Question

For your post-lab questions: some of you made red-colored Co(salen), while others made brown-colored Co(salen). The difference is due to different amount of O2 incorporated into the reaction to make (salen)Co-O-O-Co(salen). The red compound has less O2 and usually forms when the temperature is higher. (1) Why you did not see the same phenomenon last week for the synthesis of Ni(salen)? (2) Why higher temperatures favor the product with less O2 incorporated? (3) Assuming you made pure (salen)Co-O-O-Co(salen), how would that affect your calculated isolated yield?  

Answer 1

cobalt forms a complex with salen.

Salen is formed from reactio of ethylene diamine and salicaldehyde (sal + en)

The cobalt reversibly bind to oxygen.

1) Nickel do not form complex like cobalt, it forms low spin complex. So it cant reversibly bind to oxygen like cobalt.

2) The higher temperature favours formation of suffecient void, the molecular oxygen can easily penetrate in these voids of cobal-silane complex crystal

3) we need isolated yield to answer this question.