Ligand concentration and reaction time controlled successive substitution of chloro and η6-benzene of di-μ-chlorobis{η6-benzene)dichlororuthenium(II)} with selenated Schiff base: Formation of half sandwich Ru(II) complex highly active catalyst for oxidation of alcohols

Nucleophilic substitution reaction as an important tool in the synthetic protocol for selenium donor containing Schiff bases: applications of metal complexes in homogeneous catalysis

“…26,29 At room temperature, 2-(phenylseleno)ethylamine and pyridine 2-carboxaldehyde combine (Chart 2) to produce the ligand L9 . 27 Ligand L10 is synthesized (Chart 2) by mixing a solution of 2-(phenylseleno)ethylamine and 2-methylthiobenzaldehyde in dry CH 3 OH, 28,30,31 followed by stirring. For the synthesis of ligand L11 , 2-(phenylseleno)ethylamine and o -hydroxyacetophenone (Chart 2) are stirred 18 together in dry ethanol at room temperature.…”

“…, 1 , 2 and 3 . 26,28,30 For the synthesis of complex 1 , it is reacted (Chart 4) with the ligand L8 in MeOH. 26 For the synthesis of complexes 2 ( i.e.…”

“…, [Ru( L10 ) 2 ][PF 6 ] 2 ) (Chart 4), it is reacted with ligand L10 . 28,30 The formation of the complex (either 2 or 3 ) depends on the concentration of the ligand L10 and/or the reaction time. When the molar concentration of the ligand is four times higher than that of the precursor and the reaction mixture is subjected to stirring for 8 hours, the formation of complex 3 occurs.…”

“…The geometry around ruthenium in complex 3 is deformed octahedral. However, it is pseudo-octahedral half sandwich, or “piano-stool” type 28,30 in complex 2 .…”

“…In the recent past, such selenium containing ligands have been used to develop interesting and highly competent homogeneous catalytic systems for various organic transformations. 10,12,16–19,22–35 This article aims at covering the utility of nucleophilic substitution reaction as a tool in the synthetic methodologies for selenium containing Schiff base ligands and their metal complexes, and also analyzing their applications in catalysis of various organic transformations such as Suzuki coupling, Heck coupling, Sonogashira coupling, C–O coupling, oxidation of alcohols and transfer hydrogenation reactions.…”