The Two‐Electron Reduction of 1,1′‐Diphenylethene by Lithium or Sodium to Different 1,1,4,4‐Tetraphenylbutane‐1,4‐diide Salts via CC Bond Formation—A Monomeric Dilithium Contact Ion Triple and a Polymer String of “Hydrocarbon Oysters Containing Solvated Sodium Pearls”

The reduction of 1,1‐diphenylethene with alkali metals to give 1,1,4,4‐tetraphenylbutane has model character for the course of anionic styrene copolymerization. It has been possible to grow single crystal of the air‐sensitive dianionic intermediates and to determine their structure. The structures of the butane‐1,4‐diide salts are decisively influenced by the radii of the counterions: in the momomeric dilithium contact ion triple, an anti‐periplanar ⊖CH2CCH2C⊖ chain is present. In comparison the polymer strand of the disodium salt consists of contact ion pair anions, which form intramolecular Na⊕ ‐diphenyl sand which units with synclinal butane conformation, and are coupled via further ether‐coordinated Na⊕ counterions.