**Table 2:** Selected equilibrium constants, *β*_{1}, for the monoazide complexes of lanthanides.

Ln | a |
b |
β_{1} (mol^{−1} L) |
I (mol L^{−1}) |
Method | Ref. |

La(III) | (1.0000) | (0.000) | 3.70 | — | Mathematical | (c) |

4.20 ± 1.0 | 1.0 | Spectrophotometry | 7 | |||

4.46 ± 1.02 | 3.0 (e) | Potentiometry | 4 | |||

Ce(III) | 1.0354 | 0.027 | 4.12 | — | Mathematical | (c) |

4.36 ± 1.02 | 3.0 (e) | Potentiometry | 4 | |||

Pr(III) | 1.0639 | 0.051 | 4.52 | — | Mathematical | (c) |

0.298 ± 0.03 | 2.0 | Spectrophotometry (Scott method) | 5 | |||

0.246 ± 0.06 | 2.0 | Spectrophotometry (dilution method) | 5 | |||

Nd(III) | 1.0869 | 0.053 | 4.68 | — | Mathematical | (c) |

3.80 ± 1.0 | 1.0 | Spectrophotometry | 7 | |||

0.501 ± 0.05 | 2.0 | Spectrophotometry (Scott method) | 5 | |||

0.499 ± 0.02 | 2.0 | Spectrophotometry (dilution method) | 5 | |||

2.5 | NA | NMR, UV, and Raman | 9 | |||

Pm(III) | 3.31 ± 0.48 | 0.5 (e) | Radioanalysis | 8 | ||

Sm(III) | 1.1204 | −0.007 | 4.26 | — | Mathematical | (c) |

1.65 ± 0.04 | 2.0 | Spectrophotometry (Scott method) | 5 | |||

1.69 ± 0.08 | 2.0 | Spectrophotometry (dilution method) | 5 | |||

Eu(III) | 3.75 ± 0.33 | 0.5 (e) | Radio analysis | 8 | ||

2.5 | NA | NMR, UV, and Raman | 9 | |||

1.1367 | 0.009 | 4.51 ± 0.11 | 2.0 (e) | Potentiometry | (d) | |

Gd(III) | 1.1357 | −0.143 | 3.18 | — | Mathematical | (c) |

Tb(III) | 1.1693 | −0.271 | 2.47 | — | Mathematical | (d) |

Dy(III) | 1.1792 | −0.366 | 2.01 | — | Mathematical | (c) |

Ho(III) | 1.1796 | −0.345 | 2.11 | — | Mathematical | (c) |

Er(III) | 1.1900 | −0.326 | 2.24 | — | Mathematical | (c) |

3.90 ± 1.0 | 1.0 | Spectrophotometry | 7 | |||

1.2 | NA | NMR, UV, and Raman | 9 | |||

Tm(III) | 1.1833 | −0.106 | 3.68 | — | Mathematical | (c) |

3.21 ± 0.4 | 0.5 (e) | Radio analysis | 8 | |||

Yb(III) | 1.2023 | −0.240 | 2.77 | — | Mathematical | (c) |

2.5 | NA | NMR, UV, and Raman | 9 | |||

Lu(III) | 1.2022 | −0.053 | 4.26 | — | Mathematical | (c) |

All studies were performed at T = 25 °C [5,9] and there is no mention of temperature control; “a” and “b” are the parameters of (4) developed by Kumok and Serebrennikov [24]. “Mathematical” means obtained using (4) developed by Kumok and Serebrennikov [24]. (c) Calculated value in the present work using (4). (d) Present work. (e) NaClO_{4} was used to maintain constant ionic strength. NA: not available. |