The reaction of (trifluoromethyl)dialkylaminoboranes with HF, HCl and HBr. X-Ray structure investigation of the amineboranes (CF 3) 2B(X)NHMe 2, X  F and OH

Abstract

The reactions of CF 3B(NMe 2) 2 (I) and (CF 3) 2BNMe 2 (II) with HX (X  F, Cl and Br) have been investigated. Additions with preservation of the BC bonds to yield species with tetracoordinate boron, along with some BN cleavage, were observed. While I formed boronium salts CF 3B(X)(NHMe 2) 2 +X − with X  Cl and Br, CF 3BF 2 · NHMe 2 (V) was obtained with HF. On the other hand, reactions of II with HX yielded the 1 : 1 adducts (CF 3) 2B(X) · HNMe 2 in each case. Of these, the species with X  F (VI) and X  OH (IX) (obtained by hydrolysis) were examined by single crystal X-ray diffraction. Surprisingly, no difference was found between the average BC bond lengths of these borates (VI 1.612(8), IX 1.624(4) Å) and that of II. The implications of this observation for BCF 3 bonding are discussed.