Infrared Spectra of the SO2F2- Anion in Solid Argon and Neon - The

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Infrared Spectra of the SOF Anion in Solid Argon and Neon Rui Wei, Xiuting Chen, and Yu Gong J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.8b07756 • Publication Date (Web): 05 Sep 2018 Downloaded from http://pubs.acs.org on September 5, 2018

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The Journal of Physical Chemistry

Infrared Spectra of the SO2F2- Anion in Solid Argon and Neon Rui Wei,a,b Xiuting Chen,a,b Yu Gong*,a a

Department of Radiochemistry, Shanghai Institute of Applied Physics, Chinese

Academy of Sciences, Shanghai 201800, China b

University of Chinese Academy of Sciences, Beijing 100049, China

Abstract Sulfonyl fluoride anion (SO2F2-) was produced during co-deposition of laser ablated metal atoms, ions and electrons with SO2F2 in argon and neon matrixes at 4 K. The structure of SO2F2- was determined by infrared spectroscopy and density functional theory calculations. On the basis of the experiments using

34

SO2F2 and

S18O2F2 samples, the three absorptions at 1284.9, 1109.3, 567.0 cm-1 in argon and 1289.0, 1116.2, 576.8 cm-1 in neon were assigned to the antisymmetric, symmetric O-S-O stretching and SO2 wagging modes of SO2F2-, which was further supported by the frequency and isotopic frequency ratio calculations. The SO2F2- anion possesses a 2

A1 ground state with non-planar C2v symmetry. Compared with the neutral SO2F2

molecule, dramatic increase in the S-F bond length (0.295 Å) and F-S-F bond angle (41.0 degree) was found for the anion, which results from the S-F antibonding character of the singly occupied molecular orbital. The SO2F2- anion was formed via electron capture by SO2F2 in the gas phase before being deposited into cryogenic matrix. The matrix environment stabilized this anion, but it was destroyed by uv-vis irradiation and presumably converted to the neutral SO2F2 molecule. Email: [email protected] 1

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Introduction Sulfur oxyfluorides are observed as the decomposition and hydrolysis products of SF6 upon reactions with O2 and H2O in the plasma environments where SF6 is used as plasma etching gas and electron scavenger.1-4 In addition to the neutral sulfur oxyfluorides such as SOF2, SOF4 and SO2F2, anionic species containing sulfur, oxygen and fluorine are also present in the plasma. The reactivities of these anions have been the focus of a series of investigations which help understand their formation pathways as well as thermochemical properties in the gas phase.5-8 Since the reactivity is correlated with the geometry of the reactant, it is also necessary to identify the molecular structure of these anions. For the SO2Fx- family, SO2F- is the anion that has been the subject of a number of spectroscopic, crystallographic, ab initio and density functional theory (DFT) studies, and it possesses a pyramidal geometry with the S-F bond length being 0.3 Å longer than the S-O bond length.7-10 SO2F3- was observed as the reaction product of SO2F2 and fluorine anions,6 and its trigonal-bipyramidal geometry was confirmed by matrix isolation infrared spectroscopy and theoretical calculations.8,11,12 Our knowledge on the SO2F2- anion is mainly from the computational studies8 while experimental information regarding its structure and bonding is still unavailable presumably due to the difficulties in the formation and stabilization of molecular anions.13 Laser ablation of metal target is an effective method for the generation of charged species such as molecular anions which can be subsequently trapped and stabilized in the inert cryogenic matrix.14 A number of molecular anions have been prepared via the 2


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reactions of metal atoms and neutral molecules and characterized by infrared spectroscopy.15-18 Recent experimental studies on the reactions of laser ablated metal atoms and SO2 revealed the formation of SO2- in the matrix,19,20 the spectral features of which are the same as the SO2- anion prepared by different methods.21,22 The stabilization of SO2- in the matrix suggests that it should be possible to trap the SO2F2anion by laser ablation since the electron affinity of SO2F2 is slightly higher than that of SO2.23 In this paper, we present a combined matrix isolation infrared spectroscopic and theoretical study on the SO2F2- anion which was produced via the co-deposition of SO2F2 with laser ablated metal atoms, ions and electrons in argon and neon matrixes. The assignment for the SO2F2- anion was supported by the experiments using isotopically labeled

