E4: Complex Ion Formation Constants
- Page ID
- 6648
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)A stability constant is an equilibrium constant for the formation of a complex in solution that measures the strength of the interaction between the ligands and metal that form the complex. The formation of complexes between a metal ion, M, and ligands, L, is really a ligand exchange (i.e., substitution reaction) with metal ions in aqueous solutions present as aqua-ligated ions.
| Halo Ligands | \(K_f\) |
|---|---|
| Al3+ + 6 F- \(\rightleftharpoons\) [AlF6]3- | 2.5 x 104 |
| Al3+ + 4 F- \(\rightleftharpoons\) [AlF4]-1 | 2.0 x 108 |
| Be2+ + 4 F- \(\rightleftharpoons\) [BeF4]2- | 1.3 x 1013 |
| Sn4+ + 6 F- \(\rightleftharpoons\) [SnF6]2- | 1.0 x 1025 |
| Cu+ + 2 Cl- \(\rightleftharpoons\) [CuCl2]-1 | 3.0 x 105 |
| Ag+ + 2 Cl- \(\rightleftharpoons\) [AgCl2]-1 | 1.8 x 105 |
| Pb2+ + 4 Cl- \(\rightleftharpoons\) [PbCl4]2- | 2.5 x 1015 |
| Zn2+ + 4 Cl- \(\rightleftharpoons\) [ZnCl4]2- | 1.6 |
| Hg2+ + 4 Cl- \(\rightleftharpoons\) [HgCl4]2- | 5.0 x 1015 |
| Cu+ + 2 Br- \(\rightleftharpoons\) [CuBr2]-1 | 8.0 x 105 |
| Ag+ + 2 Br- \(\rightleftharpoons\) [AgBr2]-1 | 1.0 x 1011 |
| Hg2+ + 4 Br- \(\rightleftharpoons\) [HgBr4]2- | 3.0 x 104 |
| Cu+ + 2 I- \(\rightleftharpoons\) [CuI2]-1 | 8.0 x 108 |
| Ag+ + 2 I- \(\rightleftharpoons\) [AgI2]-1 | 1.0 x 1011 |
| Pb2+ + 4 I- \(\rightleftharpoons\) [PbI4]2- | 3.0 x 104 |
| Hg2+ + 4 I- \(\rightleftharpoons\) [HgI4]2- | 1.9 x 1030 |
| Ammine Ligands | \(K_f\) |
|---|---|
| Ag+ + 2 NH3 \(\rightleftharpoons\) [Ag(NH3)2]+ | 1.6 x 107 |
| Zn2+ + 4 NH3 \(\rightleftharpoons\) [Zn(NH3)4]2+ | 7.8 x 108 |
| Cu2+ + 4 NH3 \(\rightleftharpoons\) [Cu(NH3)4]2+ | 1.1 x 1013 |
| Hg2+ + 4 NH3 \(\rightleftharpoons\) [Hg(NH3)4]2+ | 1.8 x 1019 |
| Co2+ + 6 NH3 \(\rightleftharpoons\) [Co(NH3)6]2+ | 5.0 x 104 |
| Co3+ + 6 NH3 \(\rightleftharpoons\) [Co(NH3)6]3+ | 4.6 x 1033 |
| Cd2+ + 6 NH3 \(\rightleftharpoons\) [Cd(NH3)6]2+ | 2.6 x 105 |
| Ni2+ + 6 NH3 \(\rightleftharpoons\) [Ni(NH3)6]2+ | 2.0 x 108 |
| Cyanide Ligands | \(K_f\) |
|---|---|
| Fe2+ + 6 CN- \(\rightleftharpoons\) [Fe(CN)6]4- | 1.0 x 1024 |
| Fe3+ + 6 CN- \(\rightleftharpoons\) [Fe(CN)6]3- | 1.0 x 1031 |
| Ag+ + 2 CN- \(\rightleftharpoons\) [Ag(CN)2]-1 | 5.3 x 1018 |
| Cu+ + 2 CN- \(\rightleftharpoons\) [Cu(CN)2]-1 | 1.0 x 1016 |
| Cd2+ + 4 CN- \(\rightleftharpoons\) [Cd(CN)4]2- | 7.7 x 1016 |
| Au+ + 2 CN- \(\rightleftharpoons\) [Au(CN)2]-1 | 2.0 x 1038 |
| Other monodentate ligands | \(K_f\) |
|---|---|
| Ag+ + 2 CH3NH2 \(\rightleftharpoons\) [Ag(CH3NH2)2]+1 | 7.8 x 106 |
| Cd2+ + 4 SCN- \(\rightleftharpoons\) [Cd(SCN)4]2- | 1.0 x 103 |
| Cu2+ 2 SCN- \(\rightleftharpoons\) [Cu(SCN)2] | 5.6 x 103 |
| Fe3+ 3 SCN- \(\rightleftharpoons\) [Fe(SCN)3] | 2.0 x 106 |
| Hg2+ 4 SCN- \(\rightleftharpoons\) [Hg(SCN)4]2- | 5.0 x 1021 |
| Cu2+ 4 OH- \(\rightleftharpoons\) [Cu(OH)4]2- | 1.3 x 1016 |
| Zn2+ 4 OH- \(\rightleftharpoons\) [Zn(OH)4]2- | 2.0 x 1020 |
| Bidentate ligands | \(K_f\) |
|---|---|
| Mn2+ + 3 en \(\rightleftharpoons\) [Mn(en)3]2+ | 6.5 x 105 |
| Fe2+ + 3 en \(\rightleftharpoons\) [Fe(en)3]2+ | 5.2 x 109 |
| Co2+ + 3 en \(\rightleftharpoons\) [Co(en)3]2+ | 1.3 x 1014 |
| Co3+ + 3 en \(\rightleftharpoons\) [Co(en)3]3+ | 4.8 x 1048 |
| Ni2+ + 3 en \(\rightleftharpoons\) [Ni(en)3]2+ | 4.1 x 1017 |
| Cu2+ + 2 en \(\rightleftharpoons\) [Cu(en)2]2+ | 3.5 x 1019 |
| Co2+ + 3 C2O42- \(\rightleftharpoons\) [Co(C2O4)3]4- | 4.5 x 106 |
| Fe3+ + 3 C2O42- \(\rightleftharpoons\) [Fe(C2O4)3]3- | 3.3 x 1020 |