Square planar complexes platinum

Insertion of alkenes. Alkene insertions have also been widely studied and many insertion products have been isolated [31], Alkene insertions follow a migratory mechanism in the palladium and platinum square planar complexes with diphosphine ligands [18],... 

Platinum square planar complexes Alkenes, allenes, arsines, phosphines, sulfoxides, cyclic ethers, etc. [49,50]... 

Let us try to predicf qualitatively (without making calculations) the band structure of a stack of platinum square planar complexes, typically [Pt(CN )4 ]co- Con-... 

Let us try to predict" qualitatively (without making calculations) the band structure of a stack of platinum square planar complexes - typically [Pt(CN )4 ]oo. Consider the eclipsed configuration of all the monomeric units. Let us first simplify our task. Who likes cyanides Let us throw them away and take something theoreticians really love H . This isn t just laziness. If needed, we are able to make calculations for cyanides too, but to demonstrate that we really understand the machinery, we are always recommended to make the system as simple as possible (but not simpler). We suspect that the main role of CN is just to interact electrostatically, and H does this too (being much smaller). In reality, it turns out that what decides is the Pauli exclusion principle, rather than the ligand charge." " ... 

Square planar complexes of palladium(II) and platinum(II) readily undergo ligand substitution reactions. Those of palladium have been studied less but appear to behave similarly to platinum complexes, though around five orders of magnitude faster (ascribable to the relative weakness of the bonds to palladium). 

Like palladium(II) and platinum(II), gold(III) has the d8 electronic configuration and is, therefore, expected to form square planar complexes. The d-orbital sequence for complexes like AuC14 is dx2 yi dxy > dvz, dxz > dzi in practice in a complex, most of these will have some ligand character. 

As already mentioned, complexes of chromium(iii), cobalt(iii), rhodium(iii) and iridium(iii) are particularly inert, with substitution reactions often taking many hours or days under relatively forcing conditions. The majority of kinetic studies on the reactions of transition-metal complexes have been performed on complexes of these metal ions. This is for two reasons. Firstly, the rates of reactions are comparable to those in organic chemistry, and the techniques which have been developed for the investigation of such reactions are readily available and appropriate. The time scales of minutes to days are compatible with relatively slow spectroscopic techniques. The second reason is associated with the kinetic inertness of the products. If the products are non-labile, valuable stereochemical information about the course of the substitution reaction may be obtained. Much is known about the stereochemistry of ligand substitution reactions of cobalt(iii) complexes, from which certain inferences about the nature of the intermediates or transition states involved may be drawn. This is also the case for substitution reactions of square-planar complexes of platinum(ii), where study has led to the development of rules to predict the stereochemical course of reactions at this centre. 

C20-0004. Platinum forms a large collection of square planar complexes. Draw ball-and-stick models similar to those in Example for the cis and trans Isomers of [Pt (NH3)2 CI2 ]. 

Isomerization involving a square planar complex is also known. Because of the trans effect, it is easier to synthesize the trans isomer of many complexes than it is to prepare the cis complex. The following reactions lead to the formation of an unusual platinum complex ... 

Square-planar complexes of platinum(II) and palladium(II) have been known for a long time the comparatively simple unit cells of compounds such as K2PdCl4, K2PtCl4, and Pd(NH3)4Cl2H20 led to early elucidation of the structures (257) and they all contain square-planar ions. The simple halides PdCl2 and Pt,Cl2 (71) consist of chains in which the metal is bonded from the corners of a square. Nickel chloride, on the other hand, has a layer lattice in which the nickel is octahedrally coordinated, and in the halide complexes the coordination is tetrahedral, as described in Section IV,B. 

When the apparently penta-coordinated diarsine complexes just described are dissolved in solvents more polar than nitrobenzene, they tend to dissociate into halide ions and bivalent cations, thus becoming 2 1 electrolytes (119). The effect is most marked with the platinum compounds. It has been shown that solvation effects might be less with platinum than with palladium, and so, other things in the equilibria being equal, it can also be concluded that the bonding of further ligands by a square-planar complex is much weaker with platinum than with palladium. Square-planar nickel complexes are of course the most ready to take up further ligands. 

In general, penta-coordinated complexes are rather rare. So far as nickel, palladium, and platinum are concerned, it seems that such complexes may be formed as intermediates when square-planar complexes accept further ligands in their tendency to become hexa-coordinated. The... 

A structural investif tion of the anion in Zeise s salt has shown that the ethylene occupies the fourth coordination site of the square planar complex wth the C—C axis perpendicular to the platinum-ligand plane (Fig. 15.22).75 Relative to free ethylene, the C—C bond is lengthened slightly (from 133.7 pm to 137.5 pm), and the hydregens are slightly tilled back from a planar arrangement. 

Platinum(II) forms square planar complexes, and platinum(IV) gives octahedral complexes. How many diastereoisomers are possible for each of the following complexes Describe their structures. 

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. 

The / (195Pt—XH) coupling, 39-40 Hz, shows that the phosphine is coordinated to platinum. Since it occupies an axial position of the basically square planar complex, the phosphine is rather labile. Activation energies for exchange of 4.2 and 19.7 kcal/mole were found where the ligand was p-dithiocumate and 3,4,5-trimethoxydithiobenzoate, respectively. 

Burmeister and colleagues have described the related pseudohalogen derivatives MfterpyjXj (X = SCN or SeCN) (90-92). The platinum compound exhibits the two thiocyanate stretching frequencies expected for a square-planar complex, and is formulated [Pt(terpy)(NCS)][NCS], However, the palladium complexes are less easily formulated, exhibiting absorptions due to coordinated ECN (E = S or Se) only. These observations were interpreted in terms of a square-planar structure, with a bidentate terpy ligand in view of the known ability for palladium and platinum diimine complexes to form five-coordinate species, this formulation must also be considered. In the absence of definitive structural evidence, the formulation as five-coordinate species must be regarded as speculative. 

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