Infrared Spectra of Novel NgBeSO2 Complexes (Ng = Ne, Ar, Kr, Xe

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Infrared Spectra of Novel NgBeSO Complexes (Ng = Ne, Ar, Kr, Xe) in Low Temperature Matrices Wenjie Yu, Xing Liu, Bing Xu, Xiaopeng Xing, and Xuefeng Wang J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.6b08799 • Publication Date (Web): 11 Oct 2016 Downloaded from http://pubs.acs.org on October 17, 2016

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The Journal of Physical Chemistry

Infrared Spectra of Novel NgBeSO2 Complexes (Ng = Ne, Ar, Kr, Xe) in Low Temperature Matrices Wenjie Yu, Xing Liu, Bing Xu, Xiaopeng Xing and Xuefeng Wang* School of Chemical Science and Engineering, and Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092, P. R. China

Abstract The novel noble-gas complexes NgBeSO2 (Ng=Ne, Ar, Kr, Xe) have been prepared in the laser-evaporated beryllium

atom

reactions with

SO2 in

low-temperature matrices. Doped with heavier noble gas, the guest (Ar, Kr, Xe) atom can substitute neon to form more stable complex. Infrared spectroscopy and theoretical calculations are used to confirm the band assignment. The dissociation energies are calculated at 0.9, 4.0, 4.7, and 6.0 kcal/mol for NeBeSO2, ArBeSO2, KrBeSO2, and XeBeSO2, respectively, at the CCSD(T) level. Quantum chemical calculations demonstrate that the Ng−Be bonds in NgBeSO2 could be formed by the combination of electron-donation and ion-induced dipole interactions. The WBI (Wiberg bond index ) values of Ng-Be bonds and LOL (localized orbital locator ) profile indicate that the Ng-Be bond exhibits a gradual increase in covalent character along Ne to Xe.

* Email: [email protected]

Tel: (+86) 134 8228 7768

ACS Paragon Plus Environment


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Introduction Beryllium chemistry has aroused considerable interest in view of its peculiar electron-deficient properties.1-4 Recently a zero-valent beryllium complexes with strong multiple Be-C bonding have been isolated and characterized.1 Due to the large charge-to-radius ratio, beryllium(II) cation is supposed as a sound coordination center, which has a high affinity for oxygen and other donors.5-7 For example beryllium-containing dioxo,8,9 oxo-carboxylic,10,11 and dicarboxylic12,13 organic compounds have been synthesized in aqueous solution, exhibiting significant chelating behaviors. Interestingly in each crystal structure of such complexation, the beryllium metal atom is tetrahedrally coordinated by four oxygen atoms of the ligands.4 For decades, the quest for beryllium-containing compounds using the pulsed-laser ablation matrix isolation spectroscopic technique has achieved abundant products.14-18 In 1994, Thomson and Andrews reported the preparation and characterization of ArBeO, KrBeO, and XeBeO in low temperature matrices of argon, krypton, and xenon.14,15 In addition, carbonyl complexes OCBeO and COBeO were successfully isolated in argon matrix by the same group, suggesting the BeO molecule is a strong Lewis acid which assists the formation of ArBeO.16 Similar experiments have been done on donor-acceptor complexes NgBeCO3 (Ng = Ne, Ar, Kr, Xe) in low-temperature matrices.17 Four noble-gas compounds, NgBeS, have been identified, and the BeS Lewis acid molecule favors strong chemical binding between the Be and Ng atoms.18 In addition, a wealth of theoretical investigations on the donor-acceptor


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interaction have been studied in NgBeY (Y = O, S, Se, Te, NH, CO3, SO4).17-24 Recently, ab initio computations were carried out to assess the noble gas (Ng) binding capability of BeSO4 cluster and further compared the stability of NgBeSO4 with that of the recently detected NgBeCO3 cluster and NgBeO.24 Herein we report that BeSO2 molecule forms strong noble-gas complexes in solid neon, argon, krypton, and xenon matrices. Doped with heavier noble gas, the guest (Ar, Kr, Xe) atom can substitute neon to form more stable complex. Theoretical calculations are used to confirm the band assignment and calculate dissociation energy together with other bonding information. The present system shows a strong interaction between the electron-deficient Be and Ng atoms that widens the scope of beryllium chemistry.

