Aminoboranes and other Compounds containing B---N Bonds

Structural parameters for the planar and orthogonal forms of H2BNH2 have been computed from ab initio calculations.151 The best estimate of the internal rotation barrier is 33.3 kcal mol-1. 

Using the geometry recently deduced for H2NBF2 by microwave spectroscopy, MO calculations (CNDO and INDO) have been carried out on this molecule.152 The following conclusions were reached (a) The 120° FBF and HNH angles are due to repulsive N- F and B- H interactions. (b) The 

B—N bond order is approx. 1.3. (c) There is very little transfer of charge F2B— NH2, only ca. 0.015 electron. 

Tetrachloroaminoborane, C12BNC12, has been characterized as an intermediate in the reaction  

The following vibrational assignments, in particular, were given for this species B—N stretch (Ai) 1350 (10B), 1312(UB) B—Cl stretch (B,) 1026 (10B), 986 (nB) B—Cl stretch (A,) 446 N—Cl stretch (B,) 735 and N—Cl stretch (AO 541 cm 1. The tetrachloroaminoborane is extremely and unpre-dictably explosive, so great care must be exercised.153 

Aminoboranes and Other Compounds containing B—N Bonds.— H n.m.r. measurements (120—350 K) for MesNBHa have been used to elucidate molecular motions in the adduct. Minima in Tj found at 157 and 259 K could be attributed to three-fold reorientation of each of the three Me groups and the borane group, and to three-fold reorientation of the whole molecule about the B—N axis, respectively.  

The Simmons-Smith reagent (an organometallic complex formed between Zn and CH2I2) reacts with McaNBHa to give ready methylene transfer and resultant formation of BMea.  

Hydrolysis of MesNBFa occurs via both acid-independent and acid-dependent pathways, each of which is first-order in substrate.  

The adducts L,BH2X, where L = py, NMea, or PMcs X = F, Cl, Br, I, NCS, or NCSe, have been prepared and characterized. An empirical correlation was proposed between 7bh, the electronegativity of X (E, and the estimated B— X bond distance (Dx)  

There was almost no change in Jbh with X for L = PMe3. No theoretical justification has been given for these relationships.  

---