The complex trans-bis(dimethylsulfoxide)chloromethylplatinum(II) (1) is fairly soluble in water, where it undergoes multiple equilibria involving the formation of geometrically distinct [Pt(H2O)(DMSO)Cl(CH3)] aqua-species. On reacting ail aqueous solution of 1 with monodentate nitrogen donor ligands L, such as pyridines or amines, two well distinct patterns of behavior can be recognized: (i) a single stage fast substitution of one DMSO by the entering ligand, yielding a complex of the type trans(C,N)-[Pt(DMSO)(L)Cl(CH3)] which contains four different groups coordinated to the metal and which undergoes a slow conversion into its cis-isomer, (ii) a double substitution affording cationic complex ions of the type cis- [Pt(L)(2) (DMSO)(CH3)](+). When this latter reaction is carried out using sterically hindered ligands, slow rotation of the bulk ligand around the Pt-N bond. allows for the identification of head-to-head and head-to-tail rotamers in solution, through H-1 NMR spectrometry. The addition of chloride anion to 1 leads to the anionic species cis-[Pt(DMSO)Cl-2(CH3)](-), where a molecule of DMSO still remains coordinated to the metal center, despite its quite fast rate of ligand exchange (k(exch) with free DMSO=12+/-1 s(-1)). The reaction of complex I with bidentate ligands, such as ethylenediamine (en) or simple amino acids, leads to the cationic species [Pt(en)(DMSO)(CH3)](+) or to the neutral [Pt(DMSO)(N-O)(CH3)], (where N-O=GlyO(-), AlaO(-)).
Synthetic procedures to monomethyl-platinum(II) complexes containing nitrogen ligands of biological relevance
MAZZAGLIA A;
2002
Abstract
The complex trans-bis(dimethylsulfoxide)chloromethylplatinum(II) (1) is fairly soluble in water, where it undergoes multiple equilibria involving the formation of geometrically distinct [Pt(H2O)(DMSO)Cl(CH3)] aqua-species. On reacting ail aqueous solution of 1 with monodentate nitrogen donor ligands L, such as pyridines or amines, two well distinct patterns of behavior can be recognized: (i) a single stage fast substitution of one DMSO by the entering ligand, yielding a complex of the type trans(C,N)-[Pt(DMSO)(L)Cl(CH3)] which contains four different groups coordinated to the metal and which undergoes a slow conversion into its cis-isomer, (ii) a double substitution affording cationic complex ions of the type cis- [Pt(L)(2) (DMSO)(CH3)](+). When this latter reaction is carried out using sterically hindered ligands, slow rotation of the bulk ligand around the Pt-N bond. allows for the identification of head-to-head and head-to-tail rotamers in solution, through H-1 NMR spectrometry. The addition of chloride anion to 1 leads to the anionic species cis-[Pt(DMSO)Cl-2(CH3)](-), where a molecule of DMSO still remains coordinated to the metal center, despite its quite fast rate of ligand exchange (k(exch) with free DMSO=12+/-1 s(-1)). The reaction of complex I with bidentate ligands, such as ethylenediamine (en) or simple amino acids, leads to the cationic species [Pt(en)(DMSO)(CH3)](+) or to the neutral [Pt(DMSO)(N-O)(CH3)], (where N-O=GlyO(-), AlaO(-)).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
