Formation of high nuclearity mixed-valent polyoxovanadates in the presence of copper amine complexes

Two new Müller-type clusters, a one-dimensional solid {Cu(en)2}4[C1 subset of V15O36]12H2O 1, and a three-dimensional solid {Cu(pn)2}4[C1subset of V18O42] 12H2O 2, have been synthesised by employing identical hydrothermal conditions except varying the nature of organic diamine. 1 crystallised in a chiral space group P212121 with a = 12,757(1), b = 18,927(2) and c = 28,59(3) Å, and Z = 4. 2 crystallised in a tetragonal system with space group P4/nnc, a = 15,113(1) and c = 18,542(3) Å, and Z = 2. Mixed-valent vanadium ions in structures 1 and 2 have been established both by magnetisation and bond-length bondvalence measurements. Chemistry of formation of high nuclearity polyoxovanadate clusters is discussed.