Complex Formation of Nickel(II) and Copper(II) with Barbituric Acid

Table 1

Acid dissociation constants of Barbituric acid (BA) and the stability constants of the Ni(II), Cu(II)-BA complexes (25.0±0.1°C, 𝐼=0.1 M KNO₃).

Equilibrium	Constant	BA	Ni(II)	Cu(II)
H2L ⇌ HL^− + H^+	log𝐾H2L	3.89±0.04; (3.78) [23]
HL^−⇌ L^−2 + H^+	log𝐾HL	11.90±0.04; (12.30) [23]
𝑝M + 𝑞L + 𝑟H^−⇌ [M𝑝L𝑞H𝑟]	log𝛽110		6.62±0.09	8.39±0.05
	log𝛽120		11.65±0.03	14.16±0.06
	log𝛽131		17.94±0.04	19.20±0.04