Spontaneous reaction and self-assembly of copper nitrate and cyclic 1,3-dione dioximes into multicopper complexes

We have found that Cu(NO3)2 and 1,3-dione dioxime afford a variety of multicopper complexes under ambient conditions. Specifically, Cu(NO3)2 and cyclohexane-1,3-dione dioxime gave a trinuclear complex in which the central α-carbons of the three dioxime ligands are oxidized into carbonyl groups, two of which were further reacted with solvent MeOH to give a hemiacetal structure. On the other hand, Cu(NO3)2 and cyclopentane-1,3-dione dioxime gave a dinuclear complex in which Cu(II) was reduced to Cu(I) and two of the three ligands couple to give the fulvalene structure. Together with the previously reported reaction of Cu(NO3)2 and pentane-2,4-dione dioxime into a pentanuclear complex in which the four ligands were changed into trioximes, surprisingly rich chemistry has been discovered for combinations of Cu(NO3)2 and 1,3-dione dioximes.