Naming monodentate ligand complexes

[crays]

Hi guys, i know how to name monodentate ligand complexes but there is a particular one that my textbook and teacher's notes is quite the opposite, its regarding the fac and mer isomer.

for a Ma₃b₃ structure,

a fac forms a face and a mer have the ligands in meridian position, but for these two, which are the cis and which are the fac? My textbook says, fac is equivalent to cis but my teacher's notes says the opposite, help please?

 

[chemisttree]

Nobody's perfect.

 

[Blueshift5]

Hello,

Thank you for reaching out about naming monodentate ligand complexes. The fac and mer isomers can be a bit confusing, but I will do my best to clarify.

First, let's define what fac and mer mean. Fac stands for facial, which means the ligands are arranged in a way that forms a face. Mer stands for meridional, which means the ligands are arranged in a way that forms a meridian line.

Now, for a Ma3b3 structure, the fac isomer would have all three ligands on one face of the central metal ion, while the mer isomer would have the ligands arranged around a meridian line. It may help to visualize the structures in three dimensions to better understand this.

In terms of cis and trans, these terms refer to the relative positions of two ligands on opposite sides of the central metal ion. In a cis isomer, the two ligands are on the same side, while in a trans isomer, the two ligands are on opposite sides.

So, to answer your question, the fac is equivalent to the cis isomer, as they both have the ligands arranged on one face of the central metal ion. The mer is equivalent to the trans isomer, as they both have the ligands arranged around a meridian line.

I hope this helps clarify things for you. If you have any further questions, please don't hesitate to ask. Best of luck with your studies!