Rubidium oxalate

Rubidium oxalate is a chemical compound with the chemical formula. It is a rubidium salt of oxalic acid. It consists of rubidium cations and oxalate anions. Rubidium oxalate forms a monohydrate.

Structure

From an aqueous solution, rubidium oxalate crystallizes as a monohydrate in the monoclinic crystal system and is isomorphic to potassium oxalate monohydrate. Two forms of the anhydrous form exist at room temperature: one form is monoclinic and isotypic to caesium oxalate, the other is orthorhombic and isotypic to potassium oxalate. Freshly prepared anhydrous rubidium oxalate initially contains mainly the monoclinic form, but this slowly transforms irreversibly into the orthorhombic form. In 2004, two more high-temperature forms of rubidium oxalate were discovered.
Crystal data of the different forms of rubidium oxalate

Form	Crystal system	Space group	a in Å	b in Å	c in Å	β	Z
Alpha	monoclinic	P2₁/c	6.328	10.455	8.217	98.016°	4
Beta	orthorhombic	Pbam	11.288	6.295	3.622	—	2
Monohydrate	monoclinic	C2/c	9.617	6.353	11.010	109.46°	4

Preparation

and oxalic acid react to form rubidium oxalate:
Rubidium oxalate can also be obtained via the thermal decomposition of rubidium formate:

Reactions

The decomposition of rubidium oxalate with the release of carbon monoxide and subsequently carbon dioxide and oxygen takes place at.
Upon evaporation of a solution in hydrogen peroxide, rubidium oxalate forms a monoperhydrate of the formula, which forms monoclinic crystals that are relatively stable in air.
Rubidium oxalate reacts with hydrogen fluoride to form a hydrofluoridate salt :

Related compounds

In addition to the neutral rubidium oxalate, there is also an acidic salt, rubidium hydrogen oxalate with the formula, which is isomorphic to potassium hydrogen oxalate and forms monoclinic crystals, and an acidic dioxalate with the formula, which exists as a dihydrate, has a density of 2.125 g/cm³ at 18 °C and a solubility of 21 g/L at 21 °C.