Experimental and computational methods Our experimental method for co-deposition of laser-ablated metal atoms with SO2 diluted in noble gases has been described in detail previously.18,25 Briefly, a Nd:YAG laser fundamental (1064 nm, 10 Hz repetition rate with 10 ns pulse width) was focused onto a rotating beryllium target (Alfa Aesar), which gave a bright plume reacting with SO2/Ng and spreading uniformly to the 4 K CsI window cooled by a closed-cycle helium refrigerator (Sumitomo Heavy Industrious, Model RDK408D). A mixture of S18O2, S16,18O2, and a trace of S16O2 was prepared by tesla coil discharge in a 0.5 L pyrex bulb. This bulb was filled with ∼2 Torr 18O2 (>99%, Shanghai Research Institute of Chemical Industry), and there is 10 mg of sulfur powder (99.5%, Alfa Aesar) sublimed onto its walls, which was heated by external hot air (>450 °C) during



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the preparation options. The sample of (98.8%

34

34

SO2 was similarly prepared from sulfur-34

S, Cambridge Isotope Laboratories) and oxygen (99.999%, British Oxygen

Company). Laser-ablated beryllium atoms reacted with SO2 in excess solid noble-gas matrices for around 1 h at a rate of 2−4 mmol/h, respectively. The laser energy varied about 20−30 mJ/pulse, typically, was employed to split beryllium atoms for reaction. Following deposition, infrared spectra were recorded on a Bruker Vertex 80V spectrometer equipped with a mercury cadmium telluride (MCTB) detector at a resolution of 0.5 cm−1. Samples were later irradiated for 15 min periods by a mercury arc lamp (Philips, 175 W) combined with diverse wavelength-selective optical filters, and then annealed to allow reagent diffusion and further reaction. Complementary density functional theory (B3LYP) calculations were performed using the Gaussian 09 package.26 The 6-311++G(3df, 3pd) basis sets were employed for sulfur, oxygen, beryllium, neon, argon and krypton atoms, and the SDD pseudo-potential was applied for xenon. All of the geometrical parameters were fully optimized to locate the energy minima, and the harmonic vibrational frequencies were obtained analytically at the optimized structures. The natural charges on each atom of the molecule and Wiberg bond index (WBI)27 are computed based upon natural population analysis (NPA) by NBO program embedded in the Gaussian 09 package at the same level. The dissociation energies of the NgBeSO2 complexes into BeSO2 and Ng were computed at the CCSD(T)//B3LYP/6-311++G(3df,3pd) level of theory and the correction to basis-set superposition error (BSSE) is included by employing the standard counterpoise (CP) method proposed by Boys and Bernardi.28 The wave


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function analysis of the NgBeSO2 complexes has been computed using the theory of atoms-in-molecules (AIM) developed by Bader to investigate the electronic structure of these species.29 The color-filled maps of localized orbital locator (LOL) of the electronic density of NgBeSO2 are plotted using Multiwfn software.30

Results and Discussion Infrared Spectra. Infrared spectra recorded for Be atom reactions with SO2 in solid neon are illustrated in Figure 1 and product absorptions are listed in Table 1. After 1 h deposition, two medium-strength bands were found at 1109.8 and 1034.1 cm−1 and three comparatively weak bands at 712.6, 624.8 and 618.1 cm−1 tracked upper bands. These bands were sharpened on annealing to 8 K, enhanced 20% upon 300 nm < λ < 780 nm, and increased 50% upon broad-band photolysis, but decreased slightly on further annealing to 12 K. With the alternation of argon matrix, these bands shifted to 1067.9 (site at 1065.5), 1022.6 (site at 1016.8), 718.8 (site at 715.9), 628.2 and 631.6 cm−1, respectively, exhibiting the analogous annealing and photolysis behavior to that of neon matrix. Isotopic substituted samples (34SO2 and S18O2) have been applied to react with Be atom, and isotopic shift bands are shown in Figure 2 and absorptions listed in the same table. Similar experiments have been done in pure krypton and xenon matrices, respectively (Figure 3), and the counterpart bands are listed in Table 2. Experiments were also done using mixtures of a lighter neon gas host doped with heavier noble gas guest atoms. In the experiment of laser-evaporated Be atoms with



