Polynuclear complexes of vanadium and molybdenum with organoarsonato- and organophosphonato ligands: Their syntheses and characterizations

A new series of polyoxometalate clusters has been synthesized by reacting organophosphonates and organoarsonates with vanadium and molybdenum starting materials in non-aqueous systems. The chemistry of these polynuclear clusters has been examined spectroscopically and X-ray crystallographically. In chapter two, one fully oxidized compound, (TBA)$\rm\sb2(NH\sb4)\sb2$(V$\rm\sb{10}O\sb{24}(O\sb3AsC\sb6H\sb4$-4-NH$\sb2)\sb3$) (TBA = (n-C$\rm\sb4H\sb9)\sb4N\sp{+}$), and a mixed valence cluster, (TBA)$\sb2$ (H$\rm \sb2\{V\sb6O\sb{10}(O\sb3AsC\sb6H\sb5)\sb6\}$) $\cdot$ 2H$\sb2$O are described along with two additional organophosphonato-polyoxovanadates: a novel pentanuclear oxovanadium organophosphonate, (Ph$\sb4$P) (V$\rm\sb5O\sb7(OCH\sb3)\sb2(PhPO\sb3)\sb5$) $\cdot$ CH$\sb3$OH $\cdot$ 0.5CH$\rm\sb2Cl\sb2$ and a cluster of clusters , (Ph$\rm\sb4P)\sb4$ (V$\rm\sb{18}O\sb{25}(H\sb2O)\sb2 (PhPO\sb3)\sb2OCl\sb4$) $\cdot$ 6CH$\sb3$CN $\cdot$ 2CH$\sb3$OH which shows an unusual relationship resulting from aggregation of four subunits of the pentamer structure. In chapter three, reactions between MoCl$\sb5$ and organoarsonates and/or organophosphonates in either conventional or solvothermal conditions are reported. (MoOCl$\sb4$) (Mo$\rm\sb4O\sb8(C\sb6H\sb4AsO\sb2Cl)\sb4$) $\cdot$ Cl $\cdot$ 4H$\sb2$O and (Mo$\rm \sb4O\sb8(ClO\sb2AsC\sb6H\sb4$-4-CH$\sb3)\sb4$) $\cdot$ Cl $\cdot$ 8MeOH $\cdot$ 9H$\sb2$O show similar geometries of shallow bowl-like constructions. (Mo$\rm\sb2O\sb2Cl\sb7$) $\sb2$ (Cl$\rm\sb3AsC\sb6H\sb4$-4-NH$\sb3$) demonstrates a non-superimposable mirror plane between two binuclear units whose two metal centers are linked by face-sharing resulting from three chloride atoms adapting bridging geometries. (Mo$\rm\sb2(OH)\sb2Cl\sb4\{$(2-CH$\sb3$-C$\rm\ sb6H\sb4$-CH$\sb2$-)$\rm\sb2P\sb2O\sb4(OC\sb2H\sb5)\}\sb2$) $\cdot$ (C$\rm\sb2H\sb5)\sb2$O consists of two octahedral Mo units linked by condensed organodiphosphonate ligands. In chapter four, the Mo/O/REO$\sb3$ system (E = P, As) is further developed by using molybdenyl acetylacetonate to react with a series of organic ligands. The results include a wide range of polynuclear species assembled from bi-, tetra-, penta- and hexanuclear Mo units with different types of connections including edge-, corner- and face-sharing linkages. ((Et)$\sb3$NH) $\sb4$ ((Mo$\rm\sb2O\sb5)\sb2(C\sb6H\sb5PO\sb3)\sb4$) $\cdot$ 2CH$\sb3$CN and ((Et)$\sb3$NH) $\sb4$ ((Mo$\rm\sb2O\sb5) \sb2(C\sb6H\sb5AsO\sb3)\sb4$) $\cdot$ 4H$\sb2$O exhibit the same composition and geometry of the tetranuclear anionic arrangement. ((Et)$\sb3$NH) $\sb4$ (Mo$\rm\sb6O\sb{18}(\{CH\sb3\}\sb3CPO\sb3)\sb2$) $\cdot$ CH$\rm\sb3CH(OH)CH\sb3$ and ((Et)$\sb3$NH) $\sb4$ ((Mo$\rm \sb2O\sb5)\sb2(CH\sb2(PO\sb3)\sb2)\sb2$) $\cdot$ 2CH$\sb3$CN demonstrate the unusual twist observed in the binuclear Mo subunits within the anions. ((Et)$\sb3$NH) $\sb2$ (Mo$\rm\sb2O\sb5(\{C\sb6H\sb5\}\sb2PO\sb2)\sb4$) $\cdot$ CH$\sb3$CN demonstrates that two of the organophosphinato ligands still choose cis-positions to bridge two Mo centers despite the bulky phenyl-ring substituents. ((Pr)$\sb3$NH) $\sb4$ (Mo$\rm\sb5O\sb{15}(CH\sb3PO\sb3)\sb2$), ((Et)$\sb3$NH) $\sb4$ (Mo$\rm\sb5O\sb{15}(C\sb6H\sb5CH\sb2PO\sb3)\sb2$) and ((Et)$\sb3$NH) $\sb4$ (Mo$\rm\sb6O\sb{18}$(2-NH$\sb2$-C$\rm\sb6H\sb4AsO \sb3)\sb2$) provide examples of analogous anionic structures with different organo-group substituents. ((Et)$\sb3$NH) $\sb3$ (Mo$\rm\sb4 O\sb{10}$(4-CH$\sb3$-C$\rm\sb6H\sb4AsO\sb3)\sb2$(4-CH$\sb3$-C$\rm \sb6H\sb4AsO\sb3H)\sb2$) $\cdot$ (4-CH$\sb3$-C$\rm\sb6H\sb4AsO\sb3$H) $\cdot$ H$\sb2$O shows the phenomenon of alternating arrangement of inorganic- and organic layers throughout the framework which is a characteristic property observed in solid state chemistry