Effect of Ph on the Complexing Behaviour of Some Nitrogen and Sulphur Containing Ligands With Chromium (Iii) Ions  

Ashok Kumar Yadav¹*, Anil Kumar², Anvadya Kumari² and S.P. Yadav³

¹Department of Chemistry, Patna University, Patna- 800 005 (India) ²Department of Chemistry, P.Sc. College, B.M.M. University, Madhepura- 852 113 (India) ³Department of Chemistry, R.L. College, Bihar (India)

Six complexes of Cr(III) have been prepared at pH=3, pH=7, pH=8 and pH=9 with thiourea and thiosemicarbazide. It has been found that the acidic medium (pH=3) is the best medium of coordination of the ligands to Cr(III) ion. At pH=3, complexes [Cr(TU)2(NH3)Cl3]3H2O and [Cr(TSC)2Cl2(H2O)(OH)]; at pH=7 complexes [Cr(TU)Cl3(H2O)2]H2O and [Cr(S=C=N-H)Cl3(H2O)]4H2O and at pH=8 and 9, complexes [Cr2(TU)Cl(H2O)8]Cl5.5H2O and [Cr(TSC)2(CH3COOH3)2(OH)2]Cl respectively have been prepared. The structure of the complexes have been determined and metal-ligand vibrational bands have been located. Complexes prepared in acidic medium (pH=3) are water soluble and those prepared in neutral (pH=7) and alkaline medium (pH=8 and 9) and polymeric and insoluble.

Complexes of thiourea; Thiosemicarbazone