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Download filePreparation, Structure, and Properties of Tetranuclear Vanadium(III) and (IV) Complexes Bridged by Diphenyl Phosphate or Phosphate
journal contribution
posted on 2012-05-07, 00:00 authored by Kyouhei Sato, Tetsuya Ohnuki, Haruka Takahashi, Yoshitaro Miyashita, Koichi Nozaki, Kan KanamoriThree novel tetranuclear vanadium(III) or (IV) complexes
bridged by diphenyl phosphate or phosphate were prepared and their
structures characterized by X-ray crystallography. The novel complexes
are [{V(III)2(μ-hpnbpda)}2{μ-(C6H5O)2PO2}2(μ-O)2]·6CH3OH (1), [{V(III)2(μ-tphpn)(μ-η3-HPO4)}2(μ-η4-PO4)](ClO4)3·4.5H2O (2), and [{(V(IV)O)2(μ-tphpn)}2(μ-η4-PO4)](ClO4)3·H2O (3), where hpnbpda and tphpn are alkoxo-bridging dinucleating
ligands. H3hpnbpda represents 2-hydroxypropane-1,3-diamino-N,N′-bis(2-pyridylmethyl)-N,N′-diacetic acid, and Htphpn represents N,N,N′,N′-tetrakis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine. A dinuclear
vanadium(IV) complex without a phosphate bridge, [(VO)2(μ-tphpn)(H2O)2](ClO4)3·2H2O (4), was also prepared
and structurally characterized for comparison. The vanadium(III) center
in 1 adopts a hexacoordinate structure while that in 2 adopts a heptacoordinate structure. In 1, the
two dinuclear vanadium(III) units bridged by the alkoxo group of hpnbpda
are further linked by two diphenylphosphato and two oxo groups, resulting
in a dimer-of-dimers. In 2, the two vanadium(III) units
bridged by tphpn are further bridged by three phosphate ions with
two different coordination modes. Complex 2 is oxidized
in aerobic solution to yield complex 3, in which two
of the three phosphate groups in 2 are substituted by
oxo groups.
