Spina Carla J, Notarandrea-Alfonzo Johanny E, Guerra Elizabeth D, Goodall Carlie, Bohle D Scott, Precht Rod
Exciton Pharma Corp, Toronto, Ontario M5G 1L7, Canada.
McGill University, Montreal, Quebec H3A 0B8, Canada.
ACS Omega. 2021 Oct 6;6(41):27017-27025. doi: 10.1021/acsomega.1c03523. eCollection 2021 Oct 19.
The preparation of stable hypervalent metal complexes containing Ag(III) has historically been challenging due to their propensity for reduction under ambient conditions. This work explores the preparation of a tripotassium silver bisperiodate complex as a tetrahydrate via chemical oxidation of the central silver atom and orthoperiodate chelation. The isolation of the chelate complex in high yield and purity was achieved via acidimetric titration. The comprehensive physiochemical characterization of the tribasic silver bisperiodate included single crystal X-ray diffraction, thermogravimetric and differential scanning calorimetry, and infrared and ultraviolet-visible spectroscopy. Infrared and UV-visible absorption spectra (λ 255 and 365 nm) were in good agreement with historically prepared pentabasic diperiodatoargentate chelate complexes. The 2/ monoclinic distorted square planar structure of the bis-chelate complex affords a mutually supportive framework to both Ag(III) and I(VII), conferring stability under both thermal and long-term ambient conditions. Thermal analysis of the tribasic silver bisperiodate complex identified an endothermic mass loss, Δ = +278.35 kJ/mol, observed at 139.0 °C corresponding to a solid-state reduction of silver from Ag(III) to Ag(I). Under ambient conditions, no significant degradation was observed over a 12 month period ( = 0.30) for the silver bisperiodate complex in a solid state, with an observed half-life of τ = 147 days in a pH-neutral aqueous solution.
由于在环境条件下易于还原，制备含Ag(III)的稳定高价金属配合物在历史上一直具有挑战性。这项工作探索了通过中心银原子的化学氧化和原高碘酸盐螯合来制备三水合三钾双高碘酸银配合物。通过酸碱滴定法以高收率和高纯度分离出螯合配合物。对三元双高碘酸银进行了全面的物理化学表征，包括单晶X射线衍射、热重分析和差示扫描量热法，以及红外和紫外可见光谱。红外和紫外可见吸收光谱（λ 255和365 nm）与历史上制备的五元二高碘酸银螯合配合物吻合良好。双螯合配合物的单斜扭曲正方形平面结构为Ag(III)和I(VII)提供了相互支撑的框架，使其在热和长期环境条件下都具有稳定性。对三元双高碘酸银配合物的热分析确定了在139.0 °C观察到的吸热质量损失，Δ = +278.35 kJ/mol，这对应于银从Ag(III)固态还原为Ag(I)。在环境条件下，固态双高碘酸银配合物在12个月期间未观察到明显降解（ = 0.30），在pH中性水溶液中的观察半衰期为τ = 147天。
