THE AMMINE COMPLEX OF TRIS(TRIFLUOROMETHYL)BORANE, AND SOME N-ACYL DERIVATIVES - CRYSTAL-STRUCTURE OF (CF3)3B.NH3 AND (CF3)3B.NH=CHN(CH3)2

The complex (CF3)3B . NH3 (I) has been prepared both by catalytic hydrogenation of (CF3)3B - NH2CH2C6H5 and by pyrolysis of (CF3)3B . NH2CMe2(CH2)2CH=CMe2. Compound I reacts with moisture and DMSO to form a trihydrate (II) and a 1 : 1 solvate (III), respectively. Deprotonation with KOH yields K[(CF3)3BNH2] (IV). The salt IV was alkylated with n-C4F9SO3CH2CF3 to form K[(CF3)3BNHCH2CF3] (V), whose protonation in DMSO yields (CF3)3B . NH2CH2CF3 . DMSO (VI). Acylation of IV with (CH3CO)2O, (CF3CO)2O and C6F5COCl affords the salts K[(CF3)3BNHCOR] (R = CH3 (VII), CF3 (VIII) and C6F5 (IX)), which give the corresponding acetamide adducts (X, XI, XII) upon treatment with HCI. The complex (CF3)3B . NCCH3 (XIII) was obtained by dehydration of X with P4O10. Reaction of IV with (CF3SO2)2O in the presence of DMF gives (CF3)3B . NH=CHNMe2 (XIV). Structural assignments are based on multinuclear NMR spectra. Mass spectral data for the molecular adducts are presented, and the vibrational spectra of II and XIII discussed. The crystal structures of I and XIV have been determined; while the average B-C bond distances in these two adducts are 1.612(9) and 1.616(5) angstrom, respectively, the B-N bond length in XIV (1.541(4) angstrom) is significantly shorter than that in I (1.595(8) angstrom).