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E4a: Stepwise Association Constants

  • Page ID
    11228
  • The following table provides Ki and βi values for selected metal–ligand complexes, arranged by the ligand (red). All values are from Martell, A. E.; Smith, R. M. Critical Stability Constants, Vols. 1–4. Plenum Press: New York, 1976. Unless otherwise stated, values are for 25 oC and zero ionic strength. Those values in brackets are considered less reliable. For more details read here.

    Acetate
    Acetate \(CH_3COO^{-}\) log K1 log K2 log K3 log K4 log K5 log K6
    Mg2+ 1.27 - - - - -
    Ca2+ 1.18 - - - - -
    Ba2+ 1.07 - - - - -
    Mn2+ 1.40 - - - - -
    Fe2+ 1.40 - - - - -
    Co2+ 1.46 - - - - -
    Ni2+ 1.43 - - - - -
    Cu2+ 2.22 1.41 - - - -
    Ag2+ 0.73 –0.09 - - - -
    Zn2+ 1.57 - - - - -
    Cd2+ 1.93 1.22 –0.89 - - -
    Pb2+ 2.68 1.40 - - - -
    Ammonia
    Ammonia: NH3 log K1 log K2 log K3 log K4 log K5 log K6
    Ag+ 3.31 3.91 - - - -
    Co2+ (T = 20 oC) 1.99 1.51 0.93 0.64 0.06 –0.73
    Ni2+ 2.72 2.17 1.66 1.12 0.67 –0.03
    Cu2+ 4.04 3.43 2.80 1.48 - -
    Zn2+ 2.21 2.29 2.36 2.03 - -
    Cd2+ 2.55 2.01 1.34 0.84 - -
    Chloride
    Chloride: Cl log K1 log K2 log K3 log K4 log K5 log K6
    Cu2+ 0.40 - - - - -
    Fe3+ 1.48 0.65 - - - -
    Ag+ (μ = 5.0 M) 3.70 1.92 0.78 –0.3 - -
    Zn2+ 0.43 0.18 –0.11 –0.3 - -
    Cd2+ 1.98 1.62 –0.2 –0.7 - -
    Pb2+ 1.59 0.21 –0.1 –0.3 - -
    Cyanide
    Cyanide: CN log K1 log K2 log K3 log K4 log K5 log K6
    Fe2+ - - - - - 35.4 (β6)
    Fe3+ - - - - - 43.6 (β6)
    Ag+ - 20.48 β2 0.92 - - -
    Zn2+ - 11.07 β2 4.98 3.57 - -
    Cd2+ 6.01 5.11 4.53 2.27 - -
    Hg2+ 17.00 15.75 3.56 2.66 - -
    Ni2+ - - - 30.22 (β4) - -
    Ethylenediamine

    Ethylenediamine
    A12ethylenediamine.jpg

    log K1 log K2 log K3 log K4 log K5 log K6
    Ni2+ 7.38 6.18 4.11 - - -
    Cu2+ 10.48 9.07 - - - -
    Ag+ (T = 20 oC, μ = 0.1 M) 4.700 3.00 - - - -
    Zn2+ 5.66 4.98 3.25 - - -
    Cd2+ 5.41 4.50 2.78 - - -
    EDTA

