Xinyi Wei

New developments in the chemistry of heteropolytungstates of rhodium and cerium

The heteropolytungstates [PW11O39RhCl]5− (I), [PW11O39RhCH2COOH]5− (III), and [PW11O39Rh2(OAc)2]5− (IV) are prepared by hydrothermal reaction of [PW11O39]7− with RhCl3 or Rh2(OAc)4 and characterized by NMR and X-ray structure determination. Electrolytic reduction of I yields the dimeric species [(PW11O39Rh2)]10− (II) which reacts with C6H5CH2Br under photochemical conditions to yield dibenzyl and [PW11O39RhBr]5− in a process analogous to Rh-porphyrins. Anion III and the corresponding Sicentered anion are rare examples of complexes with Rh-C bonds prepared in aqueous solution. Reaction of B-α [AsIIIW9O33]9− with LnIII yields new, massive heteropolytungstates [As2Ln2(H2O)W29O103]17− Ln = La, Ce(V), [Ce4(H2O)4 − 4x(AsW9O33)4As(WO3)2 + x(WO5)]25−, x < 0.5 (VI), and As12Ln16(H2O)36W184O324]76−; Ln La,Ce (VII) with approximate relative molecular masses of 7 600, 10 500, and 40 000 respectively. Anion VII has a folded cyclic structure with a radius of 4 nm and is the largest heteropolytungstate so far reported. It is synthesized in yields of ca 30 % under mild conditions.