The x-ray crystal and molecular structure of an unusually stable cyclic organic peroxide

Structure of 5H,8H-dibenzo[d,f][1,2]oxathiocin 7,7-dioxide, C14H12O3S

“…The bridging of the two phenyl rings keeps them at 63 (0.5) ° with respect to one another. This dihedral angle compares well to the values of 65 ° observed for (II), 67 ° reported for (III) and 62 ° for the peroxide analog of (III) (Brown et al, 1976).…”

“…The S-O distance in the eight-membered ring with a value of 1.550 (2) A is very acceptable, as is the S-C bond distance of 1.783 (2)A. However, the C-O bond distance of 1.468 (4) A is significantly longer than that observed in either the peroxide analog of (III) (Brown et al, 1976) or the trimeric acetone peroxide (Groth, 1969). Another remarkable quantity is the very large S-O(1)-C(1) angle with a value of 119.7 (2) °.…”

“…The same conformation was also found to be favored by the related disulfide (III) (Wahl, Bordner, Harpp & Gleason, 1972). However, a totally different ring conformation was observed in the case of the peroxide analog of (III) (Brown, Towns, Kovelan & Andrist, 1976 …”

“…The torsion angles characterizing such a conformation are compared in Table 2 to the corresponding angles in the dithiocin analog (Wahl et al, 1973) and those of the peroxide analog of (III) (Brown et al, 1976). The torsion angles in the dithiocin analog of (I) are more symmetrically distributed around the eight-membered ring than those of (I).…”

“…This, of course, is probably related to the more chemically symmetrical eightmembered ring present in this structure. However, in the peroxide (Brown et al, 1976), the conformation is that of a 'pseudo-boat'. The reported shortening of the 'pseudo-axial' S-O bond in (II) is not observed here.…”