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Study of Intramolecular Competition between Carboxylate and Phosphonate for Pt II with the Aid of a Novel Tridentate Carboxylato‐Thioether‐Phosphonato Ligand
Author(s) -
Hamel Matthieu,
Rizzato Silvia,
Lecinq Matthieu,
Sène Aboubacary,
Vazeux Michel,
Gulea Mihaela,
Albinati Alberto,
Kozelka Jiří
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601573
Subject(s) - carboxylate , chemistry , protonation , phosphonate , ligand (biochemistry) , medicinal chemistry , thioether , perchlorate , intramolecular force , stereochemistry , crystallography , organic chemistry , ion , biochemistry , receptor
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.