1. Chemsheets AS006 (Electron arrangement)
21/04/2017
INORGANIC COMPLEXES
© A Jul-12

2. Metal aqua ions Substitution by Cl- Hydrolysis Substitution by NH3
Metal aqua ions + OH-
Summary 1
Metal aqua ions + NH3
Chelate effect
Metal aqua ions + CO32-
Redox
Summary 2
© A Jul-12

3. METAL AQUA IONS
© A Jul-12

4. METAL AQUA IONS e.g.[Cu(H2O)6]2+
© A Jul-12

5. METAL AQUA IONS complex colour [Cu(H2O)6]2+ blue [Co(H2O)6]2+ pink
[Fe(H2O)6]2+
green
[V(H2O)6]2+
[Cr(H2O)6]3+
violet*
[Fe(H2O)6]3+
pale violet**
[Al(H2O)6]3+
colourless
© A Jul-12

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12. REACTIONS Hydrolysis O-H bond in H2O ligand breaks
Substitution M-ligand bond breaks
Redox change in oxidation state of M
© A Jul-12

13. HYDROLYSIS
© A Jul-12

14. HYDROLYSIS OF Mn+(aq)

15. HYDROLYSIS OF Mn+(aq) M3+ more acidic due to:
M3+ smaller and greater charge than M2+ so O-H bond breaks more easily.

16. HYDROLYSIS OF M2+(aq) [M(H2O)6]2+  [M(H2O)5(OH)]+ + H+
[M(H2O)5(OH)]+  [M(H2O)4(OH)2] H+
[M(H2O)4(OH)2]  [M(H2O)3(OH)3] H+
[M(H2O)3(OH)3]-  [M(H2O)2(OH)4] H+
[M(H2O)2(OH)4]2-  [M(H2O)(OH)5] H+
[M(H2O)(OH)5]3-  [M(OH)6] H+

17. HYDROLYSIS OF M3+(aq) [M(H2O)6]3+  [M(H2O)5(OH)]2+ + H+
[M(H2O)5(OH)]2+  [M(H2O)4(OH)2] H+
[M(H2O)4(OH)2]+  [M(H2O)3(OH)3] H+
[M(H2O)3(OH)3]  [M(H2O)2(OH)4] H+
[M(H2O)2(OH)4]-  [M(H2O)(OH)5] H+
[M(H2O)(OH)5]2-  [M(OH)6] H+

18. METAL AQUA IONS + OH-

19. © www.chemsheets.co.uk A2 042 20-Jul-12

20. AQUA IONS + OH- [M(H2O)6]2+ + 2 OH- → [M(H2O)4(OH)2] + 2 H2O
M2+(aq) OH-(aq) → M(OH)2(s)
[Cu(H2O)6] OH- → [Cu(H2O)4(OH)2] H2O
Cu2+(aq) OH-(aq) → Cu(OH)2(s)
© A Jul-12

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22. AQUA IONS + OH- [M(H2O)6]2+ + 2 OH- → [M(H2O)4(OH)2] + 2 H2O
M2+(aq) OH-(aq) → M(OH)2(s)
[Co(H2O)6] OH- → [Co(H2O)4(OH)2] H2O
Co2+(aq) OH-(aq) → Co(OH)2(s)
© A Jul-12

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24. AQUA IONS + OH- [M(H2O)6]2+ + 2 OH- → [M(H2O)4(OH)2] + 2 H2O
M2+(aq) OH-(aq) → M(OH)2(s)
[Fe(H2O)6] OH- → [Fe(H2O)4(OH)2] H2O
Fe2+(aq) OH-(aq) → Fe(OH)2(s)
© A Jul-12

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26. AQUA IONS + OH- [M(H2O)6]3+ + 3 OH- → [M(H2O)3(OH)3] + 3 H2O
M3+(aq) OH-(aq) → M(OH)3(s)
[Al(H2O)6] OH- → [Al(H2O)3(OH)3] H2O
Al3+(aq) OH-(aq) → Al(OH)3(s)
© A Jul-12

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28. AQUA IONS + OH- [M(H2O)6]3+ + 3 OH- → [M(H2O)3(OH)3] + 3 H2O
M3+(aq) OH-(aq) → M(OH)3(s)
[Fe(H2O)6] OH- → [Fe(H2O)3(OH)3] H2O
Fe3+(aq) OH-(aq) → Fe(OH)3(s)
© A Jul-12

