MOLECULAR-STRUCTURE OF TRI(2-THIENYL)BORANE

The molecular structure of tri(2-thienyl)borane (1) was determined [mo noclinic, space group P2(1)/c; a = 12.216(2), b = 7.765(2), c = 12.605 (2) Angstrom, beta = 93.13(2)degrees]; two of the three thienyl groups are disordered, as is also indicated by the solid-state C-13 CP/MAS N MR spectrum of 1. The C-13 NMR spectra of 1 were measured at variable temperature in solution and the barrier to rotation about the B-C bond s was found to be <35 kJ/mol. Thus, CB(pp)pi interactions must be rega rded as rather weak, in spite of suggestive delta(11)B, delta(13)C dat a and structural parameters.