Sentence:  However , any oxygen nonequivalence would shorten either the already extremely short **f interlayer distance of 2.55 A or the non <WSD>hydrogen</WSD> bonded **f interlayer interactions which are already quite short at 2.58 A . 
Meaning of the word marked with <WSD> tags:  a chemical bond consisting of a hydrogen atom between two electronegative atoms (e.g., oxygen or nitrogen) with one side be a covalent bond and the other being an ionic bond