Preparation of Diboron Compounds and Their Properties

Synthesis of diboron compounds may involve either reductive coupling reactions of monoboron derivatives to form the boron-boron bond,19 or reactions of compounds possessing preformed B2 fragments.20 

The earliest synthesis of characterized diboron compounds was the preparation of B2C14 by Stock,1 using an electric discharge between zinc electrodes immersed in liquid BC13. Many discharge procedures have been reported for the synthesis of B2C14.21 26 Structures of some halogenated diboranes, 1, 2, and 3 are shown in Fig. 1. Diborane(6) 3 (or diboron hexahydride) has been reviewed.27 31 

Synthesis, Structure, and Properties of Some Halogenated Diboranes 

However, tetra(amino)diboranes(4) of type R2N(Me2N)B-B(NMe2)NR2 are more readily accessible from LiNR2 and B2(NMe2)2Cl2. Similarly, 

B(NMe2)3 impurity present after the preparation of 36 needs to be removed by distillation prior to reaction with alcohols.56 

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