Organometallic Solutions: #9

9.* (1994 3 1)

A. Which is the stronger oxidizing agent?

KReO4 vs. KMnO4

An oxidizing agent is one which can easily oxidize other substances. Therefore, it must be easily reduced (it must want additional electrons.) These two species are isoelectronic, but Mn is more electronegative. Electronegative species "want" electrons, so they are good oxidizing agents.

KMnO4 is the better oxidizing agent.

K2IrCl6 vs. K2PtCl6

Ir(IV), d5 vs. Pt(IV), d6

 

Addition of 1 electron to Ir(IV) gives a stable filled level, making it a good electron acceptor. Addition of an electron to Pt(IV) destabilizes it. K2IrCl6 is the better oxidizing agent.

B. Which is the better reducing agent?

CrCl2 vs. MnCl2

Cr(II), d4 vs. Mn(II), d5

A reducing agent easily reduces other species. As such, it is easily oxidized and wants to lose electrons. In this case, oxidizing Cr yields a stable half-filled level, whereas oxidation of Mn breaks a half-filled level. CrCl2 is the better reducing agent.

 

Al vs. Au

The electron configuration of Al is 1s2 2s2 2p6 3s2 3p1. Therefore, its outer electron is easily removed. Au, by contrast, is very inert. Al is the better reducing agent.