Organometallic Solutions: #17

17.* (1992 F 25) Consider the diamagnetic complex [M(en)₃(ClO₄)₃] where M is a 3d metal.

A. What is M?

M is Co (which is d6 in its III oxidation state.)

B. What is the oxidation state of M?

The oxidation state is III, because each ClO₄^- has a -1 charge. This way, we can also have a low-spin system.

C. How many d electrons?

There are 6 d electrons.

D. Will this complex be a strong oxidizing agent?

To be a strong oxidizing agent the complex must gain electrons easily. However, any electrons this complex gains will go into the high energy e_g antibonding orbitals. Therefore, this compound won't be a strong oxidizing agent.

E. Sketch a picture of all stereoisomers of this complex.

F. What features would the ¹³C NMR spectrum exhibit?

The ¹³C NMR of the racemic mixture would show a single peak. This peak would be a triplet in high-resolution proton-coupled spectra due to the effects of the 2 hydrogens attached to each C, but would be a singlet in the proton-decoupled spectra. (Note: the spectrum of a pure enantiomer would be the same. NMR cannot distinguish between enantiomers!)