34

SO2F2 and S18O2F2 samples as well as computed

vibrational frequencies and isotopic frequency ratios. Experimental and Theoretical Methods Details on the experimental apparatus employed have been described previously.24,25 In this experiment, the electrons were generated by laser ablation of various rotating metal targets (La, Zr, Hf, Nb, Ta, Cd and Al) using a pulsed Nd:YAG laser fundamental (1064 nm, 10 Hz repetition rate with 6 ns pulse width). Laser-ablated metal atoms, ions and electrons were co-deposited with approximately 3 mmol argon or 1.5 mmol neon containing 0.5% SO2F2 (99.9% Maotoo Gas, China) onto a cesium iodide window at 4 K for 60 or 30 minutes respectively. 18O enriched S18O2F2 sample (containing approximately 78%

18

O) was synthesized and purified

according to the procedures reported by Fristrom.26 Briefly, S18O2F2 was prepared 3



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through the reaction of AgF2 (99.9%, Sigma-Aldrich) and S18O2, the latter of which was synthesized by reacting

18

O2 (99.7%, Taiyo Nippon Sanso, Japan) with sulfur

powder (99.9%, Sinopharm Chemical Reagent, China) at 300 °C. The 34

34

S enriched

SO2F2 sample was prepared similarly, and 34SO2 was prepared through the reaction

of

34

S powder (99.3%, ISOFLEX, USA) and O2 (99.999%, Xiangkun Special Gas,

China).

The

S18O2F2

and

34

SO2F2

samples

were

subjected

to

several

freeze-pump-thaw cycles using liquid nitrogen before use. The infrared spectra were recorded on a Bruker Vertex 70 V spectrometer at 0.5 cm-1 resolution. KBr beam splitter and DLaTGS detector were used in the mid-IR region (4000-400 cm-1). Matrix samples were annealed at different temperatures and cooled back to 4 K for spectral acquisition. Selected samples were subjected to λ > 220 nm irradiation by a high-pressure mercury arc lamp with the outer globe removed. DFT calculations were performed using the Gaussian 09 package.27 The hybrid B3LYP density functional and 6-311+G(3df) basis set were employed for sulfur, oxygen and fluorine.28-31 Molecular geometrical parameters were fully optimized, and harmonic vibrational frequencies were obtained analytically. The two-dimensional LOL (localized orbital locator) maps of SO2F2- and SO2F2 were plotted using Multiwfn.32 The wave functions for LOL analysis were generated by Gaussian 09 at the B3LYP/6-311+G(3df) level. Results and Discussion Reactions of a series of laser ablated metal atoms, ions and electrons with 0.5% SO2F2 in excess argon were studied in order to identify the metal independent product. 4


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As shown in Figure S1, the infrared spectra are dominated by the intense SO2F2 precursor absorptions. Very weak bands at 1351.0 and 1149.7 cm-1 arise from SO2 which was only produced during the co-deposition of laser-ablated metal atoms and SO2F2. In addition to the metal dependent reaction products, a group of new absorptions at 1284.9, 1109.3 and 567.0 cm-1 were observed regardless of the metal used for laser ablation, and their relative intensities remained unchanged although the yield varied depending on the metal. To investigate the behaviors of this new product upon irradiation and sample annealing, a series of infrared spectra from the reactions of Ta and SO2F2/Ar mixtures were obtained and shown in Figure 1. The metal independent product absorptions were observed at 1284.9, 1109.3 and 570.0 cm-1 upon sample deposition. These bands decreased when the sample was annealed to 25K, during which the 570.0 cm-1 band split into two matrix site absorptions at 574.0 and 567.0 cm-1 (Figure 1, trace b). Irradiation using mercury arc light (λ > 220 nm) almost destroyed all the bands, and their intensities were not recovered during subsequent sample annealing to 30 K (Figure 1, trace d). The behaviors of these new bands upon irradiation and annealing are similar to those of the molecular anions previously identified in the matrix,33-36 suggesting the 1284.9, 1109.3 and 567.0 cm-1 absorptions should arise from an anionic species that is correlated with SO2F2. To help with product identification, experiments with S18O2F2 and 34SO2F2 samples were carried out under similar experimental conditions. Each band of the new product exhibits certain 18O and 34S isotopic shifts (Figure 2), the extent of which depends on the nature of the vibrational mode. The infrared spectrum of Ta and S18O2F2 reaction 5



