Synthesis and characterisation of mixed ligand Pt(II) and Pt(IV) oxadiazoline complexes.
The nitrile ligands in trans-[PtX2(PhCN)2] (X = Cl, Br, I) undergo sequential 1,3 dipolar cycloadditions with nitrones R1R2C=N+(Me)-O(-) (R1 = H, R2 = Ph; R1 = CO2Et, R2 = CH2CO2Et) to selectively form the Delta4-1,2,4-oxadiazoline complexes trans-[PtX2(PhCN) (N=C(Ph)-O-N(Me)-CR1R2)] or trans-[PtX2(N=C(Ph)-O-N(Me)-CR1R2)2] in high yields. The reactivity of the mixed ligand complexes trans-[PtX2(PhCN)(N=C(Ph)-O-N(Me)-CR1R2)] towards oxidation and ligand substitution was studied in more detail. Oxidation with Cl2 or Br2 provides the Pt(IV) species trans-[PtX2Y2(PhCN)(N=C(Ph)-O-N(Me)-CH(Ph))] (X, Y = Cl, Br). The mixed halide complex (X = Cl, Y = Br) undergoes halide scrambling in solution to form trans-[PtX(4-n)Yn(PhCN)(N=C(Ph)-O-N(Me)-CH(Ph))] as a statistical mixture. Ligand substitution in trans-[PtCl2(PhCN)(N=C(Ph)-O-N(Me)-CR1R2)] allows for selective replacement of the coordinated nitrile by nitrogen heterocycles such as pyridine, DMAP or 1-benzyl-2-methylimidazole to produce mixed ligand Pt(II) complexes of the type trans- [PtX2(heterocycle)(N=C(Ph)-O-N(Me)-CR1R2)]. All compounds were characterised by elemental analysis, mass spectrometry, IR and 1H, 13C and 195Pt NMR spectroscopy. Single-crystal X-ray structural analysis of (R,S)-trans-[PtBr2(N=C(Ph)-O-N(Me)-CH(Ph))2] and trans-[PtCl2(C5H5N)(N=C(Ph)-O-N(Me)-CH(Ph))] confirms the molecular structure and the trans configuration of the heterocycles relative to each other.
Sarju
Julien
J
Chemical Sciences, FHMS, University of Surrey, Guildford, Surrey, UK GU2 7XH.
Arbour
Jannine
J
Sayer
James
J
Rohrmoser
Benjamin
B
Scherer
Wolfgang
W
Wagner
Gabriele
G
D000970:Antineoplastic Agents / Q000494:pharmacology; D001966:Bromine / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002713:Chlorine / Q000737:chemistry; D015195:Drug Design; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009944:Organoplatinum Compounds / Q000737:chemistry; D010080:Oxazoles / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods
D000970:Antineoplastic Agents; D008024:Ligands; D009944:Organoplatinum Compounds; D010080:Oxazoles; D010984:Platinum; D002713:Chlorine; D010100:Oxygen; D001966:Bromine