I have searched high and low for this compound and I can't find it. If (NH3)2Cl4Pt(IV) exists it will have an oxidation state of 0 since NH3 is zero and the +4 for Pt is balanced by the -4 of 4Cl^-. Since you write a space between sodium and the rest of it it should mean sodium is a cation and the other part an anion. Here is a quote from Whitten, Davis, and Peck General Chemistry, page 899, 5th edition. "The suffice 'ate' at the end of the name of the complex signifies that it is an anion. If the complex is neutral or cationic)(italics mine), no suffix is used." Therefore, Na[(NH3)2PtCl4]+ won't fit the rules (and I think an earlier post said that was not the correct answer). It must be an anion to have the name "ate" and it isn't an anion.
