PUB - Publikationen an der Universität Bielefeld

The reaction of the aminohaloboranes (Me(2)N)(R)BX (1) (a: R = Ph, X = Cl; b: R = Me, X = Br; c: R = iPr, X = Cl) with the di-Grignard reagent (BrMg)(2)CH(2) in ethyl ether/benzene mixtures afforded the diborylmethanes [(Me(2)N)(R)B](2)CH(2) (2) (a: R = Ph; b: R = Me; c: R = iPr), which were subsequently converted into the corresponding bis(chloroboryl)methanes [(Cl)(R)B](2)CH(2) (3) (a: R = Ph; b: R = Me; c: R = iPr). Base-assisted cyclocondensation of 3a-c with 1,2-diisopropylhydrazine afforded 1,2-diisopropyl-1,2-diaza-3,5-diorgano-3,5-diborolidines (4) (a: R = Ph; b: R = Me; c: R = iPr). Derivative 4a was deprotonated by potassium bis(trimethylsilyl) amide to give (1,2-diisopropyl-1,2-diaza-3,5-diphenyl-3,5-diborolidinyl)potassium (5). Attempts to introduce a halogen atom to the carbon bridge between the two boron atom by treating 5 with either iodine or 1,2-dibromoethane failed. Instead, bis(1,2-diisopropyl-1,2-diaza-3,5-diphenyl-3,5diborolidinyl) (C-C) (6) was formed. In contrast to this, C-silylation of the heterocycle to give 7 was effected by reaction of salt 5 with trimethylsilyl chloride. Similarly, treatment of HgCl(2) with two molar equivalents of 5 gave rise to the formation of bis(1,2-diisopropyl-1,2diaza-3,5-diphenyl-3,5-diborolidinyl)mercury (8). The novel compounds were characterized by elemental analyses and various spectroscopic methods ((1)H-, (11)B{(1)H}-, (13)C{(1)H} NMR, MS). The molecular structures of 4a and 6-8 were elucidated by X-ray diffraction analyses.