Complex sentence: In the IUPAC nomenclature, however, hexane is the unbranched isomer ("n"-hexane); the other four structures are named as methylated derivatives of pentane and butane.
Split into simpler sentences: In the IUPAC nomenclature, hexane is the unbranched isomer ("n"-hexane). In IUPAC nomenclature, the other four structures are named as methylated derivatives of pentane and butane.