    EDTA
    A12edta.jpg

    log K1 log K2 log K3 log K4 log K5 log K6
    Mg2+ (T = 20 oC, μ = 0.1 M) 8.79 - - - - -
    Ca2+ (T = 20 oC, μ = 0.1 M) 10.69 - - - - -
    Ba2+ (T = 20 oC, μ = 0.1 M) 7.86 - - - - -
    Bi3+ (T = 20 oC, μ = 0.1 M) 27.8 - - - - -
    Co2+ (T = 20 oC, μ = 0.1 M) 16.31 - - - - -
    Ni2+ (T = 20 oC, μ = 0.1 M) 18.62 - - - - -
    Cu2+ (T = 20 oC, μ = 0.1 M) 18.80 - - - - -
    Cr3+ (T = 20 oC, μ = 0.1 M) [23.4] - - - - -
    Fe3+ (T = 20 oC, μ = 0.1 M) 25.1 - - - - -
    Ag+ (T = 20 oC, μ = 0.1 M) 7.32 - - - - -
    Zn2+ (T = 20 oC, μ = 0.1 M) 16.50 - - - - -
    Cd2+ (T = 20 oC, μ = 0.1 M) 16.46 - - - - -
    Hg2+ (T = 20 oC, μ = 0.1 M) 21.7 - - - - -
    Pb2+ (T = 20 oC, μ = 0.1 M) 18.04 - - - - -
    Al3+ (T = 20 oC, μ = 0.1 M) 16.3 - - - - -
    Fluoride
    Fluoride: F log K1 log K2 log K3 log K4 log K5 log K6
    Al3+ (μ = 0.5 M) 6.11 5.01 3.88 3.0 1.4 0.4
    Hydroxide
    Hydroxide: OH log K1 log K2 log K3 log K4 log K5 log K6
    Al3+ 9.01 [9.69] [8.3] 6.0 - -
    Co2+ 4.3 4.1 1.3 0.5 - -
    Fe2+ 4.5 [2.9] 2.6 –0.4 - -
    Fe3+ 11.81 10.5 12.1 - - -
    Ni2+ 4.1 3.9 3. - - -
    Pb2+ 6.3 4.6 3.0 - - -
    Zn2+ 5.0 [6.1] 2.5 [1.2] - -
    Iodide
    Iodide: I log K1 log K2 log K3 log K4 log K5 log K6
    Ag+ (T = 18 oC) 6.58 [5.12] [1.4] - - -
    Cd2+ 2.28 1.64 1.08 1.0 - -
    Pb2+ 1.92 1.28 0.7 0.6 - -
    Nitriloacetate
    Nitriloacetate
    A12nitriloacetate.jpg
    log K1 log K2 log K3 log K4 log K5 log K6
    Mg2+ (T = 20 oC, μ = 0.1 M) 5.41 - - - - -
    Ca2+ (T = 20 oC, μ = 0.1 M) 6.41 - - - - -
    Ba2+ (T = 20 oC, μ = 0.1 M) 4.82 - - - - -
    Mn2+ (T = 20 oC, μ = 0.1 M) 7.44 - - - - -
    Fe2+ (T = 20 oC, μ = 0.1 M) 8.33 - - - - -
    Co2+ (T = 20 oC, μ = 0.1 M) 10.38 - - - - -
    Ni2+ (T = 20 oC, μ = 0.1 M) 11.53 - - - - -
    Cu2+ (T = 20 oC, μ = 0.1 M) 12.96 - - - - -
    Fe3+ (T = 20 oC, μ = 0.1 M) 15.9 - - - - -
    Zn2+ (T = 20 oC, μ = 0.1 M) 10.67 - - - - -
    Cd2+ (T = 20 oC, μ = 0.1 M) 9.83 - - - - -
    Pb2+ (T = 20 oC, μ = 0.1 M) 11.39 - - - - -
    Oxalate
    Oxalate: C2O42– log K1 log K2 log K3 log K4 log K5 log K6
    Ca2+ (μ = 1 M) 1.66 1.03 - - - -
    Fe2+ (μ = 1 M) 3.05 2.10 - - - -
    Co2+ 4.72 2.28 - - - -
    Ni2+ 5.16 - - - - -
    Cu2+ 6.23 4.04 - - - -
    Fe3+ (μ = 0.5 M) 7.53 6.11 4.85 - - -
    Zn2+ 4.87 2.78 - - - -
    1,10-Phenanthroline
    1,10-Phenanthroline

    A121,10-phenanthroline.jpg

    log K1 log K2 log K3 log K4 log K5 log K6
    Fe2+ - - 20.7 (β3) - - -
    Mn2+ (μ = 0.1 M) 4.0 3.3 3.0 - - -
    Co2+ (μ = 0.1 M) 7.08 6.64 6.08 - - -
    Ni2+ 8.6 8.1 7.6 - - -
    Fe3+ - - 13.8 (β3) - - -
    Ag+ (μ = 0.1 M) 5.02 7.04 - - - -
    Zn2+ 6.2 [5.9] [5.2] - - -
    Thiosulfate
    Thiosulfate: S2O32– log K1 log K2 log K3 log K4 log K5 log K6
    Ag+ (T = 20 oC) 8.82 4.85 0.53 - - -
    Thiocyanate
    Thiocyanate: SCN log K1 log K2 log K3 log K4 log K5 log K6
    Mn2+ 1.23 - - - - -
    Fe2+ 1.31 - - - - -
    Co2+ 1.72 - - - - -
    Ni2+ 1.76 - - - - -
    Cu2+ 2.33 - - - - -
    Fe3+ 3.02 - - - - -
    Ag+ 4.8 3.43 1.27 0.2 - -
    Zn2+ 1.33 0.58 0.09 –0.4 - -
    Cd2+ 1.89 0.89 0.02 –0.5 - -
    Hg2+ - 17.26 (β2) 2.71 1.83 - -