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

Article abstract of DOI:10.1016/0022-328X(93)80031-6

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 slat 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 HCl.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) Angstroem, respectively, the B-N bond length in XIV (1.541(4) Angstroem) is significantly shorter than that in I (1.595(8) Angstroem).