Table 2 Equilibrium constants and proposed coordination modes for Zn²⁺ complexes at T = 298 K and I = 0.1 M (KCl).

[ZnH₂L]⁴⁺

–

–

–

20.29(6)

6.14

2N_Im

[ZnHL]³⁺

11.00(5)

5.80

2N_Im

14.15(4)

7.63

3N_Im

[ZnL]²⁺

5.21(2)

7.33

3N_Im

6.52(5)

8.93

3N_Im, OH^–

[ZnH_-1L]⁺

 − 2.12(3)

–

3N_Im, OH^–

 − 2.41(7)

9.44

3N_Im, 2OH^–

[ZnH_-2L]

 − 11.85(3)

–

3N_Im, 2OH^–

[ZnH₅L]⁵⁺

48.7(1)

5.6

2N_Im

[ZnH₄L]⁴⁺

43.07(3)

7.32

3N_Im

[ZnH₃L]³⁺

35.75(6)

7.69

3N_Im, OH^–

[ZnH₂L]²⁺

28.06(4)

8.65

3N_Im, OH^–

[ZnHL]⁺

19.40(5)

9.47

3N_Im, 2OH^–

[ZnL]

9.94(4)

–

3N_Im, 2OH^–

[ZnH_-2L]^2–

 − 10.70(7)

–

3N_Im, 2OH^–