Silane bilayers in liquid ammonia: a hypothetical carbon-free compartment model and its unresolved constrains

At cryogenic temperatures, carbon-based biochemistry is kinetically arrested even where it remains thermodynamically favorable, motivating the question of whether another element could take its place. Here I ask whether silicon-nitrogen chemistry could support a membrane-bounded compartment in liquid ammonia at 205K. The proposed amphiphile - "monosyn," with a Si(NH₂)₂ head group, a cyclotrisilazane linker, and polysilane tails - is argued capable of forming a bilayer from the cohesive energy density of liquid ammonia and a packing-parameter analysis, though self-assembly is adopted as an explicit assumption rather than demonstrated. The core energy-releasing reaction is the aminolysis of monosilane, SiH₄ + NH₃ → H₃SiNH₂ + H₂. Using transition state theory, I show it is kinetically inaccessible at 205K: the uncatalyzed turnover time exceeds the age of the universe. The model thus depends entirely on a catalyst lowering the barrier by roughly 30 kcal mol⁻¹, selectively - its central, least-supported assumption. Lacking any silicon-based carrier of heredity, it describes a compartment, not a protocell. Rather than argue for its likelihood, I set out the model's assumptions, vulnerabilities, and open questions as explicit, unresolved constraints - each specifiable and falsifiable by computation, experiment, or observation of icy bodies.