# Why doesn't LiHCO3 exist in solid state?

I have read that $\ce{LiHCO3}$ does not exist in solid state. Is it because of the size of anion-cation concept or is it something else? So why is it only for lithium and not for sodium too?

• This site states that it is a solid at room temperature, guidechem.com/dictionary/5006-97-3.html but information on this compound seems scarce. – porphyrin Feb 27 '17 at 11:58
• Why does beryllium peroxide not exist? Why is magnesium peroxide only metastable but by the time you get to barium the peroxide is fully stable? Polarization by small, densely packed cations tends to pull polyatomic anions like peroxide or bicarbonate apart, leaving smaller nations in the compound like oxide or carbonate. – Oscar Lanzi May 1 '17 at 1:27
• CRC handbook of chemistry and physics (also latest 97th Ed.) includes $\ce{LiHCO3}$ in the table "Physical Constants of Inorganic Compounds" (4-70) as white powder, slightly soluble in water 0_O. – andselisk Aug 29 '17 at 2:52

It's is because $\ce{Li}$ is in diagonal relationship with $\ce{Mg}$ in periodic table. As magnesium hydrogen carbonate is not obtained in solid form, $\ce{LiHCO3}$ also cannot be since both have similar properties.
Due to the small size of lithium, it will polarize the large anion oxygen, the $\ce{C-O}$ bond will weaken and $\ce{Li-O}$ bond will strengthen, they will split, and they will not be in the solid state.