Symmetrically Substituted Triaminoboranes, B NRR

B(NHCH3)3. NMR data (as given in Boron Compounds 3rd Suppl. Vol. 3,1988, p. 92) have been compiled with those of other aminoboranes in a correlation of J( N, B) with J( P, B) coupling constants [2]. 

B(NHC3H7-/)3 is formed upon treatment of C4H9B(NC2H5)2 with excess isopropylamine in CH2CI2 under acid catalysis [3]. 

B[N(CH3)2]3. The AM1 program [4] (third generation of MNDO) has been parametrized for boron [5]. While the geometrical parameters obtained with r(BN)=144.9, r(CN)=142.9 pm, (CNB) =122.1° are in fair agreement with the results from an X-ray diffraction study (see Boron Compounds 3rd Suppl. Vol. 3,1988, p. 93) and the calculated ionization potential of 8.48 eV is only 0.88 eV above the observed value the calculated AHf, -34.3 kcal/mol, compares poorly with an experimental value of AHf = -65.9 kcal/mol [5]. 

B(NC4H4)3, tris(pyrrol-1-yl)borane, has been prepared from pyrrole and triethylamine-borane (3 1 mole ratio) by elimination of hydrogen and triethylamine. NMR data (in ppm solvent CDCI3) 6 1B = 27.8, b H = -207, 6 3C = 126.6, 113.6 [12]. 

B[NHB C6H2(CH3)3-2,4,6 2]3, prepared from (C2H5)0-Bp3and lithiated dimesitylborylamine, forms colorless crystals (from pentane) with a melting point of 268°C. The X-ray structure (rhombohedral, C3 symmetry) shows two B-N distances of 145.1 and 142.6 pm [13]. 

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