Standard enthalpies of formation of diamine(dicarboxylato)platinum(II) complexes and of bis(pentane-2,4-dionato)platinum(II): the mean Pt–O bond dissociation enthalpies
Abstract
The following standard enthalpies of formation (kJ mol–1) of the crystalline solids were determined at 298.15 K using solution reaction calorimetry: ΔHf⊖{[Pt{(O2C)2CH2}(NH2CH2CH2NH2)]}=–974 ± 7; ΔHf⊖{[Pt{(O2C)2CHMe}(NH2Et)2]}=–1 087 ± 10; ΔHf⊖{[Pt{(O2C)2CHEt}(NH3)2]}=–1 080 ± 3; ΔHf⊖{[Pt{(O2C)2CHEt}(NH2Et)2]}=–1 083 ± 10; ΔHf⊖{[Pt{(O2C)2CH(OH)}(NH3)2]}=–1 193 ± 3; ΔHf⊖{[Pt(cbda-1,1)(NH3)2]}=–959 ± 3, (H2cbda-1,1 = cyclobutane-1,1-dicarboxylic acid); ΔHf⊖{[Pt(cbda-1,1)(NH2Me)2]}=–910 ± 8; ΔHf⊖{[Pt(cbda-1,1)(NH2Et)2]}=–983 ± 10; ΔHf⊖{[Pt(cbda-1,1)(NH2Pri)2]}=–1 095 ± 6; ΔHf⊖{[Pt(cbda-1,2)(NH2Me)2]}=–852 ± 8 (H2cbda-1,2 = cyclobutane-1,2-dicarboxylic acid); ΔHf⊖{[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].