Final answer:
The relationship between (2R,3R)-2,3-dibromopentane and (2R,3S)-2,3-dibromopentane is that they are Diastereomers, as they are stereoisomers that are not mirror images and have different configurations at one or more stereocenters.
Step-by-step explanation:
The relationship between (2R,3R)-2,3-dibromopentane and (2R,3S)-2,3-dibromopentane is that they are Diastereomers. Diastereomers are stereoisomers that are not mirror images of each other and have different configurations at one or more (but not all) of the relevant stereocenters. Since (2R,3R)-2,3-dibromopentane has opposite configurations at the 3rd carbon compared to (2R,3S)-2,3-dibromopentane, they cannot be mirror images, and thus cannot be Enantiomers. Constitutional Isomers have the same molecular formula but different connections among their atoms, which is not the case here as the connectivity is the same in both compounds. Because they share the same connections, they are not Constitutional Isomers, and because they are not identical in their 3-D structure, they are not Identical Compounds.