THE EFFECT OF TRIFLUOROMETHYL SUBSTITUTION ON THE B=N BOND IN TRIFLUOROMETHYL-DIMETHYLAMINOBORANES, CF3(R)BNME(2) - CRYSTAL AND MOLECULAR-STRUCTURE OF CF3(ET)(NCCH2)B.NHME(2)

Chloro-trifluoromethyl-dimethylaminoborane, CF3(Cl)BNMe(2) (I), has be en prepared from Cl(2)BNMe(2) using the reagent combination P(NEt(2))( 3)-CF3Br in sulpholane. Compound I undergoes [2 + 2] cycloaddition rea ctions with (t)BuNCO and Cl(2)BNMe(2) to yield the four-membered heter ocycles CF3(Cl)B-NMe(2)-C(O)-N(t)Bu (II) and CF3(C1)B-NMe(2)-BCl2-NMe( 2) (III). Addition of HCl to I formed CF3(Cl-2)B . NHMe(2) (IV). The C l atom in I has been substituted by RMgX (R = Et or Pr-i) to yield the respective aminoboranes CF3(Et)BNMe(2) (V) and CF3(Pr-i)BNMe(2) (VI). Compounds V and VI react slowly with CH3CN in an ene-type reaction to form the amine-boranes CF3(Et)(NCCH2)B . NHMe, (VII) and CF3(Pr-i)(NC CH2)B . NHMe(2) (VIII). The novel boron compounds have been characteri zed by multinuclear NMR, IR and mass spectra. The structure of VII has been determined by single-crystal X-ray diffraction.