products is complicated by the presence of 30% SO18OF2, and the product bands arising from both S18O2F2 and SO18OF2 are labeled in Figure 2 (trace a). The observed vibrational frequencies in all the experiments are listed in Table 1. Since it is well-known that the charged species are better stabilized in neon matrix,37-40 the reactions of SO2F2 and several metals in excess neon were also investigated (Figure S2). The new metal independent absorptions were observed at 1289.0, 1116.2 and 576.8 cm-1 in all cases, but the yield of the product depends on the metal as observed in argon matrix. These three sharp peaks slightly decreased when the sample was annealed to 6 K, and they lost 2/3 of the intensities upon λ > 220 nm irradiation (Figure 3). No change was observed when the sample was further annealed to 10 K. It should be noted that the neon to argon matrix shifts for the new product bands are less than 10 cm-1, suggesting the interactions between the new product anion and argon matrix is negligible.39,40 As shown in Figure 4, the new absorptions at 1289.0, 1116.2 and 576.8 cm-1 exhibit 34

18

O and

34

S isotopic shifts when S18O2F2 and

SO2F2 were used as the reactants, which is similar to the results obtained in argon

matrix. All of the new absorptions observed in neon matrix are listed in Table 1 as well. As shown in Figure 1, the 1284.9, 1109.3 and 567.0 cm-1 absorptions observed in argon matrix have identical behaviors during sample annealing and irradiation, suggesting that they arise from different vibrational modes of the same molecule. The 1284.9 and 1109.3 cm-1 bands shifted to 1245.3 and 1065.0 cm-1 upon 18O substitution with

16

O/18O isotopic frequency ratios of 1.0318 and 1.0416. Experiment using 6


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34

SO2F2 sample gave two bands at 1267.9 and 1098.8 cm-1 with

32

S/34S isotopic

frequency ratios of 1.0134 and 1.0096. Note that the isotopic ratios for the 1284.9 and 1109.3 cm-1 bands are almost the same as those of the 1494.7 (16O/18O:1.0302; 32

S/34S:1.0138) and 1264.0 cm-1 (16O/18O:1.0389;

32

S/34S:1.0081) bands of the SO2F2

precursor, suggesting both new product bands should arise from the same vibrational modes as those of SO2F2. Accordingly, we assign the 1284.9 and 1109.3 cm-1 bands to the antisymmetric and symmetric O-S-O stretching modes of the new product. The involvement of single SO2 moiety is also confirmed by the intermediate absorption at 1086.7 cm-1 which is the symmetric O-S-18O stretching mode of the product isotopomer due to the existence of 30% SO18OF2 in the S18O2F2 sample (Figure 2, trace a). The third band of the new product was observed at 567.0 cm-1 which exhibits 10.6 and 10.1 cm-1 red shifts when S18O2F2 and

34

SO2F2 were used as the reactants.

The position and isotopic frequency ratios of this band indicate it should be due to a SO2 bending or wagging mode. Since the 1284.9, 1109.3 and 567.0 cm-1 absorptions behave like a typical matrix isolated anion throughout the experiment, we assign these three new bands to the different vibrational modes of SO2Fx-. Previous studies on the reactions of cesium fluoride with SO2 and sulfur oxyfluorides revealed the formation of SO2F- and SO2F3- as ion pairs with Cs+ in argon matrix,12 and their vibrational frequencies should be close to those of isolated anions as in the case of SO2-.19-21 The three new absorptions at 1284.9, 1109.3 and 567.0 cm-1 do not match those reported for SO2F- (1178, 1100, 598 and 471 cm-1) and SO2F3- (1408, 1130, 925, 810, 649 cm-1), and these anions were not observed in our experiment. Therefore, it is 7



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reasonable to assign the new product to the SO2F2- anion (x=2, SO2Fx-) which possesses the same stoichiometry as the SO2F2 precursor. The 1289.0, 1116.2 and 576.8 cm-1 bands observed in neon matrix possess similar

