Heptacoordinate vanadium(III) complexes containing a didentate sulfate ligand. X-ray structures of [V2(SO4)3{N, N′-bis(2-pyridylmethyl)-1,2-ethanediamine}2] and [V(SO4){N,N,N′, N′-tetrakis(2-pyridylmethyl)-1,2-ethanediamine}]+ and their solution properties

Article abstract of DOI:10.1246/bcsj.69.2901

Several vanadium(III) complexes with a tetradentate N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine (bispicen) or a hexadentate N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-ethanediamine (tpen) ligand were prepared and characterized by UV-vis and Raman spectroscopy. Of these complexes, the structures of two vanadium(III) complexes with a didentate sulfate were determined by X-ray crystallography. [V₂(SO₄)₃(bispicen)₂] crystallizes in the monoclinic space group ClIc with a=25.083(7), b=24.236(5), c=15.708(5) A, β=114.96(2)°, Z=8, and R=0.087. The complex containing the [V(SO₄)-(tpen)⁺ cation crystallizes in the orthorhombic space group Aba2 with a=20.1836(8), b=19.793(1), c=15.6107(7) A, Z=8, and R=0.069. Both complexes adopt a heptacoordinate pentagonal bipyramidal structure in which the didentate sulfate is situated in the pentagonal plane. The heptacoordinate structure of the tpen-SO₄^2- complex is stable in an aqueous solution, whereas the bispicen-SO₄^2- complex is easily aquated to yield a hexacoordinate oxo-bridged dinuclear species.