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Papers by Rajesh Kunjanpillai

Asian Journal of Organic Chemistry

Chapter 1 General Introduction Homogeneous Hydrogenations and Related Reductive Reactions Catalyz... more Chapter 1 General Introduction Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes hydrogen molecule can coordinate to a metal centre in a side-on fashion (ɳ 2) primarily via donation of its two σ electrons to a vacant d orbital of the metal to form a stable dihydrogen complex. The first structurally characterized dihydrogen metal complex W(CO) 3 (Pi-Pr 3) 2 (H 2) was discovered in 1983 by Kubas and co-workers. 2 The stabilization of ɳ 2-H 2 complexes arises from the back donation of electrons from a filled metal d orbital of metal to the σ* anti bonding orbital of H 2. The back donation is analogous to that of Dewar-Chatt-Duncanson model for olefin coordination (Figure. 1.1). 3 Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes 1.4. Hydrogenation of Various Functional Groups 1.4.1. Hydrogenation of Alkenes The first documented example of homogeneous hydrogenation by metal compounds was reported by Calvin in 1938, reporting that quinoline solutions of copper acetate, at 100 °C, were found to be active catalysts for the hydrogenation of quinines 7. The most significant advances in homogeneous hydrogenation catalysis have been the discovery of rhodium phosphine complex [RhH(CO)(PPh 3) 3 ] by Bath and Vaska in 1963. 8 Later in few years, the catalytic activity of this complex for hydrogenation, isomerisation and hydroformylation reactions were reported by Wilkinson and co-workers. 9 The most important rhodium catalyst, the [RhCl(PPh 3) 3 ] complex, was reported during the period 1965-1966 independently by Wilkinson, Bennett and Vaska. 10 Wilkinson and co-workers extensively studied the remarkable catalytic properties of this complex, which is usually known as Wilkinson's catalyst. This turned out to be the first practical hydrogenation system working usually at room temperature and atmospheric pressure of hydrogen. During this time [IrCl(CO)(PPh 3) 2 ] was discovered by Vaska, called Vaska's complex, 11 which was susceptible for oxidative addition-reductive elimination with dihydrogen to form [IrH 2 Cl(CO)(PPh 3) 2 ] whose activity was very weak. Also, the iridium analogue of Wilkinson catalyst, [IrCl(PPh 3) 3 ] was also weakly active. 10b The almost inactivity of these complexes towards hydrogenation were due to inability to form vacant sites by dissociation of PPh 3 ligand from [IrH 2 (PPh 3) 3 ]. For the two decades, rhodium chemistry dominated in the field of hydrogenation, due to the remarkable investigations of Wilkinson, Kagan, Osborn, and Knowles. 12 Ruthenium was slowly developing during these period starting with studies by Halpern 6,13 and Wilkinson. 6,14 In 1965, Wilkinson and co-workers found that the reaction of RuCl 2 (PPh 3) 3 with hydrogen and a base gave the hydride complex RuHCl(PPh 3) 3 , a very active catalyst for hydrogenation. 13 This monohydride complex is formed by the abstraction of proton from the Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

European Journal of Inorganic Chemistry, 2015

A number of recent high-profi le reports have described suboptimal care of older people in UK hos... more A number of recent high-profi le reports have described suboptimal care of older people in UK hospitals. Older people already form the bulk of hospital inpatient work and it is recognised that they often experience adverse events as a result of their hospitalisation. This, coupled with an ageing population, means there is great need to improve the quality of care for older hospitalised patients. In this article, we argue that junior doctors can, and should, play a central role in the process of improving the quality of care for older people in hospital. We describe a series of innovative, trainee-led projects that have sought to improve quality of care for hospitalised older people. Lastly, we explore how senior clinicians can support junior colleagues to make meaningful, sustainable change, with specifi c reference to induction processes, quality-improvement projects and role modelling.

Asian Journal of Organic Chemistry

Chapter 1 General Introduction Homogeneous Hydrogenations and Related Reductive Reactions Catalyz... more Chapter 1 General Introduction Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes hydrogen molecule can coordinate to a metal centre in a side-on fashion (ɳ 2) primarily via donation of its two σ electrons to a vacant d orbital of the metal to form a stable dihydrogen complex. The first structurally characterized dihydrogen metal complex W(CO) 3 (Pi-Pr 3) 2 (H 2) was discovered in 1983 by Kubas and co-workers. 2 The stabilization of ɳ 2-H 2 complexes arises from the back donation of electrons from a filled metal d orbital of metal to the σ* anti bonding orbital of H 2. The back donation is analogous to that of Dewar-Chatt-Duncanson model for olefin coordination (Figure. 1.1). 3 Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes 1.4. Hydrogenation of Various Functional Groups 1.4.1. Hydrogenation of Alkenes The first documented example of homogeneous hydrogenation by metal compounds was reported by Calvin in 1938, reporting that quinoline solutions of copper acetate, at 100 °C, were found to be active catalysts for the hydrogenation of quinines 7. The most significant advances in homogeneous hydrogenation catalysis have been the discovery of rhodium phosphine complex [RhH(CO)(PPh 3) 3 ] by Bath and Vaska in 1963. 8 Later in few years, the catalytic activity of this complex for hydrogenation, isomerisation and hydroformylation reactions were reported by Wilkinson and co-workers. 9 The most important rhodium catalyst, the [RhCl(PPh 3) 3 ] complex, was reported during the period 1965-1966 independently by Wilkinson, Bennett and Vaska. 10 Wilkinson and co-workers extensively studied the remarkable catalytic properties of this complex, which is usually known as Wilkinson's catalyst. This turned out to be the first practical hydrogenation system working usually at room temperature and atmospheric pressure of hydrogen. During this time [IrCl(CO)(PPh 3) 2 ] was discovered by Vaska, called Vaska's complex, 11 which was susceptible for oxidative addition-reductive elimination with dihydrogen to form [IrH 2 Cl(CO)(PPh 3) 2 ] whose activity was very weak. Also, the iridium analogue of Wilkinson catalyst, [IrCl(PPh 3) 3 ] was also weakly active. 10b The almost inactivity of these complexes towards hydrogenation were due to inability to form vacant sites by dissociation of PPh 3 ligand from [IrH 2 (PPh 3) 3 ]. For the two decades, rhodium chemistry dominated in the field of hydrogenation, due to the remarkable investigations of Wilkinson, Kagan, Osborn, and Knowles. 12 Ruthenium was slowly developing during these period starting with studies by Halpern 6,13 and Wilkinson. 6,14 In 1965, Wilkinson and co-workers found that the reaction of RuCl 2 (PPh 3) 3 with hydrogen and a base gave the hydride complex RuHCl(PPh 3) 3 , a very active catalyst for hydrogenation. 13 This monohydride complex is formed by the abstraction of proton from the Homogeneous Hydrogenations and Related Reductive Reactions Catalyzed by Rhenium Complexes

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

European Journal of Inorganic Chemistry, 2015

A number of recent high-profi le reports have described suboptimal care of older people in UK hos... more A number of recent high-profi le reports have described suboptimal care of older people in UK hospitals. Older people already form the bulk of hospital inpatient work and it is recognised that they often experience adverse events as a result of their hospitalisation. This, coupled with an ageing population, means there is great need to improve the quality of care for older hospitalised patients. In this article, we argue that junior doctors can, and should, play a central role in the process of improving the quality of care for older people in hospital. We describe a series of innovative, trainee-led projects that have sought to improve quality of care for hospitalised older people. Lastly, we explore how senior clinicians can support junior colleagues to make meaningful, sustainable change, with specifi c reference to induction processes, quality-improvement projects and role modelling.