... Tetrahedron. Volume 69, Issue 2, 14 January 2013, Pages 613–617. Cover image Cover image. ... Initially, several Cu(I) and Cu(II) salts, such as Cu 2 O, CuI, CuO, CuSO 4 , and CuCl 2 were tested with 2 equiv of K 3 PO 4 in PEG-400 at 120 °C for 6 h in argon. ...