| Abstract
| - Dibenzylbarium is prepared in yields of 80−90% by reaction of the tetramethyl ethylenediamine adduct of benzyllithium with the bis-THF adduct of barium bis(bis-trimethylsilylamide) or with barium bis(2,4,6-tri-tert-butyl phenolate). It is converted, by reaction withdiphenylmethane in THF, to bis(diphenylmethyl)barium in 90% yield and, by reaction with1,1-diphenylethene in THF, to bis(1,1,3-triphenylpropyl)barium in essentially quantitativeyield. The latter is soluble also in hydrocarbon solvents, while dibenzylbarium andbis(diphenylmethyl)barium are soluble only in THF. Reaction of the bis-chelate complex(C5Me4SiMe2C6H5)2Ba, the phenyl residues of which are coordinated to the Ba center, witheach of the bis(arylalkyl)barium species generates heteroleptic barium complexes with onechelate and one reactive arylalkyl ligand. Homoleptic and heteroleptic triphenylpropylbariumcomplexes both induce, in cyclohexane solution, living polymerization of styrene to atacticpolystyrene.
- Dibenzylbarium, for which a novel, high-yield synthesis is described, is converted to bis(1,1,3-triphenylpropyl)barium by reaction with diphenylethene. This compound as well as the heteroleptic complex (Me4C5SiMe2C6H5)Ba(CPh2CH2CH2Ph), obtained by its reaction with the bis-chelate (Me4C5SiMe2C6H5)2Ba, induces the living polymerization of styrene to atactic polystyrene.
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