What would be the name of 6-ring (hexane) linked to a 7-ring (heptane)?
The name would be cyclohexylcycloheptane.
Are you referring to the structure below?
You start by finding the largest ring (7 carbons).
The base name becomes cycloheptane.
Then you identify the substituent. It is a six membered ring (cyclohexane).
You form the name of a substituent by replacing the "ane" ending with "yl".
The name of the substituent is cyclohexyl.
Place the name of the substituent in front of the base name.
The name of the compound is cyclohexylcycloheptane.