SYNTHESIS OF THE MONOMERIC HB2,4,6-I-PR3C6H2 AND THE X-RAY CRYSTAL-STRUCTURES OF [HB2,4,6-ME3C6H22]2 AND HBTRIP2

The synthesis and spectroscopic properties of HBTrip2 (1) and the X-ray crystal structures of 1 and the dimeric species [HBMes2]2 (2) are described. The synthesis of 1 was carried out by treatment of Me2S·BHCl2 with 2 equiv of TripMgBr in THF solution. Standard workup gave 1 as a colorless crystalline material that exhibited a broad singlet at 73.5 ppm downfield in the11B NMR spectrum. X-ray data confirmed a monomeric structure with a planar boron center and a wide CBC angle of 128.0 (4)°. The less sterically encumbered 2 was prepared according to a literature procedure. The X-ray crystal structure reveals a dimeric structure with the expected bridging hydrogens. The compounds of 1 and 2 are the first diorganoboranes to be structurally characterized by X-ray crystallography. In addition, the structure of 1 represents the first structural characterization of a monomeric diorganoboranE. C.rystal data at 225 K for 1 or 140 K for 2, with Mo Kα (λ = 0.71069 Å) radiation: 1, monoclinic, a = 11.116 (4) Å, b = 14.869 (5) Å, c = 17.321 (6) Å, β = 100.19 (3)°, Z = 4, space group P21/c, R = 0.093; 2, monoclinic, a = 12.254 (6) Å, b = 7.768 (2) Å, c = 16.785 (6) Å, β = 109.43 (3)°, Z = 2, space group P2/n, R = 0.047. © 1990, American Chemical Society. All rights reserved.