title: Substitution reactions at tetracoordinate boron: synthesis of N-heterocyclic carbene boranes with boron-heteroatom bonds.
abstract: Boryl halide, carboxylate and sulfonate complexes of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (dipp-Imd-BH(2)X, X = halide or sulfonate) have been prepared from the parent borane dipp-Imd-BH(3) by (1) substitution reactions with R-X (X = halide or sulfonate), (2) reactions with electrophiles (like I(2) or NIS), or (3) acid/base reactions with HX (provided that HX has a pK(a) of about 2 or less). Dipp-Imd-BH(2)I is most conveniently prepared by reaction with diiodine while dipp-Imd-BH(2)OTf is best prepared by reaction with triflic acid. These and other less reactive complexes behave as electrophiles and can be substituted by a wide range of heteroatom nucleophiles including halides, thiolates and other sulfur-based nucleophiles, isocyanate, azide, nitrite, and cyanide. The resulting products are remarkably stable, and many have been characterized by X-ray crystallography. Several are members of very rare classes of functionalized boron compounds (boron azide, nitro compound, nitrous ester, etc.).
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Andrey
authors.initials: A
authors.lastname: Solovyev
authors.forename: Qianli
authors.initials: Q
authors.lastname: Chu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Geib
authors.forename: Louis
authors.initials: L
authors.lastname: Fensterbank
authors.forename: Max
authors.initials: M
authors.lastname: Malacria
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Lacôte
authors.forename: Dennis P
authors.initials: DP
authors.lastname: Curran