Question

What is the ionic compound with the formula Pr2(SeO4)3?

Answer 1

This is praseodymium salt of selenic acid.

You can look structrure here .

Answer 2

The formula `"Pr"_2"(SeO"_4)""_3"` is an ionic compound composed of the praseodymium cation `"Pr"^(3+)`, and the selenate anion `"H"_2"SeO"_4""^(2-)`. Ionic compounds are named according the ions that are present so that the name of the cation goes first, followed by the name of the anion.

The name of `"Pr"_2"(SeO"_4)""_3"` is praseodymium selenate.
(Source):
http://praseodymium.atomistry.com/praseodymium_selenate.html

Its IUPAC* name is praseodymium(3+);triselenate.

*IUPAC is the International Union of Pure and Applied Chemistry.

An alternate chemical formula is `"O"_12"Pr"_2"Se"_3`.
(Source:)
http://www.chemicalbook.com/ProductChemicalPropertiesCB6840026_EN.htm

2D structural formula is: