Triggering dynamics of acetylene topochemical polymerization

Topochemical reactions are a promising method to obtain crystalline polymeric materials with distance-determined regio- or stereoselectivity. It has been concluded on an empirical basis that the closest intermolecular C⋯C distance in crystals of alkynes, d(C⋯C)min, should reach threshold ∼3 Å for bonding occur at room temperature. To understand this threshold, we study here polymerization acetylene state under high pressure by calculating structural geometry, vibrational modes, and reaction profile. We find d(C⋯C)min be sum intrinsic 2.3 thermal displacement 0.8 (at temperature). Molecules move via several phonon modes which electronic interaction is sharply enhanced commences. A distance–vibration-based picture thus demonstrated, provides prediction design topochemical reactions, as well understanding process solids.