Following the RDBE blogs, I decided to run a little test pointed out to me by Robin Martin, Ph.D. Without using the RDBE formula, what is the RDBE (number of rings) for cubane (structure shown below)?
Starting with the 2D representation of cubane, it comes down to counting how many bonds are removed to displace a ring.
According to the diagram above, the RDBE of cubane is 5 and not 6 according to the 3D representation.
TIP: The number of faces on a 3D structure does not dictate the RDBE value.