Platinum atomic properties

Similar to (SN)t in their one-dimenston.il conductivity properties arc the stacked columnar complexes typified by [Pl(CN)j i. These square planar ions adopt a closely spaced parallel arrangement, allowing for considerable interaction among the d i orbitals of the platinum atoms. These orbitals are normally filled with electrons, so in order to get a conduction band some oxidation (removal of electrons) must take place. This may be readily accomplished by adding a little elemental chlorine or bromine to the pure tetracyanoplatinate salt to get stoichiometries such as K-.[Pt(CN)jBr0, in which the platinum has an average oxidation state of +2.3. The oxidation may also be accomplished electrolytically. as in the preparation of Rbj(Pt(CN)4J(FHF)04 (Fig. 16.8). which has a short Pt—Pi separation. The Pt—Pt distance is only 280 pm. almost as short as that (bund in platinum metal itself (277 pm) and in oxidized platinum "pop complexes (270 to 278 pm see Chapter l5).4- Cold-bronze materials of this type were discovered as early as 1842. though they have been little understood until recent times. The complexes behave not only as one-dimensional conductors, but... 

From the symmetry properties of the products in these integrals, it can be concluded that transitions from the dz2 band to the d xy and from the dtf-y band to the d xy band are dipole-forbidden. However, a transition from the dxz band to the d xy band is dipole-allowed in the y polarization and from the dyz band to the d xy band is dipole-allowed in the x direction. Therefore, the band theory predicts a dipole-allowed transition normal to the chain from the bands arising from the orbitals which are degenerate (eg) in D4h symmetry. Since presumably interactions of the electrons between the platinum atoms are not large, the band is narrow and of low intensity. However, the band theory does account very nicely for the observed dipole-allowed transition in y polarization. 

Occurrence and History of Platinum--Proparatioi) -Punlioulimi Physical Properties—Volatilisation -Diffusion of Cases Solubility of (laMes Chemical Properties - -Catalytic Activity -Passivity Crystalline Platinum —Colloidal Platinum — Platinum Black Platinum Mpongo Explosive Platinum —Atomic Weight — Uses Buhstitutes Alloys Platinum Amalgam. 

The partial confusion arising after Dewar s and Chatt s reviews were published, was resolved after Chatt and Duncanson reported in 1953 in the Journal of the Chemical Society the results of infrared spectroscopic studies on a range of olefin platinum(II) complexes [38]. In this highly cited paper they proposed, with particular reference to Dewar s model, that in the olefin platinum(II) complexes the cr-type bond would be formed by overlap of the filled re-orbital of the olefin with a vacant 5d6s6p2 hybrid orbital of the platinum atom, and the re-type bond by overlap of a filled 5d6p hybrid orbital of the metal with the empty antibonding re-orbital of the olefin (Fig. 7.8). In addition, Chatt and Duncanson illustrated how the model could be used to interpret not only the physical properties of the olefin platinum compounds, such as the spectroscopic data and dipole moments, but also their reactivity and their greater stability compared to the olefin silver salts. 

Metal-chain complexes containing stacked square-planar tetracyanoplatinate groups, [Pt(CN)4]2", are currently of high interest because of their one-dimensional (very anisotropic ) metallic properties. Complexes of this type contain metal-atom chains and often possess a characteristic brilliant, metallic luster. They may be synthesized by oxidation using chemical or electrolytic techniques.1 Although these compounds often appear metallic, they may also be semiconductors. These complexes differ in their Pt-Pt intrachain separations, degree of partial oxidation of the platinum atom (Pt2-1 2 4), electrical conductivity, and metallic color.2 Compounds in this series which contain platinum atoms in a nonintegral oxidation state are known as partially oxidized tetra-cyanoplatinate (POTCP) complexes. Some complexes also possess a metallic luster but are not metallic, as is the case for Tl4(C03)[Pt(CN)4] (see below). 

Since square planar platinum(II) complexes have vacant coordination site at the platinum atom, upon intercalation with DNA base pairs, the local environment around the Pt core changes and the mobility of the complexes decreases. Subsequently, a profound impact upon the photoluminescent properties can be envisioned. 

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