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(E)-l,2-Difluoro-l-(pentafluoro-A6-sulfanyl)- Discussion 2-iodoethylene Trimethylphosphine and 1,2,2-trifluoro-l- Holger Wessolowskia, (pentafluoro-^ 6-sulfanyl) ( 1 ) reacted at Gerd-Volker Röschenthaler*a, Rolf Winterb, -2 0 °C to give the monofluorophosphorane 2 [5], which was not isolated but treated with boron tri- and Gary L. Gard [l]b fluoride-etherate to furnish the thermally stable a Institut für Anorganische und Physikalische solid phosphonium tetrafluoroborate 3. Using Chemie der Universität Bremen, Leobener Straße, D-2800 Bremen 33, F.R.G. iodine and sodium carbonate [ 6] 3 was trans­ b Department of Chemistry, Portland State formed to (E)-l,2-Difluoro-l-(pentafluoro-A 6-sul- University, Portland, Oregon 97207, U.S.A. fanyl)-2-iodoethylene (4), a colorless liquid. Z. Naturforsch. 46b, 123- 125 (1991); The FAB mass spectrum of 3 exhibits received August 24, 1990 [F5SCF=CFPMe3]+ and BF4~ ions, whereas the 1,2,2-T rifluoro-1 -(pentafluoro-/6-sulfanyl)- 70 eV El mass spectrum of 4 shows the molecular ethylene, [(E)-1,2-Difluoro-2-(pentafluoro- ion M + (100%) and other characteristic fragments, Ä6-sulfanyl)]ethenyltrimethylphosphonium-tetra- e.g. (M -F )+, C2F 3I+, C2F 2I+ and SF3+. fluoroborate, 1,2-Difluoro-1 -(pentafluoro- Weak C = C stretching modes are observed in / 6-sulfanyl)-2-iodo-ethylene the 1660-1672 cm “ 1 range of the IR spectra. In The first SF5-substituted perfluoro iodo SF5CFCF 2 the strong C = C stretching frequency is (E )-F 5SCF = CFI was synthesized from the phos- located at 1782 cm “ 1 [7], F'(F24)S resonances ap­ phonium salt precursor pear in the 19F NMR spectra in the expected re­ [(E )-F 5SCF = CFPMe3] + BF4- and iodine. gions [4, 8], The fine structure allows to determine the values for V Fv (138.0 (3), 147.3 (4)) Introduction which are indicative of the (E)-configuration. Sur­ Fluoralkyl iodides are an important class of prisingly, the 19F signal for F 4 (4) is found at a compounds and are used in preparing large num­ much lower field than the respective resonance for bers of useful organo and organometallic deriva­ 3 and other SF 5 containing phosphorus com­ tives [2]. The SF5 containing perfluoroalkyl pounds. iodides, SF 5(C2F4)„I (n = 1, 2, 3) and SF5CF(I)CF3 have been prepared [3, 4], but no corresponding Experimental iodo alkene have been synthesized. We wish to re­ The appropriate precautions in handling mois­ port the first SF5-substituted iodo perfluoro- ture and -sensitive compounds were ob­ alkene. served throughout this work.

F2 F\ I ,'F F1. I -F2 F4 1 .2 I , 2. N a2 C O3 . 3. H 2 0 F .-Me BF4e f p3 ,p: I D M F) t ' l x Me/ ^Me - M e -3P0 . - N a l . - NaBF; 3

* Reprint requests to Prof. Dr. G.-V. Röschenthaler. Scheme 1 Verlag der Zeitschrift für Naturforschung, D-7400 Tübingen 0932-0776/91 /0100-0123/$ 01.00/0 124 Notizen

