Mr. Alvarez,

Oh symmetry of the metal-chromophore is among the most probable one.

Thank you for your opinion

It is not as simple as it looks like. What W ion are you talking about?  Tungsten metal usually is first attacked by fusion with NaOH (it is hardly attacked by acids). The cooled melt is leached with water yielding a solution of sodium tungstate, NaWO4. Tungsten in NaWO4 form can then be reduced to any oxidaton state from 2+ to 6+. Lower valent tungsten ions in water form mainly oxo bridged dinuclear to polynuclear chain ions. Stable aqueous solutions of tungsten species contain almost invariably W(VI) and, depending on the pH of the solution formation of one of many possible  isopolytungstates can take place, in which the tungsten atoms are octahedrally coordinated to oxygen, So you need to know the experimental conditions to figure out in which form tungsten is present in your aqueous solution.