Square-planar complexes calculations

Large geometrical distortion in the lowest excited states of Pt(gly)2 is also suggested by spectroscopic studies, which have indicated that similar square planar complexes have pseudotetra-hedral excited states (93a), by semi-empirical molecular orbital calculations (56), and also by recent quenching and sensitization studies of the cis trans reaction (Section lII-D-1). ... 

Use the data to calculate k, and k2 for substitution in this square planar complex. 

As Figure 22.24 shows, the splitting pattern for square-planar complexes is the most complicated. Clearly, the orbital possesses the highest energy (as in the octahedral case), and the d y orbital the next highest. However, the relative placement of the d 2 and the d and dy orbitals cannot be determined simply by inspection and must be calculated. 

The period under discussion has seen intense interest in the recently discovered i7 -H2 complexes. The relevance of these to some isomerization reactions of square-planar complexes was reported in Volume 5 of this series, and is covered in another recent review. " More of these fluxional ds-dihydridoplatinum compounds have been reported, and the role of 17 -H2 derivatives in oxidative additions to d rhodium(I) and iridium(I) has been discussed. The increasing role of theoretical and bonding studies is reflected in four works relevant to 4-and 5-coordinate molecules. Electronic structure is related to chemical reactivity in the reactions of phosphine bases with d bis(l,l-dithiolato)platinum com-plexes. Huckel calculations on the reactions of bis(nitrogen donor) ligands with 16-electron platinum(II) complexes have been carried out, as has more work on symmetry selection rules for isomerization reactions, which includes pseudorotation of 5-coordinate complexes and square-planar to tetrahedral conversions of 4-coordinate molecules. ... 

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-... 

The vibrations of A2u pccies of the square planar complex ions arc not given, because they are the out of-plane modes and were not used for the calculation of the force constants. 

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." " ... 

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