Complex sentence: At the same time, very high oxidation states are known for oxygen-based species only; for example, ruthenium octafluoride has not been synthesized, while ruthenium tetroxide is well-studied.
Split into simpler sentences: At the same time, very high oxidation states are known for oxygen-based species only. For example, ruthenium octafluoride has not been synthesized, while ruthenium tetroxide is well-studied.