Heteropolymetalate Clusters of the Subvalent Main Group Elements BiIII and SbIII

The heteropolyanions [Bi2W22O74(OH)2]12- (1) and [X2W20M2O70(H2O)6](14-2n)- (X = Sb3+, Bi3+; Mn+ = Fe3+, Co2+, Zn2+) (2−7) have been synthesized as alkali metal and ammonium salts, respectively, and characterized by elemental analysis, infrared spectroscopy, and X-ray crystallography. These tungsto bismutates and antimonates reveal one common feature: the trivacant β-B−XW9O33 Keggin fragment as the structural building unit. Formally, the unit can be derived from the Keggin structure by removing one trimetalate fragment, W3O13, and a 60° rotation of one of the remaining W3O13 subunits around the X−OW3X bond vector (the subscript indicates the element(s) bonded). The unshared pair of electrons of the respective central, pyramidally coordinated heteroatom SbIII or BiIII prevents formation of the complete spherical structure. In the presented heteropolyanions 1−7, two β-B-XW9O33 units are connected by two WO2 groups. Further stabilization of this hitherto unknown bis-decatungsto ion [X2W20O70]14- is reached either by addition of two formal fac-WO3 anti-Lipscomb's rule units to give the bis-undecatungsto bismutate [Bi2W22O74(OH)2]12- (1) or by addition of two Mn+(H2O)3 groups (Mn+ = Fe3+, Co2+, Zn2+) forming the large, transition-metal-substituted heteropolyanion clusters [X2W20M2O70(H2O)6](14-2n)- (X = Sb3+, Bi3+; Mn+ = Fe3+, Co2+, Zn2+) (2−7).