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30. AQUA IONS + OH- [M(H2O)6]3+ + 3 OH- → [M(H2O)3(OH)3] + 3 H2O
M3+(aq) OH-(aq) → M(OH)3(s)
[Cr(H2O)6] OH- → [Cr(H2O)3(OH)3] H2O
Cr3+(aq) OH-(aq) → Cr(OH)3(s)
© A Jul-12

31. AMPHOTERIC NATURE Amphoteric = reacts with acids and bases
XS H+
XS OH-
[Cu(H2O)6]2+
[Cu(OH)2]
[Fe(H2O)6]2+
[Fe(OH)2]
[Co(H2O)6]2+
[Co(OH)2]
[Fe(H2O)6]3+
[Fe(OH)3]
[Cr(H2O)6]3+
[Cr(OH)3]
[Cr(OH)6]3-
[Al(H2O)6]3+
[Al(OH)3]
[Al(OH)4]-
© A Jul-12

32. AQUA IONS + XS OH- [Cr(H2O)3(OH)3]  [Cr(OH)6]3- + 3 OH- + 3 H2O
Cr(OH)3(s) → [Cr(OH)63-](aq)
+ 3 OH-(aq)
[Al(H2O)3(OH)3]  [Al(H2O)2(OH)4]-
+ OH H2O
Al(OH)3(s) → [Al(OH)4-](aq)
+ OH-(aq)
© A Jul-12

33. METAL AQUA IONS + NH3
© A Jul-12

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35. AQUA IONS + NH3 [M(H2O)6]2+ + 2 NH3 → [M(H2O)4(OH)2] + 2 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M2+(aq) OH-(aq) → M(OH)2
[Cu(H2O)6] NH3 → [Cu(H2O)4(OH)2] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Cu2+(aq) OH-(aq) → Cu(OH)2
© A Jul-12

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37. AQUA IONS + NH3 [M(H2O)6]2+ + 2 NH3 → [M(H2O)4(OH)2] + 2 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M2+(aq) OH-(aq) → M(OH)2
[Fe(H2O)6] NH3 → [Fe(H2O)4(OH)2] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Fe2+(aq) OH-(aq) → Fe(OH)2
© A Jul-12

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39. AQUA IONS + NH3 [M(H2O)6]2+ + 2 NH3 → [M(H2O)4(OH)2] + 2 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M2+(aq) OH-(aq) → M(OH)2
[Co(H2O)6] NH3 → [Co(H2O)4(OH)2] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Co2+(aq) OH-(aq) → Co(OH)2
© A Jul-12

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41. AQUA IONS + NH3 [M(H2O)6]3+ + 3 NH3 → [M(H2O)3(OH)3] + 3 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M3+(aq) OH-(aq) → M(OH)3
[Cr(H2O)6] NH3 → [Cr(H2O)3(OH)3] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Cr3+(aq) OH-(aq) → Cr(OH)3
© A Jul-12

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43. AQUA IONS + NH3 [M(H2O)6]3+ + 3 NH3 → [M(H2O)3(OH)3] + 3 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M3+(aq) OH-(aq) → M(OH)3
[Fe(H2O)6] NH3 → [Fe(H2O)3(OH)3] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Fe3+(aq) OH-(aq) → Fe(OH)3
© A Jul-12

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45. AQUA IONS + NH3 [M(H2O)6]3+ + 3 NH3 → [M(H2O)3(OH)3] + 3 NH4+
NH3(aq) H+(aq) → NH4+(aq)
M3+(aq) OH-(aq) → M(OH)3
[Al(H2O)6] NH3 → [Al(H2O)3(OH)3] NH4+
NH3(aq) H+(aq) → NH4+(aq)
Al3+(aq) OH-(aq) → Al(OH)3
© A Jul-12

46. METAL AQUA IONS + CO32-
© A Jul-12

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48. AQUA IONS + CO32- [M(H2O)6]2+ + CO32- → [M(H2O)6]CO3
M2+(aq) CO32-(aq) → MCO3(s)
[Cu(H2O)6] CO32- → [Cu(H2O)6]CO3
Cu2+(aq) CO32-(aq) → CuCO3(s)
© A Jul-12

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50. AQUA IONS + CO32- [M(H2O)6]2+ + CO32- → [M(H2O)6]CO3
M2+(aq) CO32-(aq) → MCO3(s)
[Co(H2O)6] CO32- → [Co(H2O)6]CO3
Co2+(aq) CO32-(aq) → CoCO3(s)
© A Jul-12