18

O and

34

S shifts and

isotopic frequency ratios (Figures 3 and 4), which provide further confirmation on the formation and stabilization of a new SO2F2- anion in cryogenic matrix. To further determine the structure of the new product and validate our experimental assignment, DFT calculations at the B3LYP level were carried out. Geometry optimization on the SO2F2- anion resulted in a 2A1 ground state with non-planar C2v symmetry. Frequency calculations gave four infrared active absorptions above 400 cm-1: two absorptions at 1284.8 and 1120.9 cm-1 due to antisymmetric and symmetric O-S-O stretching vibrational modes and two absorptions at 553.5 and 531.7 cm-1 due to SO2 wagging and bending modes. The first three bands should correlate to the 1284.9, 1109.3 and 567.0 cm-1 absorptions observed in argon and 1289.0, 1116.2 and 576.8 cm-1 absorptions in neon. The computed absorptions at 1284.8 and 553.5 cm-1 are the two most intense bands of the product while the intensity of the 1120.9 cm-1 band is ~1/3 of that of the 1284.8 cm-1 band. The relative intensities of these three absorptions agree well with those observed in the argon (3.4:1:3) and neon (3.4:1:3) matrixes. For the fourth band computed at 531.7 cm-1 whose intensity is 1/2 of the 1120.9 cm-1 band, its experimental counterpart is most likely covered by the intense SO2F2 band around 550 cm-1. The assignment of SO2F2- is also supported by the comparison between calculated and experimental isotopic frequency ratios. For the antisymmetric and 8


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symmetric O-S-O stretches, the computed

16

O/18O ratios are 1.0322 and 1.0457, in

good agreement with the experimental values of 1.0318 and 1.0416 obtained in argon matrix and 1.0316 and 1.0432 obtained in neon matrix. For the

32

S/34S ratios, the

computed values of 1.0134 and 1.0068 are consistent with the observed ratios in both argon (1.0134, 1.0096) and neon (1.0131, 1.0080) matrixes. Similar agreement can be found for the SO2 wagging mode as listed in Table 2. For comparison, geometry optimization and frequency calculation were also performed on the neutral SO2F2 molecule. Agreement between computed and experimental isotopic frequency ratios were found as for the SO2F2- anion. It should be noted that the vibrational frequencies for both SO2F2- and SO2F2 observed in the experiments were slightly underestimated at the B3LYP level if the gas phase-matrix frequency shift is considered.38,40 Such deviations were also found in other molecular systems containing sulfur and oxygen when B3LYP was employed.41-43 The optimized geometries of both SO2F2- and SO2F2 are shown in Figure 5. It is obvious that the S-F bond is significantly elongated from 1.555 Å in the neutral to 1.850 Å in the anion which is much longer than a typical S-F single bond (1.67 Å).44 In contrast, the S-O bond is elongated by only 0.040 Å when the additional electron is captured by SO2F2, indicating that the presence of the additional electron has much larger influence on the S-F bond than the S-O bond. The singly occupied molecular orbital (SOMO) of the SO2F2- anion (Figure 6) is composed of two S-F σ* orbitals with the two S-O bonds retaining the 4n nonbonding character of SO2.45 As a result, the S-F bond is significantly weakened compared with that in the neutral molecule. 9



Consistent with this notion, the F-S-F stretching vibrational frequencies of the anion (381.7 and 248.4 cm-1) are much lower than those of the neutral SO2F2 molecule (845.9 and 814.6 cm-1) (Tables S1 and S2). The change on S-F bond strength upon electron attachment is also demonstrated by the LOL maps of SO2F2 and SO2F2(Figure 7) where the electron kinetic energy density between sulfur and fluorine is significantly reduced in the anion compared with that in the neutral molecule. The dissociation energies for SO2F2- to ground state SO2F/F- and SO2F-/F were computed to be 56.2 and 45.9 kcal/mol. These values are only half of that for the dissociation of neutral SO2F2 molecule to SO2F and F (96.4 kcal/mol), which is in line with the weaker S-F bond in the anion. Spin density calculation shows that the additional electron is mainly distributed on the sulfur (0.53 e) and fluorine (0.16 e) atoms, which causes a large increase of the F-S-F bond angle from 95.3 to 136.3 degree due to electrostatic repulsion. Dramatic structural change upon electron attachment was identified in the SF2/SF2- system as well46 which contrasts the case of SO2/SO2- where slight difference in bond length and angle were predicted.47 The SO2F2- anion was observed right after sample deposition, and the intensities of its infrared absorptions did not increase when the sample was annealed (Figures 1 and 3), suggesting this anion should be formed via electron capture by neutral SO2F2 molecule in the gas phase before being deposited onto the CsI window. It is known that the plume produced upon laser ablation of metal target contains electrons which could serve as an electron source for the formation of anions.14 The newly formed anions are then trapped in cryogenic matrix where the excess energy released upon 10


