Synthetic procedures to monomethyl-platinum(II) complexes containing nitrogen ligands of biological relevance.
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(H(2)O)(DMSO)Cl(CH(3))] aqua-species. On reacting an 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(CH(3))] 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)(CH(3))](+). When this latter reaction is carried out using sterically hindered ligands, slow rotation of the bulk ligand around the Pt[bond]N bond allows for the identification of head-to-head and head-to-tail rotamers in solution, through (1)H NMR spectrometry. The addition of chloride anion to 1 leads to the anionic species cis-[Pt(DMSO)Cl(2)(CH(3))](-), 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 1 with bidentate ligands, such as ethylenediamine (en) or simple amino acids, leads to the cationic species [Pt(en)(DMSO)(CH(3))](+) or to the neutral [Pt(DMSO)(N[bond]O)(CH(3))], (where N[bond]-O[double bond]GlyO(-), AlaO(-)).
Monsù Scolaro
Luigi
L
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, Universitá di Messina, and Istituto per lo Studio dei Materiali Nanostrutturati (ISMN-CNR), Sezione di Messina, Italy. monsu@chem.unime.it
Mazzaglia
Antonino
A
Romeo
Andrea
A
Romeo
Raffaello
R
D000596:Amino Acids / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D017671:Platinum Compounds / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D012996:Solutions; D014867:Water / Q000737:chemistry
D000596:Amino Acids; D002712:Chlorides; D008024:Ligands; D017671:Platinum Compounds; D011725:Pyridines; D012996:Solutions; D014867:Water; D009584:Nitrogen