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52. AQUA IONS + CO32- [M(H2O)6]2+ + CO32- → [M(H2O)6]CO3
M2+(aq) CO32-(aq) → MCO3(s)
[Fe(H2O)6] CO32- → [Fe(H2O)6]CO3
Fe2+(aq) CO32-(aq) → FeCO3(s)
© A Jul-12

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54. AQUA IONS + CO32- 2 H+ + CO32- → H2O + CO2
[M(H2O)6]3+ provides 3 H+ ions
2 [M(H2O)6] CO32- → 2 [M(H2O)3(OH)3] + 3 H2O + 3 CO2
2 [Cr(H2O)6] CO32- → 2 [Cr(H2O)3(OH)3] + 3 H2O + 3 CO2
© A Jul-12

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56. AQUA IONS + CO32- 2 H+ + CO32- → H2O + CO2
[M(H2O)6]3+ provides 3 H+ ions
2 [M(H2O)6] CO32- → 2 [M(H2O)3(OH)3] + 3 H2O + 3 CO2
2 [Fe(H2O)6] CO32- → 2 [Fe(H2O)3(OH)3] + 3 H2O + 3 CO2
© A Jul-12

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58. AQUA IONS + CO32- 2 H+ + CO32- → H2O + CO2
[M(H2O)6]3+ provides 3 H+ ions
2 [M(H2O)6] CO32- → 2 [M(H2O)3(OH)3] + 3 H2O + 3 CO2
2 [Al(H2O)6] CO32- → 2 [Al(H2O)3(OH)3] + 3 H2O + 3 CO2
© A Jul-12

59. SUBSTITUTION BY Cl-
© A Jul-12

60. [Co(H2O)6]2+ + 4 Cl-  [CoCl4]2- + 6 H2O
© A Jul-12

61. SUBSTITUTION by larger ligands
Cl- bigger than O of H2O – only four Cl-’s fit around Mn+ H
Cl- O H
© A Jul-12

62. [Cu(H2O)6]2+ + 4 Cl- → [CuCl4]2- + 6 H2O
© A Jul-12

63. SUBSTITUTION BY NH3
© A Jul-12

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65. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
© A Jul-12

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67. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
[Cu(H2O)6] NH3 → [Cu(NH3)4(H2O)2] H2O
© A Jul-12

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69. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
[Cu(H2O)6] NH3 → [Cu(NH3)4(H2O)2] H2O
[Fe(H2O)6]2+
© A Jul-12

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71. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
[Cu(H2O)6] NH3 → [Cu(NH3)4(H2O)2] H2O
[Fe(H2O)6]2+
[Fe(H2O)6]3+
© A Jul-12

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73. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
[Cu(H2O)6] NH3 → [Cu(NH3)4(H2O)2] H2O
[Fe(H2O)6]2+
[Fe(H2O)6]3+
[Cr(H2O)6] NH3 → [Cr(NH3)6] H2O
© A Jul-12

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75. SUBSTITUTION by similar sized ligands
[Co(H2O)6] NH3 → [Co(NH3)6] H2O
air
[Co(NH3)6]2+
[Cu(H2O)6] NH3 → [Cu(NH3)4(H2O)2] H2O
[Fe(H2O)6]2+
[Fe(H2O)6]3+
[Cr(H2O)6] NH3 → [Cr(NH3)6] H2O
[Al(H2O)6]3+
© A Jul-12

76. SUMMARY 1
© A Jul-12

77. SUMMARY [M(H2O)6]3+ M(OH)3 + CO2 M(OH)3 [Cr(NH3)6]3+ [Cr(OH)6]3-
OH- / NH3 H+
XS NH3
M(OH)3
[Cr(NH3)6]3+
XS OH-
[Cr(OH)6]3-
[Al(OH)4]-
© A Jul-12

78. SUMMARY [M(H2O)6]2+ MCO3 M(OH)2 [Co(NH3)6]2+ [Cu(NH3)4(H2O)2]2+
OH- / NH3 H+
XS NH3
M(OH)2
[Co(NH3)6]2+
[Cu(NH3)4(H2O)2]2+
XS OH-
No reaction
© A Jul-12

79. CHELATE EFFECT
© A Jul-12

80. THE CHELATE EFFECT [Cr(H2O)6]3+ + 3 en → [Cr(en)3]3+ + 6 H2O
4 particles → 7 particles
[Cr(H2O)6] EDTA4- → [Cr(EDTA)] H2O
2 particles → 7 particles
Small H in substitution reactions.
Big increase in entropy (large +ve S).
Products are thermodynamically more stable than reactants – known as the “chelate effect”
© A Jul-12

