▁formal ▁de h yd r ation ▁sometimes ▁yields ▁fairly ▁stable ▁ox oc ar b ons , ▁such ▁as ▁m ell it ic ▁an h yd ride ▁C 1 2 O 9 ▁from ▁m ell itate ▁ ▁via ▁m ell it ic ▁acid ▁C 1 2 H 6 O 1 2 ▁ ▁H ydro gen ated ▁an ions ▁For ▁each ▁ox oc ar bon ▁an ion ▁ ▁there ▁are ▁in ▁principle ▁n − 1 ▁partially ▁hydro gen ated ▁an ions ▁with ▁formulas ▁, ▁where ▁k ▁ranges ▁from ▁ 1 ▁to ▁n − 1 . ▁ ▁These ▁an ions ▁are ▁generally ▁indicated ▁by ▁the ▁prefix es ▁" h ydro gen " -, ▁" d ih ydro gen " -, ▁" tri h ydro gen " -, ▁etc . ▁Some ▁of ▁them , ▁however , ▁have ▁special ▁names : ▁hydro gen car bon ate ▁ ▁is ▁commonly ▁called ▁b ic ar bon ate , ▁and ▁hydro gen ox al ate ▁ ▁is ▁known ▁as ▁b ino x al ate . ▁ ▁The ▁hydro gen ated ▁an ions ▁may ▁be ▁stable ▁even ▁if ▁the ▁fully ▁pro ton ated ▁acid ▁is ▁not ▁( as ▁is ▁the ▁case ▁of ▁b ic ar bon ate ). ▁ ▁Ext reme ▁cases ▁The ▁car b ide ▁an ions , ▁such ▁as ▁ac ety lide ▁ ▁and ▁m eth an ide ▁C 4 − , ▁could ▁be ▁seen ▁as ▁extreme ▁cases ▁of ▁ox oc ar bon ▁an ions ▁, ▁with ▁y ▁equal ▁to ▁zero . ▁ ▁The ▁same ▁could ▁be ▁said ▁of ▁o