Main Question or Discussion Point
I read that coordination bonds can be formed when a Lewis base like NH3 uses its lone pair of electrons to bond to an empty d orbital on a transition metal. I don't get how this applies to elements with 5 or more electrons in their d orbital though. For example cobalt has 7 d electrons so I'm guessing that 2 of the 5 d orbitals have paired electrons and the other 3 have lone electrons in them. Doesn't that mean there are no empty d orbitals for Lewis bases to react with? How does cobalt form 6 coordination bonds?