An unexpected triammine(oxalato)platinum(II) complex obtained from the aqueous solution of tetraammineplatinum(II) oxalate.

An unexpected complex, triammine(oxalato)platinum(II) in which oxalate anion acts as a monodentate ligand, was isolated in the process of recrystallizing [Pt(NH)](CO). The complex was presumably formed via the loss of one ammonia molecule from [Pt(NH)](CO), followed by the binding of oxalate from the outer coordination sphere. Single crystal X-ray diffraction study revealed that the Pt(II) atom was coordinated on a distorted square by three N atoms of the ammine molecules and one O atom of the oxalate ligand. The crystal packing was stabilized by moderate to strong hydrogen bonds formed between ammine, water molecules and O atoms of oxalate with d(N···O) in the range of 2.84(2)-3.29(2) Å, and d(O···O) in the range of 2.86(2)-3.37(2) Å. The complex underwent thermal decomposition at 200-231 °C in the nitrogen atmosphere, giving rise to Pt, NH and CO. [ABSTRACT FROM AUTHOR]