Diiron(III)-Containing 23-Tungsto-2-Borate: First Evidence of 3d Metal Substitution in the {BW13} Framework


  • Dedicated to Professor Michael T. Pope on the occasion of his 80th birthday


The reaction of [HBW11O39]8–, (WO4)2–, and Fe3+ (1:2:3 ratio) in water at pH 1.5 resulted in [{FeIII(H2O)3}2(WO2)(HBW11O39)2]8– (1), the first 3d-metal-substituted tungstoborate whose structure differs from that of a monosubstituted Keggin framework. Polyanion 1 is composed of an unprecedented 23-tungsto-2-borate subunit stabilized by FeIII coordination at the external positions. The linkage mode of the 11-tungstoborate fragments in 1 evidences that substitution of tungsten by 3d metals can occur in the capping positions of the {BW13} skeleton.