Facile synthesis of mononuclear early transition-metal complexes of κ<sup>3</sup>cyclo-tetrametaphosphate ([P<sub>4</sub>O<sub>12</sub>]<sup>4−</sup>) and cyclo-trimetaphosphate ([P<sub>3</sub>O<sub>9</sub>]<sup>3−</sup>)
Dalton transactions