BN CLEAVAGE OF THE AZONIABORATACYCLOPROPANE RING BY H2O AND BY CARBONYL AND NITRILE DERIVATIVES - CRYSTAL-STRUCTURE OF (CF3)2B(OH)CH(SIME3)NHME2, (CF3)2BCH(SIME3)NME2CME2O AND (MEC(O)NH)(CF3)2BCH(SIME3)NHME2

1,1-Dimethyl-2,2-bis(trifluoromethyl)azoniaboratacyclopropane derivatives (CF3)2BCH-RNMe2 (R = H (I), SiMe3 (II)) react with H2O with cleavage of the NB bond to form (CF3)2 B(OH)CHRNHMe2 (R = H (III), SiMe 3 (IV)). Carbonyl compounds R1R2C=O are inserted into the NB bond of I and II to yield the five-membered heterocycles (CF3)2BCHRNMe2CR1R2O(R = H, R1 = R2 = Et (V); R = SiMe3, R1 = H, R2 = Me (VI), R1 = R2 = Me (VII), Et (VIII), R1 = Me, R2= CH=CMe2 (IX), C=CMe(CH2)2CH2 (X)). Similarly nitriles insert to form (CF3)2BCHRNMe2CR1=N (R = H, R1= CHClMe (XI); R = SiMe3, R1 = Me (XII), CHClMe (XIII), Ph (XIV)). The reaction of H2C-CHCH2CN with II is accompanied by a shift in the C=C bond whereby the substituent R1 = trans-CH=CHMe (XV) is formed. Hydrogen cyanide combines with II to yield (CF3)2B(CN)CH(SiMe3)NHMe2 (XVI). The nitrile derivatives XI-XIV are hydrolysed with formation of (R1C(O)NH)(CF3)2BCHRNHMe2 (R = H, R1= CHClMe (XVII); R = SiMe3, R1 = Me (XVIII), CHClMe (XIX), Ph (XX)). The novel boranes have been characterized by elemental analyses, multinuclear NMR, IR and mass spectra. The structures of IV and VII in a mixed crystal and of XVIII have been investigated crystallographically. In the solid state, IV and XVIII show intramolecular N-H...O hydrogen bondings which leads to formation of five- and seven-membered rings respectively. Steric repulsion between the CF3 and SiMe3 groups leads to large B-C-Si bond angles (average, 124.1(8)degrees) and variable B-CHSiN bond distances (1.648(4) angstrom in VII to 1.690(4) angstrom in IV).