The Reaction Cell of the Sulfur Pair: Co-synthesis on a Single Chrysene Unit, a Disulfide Bridge, and Two Forced Asymmetries

Abstract

The corpus establishes, by inspection, that exactly two of the twenty structures require a heteroatom with no source within the carrier, and places them under a hypothesis about the medium which it states and declines to establish [Sch26o]. This paper supplies the object in which those two structures are formed, and replaces that hypothesis with one about the carrier.

The object is one unit of the stack carrying two ether-linked tethers to adenosine, its arms leaving toward opposite faces. Its skeleton admits exactly one non-trivial symmetry, an involution realised as a point inversion, and the unit carries no datum breaking it: a symmetric object is asked to make two structures that the symmetry does not exchange.

Four results are finite. Over the site types the atom map supplies, the unit admits exactly three pairings, of which one is excluded outright and two survive the skeleton — and the pairing adopted here is the more expensive of those two on every measure the skeleton can state, a concession recorded before the argument that overturns it. A disulfide bridge cannot close between two sites exchanged by an inversion, the two substituents being antipodal about its centre: a bridge would require a site within 1.02 Å of that centre, which no peripheral vertex of a fused four-ring aromatic is. The bound is independent of bond length and of any model. The mixed pairing is the unique pairing whose sulfur sites are not so exchanged, and hence the unique pairing the unit can bridge. And the fracture of that pairing treats three of four symmetry orbits equivariantly and fails on exactly one, so that the whole of the skeletal symmetry breaking is a choice between two edges.

Two asymmetries are forced rather than assumed. The external electron demand is affine in the oxidation level of the remnant and vanishes at one value only: a redox-self-sufficient cell yields one benzylic remnant at the aldehyde level and one at the alcohol level, although the two are exchanged by the symmetry as graphs. This is the account's most directly testable consequence and a single product analysis decides it. And the choice of bridge site is the choice that resolves the edge orbit: the unit ceases to be symmetric where the disulfide binds and shows it where the skeleton breaks. Whether these are one choice is open.

The selection rests on two hypotheses — that sulfur arrives as a disulfide and that neither sulfur afterwards migrates — and the premise of co-synthesis on one unit is this paper's own. The bridge closes only on a dearomatised intermediate, and what that distortion may do to the exclusion is bounded but not closed. No energy is computed and no barrier estimated; the numbered statements read excluded, admissible, or forced under the premises named.