Trans-effect in complexes

In this chapter, a series of ligands were arranged in order of their ability to produce a trans effect in complexes of Pt2+. Where would you place SeCN- in that series Why ... 

Comparison of cobalt(III) and platinum(II) complexes, therefore, provides further evidence for the duality of mechanism (a and v) for the trans effect in the latter and shows that there is no single order of ligands which can be transferred from one metal cation to another. A comparison of the ligand orders observed for different metal cations should lead to a much better understanding of the importance of different types of bonds between the metal and ligand, and hence of the chemical properties of complexes. It is hoped that this review will stimulate interest in obtaining more experimental data on cis and trans effects in complexes of other metal cations. 

H. W. Quinn and J. H. Tsai Cis and Trans Effects in Cobalt(Ill) Complexes... 

The preparation of the dinuclear complexes is readily achieved by taking advantage of the well-established trans effect in square-planar complexes. For example, the treatment of two equivalents... 

At this point, it is appropriate to mention some of the evidence that indicates a trans effect in octahedral complexes, but only a brief description will be given. In the reaction of Mo(CO)6 with pyridine, only three CO ligands undergo replacement, and the product has the structure... 

In addition to the indications of an octahedral trans effect presented, there exists structural information in the form of bond lengths and spectral data similar to that described earlier for square planar complexes. Although the trans effect in octahedral complexes is not the dominant influence that it is in square planar complexes, there is no doubt that there is such an effect. 

Basolo, Fred and Pearson, Ralph G., The Trans Effect in Metal Complexes. . 4 381... 

Cis and Trans Effects in Cobalt(III) Complexes J. M. Pratt and R. 0. Thorp... 

For a recent review on trans-effects in octahedral transition metal complexes, see ... 

Elder, R. C., Heeg, M. J., Payne, M. D., Trkula, M., and Deutsch, E. (1978). trans Effect in octahedral complexes. 3. Comparison of kinetic and structural trans effects induced by coordinated sulfur in sulfito- and sulfinatopentaamminecobalt(III) complexes. Inorg. Chem. 17,431-440. 

The oxo moiety in these complexes exerts a strong trans effect in both the structural and kinetic senses. In the case of dichloro[hydrotris(l-pyrazolyl)borato]oxotech-netate(V)93 hexacoordination is forced by the chelating ligand however, the three pyrazole nitrogens are not equivalent. The Tc-N bond distances are 2.086 A, 2.088 A and 2.259 A, with the latter distance belonging to the nitrogen trans to the oxygen. 

Fig. 23-6. Pi-electron Overlap and the Trans-Effect in a Platinum(ll) Complex...

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