Table 2.

Physical Parameters of Cd^II, Hg^II and Pb^II complexes of α₃DIV.

Complex	UV/Vis λnm (Δε M−1cm−1)	NMR δ (ppm)		Apparent pKa	Binding Constant (Kb) (M−1)a
		113Cd	199Hg
Cd(α3DIV)−	232 (18, 200)	583		10.6±0.1b	2.0×107
		595
Hg(α3DIV)−	247 (12,500)		−244	7.1±0.1c
	265 (8,400)
	295 (3,900)
Hg(α3DIV)d	240 (850)		−938e
Pb(α3DIV)−	236 (18,000)			10.2±0.1b	3.1×107
	260 (14,400)
	278 (9,100)
	346 (3,150)

^aModel used to obtain binding constants is M^II + (α₃DIV)³⁻ ⇌ M^II(α₃DIV)⁻ (K_b). These values represent the lower limit of K_b.

^bModel used to obtain pK_a2 values for Cd^II and Pb^II is M^II(α₃DIVS(SH)₂)⁺ ⇌ M^II(α₃DIV)⁻ + 2H⁺ (K_a2).

^cModel used to obtain the pK_a for Hg^II is Hg^II(α₃DIVS₂(SH)) ⇌ Hg^II(α₃DIV)⁻ + H⁺ (K_a).

^dLinear HgS₂ complex of α₃DIV.

^e199Hg NMR δ of linear HgS₂ complex at pH 5.8.