His research interests include Organophosphorus Chemistry and Main Group Chemistry. He has over 115 publications so far and is a fellow of the Indian Academy of Sciences, Bangalore. N. N. Bhuvan Kumar was born in Cherukupalli, Guntur, India. After completing his B.Sc. from Nagarjuna University, he joined the School of Chemistry, University of Hyderabad, as a postgraduate student in the year 2000 and obtained his Master's degree in Chemistry. Currently, he is pursuing a Ph.D. on Organophosphonates under the supervision of Prof. K. C. Kumara Swamy. E. Balaraman was born in Kancheepuram, Chennai, India, in 1980. He received his M.Sc. in Chemistry from Vivekananda College [Madras University (2002)] and his Ph.D. degree in the areas of organophosphonates and modified BINOLs under the guidance of Prof. K. C. Kumara Swamy. Presently he is a postdoctoral fellow with Professors David Milstein and Ronny Neumann at the Weizmann Institute of Science, Israel. K. V. P. Pavan Kumar was born in Hyderabad (Andhra Pradesh), India, in 1979. He obtained his B.Sc. (Chemistry Honors) and M.Sc. (Chemistry) degrees from Sri Sathya Sai Institute of Higher Learning, Puttaparthi, A.P., India. He obtained his Ph.D. degree under the guidance of Prof. K. C. Kumara Swamy in October 2006. Presently he is working as a postdoctoral fellow in the area of hydroamination reactions using new titanium catalysts with Prof. Pierre Le Gendre at the Universite ´de Bourgogne, France.

Catalytic hydrogenation of organic carbonates, carbamates and formates is of significant interest both conceptually and practically, because these compounds can be produced from CO2 and CO, and their mild hydrogenation can provide alternative, mild approaches to the indirect hydrogenation of CO2 and CO to methanol, an important fuel and synthetic building block. Here, we report for the first time catalytic hydrogenation of organic carbonates to alcohols, and carbamates to alcohols and amines. Unprecedented homogeneously catalysed hydrogenation of organic formates to methanol has also been accomplished. The reactions are efficiently catalysed by dearomatized PNN Ru(II) pincer complexes derived from pyridine- and bipyridine-based tridentate ligands. These atom-economical reactions proceed under neutral, homogeneous conditions, at mild temperatures and under mild hydrogen pressures, and can operate in the absence of solvent with no generation of waste, representing the ultimate 'green' reactions. A possible mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core.

The selective, direct hydrogenation of amides to the corresponding alcohols and amines with cleavage of the C-N bond was discovered. The expected products of C-O cleavage are not formed (except as traces in the case of anilides). The reaction proceeds under mild pressure and neutral, homogeneous conditions using a dearomatized, bipyridyl-based PNN Ru(II) pincer complex as a catalyst. The postulated mechanism involves metal-ligand cooperation by aromatization-dearomatization of the heteroaromatic pincer core and does not involve hydrolytic cleavage of the amide. The simplicity, generality, and efficiency of this environmentally benign process make it attractive for the direct transformations of amides to alcohols and amines in good to excellent yields.

The oxidation of alcohols to carboxylic acids is an important industrial reaction used in the synthesis of bulk and fine chemicals. Most current processes are performed by making use of either stoichiometric amounts of toxic oxidizing agents or the use of pressurized dioxygen. Here, we describe an alternative dehydrogenative pathway effected by water and base with the concomitant generation of hydrogen gas. A homogeneous ruthenium complex catalyses the transformation of primary alcohols to carboxylic acid salts at low catalyst loadings (0.2 mol%) in basic aqueous solution. A consequence of this finding could be a safer and cleaner process for the synthesis of carboxylic acids and their derivatives at both laboratory and industrial scales.

