Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Your idiot lab mate has done it again-didn\'t label the breakers of ligands that

ID: 975908 • Letter: Y

Question

Your idiot lab mate has done it again-didn't label the breakers of ligands that you so carefully measured out for a lab involving cobalt complexes. You mixed each of these ligands with a dilute solution of Co(II, and heated for a while with H_2O_2 to produce the Co(III)L_6 compounds. They are vividly colored! While excited by the chromatic feast before your eyes, now you have to sleuth out which beaker contained which ligand, and justify your choices with a brief explanation. Your explanation should detail the (1) sigma/Pi donor/acceptor properties of each ligand, and (2) how those relate to the colors of the complex. Ligand solutions: NH_3, KCN, CsF, H_2O Colors of solutions formed: colorless, green, orange, blue You may assume that all are low-spin complexes (not strictly true in one case, but it doesn't change the answer)

Explanation / Answer

ligand------> NH3 KCN CsF H2O

COLOR ORANGE COLORLESS GREEN BLUE

1) CN- is a strong ligand due to their strong pi acceptor and leads to large splitting in t2g and eg which corresponds to ultravoilet region or colorless.

2) NH3 is strong field ligand / weak pi acceptor and leads to a less splitting in t2g and eg and shows a orange color

3) H2O is a weak sigma donor and it is a weak field ligand leads to a less splitting in t2g and eg and shows a blue color

4) F- is a strong  sigma donor and it is a weak field ligand leads to a less splitting in t2g and eg and shows a green color