Gas-phase structures of bis(pentafluorothio)difluoromethane and tetrafluoro-1,3-dithietane octafluoride

Abstract

215(Me2NCN)(SN)2, generated in situ from 2a. To test this possibility we added a solution of 2a in CC14 to a green solution of (NSCl)3 in CC14 at 60 0C.29 However, this reaction resulted in the dechlorination of (NSC1)3 by 2a to give S4N4 and la. An alternative mechanism for the production of 3a involves the formation of the monosubstituted derivative of la, (Me,NCN)(NSCl)(NSNSO), which undergoes intermolecular elimination of SO2 to give RN=S=NR (where R = (Me2NCN)(NSCl)(NS)). When R = (Ph2PN)2(SN), this type of compound readily undergoes a six-to eight-membered-ring expansion to give a spirocyclic compound, which forms a monocyclic eight-membered ring on thermal decomposition.M A similar sequence of transformations could account for the formation of h3' ConclusionsThe metathetical reaction of la-c with Me3SiNSNSiMe3 gives good yields of the corresponding bicyclic derivatives, 2a-c.32 The (29) Such solutions are thought to contain NSCl monomer (ref 2 and work cited therein).(30) Chivers, T.; Rao, M. N. S.; Richardson, J. F. Inorg. Chem. 1985, 24, 2237.(31) It is, of course, possible that the initial product is the 1,3-rather than the 1,5-isomer. In solution, however, ionization of the S-CI bond would provide a mechanism for the isomerization of the 1,3-to the presumably more stable 1,5-isomer, 3a. (32) A communication describing the preparation and X-ray structural determination of 2 (E = PhC) appeared after the submission of this manuscript ." same compound 2a is formed when l a is treated with 2 mol of Me3SiNS0. In the latter reaction a ring expansion to give the eight-membered ring 1 ,5-Me2NC(NSN)2SCl also occurs. Although the synthetic applications of this transformation are limited by the low yield and long reaction time, it may provide an initial approach to novel, ring-expanded heterocyclothiazenes from heterocyclothiazyl chlorides. The compounds 2a-c are potential sources of the eight-*-electron six-membered rings R2NCS2N3 via loss of N2S on thermolysis, but the mass spectra indicate that the fragmentation of the bicyclic rings may involve more than one pathway. Acknowledgment. We thank Dr. E. A. Dixon for assistance with recording the 13C N M R spectra, the Natural Sciences and Engineering Research Council of Canada for financial support, the Dr. K. A. Kerr for use of the diffractometer.Registry No. la, ; (NSC1)3, 5964-00-1. Supplementary Material Available:Tables containing anisotropic thermal parameters for non-hydrogen atoms, positional and isotropic thermal parameters for hydrogen atoms, best planes, and observed and calculated structure factors for 1,5-Me2NC(NSN),SC1 and IR data for compounds 2a-c (11 pages). Ordering information is given on any current masthead page. (33) Boeie, R. T.; Cordes, A. W.; Oakley, R. T. J. Chem. SOC., Chem. Commun. 1985. 929.The structures of (SF5)2CF2 and (SF4CF2)2 have been studied by gas electron diffraction. Very long S-C bonds (1.908 (7) A) and a large SCS bond angle (124.3 (7)') have been determined for (SFJ2CF2. These results are compared to the skeletal parameter...

3-Pentafluorothiopropionic acid

“…A search of the Cambridge Structural Database reveals that the structures of 20 other organic or organometallic compounds containing the SF 5 group have been determined (Allen & Kennard, 1993; Refcodes: DIVPAZ, JANYAY, JEBNEZ, JEBNIM, JESJUM, KUYPEZ, KUYYUY, LANWEC, LAYHEY, LECRUG, LECSAN, LECSER, NALWIG, QAFGOT, YAMGIC, YAMGOI, ZEZNIB, ZEZNOH, ZEZNUN, ZOVZAL). Additionally, three molecules are known, whose structure was determined by gas phase electron diffraction (Gupta et al, 1986;Weiss et al, 1990;Gard et al, 1998). From the set of X-ray structural determinations we know of, we obtain the following structural parameters.…”

“…Additionally, three molecules are known whose structure was determined by gas phase electron diffraction (Gupta et al, 1986;Weiss et al, 1990;Gard et al, 1998). From the set of X-ray structural determinations we know of, we obtain the following structural parameters: the SF 5 C-group tends towards a regular octahedron with five identical S-F bonds and a long S-C bond, with the following average bond lengths (population standard deviations given in parentheses): S-F ax 1.574 (14) Å, S-F eq 1.571 (14) Å, S-C 1.823 (28) Å, F ax -S-C 177.1(0.8)°, and F ax -S-F eq 88.1(1.0)°.…”