# First infrared spectra of the acrylonitrile-water hydrogen-bonded complexes isolated in solid neon

Benoît Tremblay, Pascale Soulard

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Benoît Tremblay, Pascale Soulard. First infrared spectra of the acrylonitrile-water hydrogen-bonded complexes isolated in solid neon. Conference on Chemistry and Physics at Low Temperatures 2022 (CPLT 2022), Jul 2022, Visegrad, Hungary. . hal-04019271

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# First infrared spectra of the acrylonitrile-water hydrogen-bonded complexes isolated in solid neon

B.Tremblay, P.Soulard

LABORATOIRE MONARIS, SORBONNE UNIVERSITÉ, PARIS, FRANCE

The nitrile molecules have been detected in a variety of interstellar environments and these molecules are interest in astrochemistry. The experimental study of the complexation of acrylonitrile molecule (AN) with water has been undertaken from a vibrational point of view in solid neon at 3 K from 80 to 6000 cm⁻¹ using Fourier transform infrared spectroscopy. With the help of theoretical results we have identified several vibrational transitions for AN-H₂O and AN-(H₂O)₂ complexes. For the AN-H₂O complex, in which the two submolecules interacting through hydrogen bonding, the infrared spectral changes (frequencies as well as intensities) indicate that the water plays the role of the proton donor. We highlight the presence of three isomers for the AN-H₂O complex and two isomers for the AN-(H₂O)₂ complex. Theoretical calculations at the MP2/AVTZ level have been performed to obtain their equilibrium geometries and vibrational spectra at the harmonic level and comparison with experimental data allows us to give structures of these complexes.

## Advantages of our matrix isolation apparatus coupled with FTIR

Absorption spectra collected on the same sample from the Far IR (intermolecular region) to Near IR (combinations and overtones region) from 80 to 6000 cm⁻¹ with a Bruker 120 FTIR spectrometer (InSb or MCT or bolometer detectors).

<figure><img src="image_1.png" /></figure>

## MP2/AVTZ calculations for energy, geometry and frequencies

### complexes structures with D₀(kcal/mol)

<figure><img src="image_2.png" /></figure>

AW1 is the isomer observed in gas phase by millimeter spectroscopy¹

## Infrared spectra in the acrylonitrile and water regions

<figure><img src="image_3.png" /><figcaption>vCN</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>H₂O v₁</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>H₂O v₂+ 254 cm⁻¹</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>H₂O v₂</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>Intermolecular region</figcaption></figure>

<figure><img src="image_8.png" /></figure>

## Comparison with other nitrile-water complexes

<table><thead><tr><th></th><th>HCN</th><th>C<sub>6</sub>H<sub>5</sub>(CH<sub>2</sub>)<sub>2</sub>CN</th><th>CH<sub>2</sub>=CHCN</th><th>C<sub>6</sub>H<sub>5</sub>CN</th><th>CH<sub>3</sub>CN</th></tr></thead><tbody><tr><th>H<sub>2</sub>O v<sub>1</sub> red-shift</th><td>44</td><td>57</td><td>67</td><td>66</td><td>99</td></tr><tr><th>D<sub>0</sub> (kcal/mol)</th><td>3.0</td><td>4.2</td><td>3.7</td><td>4.4</td><td>4.5</td></tr><tr><th></th><td>Solid Ar</td><td>gas</td><td>Solid Ne</td><td>Solid Ar</td><td>Solid Ar</td></tr><tr><th>v<sub>CN</sub> blue-shift</th><td>19</td><td>-</td><td>10</td><td>10</td><td>8</td></tr><tr><th>Ref</th><td>2,3</td><td>4</td><td>This work</td><td>5</td><td>6</td></tr></tbody></table>

## References

[1] C. Calabrese, A. Vigorito, A. Maris, S. Mariotti, P. Fathi, W. D. Geppert, S. Melandri, Millimeter Wave Spectrum of the Weakly Bound Complex CH₂=CHCN·H₂O: Structure, Dynamics, and Implications for Astronomical Search, J. Phys. Chem. A 119 (2015) 11674-11682

[2] A. Heikkila, M.Pettersson, J. Lundell, L. Khriachtchev, M. Räsänen, Matrix Isolation and ab Initio Studies of 1:1 Hydrogen-Bonded Complexes HCN-H₂O and HNC-H₂O Produced by Photolysis of Formaldoxime, J. Phys. Chem. A 103, (1999), 2945-2951.

[3] T. Malaspina, E. E. Fileti, J. M. Riveros, and S. Canuto, Ab Initio Study of the Isomeric Equilibrium of the HCN···H₂O and H₂O···HCN Hydrogen-Bonded Clusters, J. Phys. Chem. A 110, (2006), 10303-10308.

[4] P. A. Robertson, I. A. Lobo, D.J.D. Wilson, E. G. Robertson, Nitriles as directionally tolerant hydrogen bond acceptors: IR-UV ion depletion spectroscopy of benzenepropanenitrile and its hydrate clusters; Chem. Phys. Lett. 660 (2016) 221-227.

[5] R. Gopi, N. Ramanathan, K. Sundararajan, The structure of benzonitrile-water complex as unveiled by matrix isolation infrared spectroscopy: Is it linear or cyclic at low temperatures?; J. Mol. Struct.1219 (2020) 128636.

[6] R. Gopi, N. Ramanathan, K. Sundararajan, Acetonitrile-water hydrogen-bonded interaction: Matrix-isolation infrared and ab initio computation; J. Mol. Struct. 1094 (2015) 118-129.