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their formation can be rapidly removed by the surrounding argon or neon atoms. The SO2F2- anion is photo-sensitive, and the intensities of the SO2F2- bands were significantly reduced upon λ > 220 nm irradiation. On the basis of our B3LYP calculations, the electron affinity for the SO2F2 molecule is 1.71 eV which is 0.48 eV higher than the values (~1.23 eV) obtained using the G2 and G3 procedures.8,23 The photon energy provided by λ > 220 nm irradiation is high enough for the detachment of the additional electron in the SO2F2- anion. Since no other metal independent absorption was produced upon uv-vis irradiation, it is most likely that neutral SO2F2 is the photo-detachment product. Conclusions We have provided a combined matrix isolation infrared spectroscopic and theoretical study on the structure and bonding of the SO2F2- anion. This anion was prepared via electron capture by neutral SO2F2 molecule during co-deposition in excess argon or neon at 4 K. The electrons as well as metal atoms and ions were generated by laser ablation of various metal targets. Identification of the SO2F2- anion was made on the basis of the experiments using

34

SO2F2 and S18O2F2 samples. The

three absorptions at 1284.9, 1109.3, 567.0 cm-1 in argon were assigned to the antisymmetric, symmetric O-S-O stretching and SO2 wagging modes of SO2F2-, and their behaviors are similar to other molecular anions that have been identified in cryogenic matrix. The neon counterparts were observed at 1289.0, 1116.2, 576.8 cm-1, indicating that the matrix effect on the anion is negligible. Calculations at the B3LYP level reproduced the experimental vibrational frequencies and isotopic frequency 11



ratios, which further supports the identification of the SO2F2- anion. Geometry optimization on the SO2F2- anion gave a non-planar C2v structure with 2A1 ground state. The unpaired electron is located in an orbital which is mainly S-F σ* antibonding in character. As a result, the S-F bond length and F-S-F bond angle were dramatically increased compared with the neutral SO2F2 molecule. Instead, slight geometric changes were observed for the SO2 moiety upon electron attachment. The SO2F2- anion was stabilized by the surrounding cryogenic matrix atoms, which allows for the examination of its behavior towards uv-vis irradiation. The intensities of the anion absorptions decreased when the sample was subjected to λ > 220 nm irradiation, and it is most likely that the SO2F2- anion undergoes direct electron detachment to form the neutral SO2F2 molecule. Acknowledgments This work was supported by the Strategic Priority Research Program and Frontier Science Key Program of the Chinese Academy of Sciences (Grant Nos. XDA02030000 and QYZDYSSW-JSC016) and Young Thousand Talented Program.

Supporting Information. The Supporting Information is available free of charge on the ACS Publications website at DOI: Complete citation for Reference 27, infrared spectra from the reactions of SO2F2 with various laser ablated metal atoms, ions and electrons in excess argon and neon, all of the calculated frequencies and intensities of SO2F2- and SO2F2 (PDF) 12


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Figure 1. Infrared spectra from the reactions of SO2F2 with laser ablated tantalum atoms, ions and electrons in excess argon at 4 K. (a) after 60 min deposition; (b) after annealing to 25 K; (c) after λ > 220 nm irradiation; (d) after annealing to 30 K.

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Figure 2. Infrared spectra from the reactions of laser ablated tantalum atoms, ions and electrons with isotopically substituted SO2F2 samples in solid argon. Spectra were taken after annealing to 25 K. (a) 1.0% S18O2F2; (b) 0.5% 34SO2F2; (c) 0.5% SO2F2. a, a’ and b denote SO18OF2, SO2F2 and S18OF2 respectively. The asterisks denote the absorptions of SO2 and 34SO2.

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Figure 3. Infrared spectra from the reactions of SO2F2 with laser ablated lanthanum atoms, ions and electrons in excess neon at 4 K. (a) after deposition for 30 min; (b) after annealing to 6 K; (c) after λ > 220 irradiation; (d) after annealing to 10 K.

