Be carefull with that.. Did you install your vCenter using hostname and not ip address? There are a lot of issue regarding SSO.
So, if you have a VM, Power-off your VM, take a snapshot, and make the change. (Only if you have installed your vCenter using hostname).
Changing the IP address of vCenter Server « VirtualBacon
In case , you made your install using IP address , you will need to re-install the VC.
Regards,
Randhir
