Research Interests
Research Highlights
Pincer Metal Complexes and Catalysis
New Symmetrical and Unsymmetrical Pincer Ligands
Our research is centered around synthesis and characterization of transition metals, main group elements and lanthanide compounds for catalytic applications. Our approach involves design and synthesis of novel and tailor made ligand systems which will be able to stabilize the active metal center in catalyses. For example, several pyrrole-based ligands given above were recently developed by novel synthetic methods for synthesizing several Pd(II), Ni(II), Cu(I), and Ag(I) complexes.
Representative publications
Inorg. Chem. 2012, 51, 12527-12539
Dalton Trans., 2012, 41, 9503-9512
New N-heterocyclic carbene metal complexes
A new pro-carbene ligand was synthesized which gave NHC-Pd and Ni complexes upon treatment with metal precursors in very high yields. The significance of these reactions is the simultaneous double C-H bond activation to give carbene complex in the absence of any base or via transmetalation strategies.
Dalton Transactions 2019, 48, 7203 - 7210 (invited article for the New Talent: Asia Pacific themed issue of Dalton Transactions)
Hydrosilylation:
Organometallics, 2023, 42, 732-744.
Ni and Pd Catalyzed CO2 reductions
Boron Chemistry
Heterocycle-tethered organoboranes generally dimerize by using the heteroatom present in them. When this does not take place, some interesting molecules or properties are bound to be observed. This is demonstrated in this work as well. The lithium salt of 1,2-dimethylimidazole reacts with Et2B(OMe) or 9-BBN-OMe to give the air stable intermolecular adduct of 2-(dialkylborylmethyl)-1-methyl-imidazole (alkyl = Et (1) and 9-BBN (2)) after treatment with BF3·OEt2. These two dimers exist in two stereoisomers: clockwise and anticlockwise, as shown by their X-ray structures. On the contrary, the analogous reaction between the lithium salt of 1,3,5-trimethylpyrazole and Et2B(OMe) in the presence of BF3·OEt2, an air and moisture sensitive adduct, 1-(diethylborylmethyl)-3,5-dimethylpyrazole·BF2(OMe) (3), was isolated as liquid in an excellent yield, instead of its dimer. Its structure is based on 1H, 19F, 11B, and HRMS methods, and supported by anion binding studies. Consequently, the reactive neat liquid 3 decomposes in air to give the bicyclo[3.3.1]nonane-like neutral bicycle 4. Notably, a CH2Cl2 solution of 3 decomposes differently to give the OH bridged cationic analogous bicycle 5. In addition, their precursors, [2-(diethylborylmethyl)-1-methylimidazole·LiOMe(1,2-dimethylimidazole)]2 6, [(1-(diethylborylmethyl)-3,5-dimethylpyrazole·LiOMe)2THF] 7, and [(1-(diethylborylmethyl)-3,5-dimethylpyrazole·LiOMe(DMAP)2] 8 were also isolated and structurally characterized. In the crystal lattices of structures of 4, 5 and 7, both enantiomers RR and SS are present.
Organometallics, 2018, 37, 127−135
Olefin Polymerization
Several Ni, and Pd complexes supported by unsymmetrical pincer and orthophenolate ligands catalyze norbornene polymerization reactions at room temperature in the presence of cocatalyst such as MMAO and EtAlCl2 to give polynorbornene in excellent yields with very high activities in the range of 108 g of PNB/mol/h. The polymers were characterized by NMR, IR, TGA and powder XRD.
Inorg. Chem., 2019, 58, 3444–3456.
Inorg. Chem. 2018, 57, 7735-7747
Anion Receptors
An intense research is going on all over the world to develop effective and selective receptors for anions in aqueous solution. We developed a series of novel pyrrole-based acyclic, cyclic and bicyclic receptors. Some of these receptors are shown to be selective for sulfate ion in aqueous/organic medium and fluoride ion in DMSO in the presence of other competing anions.
Representative papers
Org. Lett. 2010, 12, 3212–3215
Org. Lett. 2010, 12, 3910–3213
J. Org. Chem. 2011,76, 10114-10121
Inorg. Chem. 2012, 51, 9029–9038
Inorg. Chem. 2012, 51, 11635–11644)