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0.2% SO2 in neon, when doped with 0.25% xenon gas, a sequence of new absorptions were found at 1059.4, 1018.8, 719.5, 634.7 and 631.8 cm−1 (Figure 4), besides the previously appearing bands in pure neon matrix (1109.8, 1034.1, 712.6, 624.8 and 618.1 cm−1). Notice the new absorptions were sharply different from those in pure xenon matrix (1028.0, 998.8, 715.4, 641.7, 630.7 cm−1, Table 2). This new set of bands enhanced over two-folds upon broad-band photolysis while the other group increased about one-fold. Here we warmed the solid samples to 12 K to allow successive substitution of heavier Ng for lighter Ng in the first coordination sphere. In the Be−O stretching vibration region, interestingly, 1109.8 and 1034.1 cm−1 bands decreased whereas newly-observed 1059.4 and 1018.8 cm−1 bands increased slightly, suggesting the 1059.4 and 1018.8 cm−1 bands increased at the expense of the 1109.8 and 1034.1 cm−1 band. Similar experiments were done with 0.2% Ar doped in neon and 0.125% krypton doped in neon, and the spectra are shown in Figure 5 and frequencies are listed in Table 1. Identification of BeSO2 in Ng (Ng = Ne, Ar, Kr, Xe) Matrix As shown in Figure 1, the reaction of laser-ablated Be atoms with SO2 in excess neon gave five bands at 1109.8, 1034.1, 712.6, 624.8, and 618.1 cm−1, which tracked together in whole experimental process. The experiment was also done with

34

SO2

substitution and these bands shifted to 1109.5, 1033.7, 702.0, 624.3, and 612.3 cm-1, respectively. Notice 712.6 and 618.1 cm-1 bands show relatively large sulfur-34 isotopic shifts while 1109.8, 1034.1 and 624.8 cm-1 bands display very little shifts. With oxygen-18 substitution these bands appeared at 1090.1, 1013.9, 693.8, 598.3,


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and 595.9 cm-1, giving

16

O/18O isotopic ratio around 1.020 for 1109.8, 1034.1 and

624.8 cm-1 bands (Figure 2), which are identical for Be-O stretching mode for Be(η2-O2)Be molecules,14 and 16O/18O isotopic ratio around 1.040 for 712.6 and 618.1 cm-1, which are typical ratio for S-O stretching mode.25 The experiments of SO2/S16,18O2/S18O2 mixture gave triplet oxygen isotopic splitting pattern for all five bands (Figure 2), suggesting the existence of two equivalent oxygen atoms. These bands are appropriate for cyclic Be(η2-O2S) molecule. When we switched the matrix to argon the upper Be-O stretching modes showed red-shifts to 1067.9 and 1022.6 cm-1 while lower S-O stretching and O-Be-O bending modes exhibited blue-shifts to 718.8, 631.6, and 628.2 cm-1, respectively. Similar sulfur-34 and oxygen-18 isotopic substitution experiments were performed and the observed values are listed in Table 1. Again the experiments of SO2/S16,18O2/S18O2 mixture gave triplet oxygen isotopic splitting pattern for all five bands. Experiments have been done in solid krypton and xenon, respectively. As shown in Figure 3 upper two modes for Be-O stretching frequencies shifted red to 1052.4 and 1013.6 cm-1 (in Kr) and 1028.0 and 998.8 cm-1 (in Xe); however, the lower frequencies for S-O stretching modes showed very little shifts compared to argon values as listed in Table 2. Notice from neon to xenon the antisymmetric Be-O stretching mode shows 81.8 cm-1 red-shift, indicating noble-gas atom interacts with Be atom strongly, which increases periodically.31 The assignment to cyclic Be(η2-O2S) molecule is confirmed by B3LYP frequency calculations. Firstly a free Be(η2-O2S) molecule is calculated and the Be-O



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antisymmetric and symmetric stretching, and bending modes are predicted at 1144.6, 1050.1 and 618.0 cm-1, respectively, while S-O stretching and bending modes are at 698.0, 581.1 and 360.7 cm-1. Two Be-O stretching modes are overestimated by 3.2% and 1.5% while other three modes are underestimated by 1% compared with neon matrix values. Notice the O-S-O bending mode is located below 400 cm-1, which is beyond our measurement region. Then one neon atom is attached to Be in Be(η2-O2S) molecule, and the six modes are calculated at 1128.9, 1045.8, 707.0, 619.8, 604.4 and 389.1 cm-1. Notice the calculated two Be-O stretching modes at 1128.9 and 1045.8 cm-1 are only slightly overestimated by around 1% and other modes are much closer to the observed neon values. In addition, the DFT calculated isotopic red-shifts give 32

