Heteroatom Sb And Bi Sandwich-type Heteropoly Compounds

In the past few years, sandwich-type heteropolyoxometalates (HPOM) encapsulating clusters of early transition metals have received much attention both from applied (in material science, medicine, catalysis) and fundamental research perspectives. The great advantage of these complexes is the possibility of varing either the type of the metallic cluster (its structural topology and the nature of the transition metals) or the heteroatom. The proximity of the transition metals possessing unpaired electrons facilitates their coupling through exchange, superexchange or dipolar interaction. These are the starting points for magnetic cluster formation. The metallic cluster is usually encapsulated between two Keggin or Dawson- Wells trivacant fragments.In this paper, several heteropolytungstates containing trivacant Keggin anion XW9O339- (heteroatoms = SbIII and BiIII) have been studied and ten new heteropolyanions have been synthesized. Their formulas are as follows:Sandwich type heteropolyanions:Na9[{Na(H2O)2}3{Cu(H2O)}3(BiW9033)2]-42H2O(I)Na9[{Na(H2O)2}3 {Zn(H2O)}3(BiW9O33)2]-46H2O (II)Na9[{Na(H2O)2}3{Co(H2O)}3(SbW9O33)2]-40H2O(in)Sandwich type heteropolyanions in which coordination waters were replaced by organic ligands:Na9[{Na(H2O)}3{Co(C3H4N2)}3(BiW9033)2]-35H2O(V)Na9[{Na(H2O)}3{Co(C3H4N2)}3(SbW9033)2]-35H2O(VII)Na9[{Na(H2O)}3{Zn(C3H4N2)}3(SbW9033)2]-38H2O (VIII)Na9[{Na(H2O)}3{Ni(C3H4N2)}3(SbW9033)2]-47H2O(IX)Na9[{Na(H2O)}3{Mn(C3H4N2)}3(SbW9033)2]-42H2O(X)All the heteropolyanions are characterized by IR, UV-Vis, CV and element analysis. The crystal structure of Na9[{Na(H2O)2}3{Cu(H2O)}3(BiW9O33)2]-42H2O (I),Na7(C2H8NO)2[{Na(H2O)2}3{Co(H2O)}3(SbW9O33)2]-40H2O(IV) and Na9[{Na(H2O)}3{Co(C3H4N2)}3(BiW9033)2]-35H2O(V) were determined by X-ray single-crystal analysis. The magnetic properties and the thermogravimetry of heteropolyanions (I) and (V) were studied.In our work, there are two important contributions:1. For the first time, we characterized the crystal structure of the sandwich type heteropolyanion I, which offers strongly structural proof for the existing of the sandwich type heteropolyanion containing Bi as heteroatom, simultaneously, several wrong reports about this type of polyanion are rectified.2. For the first time, we synthesized and reported sandwich type heteropolyanions in which coordination waters were replaced by organic ligands, V-X, and the structure of compound V was determined by X-ray diffraction.