Executive Summary : | The designs of ancillary ligands have received a great deal of attention in the last two decades because they can be used to alter the structural, reactivity, electronic, chemical, and physical properties of the resulting metal complexes. This area has developed into a fascinating sub-discipline of inorganic and organometallic chemistry. By this way, novel bonding motifs, desired electronic and steric tuning in the ligands and their metal complexes have been achieved. In the current proposal, a series of redox-active N-heterocyclic carbenes [Nq(NHC); Nq = Naphthoquinone] anchored and donor functionalized species are described. According to the synthetic protocols, reactions of Nq(NHC) carbenes with suitable phosphorus reagents would furnish the P(I) species supported by redox-active carbenes. In contrast to the reported examples, the latter group can serve as a redox probe, which can help bringing novel electronic and reactivity aspects to the P(I) compounds. These species can serve as four electron donor ligands, and a series of mono, and bimetallic neutral and cationic versions could be prepared, and their catalytic efficiency can be examined in the carbon dioxide reductive functionalization reactions; for instance, CH activations in the presence of CO2 would furnish the corresponding CO2 insertion products (carboxylic acids, RCOOH). Furthermore, a series of mono-dentate and pincer type ligands with N,C,N-donor atoms bearing redox-active backbones could be achieved synthetically. These species can be converted into the corresponding P(I) compounds, whose reactivity can be further explored as novel ligands. In addition, we will also explore electrochemical and IR spectroscopic studies to understanding their electronic properties. When such species are present in the free form and when bound to various metals. This type of studies may guide us further for judicious choice of the ligand and their metal complexes in selected organic transformations such as CO2 reduction, functionalization and conversion to value added chemicals and products. Moreover, redox-active NHCs can be functionalized to yield the corresponding N-heterocyclic olefins, and reactions with CO2/CS2 would furnish the carboxylate and thio-carboxylate adducts of the type Nq(NHO)CE2. Some selected Nq(NHC)(NCN) and Nq(NHC)PR ligands supported copper complexes will be examined in the synthesis of biologically active oxazoles and triazoles derivatives by coupling azides with ethereal based internal-terminal alkynes. |