S/34S isotopic ratios at 1.0157 and 1.0095, and

16

O/18O isotopic ratios at 1.0181,

1.0216 and 1.0445, respectively, in satisfactory concert with observed isotopic ratios (32S/34S: 1.0151, 1.0095; 16O/18O:1.0181, 1.0199 and 1.0443), as can be seen in Table 1. The frequency calculation was performed for XeBeSO2 and the results are listed in Table 2. At the B3LYP level, the Be−O antisymmetric and symmetric stretching frequencies for XeBeSO2 are predicted at 1076.8 and 1025.0 cm−1, which are much lower than calculated neon values, while the calculated S-O stretching modes are slightly higher. These calculated results match the observed xenon matrix values very well. Similarly, NgBeSO2 (Ng = Ar, Kr) are also confirmed by DFT calculations. Note the differences between the antisymmetric and symmetric stretching modes for NgBeSO2 are predicted at 83.1, 63.1, 58.2, and 51.8 cm−1, respectively. This


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corresponds very well to our observation data, 75.7, 45.3, 38.8, and 29.2 cm−1, in terms of variation tendency and rough difference values. Therefore, such assignment for NgBeSO2 (Ng = Ne, Ar, Kr, Xe) is reasonable based upon theoretical and experimental analysis. Further experiments have been done with doped heavier noble gas in solid neon, and results are shown in Figure 4. When doped by 0.25% xenon in neon matrix, 1059.4, 1018.8, 719.5, 634.7 and 631.8 cm−1 emerged as a new group on condensation, but increased significantly on annealing, in contrast to that of pure neon absorptions, apparently, suggesting an interesting conversion in such process. Similarly, new different bands were also found in 0.2% Ar/Ne and 0.125% Kr/Ne doping experiments, exhibiting marked frequency difference from that of pure neon matrix (shown in Figure 5 and Table 2). These significant frequency shifts related to diverse matrices imply that all the absorptions are not due to isolated BeSO2 but the coupling of noble gas atoms must be taken into account. One appropriate explication is that the BeSO2 species trapped in solid matrix should be viewed as NgBeSO2. Note that in solid neon five absorptions arising from NeBeSO2 keep the same frequencies when doped by heavier noble gas atoms, while five new absorptions produced in the heavier noble gas atom doping experiments are assigned to the NgBeSO2 complexes (Ng = Ar, Kr, Xe), respectively, as listed in Table 2. The lighter neon atom replaced by heavier Ng atom confirms the strong bonding between Ng and Be in NgBeSO2 complexes. Structure and Bonding for NgBeSO2 Donor-Acceptor Complexes Figure 6 shows the optimized structures for NgBeSO2 (Ng = Ne, Ar, Kr, Xe)



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molecules. As we can see, the Ng−Be distance gradually increases from Ne to Xe, in coherence with the periodic radius trend of noble-gas atoms. Notice the Be−O bond length increases from 1.467 Å to 1.480 Å at the B3LYP level while the O−Be−O angle shrinks varying from 108.3° to 106.0°. On the other hand, the S−O bond length decreases slightly in contrast to that of Be−O bond, ranging from 1.706 Å to 1.696 Å at the same level. However, no remarkable change happens for the O−S−O angle. Such bond length and bond angle periodic change, it turns out, is reflected by significant vibrational frequency shifts in the infrared spectra. Remarkable red shifts arising from the Be−O stretching in high-frequency region and blue shifts originated from the S−O stretching in low-frequency region are shown intuitively in Figure 3, in accordance with the calculation results (Table 2). We also performed natural population analysis (NPA) as shown in Table 3. The Be center carries a large positive charge, 1.19 |e|, which can impose a considerable polarizing power on the electron density of Ng center. Consequently, electron transfer of diverse degrees from Ng to the Be center accompanies with the polarization, suggesting an increase of natural charge of Ng, or q(Ng), as well as the corresponding decrease of q(Be) from neon to xenon. Partial-condensed electron cloud towards the Be center elongates the distance of Be−O bond and deforms the angle of O−Be−O. As a result, sharply different frequency shifts due to corresponding vibrational modes are evidently displayed in our matrix infrared spectra. Similar phenomenon has also been found in NgBeCO3,17 indicating Ng-Be bond essentially belongs to donor-acceptor interaction. Donor-acceptor complex structure facilitates the formation of Ng−Be interaction


