[idgirl]

Hey...

I was wondering:

I am in inorganic chemistry and I was reviewing VSPEPR stuff.  I was looking at the two molecules, Sb(Ph)5 and P(Cl)5.  Sb(Ph)5 has square pyramidal geometry, whereas PCl5 has trigonal bipyramidal geometry.  This occurs even though both have the same coordination number.  Why is this?  Does it have to do with the size of the atoms?  Or the influence of different orbitals in the molecular orbital? 

Thanks in advance ^_^

-Mary-

[FeLiXe]

i would guess it's the size of the ligand
maybe you can arrange those 5 phenyl rings better in a square pyramid (?)

[complex]

Are they both neutral complexes? If the charges on the metal ion are different I think that could potentially affect geometry.