title: Isobutene polymerization using a chelating diborane co-initiator.
abstract: Lewis acidic diborane 1 (J. Am. Chem. Soc. 1999, 121, 3244-3245) is highly effective for both proton- and cationogen-initiated isobutene polymerization in hydrocarbon media at low temperature. Reactions of diborane 1 with cumyl chloride and cumyl methyl ether were studied by variable-temperature 1H and 19F NMR spectroscopy. At low temperatures stable ion pairs 2a and 2b are formed; at higher temperatures these ion-pairs form phenyl-1,3,3-trimethylindan (3) with concomitant release of HCl to form 1 in the case of 2a or degradation of the anion (2b). Reaction between Ph3C-Cl and diborane 1 resulted in the generation of an ion-pair 4 consisting of the Ph3C cation very weakly associated with the chelated, mu-Cl counteranion as revealed by X-ray crystallography.
authors.affiliation: Department of Polymer Science, University of Akron, Akron, OH 44325-3909, USA.
authors.forename: Stewart P
authors.initials: SP
authors.lastname: Lewis
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Taylor
authors.forename: Warren E
authors.initials: WE
authors.lastname: Piers
authors.forename: Scott
authors.initials: S
authors.lastname: Collins