The important oxidation states of titanium, chromium and vanadium are given below with the formula for oxyanions or cations at higher oxidation levels.

Chromium
+6* (in base) Cr2O72–, CrO42–
24
24
+3* (in acid)
+2
 0
Vanadium
2
+5* VO2+, VO43-
+4* VO2+
+3
+2
 0
 
Titanium
24
42
+4* TiO2+, TiO32–
+3
+2
  0

  • The oxoanions are only important in base for metals in the +4 and +5 oxidation states.
  • For metals in the+6 and +7 oxidation states only oxoanions exist
    Cr(VI) exists predominantly as Cr2O72– at low pH and as CrO42– at high pH.
     
  • If you know the oxidation state,

    • the oxoanion formulae can be deduced by combining the "metal cation" with the minimum number of O2– to make the overall charge negative.
      For example Ti4+ + 3O2– = TiO32–
    • oxocation formulae can be deduced by combining the "metal cation" with enough O2– to make the charge +1 or +2.
      For example: V5+ + 2O2– = VO2+
Dr Sheila Woodgate
© The University of Auckland 2002