Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013 Matrix Isolation and Spectroscopic Properties • of the Methylsulfinyl Radical CH3(O)S [a] [b] [b] Hans Peter Reisenauer,* Jaroslaw Romanski, Grzegorz Mloston,* Peter R. Schreiner[a] [a] Justus-Liebig University, Institute of Organic Chemistry, Heinrich-Buff-Ring 58, D-35392 Giessen, Fax: (+49) 641-99-34209; E-mail: [email protected] [b] University of Lodz, Section of Heteroorganic Compounds, Tamka 12, PL-91-403 Lodz, Fax: (+48) (42) 665 51 62; E-mail: [email protected] Supplementary Information Table S1. Experimental (Ar, 10 K) and computed (AE-CCSD(T)/cc-pVTZ, harmonic approximation, no scaling) the IR spectra of 3. 13 3 C-3 D3-3 a b a b a b Sym. Approx. Band Position (Intensity) Band Position (Intensity) Band Position (Intensity) Mode Computation Experiment Computation Experiment Computation Experiment a’’ CH str. 3151.3 (2.1) 2995.4 3139.3 (2.1) n.o. 2336.4 (1.2) 2247.2 a’ CH str. 3149.3 (4.1) (vw) 3137.5 (4.0) n.o. 2334.5 (2.2) (vw) 2919.4 2095.5 a’ CH str. 3065.6 (4.3) 3062.7 (4.5) n.o. 2194.2 (1.4) (vw) (vw) CH 1062.8 a’ 3 1477.4 (6.5) 1417.1 (w) 1474.8 (6.6) 1414.6 (w) 1028.7 (s) def. (17.3) CH a’’ 3 1464.4 (7.8) 1405.2 (w) 1461.7 (7.8) 1401.4 (w) 1058.5 (3.7) 1025.6 (w) def. CH a’ 3 1324.7 (1.0) 1288.7 (w) 1316.2 (0.8) 1283.8 (w) 1024.8 (2.3) 1000.7 (w) def. 1077.8 1077.8 1082.5 a’ SO str. 1068.2 (vs) 1067.9 (vs) 1069.5 (vs) (33.7) (33.8) (20.4) CH a’ 3 944.7 (9.3) 926.6 (m) 936.5 (9.0) 918.9 (m) 765.5 (12.6) 751.6 (w) rock. CH a’’ 3 888.8 (1.1) 868.2 (vw) 883.7 (1.2) 863.5 (vw) 671.8 (0.3) 659.2 (vw) rock. 614.2, a’ CS str. 690.9 (11.9) 669.9 (w) 676.8 (11.9) 656.0 (m) 630.7 (5.9) 618.8 (w) CSO a’ 328.5 (7.1) 340.8 (w) 326.3 (7.) n.o. 298.8 (6.6) n.o. def. CH a’’ 3 134.0 (0.8) n. o. 134.0 (0.8) n.o. 103.1 (1.3) n.o. twist. S1 Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013 a in cm–1; b in km mol–1 (computation), vw: very weak, w: weak, m: middle, s: strong, vs: very strong, n.o.: not observed (experiment) Experimental Preparation of allylmethyl sulfoxide (4a) and its labelled derivatives 4b and 4c was based on the known protocols.1 A solution of ally1 bromide (1.94 g, 0.016 mol) and thiourea (1.0 g, 0.016 mol) in methanol (20 mL) was heated under reflux for 1 h and then after addition of a methanolic NaOH (1.28 g in 15 mL) solution heating was continued for additional 1 h. Next, the solution was cooled to –10 °C and MeI (2.28 g, 0.016 mol) was added in small portions. The solution obtained thereby was refluxed for 0.5 h. After this time the mixture was distilled and the product 9 was collected as an azeotrope with methanol (bp 62–64 °C). To this solution 30% H2O2 (1.27 g, 0.012 mol) was added dropwise and the reaction mixture was stirred for 6 h at rt. The solvents were evaporated and the liquid residue was distilled to yield allylmethyl sulfoxide (4a), bp 48–50 °C/0.25 Torr. The crude distillate contained traces of allylmethyl sulfone and was directly used for the matrix experiments.used. Note: The same procedure was applied for the synthesis of 4b 13 and 4c using CD3I and CH3I, respectively. Matrix isolation experiments: The cryostat used for the matrix isolation studies was an APD Cryogenics HC-2 closed-cycle refrigerator system fitted with CsI windows for IR and BaF2 windows for UV/Vis measurements. The IR spectra were recorded with a Bruker IFS 55 FTIR spectrometer (4500–300 cm–1, resolution 0.7 cm–1), the UV/Vis spectra with a JASCO V-670 spectrophotometer (spectral range: 190–2500 nm, resolution: >= 0.1 nm). For the combination of high-vacuum flash pyrolysis (HVFP) with matrix isolation a small home built water-cooled oven directly connected to the vacuum shroud of the cryostat was used. The pyrolysis zone consisted of a completely empty quartz tube (inner diameter 8 