Oxidation states Ti, V and Cr

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


 
Titanium
 
 
+4* TiO2, TiO2+, TiO32–
+3 Ti3+
+2 Ti2+
  0
Vanadium
 
+5* V2O5, VO2+, VO43–
+4* VO2, VO2+
+3
+2
  0
Chromium
+6 CrO3,  Cr2O72–, CrO42–
 
 
+3* Cr2O3
+2
  0


 
  • The oxoanions are only important in base for metals in +4 and +5 oxidation states.
  • For metals in +6 and +7 oxidation states only oxoanions exist
    Cr(VI) exists predominantly as Cr2O72– at low pH and as CrO42– at high pH.
     
  • Where both an anion and cation form exist due to the oxide being amphoteric, the cation form is predominant in acid, and the anion form in base.
  • 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