This gives you the pre-requisites for linked mode vSphere 5.5 Documentation Center
It states that
vCenter Server does not support Linked Mode groups that contain different 5.x versions of vCenter Server or different versions of vCenter Single Sign-On. After all 5.x vCenter Server and vCenter Single Sign-On instances in a Linked Mode group are upgraded to the same 5.x version, you can rejoin them.
So that means no you can't do it.