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in which electron is donated from the Ng lone pairs into the vacant pz orbital of Be center. The dissociation energies of the NgBeSO2 splitting into donor part (Ng) and acceptor moiety (BeSO2) with BSSE correction are calculated at 0.9, 4.0, 4.7 and 6.0 kcal/mol for NeBeSO2, ArBeSO2, KrBeSO2, and XeBeSO2, respectively, at the CCSD(T) level. Figure 7 shows the B3LYP potential energy curves for Ng−BeSO2 as a function of the Ng−Be separation, where BeSO2 fragment was simultaneously optimized when the Ng−Be distance was lengthen. It is evident that the heavier the Ng atom, the larger the binding energy. This can be reflected from our doping experiments. As shown in Figure 5, when only 0.1~0.3% argon, krypton, or xenon is added to the neon matrix, respectively, the ArBeSO2, KrBeSO2, and XeBeSO2 complexes can be observed as a partial substitution of NeBeSO2. It may also be noted that the dissociation energy gradually increases when moving from Ne to Xe, following the periodic trend. This is due to the fact that with an increase in the size of the Ng atoms down the group, the polarizability of Ng atoms also increases, which can be mirrored from dipole moment values. As is shown in Table 3, the BeSO2 molecule has a dipole moment oriented from the negatively charged SO2 fragment to the positively charged Be center with a calculated value 3.11 D. The corresponding dipole moment values for Ne−, Ar−, Kr−, and Xe−containing species are 4.11, 5.24, 5.63, 6.14 D, respectively, increasing in the order Ne < Ar < Kr < Xe. Clearly the enhanced Ng-Be bond is largely from the combination of electron-donation and ion-induced dipole interactions.32 In Table 3, the WBI values show the degree of covalency in the Ng−Be bond. A



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very small value of WBI is obtained for Ne−Be bond, signifying a closed-shell type of interaction. However, it improves when moving from Ar to Xe gradually, approaching half a bond order, which demonstrates an increase in covalent character of Ng−Be along the periodic trend. To obtain further insight into the electronic structure of the NgBeSO2 complexes, we employed a facile descriptor based on dynamic-energy density, localized orbital locator (LOL).33,34 As illustrated in Figure 8, covalent regions enjoy high LOL value, and the electron depletion regions between valence shell and inner shell are shown by the blue circles around nuclei. Lone pairs of each atom can be seen in crescent-like regions. Here we can see the Ne atom stays the most complete valence sphere in NeBeSO2 complex though slight deviation towards the Be center takes place in the localization region. It is noted that the noble-gas atoms exhibit an increasing deformation trend due to a partial electron transfer from Ng to Be, namely, Ne < Ar < Kr < Xe. The LOL profile, to some extent, suggests an increase in covalent character of the Ng−Be bond along the periodic order.

Conclusions We have prepared and characterized a set of novel noble-gas complexes NgBeSO2 (Ng = Ne, Ar, Kr, Xe) by low-temperature matrix isolation infrared spectroscopy. Doped with heavier noble gas, the guest (Ar, Kr, Xe) atom can substitute neon to form more stable complex. Theoretical calculations reasonably supports these novel Ng-Be donor-acceptor complexes. The dissociation energies are calculated at 0.9, 4.0, 4.7, and 6.0 kcal/mol for NeBeSO2, ArBeSO2, KrBeSO2, and XeBeSO2, respectively, at the CCSD(T) level. Natural population analysis


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demonstrates that the Ng−Be bonds in NgBeSO2 could be formed by the combination of electron-donation and ion-induced dipole interactions. The WBI values of Ng-Be bonds and LOL profile indicate that the Ng-Be bond exhibits a gradual increase in covalent character along Ne to Xe. In summary, the strong interaction between Ng and Be in NgBeSO2 compounds sheds light on further investigations for binding noble gas atoms in donor-acceptor complexes.

Acknowledgment This work was supported by the National Natural Science Foundation of China (No.21373152)

and

the

Ministry

of

Science

and

Technology

of

China

(No.2012YQ220113-7).

