Platinum, trimethylene

Figure 4.2 Temporal evolution in the surface coverage of [Os(bpy)2 (p3p)2]2+ adsorbed onto a gold microelectrode (bpy, 2,2,-bipyridine p3p, trimethylene-4,4 -bipyridine). From top to bottom on the left-hand side, the bulk concentrations of the complex dissolved in H2O/DMF (2 1) are 50, 20 and 10 pM. The dashed and continuous lines represent the best fits of first- and second-order models, respectively, with the error bars representing data taken from at least three independent monolayers. From R.J. Forster and J.P. O Kelly, Dynamics of [Os(bpy)2 (p3p)2]2+ adsorption and desorption on platinum and gold microelectrodes, /. Electrochem. Soc., 148, E31-E37 (2001). Reproduced by permission of The Electrochemical Society, Inc...

An interesting feature of Scheme 24, devised for palladium, is that it also provides a straightforward explanation for the bond shift isomerization on platinum. An adsorbed metallocyclobutane complex is similar to the trimethylene di-tr-complex of platinum, which is readily formed from hexa-chloroplatinic acid and cyclopropane (75). Also, platinum is known to promote easily a-y exchange of some hydrocarbons with deuterium (57, 34, 76). Therefore, in the case of platinum, the direct formation of metal-locyclobutanes, without intermediacy of 7t-allylic species, would explain the remarkable ability of this metal to promote the isomerization of neopentane to isopentane (Scheme 25). 

The self-assembling complex [Os(bpy)2(dipy)Cl](PF6) (bpy is 2,2 -bipyridine, dipy is trimethylene-4,4 -bipyridine abbreviated as Osdipy Fig. 4(C)) chemisorbs onto platinum and gold surfaces through a dangling pyridine ring with a free energy of adsorption of the order of-50 kJ/mol to form well-ordered, redox-active monolayers... 

Dihydro-4/f-p3rrid 2,l-h] oxazinium iodide (XII-639), prepared by alkylation of the silver salt of 2-pyridone with trimethylene iodide, is hydrogenated in the presence of platinum to A -(7-hydroxypropyl)piperidine. ... 

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