Study of Intramolecular Competition between Carboxylate and Phosphonate for PtII with the Aid of a Novel Tridentate Carboxylato-Thioether-Phosphonato Ligand
✍ Scribed by Matthieu Hamel; Silvia Rizzato; Matthieu Lecinq; Aboubacary Sène; Michel Vazeux; Mihaela Gulea; Alberto Albinati; Jiří Kozelka
- Book ID
- 101837260
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 208 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
The tridentate dianionic ligand 2‐[2′‐(hydroxyisopropoxyphosphoryl)phenylsulfanyl]benzoate (L^2−^) reacts with cis‐[Pt(NH~3~)~2~(H~2~O)~2~]^2+^ to form an S,O‐chelate in which the O‐coordinated group is either carboxylate or phosphonate, depending on the degree of protonation of the complex. Carboxylate appears to be the stronger ligand, and the stoichiometric reaction between cis‐[Pt(NH~3~)~2~(H~2~O)~2~]^2+^ and L^2−^ yields the neutral species [Pt(L)(NH~3~)~2~], with L bound by sulfanyl and carboxylate groups, both in solution and in the solid state. Upon protonation of [Pt(L)(NH~3~)~2~], the stronger basicity of the carboxylate causes the Pt coordination to switch from carboxylate to phosphonate, and the uncoordinated carboxylate group becomes protonated. In methanolic solution, the first‐order kinetics of this rearrangement could be observed by ^31^P NMR spectroscopy. Both complexes—the carboxylate‐bound neutral complex [Pt(L)(NH~3~)~2~]⋅H~2~O (triclinic, P$\bar 1$ (no. 2), a=9.529(6), b=9.766(6), c=12.299(7) Å, α=106.91(2), β=101.71(2), γ=102.05(2)°, Z=2) and the perchlorate salt of the phosphonate‐bound complex [Pt(LH)(NH~3~)~2~]ClO~4~⋅H~2~O (monoclinic, __P__2~1~/c (no. 14), a=12.095(2), b=14.046(2), c=14.448(2) Å, β=95.55(2)°, Z=4)—were characterized by X‐ray crystallography.