Reaction of Ir complex A with C60 gave a black solid residue B with the following spectr...

Reaction of Ir complex A with C₆₀ gave a black solid residue B with the following spectral characteristics: mass spectrum:

(multiplet, 2H), 7.48 (multiplet, 2H), 6.89 (triplet, 1H), and 5.97 (doublet, 2H); IR: v(CO) = 1998 cm^-1.

a. Propose a structure for B .

b. The carbonyl stretch of A was reported at 1954 cm^-1. How does the electron density at Ir change in going from A to B ?

c. When B was treated with PPh₃, a new complex C formed rapidly, along with some C₆₀. What is a likelystructure of C ? (See R. S. Koefod, M. F. Hudgens, J. R. Shapley, J. Am. Chem. Soc. , 1991 , 113 , 8957.)