STRUCTURES OF STERICALLY OVERCROWDED AND CHARGE-PERTURBED MOLECULES .9. THE 2-ELECTRON REDUCTION OF 1,1'-DIPHENYLETHENE BY LITHIUM OR SODIUM TO DIFFERENT 1,1,4,4-TETRAPHENYLBUTANE-1,4-DIIDE SALTS VIA C-C 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 crystals 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 sandwhich units with synclinal butane conformation, and are coupled via further ether-coordinated Na+ counterions.