Synthesis and Molecular Structures of the Base-stabilized Arylboron Dichlorides BCl 2 {2,6-(NEt 2 CH 2 ) 2 C 6 H 3 } and BCl 2 {2-(NMe 2 CH 2 )C 6 H 4 }

Abstract

The reaction of Li{2,6-(NEt₂CH₂)₂C₆H₃} with BCl₃·Et₂O in hexane yields BCl₂[2-{BCl₃(NEt₂CH₂)}-6-(NEt₂CH₂)}C₆H₃] (1) as the thermodynamically favoured product. If BCl₃ · Pyridine is employed, only Cl{2,6-(NEt₂CH₂)₂C₆H₃} is formed. 1 reacts with [PPh₄]Cl to give the BCl₃-free product BCl₂{2,6-(NEt₂CH₂)₂C₆H₃} (2) with formation of [PPh₄][BCl₄]. Li{2-(NMe₂CH₂)C₆H₄} reacts with BCl₃, to give BCl₂{2-(NMe₂CH₂)C₆H₄} (3). 1–3 were characterized spectroscopically (NMR, IR, MS) and their crystal structures were determined: 1, T = 260(2) K, triclinic, PT, with a = 7.069(2) Å, b = 10.837(5) Å, c = 14.090(5) Å, α = 90.09(2)°, β = 104.16(2)°, γ = 97.35(2)°, V = 1037.3(7) ų, Z = 2, d(ca1cd) = 1.429 g cm⁻³, 3409 independent reflections, and R1= 0.0460, wR2 = 0.0889 (for reflections with I > 2σ(I)), R1 = 0.0752, wR2 = 0.1082 (all data); 2, T = 213(2) K, monoclinic, P2₁/c, with a = 13.1797(9) Å, b = 7.5833(5) Å, c = 18.6796(13) Å, β = 108.974(1)°, V = 1765.5(2) ų, Z = 4, d(ca1cd) = 1.238 g cm⁻³,3174 independent reflections, and R1= 0.0334, wR2 = 0.0824 (for reflections with I > 2σ(I)), R1,= 0.0436, wR2 = 0.0874 (all data); 3, T = 213(2) K, orthohombic, P2₁2₁2₁, with a = 9.4540(8) Å, b = 9.5650(8) Å, c = 11.6900(10) Å, V = 1057.1(2) ų, Z = 4, d(ca1cd) = 1.357 g cm⁻³, 1913 independent reflections, and R1 = 0.0298, wR2 = 0.0651 (for reflections with I > 2σ(I)), R1 = 0.0334, wR2 = 0.0673 (all data).