Syntheses and Magnetic Properties of Ruthenium(II,III) Pivalate Dimers Axially Coordinated by Nitronyl Nitroxide Radicals [Ru2(O2CCMe3)4(L)2]BF4 and [{Ru2(O2CCMe3)4(L)2}{Ru2(O2CCMe3)4(H2O)2}]n(BF4)2n, L = 2,4,4,5,5-Pentamethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide and 2-Ethyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide

The reaction of [Ru2II,III(O2CCMe3)4]BF4 with nitronyl nitroxide radicals (2,4,4,5,5-pentamethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (nitme) and 2-ethyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-N-oxide (nitet)) in CH2Cl2/hexane gave dimer and chain complexes [Ru2(O2CCMe3)4(L)2]BF4 and [{Ru2(O2CCMe3)4(L)2}{Ru2(O2CCMe3)4(H2O)2}]n(BF4)2n (L = nitme and nitet). The latter complexes have a chain structure formed by hydrogen bonds between the axial radical ligands and the water molecules. It was shown that the antiferromagnetic interaction between the coordinated radicals through the Ru–Ru bond as well as the ferromagnetic interaction between the radical and the Ru(II,III) dimeric core are operative for all of the complexes. Both of the magnetic interactions were concluded to result from their axial Ru–Oax–N bond angles being close to 120°. The hydrogen bonds were not found to be magnetically important in the chain complexes.