“…Comparing the different O−B bond lengths in the heterobicycle, there is evidence of O−B pp (π) back-donation in the O−(sp 2 )B−O fragment of the seven-membered ring, the partial π-bond character causing short O−B bonds, especially at the O(11)−B(12) bond. The bond lengths of 1.431(5), 1.346(5), and 1.375(5) Å in the (sp 3 )B−O−(sp 2 )B−O portion are similar to corresponding bond lengths in five-membered heterocycles, where mean values of 1.471, 1.333, and 1.410 Å have been found, − although the (sp 3 )B−O and (sp 2 )B−O bond lengths are somewhat smaller. As compensation, the B(12)−C(30) bond length with 1.569(6) Å is slightly longer than the mean value for the above-mentioned compounds (1.554 Å). , Nevertheless, the B(12)−C(30) bond length is still indicative of some π-interaction between the phenyl group and the sp 2 -boron atom.…”