Reactivity of Tetrahalo- and Difluorodiboranes(4) toward Lewis Basic Platinum(0): Bis(boryl), Borylborato, and Doubly Boryl-Bridged Platinum Complexes.

The reaction of the tetrahalodiboranes(4) BF, BCl, and BBr with a Lewis basic platinum(0) complex led to the isolation of the cis-bis(difluoroboryl) complex cis-[(CyP)Pt(BF)] (1) and the novel borylborato complexes trans-[(CyP)Pt{B(X)-BX}] (2, X = Cl; 3, X = Br), respectively. The trans influence of the borylborato group was found to be one of the strongest ever observed experimentally. Furthermore, the reactivity of little-explored diaryldifluorodiboranes(4) FB-BMes and the new derivative FB-BAn (An = 9-anthryl) toward a range of platinum(0) complexes was investigated.

Desymmetrizing Electron-Deficient Diboranes(4): Diverse Products and Their Reactivity.

A comprehensive study of the reactivity of Lewis bases with dihalodiboranes(4) is presented. Diaryldihalodiboranes provide rearranged monoadducts when treated with cyclic (alkyl)(amino)carbenes, but halide-bridged adducts when treated with a range of pyridyl bases. Alternatively, the combination of diaminodihalodiboranes with strong carbene donors leads to boraborenium salts.

Controlling Regiochemistry in the Syntheses of Boraindanes from Diborane(4) Starting Materials.

The reaction of tert-butylisonitrile (tBuNC) with 1,2-dihalo-1,2-diduryldiborane leads initially to the formation of the mono-base adduct of the symmetrical diborane(4), which then undergoes an intramolecular cyclization resulting in the formation of a 1-boraindane. This result is in contrast to a previously reported cyclization of a mono-isonitrile adduct of an unsymmetrical 1,1-pinacol-2,2-diaryldiborane(4), which results in the formation of a 1-boraindane. This latter result is herein confirmed by the reaction of 1,1-difluoro-2,2-dimesityldiborane(4) with tBuNC, which yielded the 2-boraindane compound.

New outcomes of Lewis base addition to diboranes(4): electronic effects override strong steric disincentives.

Two surprising new outcomes of the reaction of Lewis bases with dihalodiboranes(4) are presented, including sp(2)-sp(3) diboranes in which the Lewis base unit is bound to a highly sterically congested boron atom, and a rearranged double base adduct. The results provide a fuller understanding of the reactivity of diboranes, a poorly-understood class of molecule of critical importance to synthetic organic chemistry.

Quaternizing diboranes(4): highly divergent outcomes and an inorganic Wagner-Meerwein rearrangement.

Apart from a few compounds under heavy use in organic chemistry, diboranes are relatively exotic and poorly understood. Recently, interest in these molecules has intensified with the advent of so-called "sp(2)-sp(3)" diboranes which exhibit useful reactivity toward organic substrates. In our hands, addition of Lewis bases to dihalodiorganyl diboranes(4) has previously shown some very surprising reactivity, including a substituent exchange between the boron atoms, and diboranes in which halide atoms bridge the B-B bond.