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Figure 4. Infrared spectra from the reactions of laser ablated lanthanum atoms, ions and electrons with isotopically substituted SO2F2 samples in solid neon. Spectra were taken after sample deposition for 30 min: (a) 1.0% S18O2F2; (b) 0.5% 34SO2F2; (c) 0.5% SO2F2. a, a’ and b denote SO18OF2, SO2F2 and S18OF2 respectively. The asterisk denotes the absorption of 34SO2.

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Figure 5. Optimized structures (bond lengths in angstroms and bond angles in degrees) of SO2F2- and SO2F2 at the B3LYP level of theory (sulfur: yellow; oxygen: red; fluorine: green).

Figure 6. SOMO of the SO2F2- anion.

Figure 7. LOL maps of SO2F2- (left) and SO2F2 in the SF2 plane. 23



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Table 1. Infrared Absorptions (cm−1) of SO2F2- and SO2F2 in Solid Argon and Neon

16

SO2F2-

SO2F2

a

18

O

Oa

34

S

mode

Ar

Ne

Ar

Ne

Ar

Ne

antisym O-S-O str.

1284.9

1289.0

1245.3

1249.5

1267.9

1272.3

sym O-S-O str.

1109.3

1116.2

1065.0

1070.0

1098.8

1107.3

SO2 wag. b

567.0

576.8

556.4

566.3

556.9

566.5

antisym O-S-O str.

1494.7

1501.9

1450.9

1458.0

1474.3

1481.2

sym O-S-O str.

1264.0

1269.2

1216.7

1221.9

1253.8

1258.9

antisym F-S-F str.

879.5

883.1

878.9

882.7

867.6

870.3

sym F-S-F str.

843.7

846.1

833.5

838.6

838.9

840.8

SO2 bend.

549.3

550.8

534.0

535.7

546.6

547.8

SF2 wag.

541.8

543.2

528.0

529.3

538.6

539.9

SO2 wag.

536.3

538.3

522.5

524.6

533.4

535.3

SO18OF2-: 1086.7, 562.8 cm-1(Ar); 1090.8, 571.3 cm-1(Ne).

absorptions observed at 574.0, 562.4 (18O) and 562.9 (34S) cm−1.

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b

broad matrix site

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Table 2. Comparisons between the Observed and Calculated (B3LYP) Vibrational Frequencies (cm-1) and Isotopic Frequency Ratios of SO2F2- and SO2F2

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freq

SO2F2-

S /34S

obsd a

calcd b

obsd

calcd

obsd

calcd

antisym O-S-O str. sym O-S-O str.

1284.9 1289.0 1109.3 1116.2 567.0 576.8

1284.8 (316) 1120.9 (90) 553.5 (288)

1.0318 1.0316 1.0416 1.0432 1.0191 1.0185

1.0322

1.0134 1.0131 1.0096 1.0080 1.0181 1.0182

1.0134

SO2 bend.

c

c

1.0395

c

1.0099

sym. F-S-F str.

c

c

1.0010

c

1.0005

antisym. F-S-F str. antisym O-S-O str. sym O-S-O str.

c

531.7 (49) 381.7 (28) 248.4 (140) 1499.4 (272) 1264.9 (157) 845.9 (239) 814.6 (126) 535.1 (23) 525.8 (29) 524.3 (18)

c

1.0135

c

1.0020

1.0302 1.0301 1.0389 1.0387 1.0007 1.0004 1.0122 1.0114 1.0287 1.0282 1.0261 1.0263 1.0264 1.0261

1.0308

1.0138 1.0132 1.0081 1.0082 1.0137 1.0147 1.0057 1.0063 1.0049 1.0055 1.0059 1.0061 1.0054 1.0056

1.0141

antisym F-S-F str. sym F-S-F str. SO2 bend. SF2 wag./ SO2 rock. SO2 wag./SF2 bend. a

32

mode

SO2 wag.

SO2F2

O /18O

1494.7 1501.9 1264.0 1269.2 879.5 883.1 843.7 846.1 549.3 550.8 541.8 543.2 536.3 538.3

1.0457 1.0186

1.0417 1.0008 1.0112 1.0284 1.0266 1.0262

neon matrix values in italic. b intensities in parenthesis (km/mol). c not observed.

25


1.0068 1.0184

1.0080 1.0151 1.0073 1.0051 1.0063 1.0052


TOC graphic

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Infrared Spectra of the SO2F2- Anion in Solid Argon and Neon - The

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