the relaxation time T1 of the quadrupolar nuclei 11B is rapid (1/T1 ~= 2*pi*J), 13C next to 11B (T1 = 10e-1 to 10e-2s, J13C-11B = 20 to 80 Hz) is likely to produce broadened lines, except 11B is positioned at the centre of the molecule and experiences a fairly symmetrical
field.