81. REDOX REACTIONS
© A Jul-12

82. REDUCTION OF Cr(+6) 2 CrO42- + 2 H+  Cr2O72- + H2O oxidation state
yellow
Cr +6
orange
oxidation state
species
colour
Cr +6
Cr2O72-
orange
© A Jul-12

83. REDUCTION OF Cr(+6) 2 CrO42- + 2 H+  Cr2O72- + H2O oxidation state
yellow
Cr +6
orange
oxidation state
species
colour
Cr +6
Cr2O72-
orange
Cr +3
Cr [Cr(H2O)6]3+
green
© A Jul-12

84. REDUCTION OF Cr(+6) 2 CrO42- + 2 H+  Cr2O72- + H2O oxidation state
yellow
Cr +6
orange
oxidation state
species
colour
Cr +6
Cr2O72-
orange
Cr +3
Cr [Cr(H2O)6]3+
green
Cr +2
Cr [Cr(H2O)6]2+
blue
Reduced by Zn/H+ from Cr +6 → +3 → +2
© A Jul-12

85. Cr(+3) – OXIDATION IN ALKALINE CONDITIONS
Easier to oxidise (take electrons) from –ve species.
Easier to reduce (add electrons) to +ve species.
e.g. Cr(+3)
in acidic conditions
in alkaline conditions
in very alkaline conditions
[Cr(H2O)6]3+
[Cr(OH)3]
[Cr(OH)6]3-
H2O2 / OH-
Zn / HCl
CrO42-
Cr(+6)
[Cr(H2O)6]2+
Cr(+2)
© A Jul-12

86. Cr(+3) – OXIDATION IN ALKALINE CONDITIONS
CrO H2O + 3 e-  Cr(OH)3 + 5 OH E = V
Cr2O H+ + 6 e-  2 Cr H2O E = V
© A Jul-12

87. Co(+2) – OXIDATION IN ALKALINE CONDITIONS
air
Co(OH)2
Co(OH)3
Co(+2)
Co(+3)
Made from Co2+ in alkaline conditions
air
[Co(NH3)6]2+
[Co(NH3)6]3+
Co(+2)
Co(+3)
Made from Co2+ in alkaline (NH3) conditions
© A Jul-12

88. M(OH)2 – OXIDATION IN ALKALINE CONDITIONS
air
Co(OH)2
Co(OH)3
Co(+2)
Co(+3)
air
Fe(OH)2
Fe(OH)3
Fe(+2)
Fe(+3)
Fe(OH)3 + e-  Fe(OH)2 + OH E = V
Fe e-  Fe2+ E = V
© A Jul-12

89. SUMMARY 2
© A Jul-12

90. SUMMARY [M(H2O)6]3+ M(OH)3 [Cr(OH)6]3- CrO42- [Al(OH)4]- [Cr(NH3)6]3+
XS OH-
OH- / NH3
XS NH3
[M(H2O)6]3+
M(OH)3
[Cr(NH3)6]3+ H+
[Cr(H2O)6]3+
Cr(OH)3
[Fe(H2O)6]3+
Fe(OH)3
[Al(H2O)6]3+
Al(OH)3
CO32-
+ CO2
© A Jul-12

91. SUMMARY [M(H2O)6]2+ M(OH)2 [CuCl4]2- [CoCl4]2- [Cu(H2O)2(NH3)4]2+
XS OH-
Cl-
OH- / NH3
XS NH3
[M(H2O)6]2+
M(OH)2
[Cu(H2O)2(NH3)4]2+ H+
[Cu(H2O)6]2+
Cu(OH)2
[Co(NH3)6]2+
[Co(H2O)6]2+
Co(OH)2
air
[Fe(H2O)6]2+
Fe(OH)2
CO32-
air
[Co(NH3)6]3+
CuCO3
Co(OH)3
CoCO3
Fe(OH)3
FeCO3
© A Jul-12

92. SUMMARY [M(H2O)6]2+ MCO3 M(OH)2 [Co(NH3)6]2+ [Cu(NH3)4(H2O)2]2+
OH- / NH3 H+
XS NH3
M(OH)2
[Co(NH3)6]2+
[Cu(NH3)4(H2O)2]2+
XS OH-
No reaction
© A Jul-12