Visible light-mediated photocatalytic organic transformation has drawn significant attention as an alternative process for replacing thermal reactions. Although precious metal/organic dyes based homogeneous photocatalysts have been developed, their toxic and nonreusable nature makes them inappropriate for large-scale production. Therefore, we have synthesized a triazine and a keto functionalized nonmetal based covalent organic framework (TpTt) for heterogeneous photocatalysis. As the catalyst shows significant absorption of visible light, it has been applied for the photocatalytic uphill conversion of trans-stilbene to cis-stilbene in the presence of blue light-emitting diodes with broad substrate scope via an energy transfer process.

The development of nanoparticle-polymer-hybrid-based heterogeneous catalysts with high reactivity and good recyclability is highly desired for their applications in the chemical and pharmaceutical industries. Herein, we have developed a novel synthetic strategy by choosing a predesigned metal-anchored building block for in situ generation of metal (Pd) nanoparticles in the stable, porous, and crystalline covalent organic framework (COF), without using conventional reducing agents. In situ generation of Pd nanoparticles in the COF skeleton is explicitly confirmed from PXRD, XPS, TEM images, and N NMR spectral analysis. This hybrid material is found to be an excellent reusable heterogeneous catalyst for the synthesis of biologically and pharmaceutically important 2-substituted benzofurans from 2-bromophenols and terminal alkynes via a tandem process with the turnover number up to 1101. The heterogeneity of the catalytic process is unambiguously verified by a mercury poisoning experiment and leaching test. This hybrid material shows superior catalytic performance compared to commercially available homogeneous as well as heterogeneous Pd catalysts.

Indirect CO2 hydrogenation: Hydrogenation of urea derivatives to the corresponding amines and methanol is reported (see picture). The reaction is catalyzed by a bipyridine‐based tridentate PNN Ru(II) pincer complex and proceeds under mild, neutral conditions using 13.6 atm of H2. A mild approach is offered for the indirect hydrogenation of CO2 to methanol as urea derivatives are available from CO2.

Electron-rich PNP- and PNN-type ruthenium(II) hydrido borohydride pincer complexes, [RuH(BH4)( t Bu-PNP)] (tBu-PNP = (2,6-bis(di-tert-butylphosphinomethyl)pyridine) (5) and [RuH(BH4)( t Bu-PNN)] ( t Bu-PNN = 2-di-tert-butylphosphinomethyl-6-diethylaminomethylpyridine) (6), were prepared from their corresponding N2-bridged dinuclear Ru(II) complexes [( t Bu-PNP)RuCl2]2(μ-N2) (3) and [( t Bu-PNN)RuCl2]2(μ-N2) (4), respectively. The X-ray structure of 5 reveals a BH4 – anion η2 coordinated to ruthenium through two bridging hydrides. A variable-temperature 1H NMR study of 6 exhibits interesting fluxional behavior of the BH4 – ligand. Similarly, the Ru(II) hydrido borohydride complex 9, in which the BH4 – moiety is coordinated in a η1 bonding mode, was obtained by reaction of [RuCl2(PPh3)( i Pr-PNP)] ( i Pr-PNP = 2,6-bis(diisopropylphosphinomethyl)pyridine) (8) with two equivalents of NaBH4 at room temperature. The hydrido borohydride pincer complexes 5, 6, and 9 catalyze the acceptorless dehydrogenative coupling of primary alcohols to esters and the dehydrogenation of secondary alcohols to the corresponding ketones, accompanied by evolution of hydrogen gas. The reactivity follows the order 6 > 9 > 5. With the hydrido borohydride complex 6 as catalyst, high yields (up to 98%) and high turnover numbers (TON ∼1000) were obtained in the dehydrogenation of primary alcohols under mild and neutral conditions. In addition, 6 effectively catalyzes the hydrogenation of nonactivated aromatic and aliphatic esters to the corresponding alcohols with TON ∼200 under a relatively mild pressure of dihydrogen and neutral and homogeneous conditions. Thus, an efficient homogeneous catalytic system for the dehydrogenation–hydrogenation reactions of alcohols is developed, which is relevant to the current interest in hydrogen storage.