DFT study of nucleophilicity of organometallic (2,2′-bipyridine)platinum(II) complexes

•A correlation was made between electron-donating power and rate of oxidative addition.•A correlation was made between the energy of Pt dZ2 orbital and rate of oxidative addition.•Theoretical support for the SN2 type mechanism in oxidative addition of polar R-X reagents on organoplatinum(II) complexes.

The structures of [Pt(bpy)R2] complexes (bpy = 2,2′-bipyridine, R = Me, Ph, 4-MeC6H4, 4-MeOC6H4, 3-MeOC6H4, 4-NMe2C6H4, 4-FC6H4, 3-FC6H4, 4-ClC6H4, CCH, CCPh, CF3, CN) were optimized. Energy of neutral, cationic and anionic forms of these complexes were calculated at the B3LYP/6-311G(d,p) level of theory. Nucleophilicity indexes and electron-donating powers were calculated for these complexes. A relatively good correlation for nucleophilicity index and a very good correlation for electron-donating power were found between these descriptors and logk2 (when available) (k2 is the second order rate constants for oxidative addition of methyl iodide on these complexes). Also a good correlation was found between the energy of platinum dZ2 orbital and logk2. The condensed-to-atom Fukui functions for nucleophilic and electrophilic attacks on these complexes show that in all of these complexes, Pt center is the especially preferable site for electrophilic attack. These observations support the mechanism of SN2 type for oxidative addition of polar organic reagents on organoplatinum(II) complexes.

Graphical abstractThe electron-donating power (1/ω−) for the [Pt(bpy)R2] (R = Me, Ph, 4-MeC6H4, 4-MeOC6H4, 3-MeOC6H4, 4-FC6H4, 3-FC6H4, 4-ClC6H4) has a very good correlation with logk2 (k2 is the experimentally determined second order rate constant for the oxidative addition of methyl iodide on these complexes).Figure optionsDownload full-size imageDownload as PowerPoint slide