## Comparison of frequencies (cm⁻¹) and shifts (Δv=v<sub>mono</sub> - v<sub>complex</sub>) for the 1:1 complex

<table><thead><tr><th rowspan="3"></th><th colspan="8">Calculated</th><th rowspan="3">Exp</th><th rowspan="3">Isomer</th></tr><tr><th colspan="2">AW1</th><th colspan="2">AW2</th><th colspan="2">AW3</th><th rowspan="2">v</th><th rowspan="2">Δ</th></tr><tr><th>ω</th><th>Δ</th><th>ω</th><th>Δ</th><th>ω</th><th>Δ</th></tr></thead><tbody><tr><td colspan="11"><strong>H<sub>2</sub>O</strong></td></tr><tr><td>v<sub>3</sub></td><td>3918</td><td>30</td><td>3925</td><td>23</td><td>3917</td><td>31</td><td>3740</td><td>20</td><td>AW2</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3736</td><td>24</td><td>AW2</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3731</td><td>29</td><td>AW1</td><td></td></tr><tr><td>v<sub>1</sub></td><td>3771</td><td>51</td><td>3791</td><td>31</td><td>3743</td><td>89</td><td>3599</td><td>67</td><td>AW3</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3621</td><td>43</td><td>AW1</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>3637</td><td>28</td><td>AW2</td><td></td></tr><tr><td>v<sub>2</sub></td><td>1632</td><td>-8</td><td>1629</td><td>-5</td><td>1652</td><td>-28</td><td>1601</td><td>-6</td><td>AW1 or 2</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1603</td><td>-8</td><td>AW1 or 2</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1618</td><td>-23</td><td>AW3</td><td></td></tr><tr><td colspan="11"><strong>Acrylonitrile</strong></td></tr><tr><td>v<sub>4</sub></td><td>2177</td><td>2</td><td>2176</td><td>3</td><td>2194</td><td>-15</td><td>2251</td><td>-10</td><td>AW3</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>2240</td><td>2</td><td>AW1 or 2</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>2238</td><td>4</td><td>AW1 or 2</td><td></td></tr><tr><td>v<sub>8</sub></td><td>1111</td><td>-5</td><td>1108</td><td>-2</td><td>1108</td><td>-2</td><td>1095</td><td>-2</td><td>AW2 or 3</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1099</td><td>-6</td><td>AW1</td><td></td></tr><tr><td>v<sub>13</sub></td><td>990</td><td>-17</td><td>975</td><td>-2</td><td>980</td><td>-7</td><td>960</td><td>-6</td><td>AW3</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>969</td><td>-15</td><td>AW1</td><td></td></tr><tr><td>v<sub>14</sub></td><td>574</td><td>-16</td><td>561</td><td>-3</td><td>563</td><td>-5</td><td>691</td><td>-6</td><td>AW3</td><td></td></tr><tr><td>v<sub>11</sub></td><td>235</td><td>-9</td><td>226</td><td>0</td><td>228</td><td>-2</td><td>231</td><td>2</td><td>AW2</td><td></td></tr><tr><td>Inter</td><td>367</td><td></td><td>303</td><td></td><td>514</td><td></td><td>453</td><td></td><td>AW3</td><td></td></tr><tr><td></td><td>291</td><td></td><td>262</td><td></td><td>302</td><td></td><td>254</td><td></td><td>AW1-2-3</td><td></td></tr></tbody></table>

Identification of three isomers for 1:1 complex: observation of three bands for the v₁ water mode separated by 12-25 cm⁻¹

## Comparison of frequencies and shifts for the 1:2 complex

<table><thead><tr><th rowspan="2">Modes</th><th colspan="4">Calculated</th><th rowspan="2">Exp</th><th rowspan="2">Isomer</th></tr><tr><th colspan="2">ADW1</th><th colspan="2">ADW2</th></tr><tr><th></th><th>ω</th><th>Δ</th><th>ω</th><th>Δ</th><th>v</th><th>Δ</th></tr></thead><tbody><tr><td colspan="7"><strong>H<sub>2</sub>O</strong></td></tr><tr><td>v<sub>1</sub> PA</td><td>3679</td><td>135</td><td>3696</td><td>118</td><td>3507</td><td>154</td><td>ADW1</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>3550</td><td>111</td><td>ADW2</td></tr><tr><td>v<sub>1</sub> PD</td><td>3598</td><td>121</td><td>3609</td><td>110</td><td>3486</td><td>105</td><td>ADW1</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>3493</td><td>98</td><td>ADW2</td></tr><tr><td colspan="7"><strong>Acrylonitrile</strong></td></tr><tr><td>v<sub>4</sub></td><td>2189</td><td>-10</td><td>2183</td><td>-4</td><td>2246</td><td>-4</td><td>ADW2</td></tr><tr><td>v<sub>12</sub></td><td>1064</td><td>-29</td><td>1026</td><td>-21</td><td>998</td><td>-27</td><td>ADW1</td></tr><tr><td>v<sub>14</sub></td><td>581</td><td>-23</td><td>575</td><td>-17</td><td>694</td><td>-11</td><td>ADW2</td></tr><tr><td>Inter</td><td>118</td><td></td><td>108</td><td></td><td>108</td><td></td><td>ADW1 or 2</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>108</td><td></td><td>ADW1 or 2</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>223</td><td></td><td>ADW1 or 2</td></tr></tbody></table>

PA: proton acceptor and PD: proton donor for H₂O dimer

Identification of two isomers for 1:2 complex: observation of two bands for the v₁ water mode