dimethylboranylboron

Dimethyldiborane is a chemical compound consisting of methyl groups attached to a diborane core. It can be considered as the dimer of methylborane, CH3BH2, the simplest alkylborane, consisting of a methyl group substituted for a hydrogen in borane. There are two isomers. The 1,2-dimethyldiborane form (CH3BH2)2 is symmetrical with one methyl on each boron. 1,2-Dimethyldiborane can exist in a cis- and a trans arrangement. The other isomer is 1,1-dimethyldiborane, known as unsymmetrical dimethyldiborane, which has two methyl groups on one boron atom, and only hydrogen on the other. Other combinations of methylation occur on diborane, including methyldiborane, trimethyldiborane, tetramethyldiborane, and trimethylborane. Tetramethyldiborane is the dimer of dimethylborane. At room temperature the substance is at equilibrium between these forms. The methylboranes were first prepared by H. I. Schlesinger and A. O. Walker in the 1930s.