The following standard enthalpies of formation (kJ mol^–1) of the crystalline solids were determined at 298.15 K using solution reaction calorimetry: ΔH_f^⊖{[Pt{(O₂C)₂CH₂}(NH₂CH₂CH₂NH₂)]}=–974 ± 7; ΔH_f^⊖{[Pt{(O₂C)₂CHMe}(NH₂Et)₂]}=–1 087 ± 10; ΔH_f^⊖{[Pt{(O₂C)₂CHEt}(NH₃)₂]}=–1 080 ± 3; ΔH_f^⊖{[Pt{(O₂C)₂CHEt}(NH₂Et)₂]}=–1 083 ± 10; ΔH_f^⊖{[Pt{(O₂C)₂CH(OH)}(NH₃)₂]}=–1 193 ± 3; ΔH_f^⊖{[Pt(cbda-1,1)(NH₃)₂]}=–959 ± 3, (H₂cbda-1,1 = cyclobutane-1,1-dicarboxylic acid); ΔH_f^⊖{[Pt(cbda-1,1)(NH₂Me)₂]}=–910 ± 8; ΔH_f^⊖{[Pt(cbda-1,1)(NH₂Et)₂]}=–983 ± 10; ΔH_f^⊖{[Pt(cbda-1,1)(NH₂Prⁱ)₂]}=–1 095 ± 6; ΔH_f^⊖{[Pt(cbda-1,2)(NH₂Me)₂]}=–852 ± 8 (H₂cbda-1,2 = cyclobutane-1,2-dicarboxylic acid); ΔH_f^⊖{[Pt(pd)₂]}=–687 ± 5 (Hpd = pentane2,4-dione). With estimated enthalpies of sublimation, it was deduced that the sum of the mean bond dissociation enthalpies, D(Pt–N)+D(Pt–O)≈ 490 kJ mol^–1. By substituting D(Pt–N) from the corresponding [PtCl₂(NH₂R)₂] complexes, D(Pt–O) for the diamine(dicarboxylato)platinum complexes ≈ 380 kJ mol^–1 compared to D(Pt–O)≈ 183 kJ mol^–1 in [Pt(pd)₂].