Questions about molec. geometry and electron pairing

[adamc637]

I have 2 questions which I'm just pondering because I can't answer them

First is

If triamminetetrachloroplatinum(V) ion (Pt(NH3)2Cl4 +) were to be put into a hexagonal planar geometry, how many geometric isomers would it have? Is it possible to have this arrangement or not from what you see from the drawings?

I drew them out, and I can't think of why it would rule hexagonal planar out other than being polar and the molecules pushing it away (which doesn't sound too plausible anyways).

Second question:
In the case of transition metals, going from group IIIB to group VB or VIB, the melting point gets higher because "the electrons are not paired". Why does having paired electrons in group VIB and up cause the boiling point to fall?

 

[quetzalcoatl9]

If triamminetetrachloroplatinum(V) ion (Pt(NH3)2Cl4 +) were to be put into a hexagonal planar geometry, how many geometric isomers would it have? Is it possible to have this arrangement or not from what you see from the drawings?

draw the molecule out and you will see that there are 3 possible isomers.

however, the hydrogens on the amines will repel each other and you will wind up with a pentagonal pyramidal structure.

 

[lotsoluv4ya]

I think this website should help you . . .

I had a huge test on molecular geometries not too long ago. I was having a lots of difficulty with them, but then I found this great website that has a link for every geometric shape and with it examples, pictures, and important notes. The website is http://intro.chem.okstate.edu/1314F00/Lecture/Chapter10/VSEPR.html. I hope it helps you, I know it really helped me. Good luck!