Hydrolytic species of V(H2O)63+ in relevance to the intracellular vanadium in ascidians

New Perspectives in the Chemistry and Biochemistry of the Tunichromes and Related Compounds

“…Michibata proposes that vanadium is bound by vanadium-binding proteins in the signet ring cells and vacuolated amoebocytes . Meier et al proposed an equilibrium in ascidian blood cells between monomeric, oligomeric, and membrane-bound vanadium(III) based on speciation studies by spectrophotometric titrations . Details for both proposals can be found in the respective reviews.…”

“…91 Meier et al proposed an equilibrium in ascidian blood cells between monomeric, oligomeric, and membrane-bound vanadium(III) based on speciation studies by spectrophotometric titrations. 92 Details for both proposals can be found in the respective reviews. A very recent report on the magnetic properties of ascidian blood cells using a superconducting quantum interference device (SQUID) suggested that the predominant form of vanadium(III) storage was as a ferromagnetically coupled dimer with a putative unprotonated µ-oxo bridge.…”

Aqua Ions. 1. The Structures of the [Ru(OH2)6]3+ and [V(OH2)6]3+ Cations in Aqueous Solution: An EPR and UV−Vis Study

“…Absorption spectra of solutions containing the vanadium-(III) cation are well-known, and an excellent review article on vanadium(III) in aqueous solution has been provided by Roland Meier and co-workers. 40 The absorption spectra of vanadium(III) as a function of sulfate concentration have been particularly well characterized 40 as the [V(OH 2 ) 6 ] 3+ , [V(OH 2 ) 5 (SO 4 )] + , and [V(OH 2 ) 4 (SO 4 ) 2 ]complexes are thought to be present, in large concentrations, in the blood of ascidians. 41 For the present study, care was taken to prepare a vanadium(III) solution free from anions such as sulfate and chloride because of their tendency to coordinate directly to vanadium(III).…”

“…41 For the present study, care was taken to prepare a vanadium(III) solution free from anions such as sulfate and chloride because of their tendency to coordinate directly to vanadium(III). 40,42 Triflate was chosen as the counteranion as it is both inert and a poor ligand. Furthermore, in the triflate salt [V(OH 2 ) 6 ][H 5 O 2 ](CF 3 SO 3 ) 4 the stereochemistry of the [V(OH 2 ) 6 ] 3+ cation has been shown to be close to all-horizontal D 3d by single-crystal neutron diffraction, 13 a result at variance with the most energetically favored structure predicted by DFT calculations.…”

“…The absorption spectra of vanadium(III) as a function of sulfate concentration have been particularly well characterized 40 as the [V(OH 2 ) 6 ] 3+ , [V(OH 2 ) 5 (SO 4 )] + , and [V(OH 2 ) 4 (SO 4 ) 2 ] - complexes are thought to be present, in large concentrations, in the blood of ascidians . For the present study, care was taken to prepare a vanadium(III) solution free from anions such as sulfate and chloride because of their tendency to coordinate directly to vanadium(III). , Triflate was chosen as the counteranion as it is both inert and a poor ligand. Furthermore, in the triflate salt [V(OH 2 ) 6 ][H 5 O 2 ](CF 3 SO 3 ) 4 the stereochemistry of the [V(OH 2 ) 6 ] 3+ cation has been shown to be close to all-horizontal D 3 d by single-crystal neutron diffraction, a result at variance with the most energetically favored structure predicted by DFT calculations .…”