Substitution Reactions of Five-coordinate Complexes. 2. Mechanism of Ligand Replacement in Trigonal-bipyramidal Nickel(ii) and Platinum(ii) Complexes Containing the Tetradentate Ligand Tris(o-(diphenylarsino)phenyl)arsine
Ligand replacement of the monodentate ligand in a series of trigonal-bipyramidal nickel(II) complexes containing the tetradentate ligand tris(o-(diphenylarsino)phenyl)arsine, QAS, is reported for methanol solutions. Entering ligands replacing Br- in order of decreasing rate were SC(NH2)2 ≫ CN-, > N3- > SCN- > I- > NO2 - ≫ PPh3. CN- replacement of leaving groups in order of decreasing rate were NCS- > N3 - > Cl- > Br- > NO2 - > I-. A second consecutive decomposition was observed to be several orders of magnitude slower than ligand replacement when CN- was the entering ligand. The kinetic data obtained at 0.050 M ionic strength and 25.0°C are consistent with either an associative interchange, Ia, mechanism or a mechanism involving formation of a four-coordinate intermediate via partial dissociation of the tetradentate ligand.
H. L. Collier and E. B. Grimley, "Substitution Reactions of Five-coordinate Complexes. 2. Mechanism of Ligand Replacement in Trigonal-bipyramidal Nickel(ii) and Platinum(ii) Complexes Containing the Tetradentate Ligand Tris(o-(diphenylarsino)phenyl)arsine," Inorganic Chemistry, vol. 19, no. 2, pp. 511-515, American Chemical Society, Feb 1980.
The definitive version is available at https://doi.org/10.1021/ic50204a046
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© 1980 American Chemical Society, All rights reserved.
01 Feb 1980