mm, length of heating zone 50 mm) resistively heated by a coax heating wire. The temperature was controlled by a Ni/CrNi thermocouple. The precursors were evaporated from a cooled storage bulb allylmethyl sulfoxide (4a) at –30 °C (dimethyl sulfoxide (8) at –23 °C) into the quartz pyrolysis tube. Immediately after leaving the tube, at a distance of ca. 50 mm, the pyrolysis products were co-condensed with a large excess of argon on the surface of the 10 K cold matrix window during a time of 2–4 hours. Pyrolysis temperatures were varied between 500 and 900 °C, the optima with respect to the yields of methylsulfinyl radical (3) was found at 600 °C for precursor 4a and 800 °C for 8. For irradiations a mercury high-pressure lamp (Osram, HBO 200 in connection with long-pass glass S2 Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013 filters or a Bausch & Lomb monochromator (slits set to a spectral half-width of ∆λ = 10 nm), a mercury low pressure lamp (Gräntzel, with vycor filter (λ > 210 nm, main line: λ = 254 nm)), or a KrF excimer laser (Lambda Physik LPX 100, (λ = 248 nm) was used. An unspecific photodegradation of 3 to COS, CS, CO, H2S, H2O was observed using λ = 248 and 254 nm (80 min or 16 h irradiation time for complete conversion), but not with visible light (λ > 475 nm). Subtraction of the respective spectra before and after photodegradation were made to discern the 13 IR and UV/Vis spectra of 3 more clearly. The same procedure was applied for the D3- and C- isotopologues 4b and 4c. Computational methods: The electronic structure computations employed the correlation- consistent triple-ξ atomic-orbital basis set cc-pVTZ.2 Geometry optimizations and evaluations of the analytical harmonic vibrational frequencies were performed with single-reference all-electron coupled-cluster theory, incorporating all single and double excitations, and with perturbative inclusion of connected triple excitations AE-CCSD(T).3 For energy evaluation of all other structures Gaussian-4 theory (G4) was employed.4,5 All stationary structures were characterized as minima or transition structures by computing analytical harmonic vibrational frequencies. For computations of electronic excitations within the adiabatic approximation of time dependent density functional theory (TD-DFT)6 with the B3LYP functional and a large basis set including polarization and diffuse functions (6-311+G(3df,3pd) was employed. 5 References: (1) (a) Prabhuswamy, B.; Ambekar, S. Y. Synth. Comm. 1999, 29, 3477. (b) Kline, M. L.; Beutow, N.; Kim, J. K.; Caserio, M. C. J. Org. Chem. 1979, 44, 1904. (c) O'Connor, D. E.; Lyness, W. I. J. Am. Chem. Soc. 1964, 86, 3840. (2) Dunning Jr., T. H. J. Chem. Phys. 1989, 90, 1007. (3) Stanton, J. F.; Gauss, J.; Harding, M. E.; Szalay P. G. with contributions from Auer, A. A.; Bartlett, R. J.; Benedikt, U.; Berger, C.; Bernholdt, D. E.; Bomble, Y. J.; Cheng, L.; Christiansen, O.; Heckert, M.; Heun, O.; Huber, C.; Jagau, T.-C.; Jonsson, D.; Jusélius, J.; Klein, K.; Lauderdale, W. J.; Matthews, D. A.; Metzroth, T.; Mück, L. A.; O'Neill, D. P.; Price, D. R.; Prochnow, E.; Puzzarini, C.; Ruud, K.; Schiffmann, F.; Schwalbach, W.; Stopkowicz, S.; Tajti, Vázquez, A.; Wang, F.; Watts J. D. and the integral packages MOLECULE (Almlöf, J.; Taylor, P. R.), PROPS (Taylor, P. R.), ABACUS (Helgaker, T.; Jensen, H. J. Aa.; Jørgensen, P.; Olsen, J.), and ECP routines by Mitin, A. V.; van Wüllen, C. For the current version, see http://www.cfour.de. (4) Curtiss, L. A.; Redfern, P. C.; Raghavachari, K. J. Chem. Phys., 2007, 126, 084108. S3 Electronic Supplementary Material (ESI) for Chemical Communications This journal is © The Royal Society of Chemistry 2013 (5) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G. B.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.; Foresman, J.