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Table 1. Experimental and Calculated Infrared Absorptions (cm-1) of Isotopic-Labled NeBeSO2 in Solid Neon and ArBeSO2 in Solid Argon (All Values in cm-1). Ne Assignment Be-O asym str Be-O sym str S-O sym str O-Be-O bend S-O asym str

S16O2 1109.8 1034.1 712.6 624.8 618.1

Obs. S16O2+S16,18O2+S18O2 1109.8, 1090.1 1034.1, 1022.6, 1013.9 712.6, 703.9, 693.8 624.8, 617.6, 598.3 618.1, 600.2, 595.9

S16O2 1067.9 (1065.5)a 1022.6 (1016.8) 718.8 (715.9) 628.2 631.6

Obs. S16O2+S16,18O2+S18O2 1067.9, 1060.2, 1048.8 (1065.5, 1057.7, 1046.3) 1034.1, 1022.6, 1013.9 (1016.8, 1004.3, 998.0) 718.8, 708.9, 699.1 (715.9, 706.8, 696.2) 628.2, 609.3, 601.9 631.6, 611.4, 605.5

34

SO2 1109.5 1033.7 702.0 624.3 612.3

S16O2 1128.9(116) 1045.8(205) 707.0(66) 619.8(80) 604.4(69)

Calc. S18O2 1108.8(110) 1023.7(207) 688.4(57) 593.4(74) 582.0(63)

S16O2 1098.8(101)

Calc. S18O2 1079.0(96)

1035.6(286)

1014.5(290)

712.5(81)

692.8(71)

702.0(83)

624.7(89) 619.6(65)

598.4(83) 596.6(60)

623.9(85) 613.9(65)

34

SO2 1128.7(115) 1045.4(207) 696.1(67) 619.3(76) 598.7(69)

Ar Be-O asym str Be-O sym str S-O sym str O-Be-O bend S-O asym str a

34

SO2 1067.8 (1065.2) 1022.1 (1016.3) 708.7 (705.8) 627.6 629.1

Absorption sites in parentheses


34

SO2 1098.5(101) 1035.3(298)


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Table 2. Observed and Calculated Fundamental Frequencies in NgBeSO2 (Ng = Ne, Ar, Kr, Xe) b and BeSO2. Species

NeBeSO2

Calculated 1128.9(116) 1045.8(205) 707.0(66) 619.8(80) 604.4(69)

Ne 1109.8 1034.1 712.6 624.8 618.1

Observed (in matrices) Ar Kr Xe

Be-O as-str Be-O s-str S-O s-str O-Be-O bend S-O as-str

389.1(69)

ArBeSO2

O-S-O bend

1098.8(101)

1082.1

1035.7(286)

1029.7 a

712.5(81) 624.8(89) 619.7(65)

720.1 717.9 634.7 631.8

1067.9 1065.5a 1022.6 1016.8a 718.8 715.9a 628.2 631.6

Be-O as-str Be-O s-str S-O s-str O-Be-O bend S-O as-str

397.3(57) 1087.7(95) 1029.5(315) KrBeSO2

XeBeSO2

BeSO2

Description

O-S-O bend 1072.6 1024.4 1021.7a

711.6(87)

718.4

624.4(95)

634.7

620.9(63)

631.3

398.1(52) 1076.8(87) 1025.0(351)

1059.4 1018.8

714.0(97)

719.5

626.9(60) 625.6(100)

631.8 634.7

1052.4 1013.6 1012.2a 720.2a 717.7 638.9 634.3a 631.8

Be-O as-str Be-O s-str S-O s-str O-Be-O bend S-O as-str 1028.0 1000.2a 998.8 717.7a 715.4 641.7 630.7

O-S-O bend Be-O as-str Be-O s-str S-O s-str S-O as-str O-Be-O bend

396.3(45)

O-S-O bend

1144.6(118) 1050.1(124) 698.0(51) 618.0(71) 581.1(68) 360.7(70)

Be-O as-str Be-O s-str S-O s-str O-Be-O bend S-O a-str O-S-O bend

a

Site. bFrequencies and intensities (in parentheses) are in cm−1 and km·mol−1.


