Platinum complex dynamic

The dynamic behavior of fixed-bed reactors has not been extensively investigated in the literature. Apparently the only reaction which has received close attention is the oxidation over platinum catalysts. The investigations reveal interesting and complex dynamic behavior and show the occurrence of oscillatory and chaotic behavior [88-90], It is easy to speculate that further studies of the dynamic behavior of catalytic/biocatalytic reactions will reveal similar complex dynamics like those discovered for the CO oxidation over a Pt catalyst, since most of these phenomena are due to nonmonotonicity of the rate process which is widespread in catalytic systems. 

A series of diastereomeric platinum(II) complexes of the type c -[PtL2Y2]2+ (L - 3-bromopyr-idine, quinoline, isoquinoline Y = PEt3, Y2 = dppp, (/ )-(I )-2,2 -bis(diphenylphosphino)-l, l -binaphthyl (R-( I )-binap)) have been prepared by the reaction of c -[PtY2(OTf)2] (OTf=tri-trifluoromethanesulfonate) with two equivalents of the N-donor ligand.207 Related complexes have also been studied, for example when L = pyridine.208 Restricted rotation about the Pt—N bonds in many of the complexes is usually detected by NMR spectroscopy, with only [Pt(dppp)(isoquinoline)2]2+ (65) exhibiting dynamic behavior at ambient temperatures. The PEt3... 

Ramakrishna G, Goodson T III, Rogers-Haley JE, Cooper TM, McLean DG, Urbas A (2009) Ultrafast intersystem crossing excited state dynamics of platinum acetylide complexes. J Phys Chem C 113 1060-1066... 

The problem of establishing the solution structure of platinum-tin complexes is complicated by the lability of this system. We have found (16, 17) (and will refer to this later) that these complexes are often dynamic on the NMR time scale. Despite these difficulties it is possible to characterize such molecules using NMR methods. 

Molecular mechanics and dynamics studies of metal-nucleotide and metal-DNA interactions to date have been limited almost exclusively to modeling the interactions involving platinum-based anticancer drugs. As with metal-amino-acid complexes, there have been surprisingly few molecular mechanics studies of simple metal-nucleotide complexes that provide a means of deriving reliable force field parameters. A study of bis(purine)diamine-platinum(II) complexes successfully reproduced the structures of such complexes and demonstrated how steric factors influenced the barriers to rotation about the Pt(II)-N(purine) coordinate bonds and interconversion of the head-to-head (HTH) to head-to-tail (HTT) isomers (Fig. 12.4)[2011. In the process, force field parameters for the Pt(II)/nucleotide interactions were developed. A promising new approach involving the use of ab-initio calculations to calculate force constants has been applied to the interaction between Pt(II) and adenine[202]. 

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...

The first applications of NMR to the study of dynamic systems of the platinum group metals appear to have been studies on the rotation about the metal-olefin bond of coordinated olefins, and this process has been investigated by many workers. There are two reasonable orientations of an olefin with respect to the rest of a square planar complex, XXIV and XXV. 

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