Different coordination modes of the dimethyldisulfide ligand in trimethylplatinum(IV) complexes

Abstract

The reaction of [PtMe 3 (bpy)(Me 2 CO)](BF 4 ) (2) (prepared from [PtMe 3 I(bpy)] (1) plus Ag(BF 4 )) with MeSSMe resulted in the formation of [PtMe 3 (bpy)(MeSSMejS)](BF 4 ) (3). A single-crystal X-ray diffraction analysis revealed in the octahedral Pt(IV) complex (configuration index: OC-6-33), a conformation of the monodentately jS bound MeSSMe ligand (C-S-S-C 92.7(4)°) being very close to that in non-coordinated MeSSMe, thus allowing some hyperconjugative interaction stabilizing the S-S bond. The reaction of [K(18C6)][(PtMe 3 ) 2 (l-I)(l-pz) 2 ] (4; 18C6 = 18-crown-6, Hpz = pyrazole) with Ag(BF 4 ) and MeSSMe resulted in the formation of dinuclear complexes [(PtMe 3 ) 2 -(l-pz) 2 (l-MeSSMe)] existing at room temperature in acetone solution as different fast interconverting isomers. At -40°C, two isomers with a l-1jS:2jS (5a) and a l-1jS:2jS 0 (5b) coordinated MeSSMe ligand in the ratio 2:1 could be identified 1 H NMR spectroscopically. DFT calculations of type 5 complexes revealed the existence of two conformers with a l-MeSSMe-1jS:2jS ligand, which differ mainly in the C-S-S-C dihedral angle (66.4 vs. 180.0°6a/6a 0 ). They have essentially the same energy and a very low activation barrier in acetone as solvent (1.3 kcal/mol) for their mutual interconversion. A further equilibrium structure was identified to be an isomer having a l-MeSSMe-1jS:2jS 0 ligand (6b) that proved to be only 1.9 kcal/mol higher in energy than 6a/6a 0 .

Cyclodextrin Capped Gold Nanoparticles as a Delivery Vehicle for a Prodrug of Cisplatin

“…For example, some fraction of the βSCD units on the surface of the particle are involved in inter- and intramolecular disulfide bonds. Because it is known that a sulfur atom in dimethyldisulfide can react with [PtMe 3 (bpy)(Me 2 CO)]BF 4 by displacement of acetone, it is possible that some of 3 is attached to 2 through a Pt(IV)–sulfur (disulfide) bond leading to the higher value of K observed for the conjugate–nanoparticle interaction …”

“…Because it is known that a sulfur atom in dimethyldisulfide can react with [PtMe 3 (bpy)(Me 2 CO)]BF 4 by displacement of acetone, it is possible that some of 3 is attached to 2 through a Pt(IV)− sulfur (disulfide) bond leading to the higher value of K observed for the conjugate−nanoparticle interaction. 49 Because cisplatin and carboplatin are used to treat childhood cancers, 50−52 neuroblastoma SK-N-SH cells were exposed to 4. Viewing the cells with an optical microscope 24 h after exposure to 4 showed that the gold nanoparticles cluster (individual nanoparticles are too small to be viewed with an optical microscope) in the nuclear regions of cells, Figure 8 (see the Supporting Information for additional images).…”