Elemental analyses: Mikroanalytisches Labora­ 5JF3H = 1.7 Hz), -148.6 (F4, dddp dec, 2/ F4p = 65.0, torium Beller, Göttingen. MS: MAT 8222 spectro­ VF4H = 1.2 Hz) ; 31 P{1H}: = 37.8 (dd). meter, IR: Nicolet 5DX FT spectrometer. Spectra C 5H 9BFhPS (351.96) were recorded either as a KBr pellet (3) or as a li­ Calcd C 17.06 H 2.58 P 8.80, quid film between NaCl plates. Found C 17.41 H 2.69 P9.61. NMR: AC 80 Bruker spectrometer, operating at 80.13 MHz ('H , internal standard, TMS), 1,2-Difluoro-l-( pentafluoro-l6-sulfanyl )-2-iodo- 75.39 MHz ( 19F, internal standard CC13F), and ethylene (4) 32.44 MHz (3IP, external standard 85% H 3P 0 4); d = doublet, p = pentet, dec = decet. Compound 1 Iodine, 25.0 g (99 mmol) was added to a solu­ was synthesized via a literature procedure [7], tion of 11.0 g (31 mmol) 3 in 35 ml dimethylform- amide. The solution was cooled to 0 °C and 10.0 g (94 mmol) sodium carbonate was added slowly. [ ( E )-l ,2- D ifluor o-2- (pentafluoro-X6-sulfanvl) - When evolution stopped the mix­ ethenyl f t rimethvlphosphonium-te traf luor obor ate ture was stirred for 15 h at room temperature. All (3) volatiles were distilled at 1 Torr (maximum bath In a 100 ml heavy-wall glass tube, fitted with a temperature 90 3C) into a receiver (-70 °C), then TEFLON® stopcock 7.6 g (36.5 mmol) 1 and 2.8 g warmed to room temperature and poured into (36.5 mmol) trimethylphosphine were combined at 50 ml of ice-. The lower organic layer was -196 °C using a vacuum line. The reaction mix­ washed three times with 10 ml ice-water. The re­ ture was allowed to warm to -20 C and was kept maining liquid was dried over P 4O 10. The distilla­ at this temperature for 24 h. During this period the tion at 48 °C gave 2.4 g (7.6 mmol) 4 (24%). solution turned from colourless to brown. The MS (inlet temperature 150 C): m /z (%): 316 product was cooled to - 196 °C, 30 ml diethylether (M +, 100), 297 (M + - F , 4), 208 (C,F 3I+, 31), 189 was added and 5.2 g (36.5 mmol) boron trifluoride- (C2F2I+, 48), 158 (CFI+, 8), 127 (SF5+, I+, 36), 89 etherate. The mixture was warmed to -20 C and (SF3+, 21). kept at this temperature for 72 h. The formation of High-resolution MS: Found: 315.8660 (C 2F7SI+, a brownish-white solid was observed. At 0 C the A 0.4 mmu), 207.9005 (C,F 3I+, 0.6), 188.9029 solid was washed three times with 10 ml ether. The (C ,F7I + , 1.6), 126.9058 (I+, 1.1), 126.9657 (SF5+, remaining ether was removed at room tempera­ 1.6). ture. IR: v = 1672 cm ' 1 w (C = C), 1220 s (CF), Yield: 12.0 g (34 mmol) 3 (94%), m. p. 159 °C. 1197m (CF), 1179s (CF), 869 vs (SF), 722 m, MS (matrix: glycerine): FAB neg.: m jz (%): 87 670 s, 620 m, 596 s(SF). (BF4-, 100), 179 (glycerine-H + BF4~, 33), 271 NMR: 19F: Ö = +67.3 (F 1 multiplet centered at (2glycerine-H + BF4~, 43); FAB pos.: m jz (%): 265 line 6 (see ref. [10]), -VF'F3 = 3.9, V F'F4 = 2.2 Hz), (F5SCF = CFPM e3+, 1). + 53,1 (F2, multiplet, V F2F4 = 19.3, V F2F3 = 2.9 Hz), IR: v = 2965 cm“' s (CH), 2892 m (CH), 1660 w -135.1 (F3, ddp, 3/fV = 147.3 Hz), -107.5 (F4, (C = C), 1425 w (CH), 1299 m (CF), 1261 m (CF, dpd). P = 0), 1209 vs (CF), 1030 vs (P -O -C ), 988 vs, C,F7IS(315.87) 922 vs, 891 vs, 870 vs (SF), 780 m (BF), 760 s, Calcd C 7.61 F42.1, 690 m, 663 m, 624 m, 598 vs (SF), 562 m, 535 m, Found C 7.79 F 42.4. 523 m (BF). NMR: 'H: Ö = 2.20 (ddd, 2JPH = 15.2, 4JF*H = The authors are grateful to the Fonds der Chemischen Industrie for financial support. G. L. G. and R. W. ex­ 1.1, V F3H = 1.6 Hz); 19F: Ö = +68.4 (F\ multiplet press their appreciation to the U.S. Department of ener­ centered at line 6 (see ref. [10]), -VF'F3 = 3.8, V F'F4 = gy (DE-FG 21-88 MC 25142) for support of this work. 2.4 Hz), +57.2 (F2, multiplet, VFv = 21.3 Hz), G. L. G. wishes to thank the Fulbright Commission for -126.5 (F3, ddd dec, V Fv = 138.0, V P'P = 8.6, a Senior Fulbright Fellowship. N otizen 125

[1] Senior Fulbright Fellow 1989/90 at the University of [6] A similar method was applied for the preparation of Bremen. (Z)-l-iodopentafluoropropene; P. L. Heinze, T. D. [2] R. E. Bank, R. N. Haszeldine, Adv. Inorg. Radio- Spawn, and D. J. Burton, J. Fluorine Chem. 38, 131 chem. 3, 337(1961). (1988). [3] J. Hutchinson, J. Fluorine Chem. 3,429 (1973/74). [7] L. H. Cross, G. Cushing, and H. L. Roberts, Spec- [4] G. L. Gard and C. Woolf, J. Fluorine Chem. 1, 487 trochimica Acta 17, 344 (1961). (1971/72). [8] J. Steward, L. Kegley, H. F. White, and G. L. Gard, [5] Phosphorane 2 decomposes completely above J. Org. Chem. 34, 760 (1969). — 20 °C to furnish SF5CF = CFH, Me3PF, and other [9] H. Wessolowski, G.-V. Röschenthaler, R. Winter, compounds; H. Wessolowski, G.-V. Röschenthaler, and G. L. Gard. Z. Naturforsch. 46b, 126 (1991). and G. L. Gard, unpublished results. [10] N. Boden, T. Feeney, and L. H. Sutcliffe, Spectro- chim. Acta 21, 627 (1965).