ChemInform Abstract: NOVEL BINUCLEAR PLATINUM(III) OCTAPHOSPHITE COMPLEXES

Pyrophosphito-bridged diplatinum chemistry

“…Electron donation from the axial ligand X" in Pt2X2 into the Pt-Pt da* orbital causes a variation of distance with axial ligand. The donor ability for X" to platinum follows the sequence SCN" ~T > N02" > Br" > CT, which correlates with the Pt-Pt distances (Table I) 22,24,[27][28][29] The long Pt-X distances are due to the large trans influence of the Pt-Pt bond. This lengthening is expected, since the Pt orbitals involved in intermetallic bonding (5dz2 and 6pz) also are employed in the attachment of the axial ligand.…”

“…The complex Pt2 undergoes thermal two-electron two-center oxidative addition of halogens or alkyl iodides to give axially substituted diplatinum(III) complexes Pt2X2 (X = Cl, Br, I) or Pt2RI (R = alkyl). 22 Mechanistic studies with methyl iodide show that the reaction follows an associative pathway and that the rate is unperturbed by added external nucleophile.23 These diamagnetic Pt2X2 and Pt2RI products have an intermetallic bond joining the diplatinum(III) centers. 22,24 Diplatinum(III) species of these types also can be synthesized by the oxidation of Pt2 in the presence of excess halide ion.…”

“…22 Mechanistic studies with methyl iodide show that the reaction follows an associative pathway and that the rate is unperturbed by added external nucleophile.23 These diamagnetic Pt2X2 and Pt2RI products have an intermetallic bond joining the diplatinum(III) centers. 22,24 Diplatinum(III) species of these types also can be synthesized by the oxidation of Pt2 in the presence of excess halide ion. The chemical oxidants that have been used include Ce4+, IrCl62", PtCl62™, Fe(CN)63™, Co(EDTA)", Ru(NH3)63+, and H202; electrochemical anodic oxidation also has been employed.…”