# Chemical bonding with f orbitals

For the elements such as rhenium, osmium, iridium how probable is for electrons in the inner 4f orbitals to gain energy and take part in a molecular orbital (such as an $f^2 d^2 s p^3$ hybrid orbital) when these elements are in their 6,7,8,9 oxidation state?

• There's no such hybrid and d block doesn't use f-electrons for bonding. Jul 9 '17 at 19:08
• en.wikipedia.org/wiki/Quintuple_bond Jul 9 '17 at 19:20
• You should read papers: here, here and here Sep 9 '20 at 3:55