Studies on the cyclotetrazenoborane ring and related systems

Work done previously on cyclotetrazenoboranes and other boron-nitrogen ring systems, excluding borazines, has been comprehensively reviewed. The frequencies of the B-H stretching frequencies in Me[sub]2N[sub]4BH and Ph[sub]2N[sub]4BH have been studied in a range of solvents, and are shown to increase with increasing polarity of the solvent. No correlation is observed with the dielectric relationship ([epsilon]-1)/(2[epsilon]+1) and non-linear relative shift (B.H.W.) plots are obtained against N-H, C=O, P-H, and transition metal hydride M-H vibrations. The results. suggest that solvent interactions occur with parts of the molecules remote from the B-H bond, and are unlikely to be due mainly to dielectric effects. Two routes for the preparation of B-substituted cyclotetrazenoboranes have been developed. The action of Grignard reagents on derivatives of the type R[sub]2N[sub]4BH produces compounds R[sub]2N[sub]4BR' in high yield, through the intermediate formation of magnesium containing complexes. Thermal degradation of a diorganoboron azide in the presence of an organic azide also produces boron-substitutedcyclotetrazenoboranes. The preparation of B-halogeno substituted cyclotetrazenoboranes has been achieved by two routes. Direct reaction of a derivative of the type R[sub]2N[sub]4BH with N-bromosuccinimide'has led to isolation of the very readily hydrolysable compound R[sub]2N[sub]4BBr. Dehydrohalogenation of a primary amine -BC1[sub]3 adduct in the presence of triethylamine has also led to the isolation of a B-chloro cyclotetrazenoborane derivative. Attempts to prepare unsymmetrically N-substituted cyclotetrazenoboranes by the reaction of a primary amine-borane (RNH[sub]2BH[sub]3) with an organic azide (R'N[sub]3) have led to the isolation of mixtures of cyclotetrazenoborane derivatives RRN[sub]4BH, RR'N[sub]4BH and R'R'N[sub]4BH. Throughout the work the U.V., I.R. and N.M.R. spectra of the compounds have been studied. A detailed mass-spectrometric study of both B- and N-substituted clotetrazenoboranes has been made and a generalised fragmentation pattern has been derived. The use of computer techniques was also established to aid the handling and interpretation of the mass spectral data.