Promethium(III) oxalate is an oxalate of promethium, with the chemical formula Pm2(C2O4)3. Its decahydrate crystallizes in the monoclinic crystal system with space group P21/m. Promethium(III) oxalate trihydrate can decompose into stable basic carbonate Pm2O2CO3,McNeilly, C. E.; Roberts, F. P. Thermal analysis of promethium oxalate. Therm. Anal., Proc. Int. Conf., 2nd, 1969 (2): 727-738. CODEN: 21RQA2. and generate promethium(III) oxide at higher temperatures.
In all lanthanide oxalates, promethium(III) oxalate has the lowest solubility.
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