Mixed-valent linear chain Pt2PdPt2 complexes

Pentanuclear linear-chain PtPd complexes {[Pt-2(NH3)(2)X-2(mu-pivalamidato)(2)(CH2COCH3)](2)[PdX'(4)]}center dot 2CH(3)COCH(3) (X = X' = Cl (1a), X = Cl, X' = Br (1b), X = Br, X' = Cl (1c), X = X' = Br (1d)) composed of a monomeric Pd-II complex sandwiched by two amidato-bridged dimeric Pt-III. units were synthesized from the reaction between the acetonyl dinuclear Pt-III complexes having equatorial halide ligands [Pt-2(NH3)(2)-X-2(mu-pivalamidato)(2)(CH2COCH3)]X '' (X = Cl (2a), Br (2b), X '' = NO3- CH3C6H4SO3-) and K-2[PdX'(4)] (X' = Cl, Br). The X-ray crystallographic analysis of 1a-1d shows that the complexes have metal-metal bonded linear Pt2PdPt2 structures. The pentanuclear PtPd complexes have either an arch backbone structure or a sigmoid backbone structure, depending on the solvent of crystallization. The UV/Vis/NIR spectra clearly show the existence of a rare charge-transfer band from Pd to Pt in the pentanuclear PtPd complexes. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).