The carbene complex I shown below undergoes the following reactions. Propose structural...

The carbene complex I shown below undergoes the following reactions. Propose structural formulas for the reaction products.

a. When a toluene solution containing I and excess triphenylphosphine is heated to reflux, compound II is formed first, and then compound III . II has infrared bands at 2038, 1958, and 1906 cm^-1 and III at 1944 and 1860 cm^-1. 1H NMR data d values (relative area) are as follows:

II: 7.62, 7.41 multiplets (15)

4.19 multiplet (4)

III: 7.70, 7.32 multiplets (15)

3.39 singlet (2)

b. When a solution of I in toluene is heated to reflux with 1,1-bis(diphenylphosphino)methane, a colorless product IV is formed that has the following properties:

IR: 2036, 1959, 1914 cm^-1

Elemental analysis (accurate to ± 0.3%): 35.87% C, 2.73% H

c. I reacts rapidly with the dimethyldithiocarbamate ion S₂CN(CH₃)₂ ^- in solution to form Re(CO)₅Br + V, a product that does not contain a metal atom. This product has no infrared bands between 1700 and 2300 cm^-1. However, it does show moderately intense bands at 1500 and 977 cm^-1. The ¹H NMR spectrum of V shows bands at δ 3.91 (triplet), 3.60 (triplet), 3.57 (singlet), and 3.41 singlet). (See G. L. Miessler, S. Kim, R. A. Jacobson, R. J. Angelici, Inorg. Chem. , 1987 , 26 , 1690.)