The complex has recently been reported, the first example of the 1,2-dihydro-1,2- zabori...

The complex has recently been reported, the first example of the 1,2-dihydro-1,2- zaborine ligand. It has strong absorptions at 1898 and 1975 cm^-1, in comparison with 1892 and 1972 cm^-1 for

The C₄BNH₆ complex has carbon–carbon distances of 1.393, 1.421, and 1.374 A, in order, in the ring.

a. Is the C₄BNH₆ ligand a (slightly) stronger or weaker acceptor than C₆H₆? Explain.

b. Account for the differences in the C–C distances in the ring. (See A. J. V. Marwitz, M. H. Matus, L. N. Zakharov, D. A. Dixon, S.-Y. Liu, Angew. Chem., Int. Ed. , 2009 , 48 , 973.)