differences are less than 8 kcal/mol between the ground state 1triplet, 1-singlet, 2-singlet, and 2-triplet of (CpNi)2(C10H10) with two (CpNi) on the opposite sides or the same side of [5]radialene. It indicates above isomers of (CpNi)2(C10H10) might be obtained in the future experiments. Ni atom adopts 18 electron-configuration in the singlet states of (CpNi)2(C10H10). ASSOCIATED CONTENT

S Supporting Information *

For free [5]radialene, (CpFe)(C10H10), (CpCo)(C10H10), and (CpNi)(C10H10), the DA energy barriers are 9.3, 12.8, 12.8, and 11.4 kcal/mol with ethene, 4.0, 5.7, 5.8, and 5.1 kcal/mol with [3]dendralene at PBEPBE/TZVP level, respectively. The coordination with CpM slightly reduces the reactivity of [5]radialene; however, the small energy barriers indicate the DA dimerization of (CpM)(C10H10) should be very easy to occur between the [3]dendralene-like fragments. Similar to free [5]radialene, the (CpM)(C10H10) monomer is hard to exist. Besides, we have carefully tried to search the potential transition states of trans and cis (CpM)2(C10H10) reacting with ethene and [3]dendralene for many times; however, the certain transition states of DA reactions are not found. We guess the reason might be that the trans and cis (CpM)2(C10H10) do not have the conjugated diene to proceed further with DA reaction. Generally DA reaction ([4 + 2] cycloaddition) occurs between

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.6b11066.

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Computational details, molecular modeling coordinates and energies, and figures (PDF)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Nan-nan Liu: 0000-0003-3428-7348 Notes

The authors declare no competing financial interest. F

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ACKNOWLEDGMENTS This work is supported by the National Natural Science Foundation of China (No. 21301041, 51476049, 21273093, 21473069, 21073074), the Natural Science Foundation of Heilongjiang Province of China (No. B201409), and the Doctoral Scientific Research Foundation of Harbin University of Commerce (No. 13DL019).

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DOI: 10.1021/acs.jpca.6b11066 J. Phys. Chem. A XXXX, XXX, XXX−XXX