An intramolecularly stabilized arylboron dibromide

Abstract

A new boron dibromide featuring intramolecular Lewis base coordination, ArBBr2 (4; Ar = 2‐[(dimethylamino)methyl]phenyl) has been prepared via the salt‐elimination reaction of [2‐(Me2NCH2)C6H4]Li with BBr3. Single‐crystal X‐ray diffraction experiments reveal that 4 rystallizes in two polymorphs, both of which are orthorhombic. The principal difference between the two polymorphs is the presence or absence of weak Br…Br intermolecular contacts. The metrical parameters for the individual molecules of 4 are very similar for both polymorphs; the amine “arm” is coordinated strongly, and the boron atom adopts a somewhat distorted tetrahedral geometry. Compound 4 is surprisingly unreactive toward a variety of hydride transfer reagents. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:79–83, 1998

Structural characteristics of dibromoborylated benzene derivatives

“…A search of the CSD for an aromatic ring carrying a -BBr 2 residue with a four-coordinated B atom revealed only two structures, dibromo(2-dimethylaminomethylphenyl)borane (CEJWUJ; Brown et al, 1998) and bromo(bromo{4-[dibromo(tricyclohexylphosphino)boranyl]phenyl}boranyl-B)bis(tricyclohexylphosphino)platinum benzene n-hexane solvate (QOMLEK; Braunschweig et al, 2008). The C-B bond lengths of 1.559 (CEJWUJ) and 1.609 Å (QOMLEK), and the B-Br bond lengths (2.019 and 2.020 Å in CEJWUJ, and 2.046 and 2.056 Å in QOMLEK) are in good agreement with those of (IV) and (V) ( Table 2).…”