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Table 3. Natural Charges at Be and Ng Centers q(au), Wiberg Bond Indices of Be−Ng Bonds (WBI), Dipole Moments µ(D), Be−Ng Bond Distances r(Be−Ng) (Å) and Dissociation Energies ∆E (kcal·mol−1) of NgBeSO2 (Ng = Ne, Ar, Kr, Xe) Compounds. Species

Dissociation energy/∆E

BeSO2

a

Natural charge q(Be)

q(Ng)

1.39/1.19

Dipole

WBI

moment/µ

(Be-Ng)

r(Be-Ng)

3.59/3.11

NeBeSO2

0.9/1.3

1.31/1.19

0.06/0.08

4.37/4.11

0.12/0.14

1.939

ArBeSO2

4.0/5.2

1.21/1.08

0.16/0.17

5.54/5.24

0.28/0.31

2.210

KrBeSO2

4.7/6.3

1.19/1.06

0.18/0.20

5.92/5.63

0.33/0.35

2.360

XeBeSO2

6.0/7.3

1.16/0.98

0.22/0.21

6.43/6.14

0.39/0.38

2.548

Calculated with CCSD(T) and B3LYP (italic values) methods and the 6-311++G(3df,3pd) basis set

for Be, O, S, Ne, Ar, and Kr, and SDD pseudopotential for Xe.

Figure 1. Infrared spectra in the 1120-1010 cm−1 and 740-590 cm−1 regions from co-deposition of laser-evaporated Be atoms with 0.2% SO2 in solid neon matrix. (a) 1 h sample deposition at 4 K, (b) 8 K annealing, (c) 15 min 300 nm < λ < 780 nm photolysis, (d)15 min broad-band photolysis, and (e) 12 K annealing.



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Figure 2. Infrared spectra in the 1120-920 cm−1 and 740-590 cm−1 regions from co-deposition of laser-evaporated Be atoms with SO2 in solid neon matrix. (1) Be + 0.2% SO2: (a) 8 K annealing after deposition at 4 K, (b) 15 min 300 nm < λ < 780 nm photolysis; (2) Be + 0.2% 34SO2: (c) 8 K annealing after deposition at 4 K, (d) 15 min 300 nm < λ < 780 nm photolysis; (3) Be + 0.6% (S16O2 + S16,18O2 + S18O2): (e) 8 K annealing after deposition at 4 K, (f) 15 min 300 nm < λ < 780 nm photolysis.


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Figure 3. Infrared spectra in the 1120-930 cm−1 and 730-600 cm−1 regions from reactions of laser-evaporated Be atoms with 0.2% SO2 in pure matrices (Spectra were taken after 15 min of broad-band photolysis). (a) Ne, (b) Ar, (c) Kr, (d) Xe.



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Figure 4. Infrared spectra in the 1130-1010 cm−1 and 720-600 cm−1 regions from co-deposition of laser-evaporated Be atoms with 0.2% SO2 in solid neon doped with 0.25% xenon gas. (a) 1 h sample deposition at 4 K, (b) 8 K annealing, (c) 15 min broad-band photolysis, (d) 12 K annealing, and (e) 15 min broad-band photolysis.


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Figure 5. Infrared spectra in the 1130-950 cm−1 region selected from reactions of laser-evaporated Be atoms with 0.2% SO2 in solid neon doped with heavier noble gases (Spectra were taken after 15 min of broad-band photolysis). (a) Ne, (b) 0.2% Ar/Ne, (c) 0.125% Kr/Ne, (d) 0.25% Xe/Ne.



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Figure 6. Optimized structures for NgBeSO2 (Ng = Ne, Ar, Kr, Xe) molecules based on B3LYP/6-311++g(3df,3pd), BPW91/6-311++g(3df,3pd) (in bold), and SDD for XeBeSO2 (bond lengths in angstroms and bond angles in degrees).


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Figure 7. Potential energy curves for Ng-BeSO2 (Ng=Ne, Ar, Kr, Xe) at the B3LYP level.



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Figure 8. Color-filled maps of localized orbital locator (LOL) of NgBeSO2 (Ng = Ne, Ar, Kr, Xe) in the plane of Be-Ng-O at B3LYP/6-311++g(3df,3pd) level and SDD used for Xe. (Covalent regions enjoy high LOL value, and the electron depletion regions between valence shell and inner shell are shown by the blue circles around nuclei. Lone pairs of each atom can be seen in crescent-like regions).


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Infrared Spectra of Novel NgBeSO2 Complexes (Ng = Ne, Ar, Kr, Xe

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