个人简介

Education: BA, MA, Cambridge U; Dip Ed, NIE; MSc, NUS; PhD, Simon Fraser U FSNIC, FRSC, CChem, CSci

研究领域

Organometallic Chemistry

Our research interest is in organometallic chemistry and its applications in a number of different areas: Bioorganometallic chemistry Bioorganometallic chemistry lies at the confluence of organometallic and biological chemistry. Current activities in this new field are already very wide-ranging and varied. Our own interest is in the application of organometallic carbonyl clusters in particular, in the biomedical areas and in biology. Nanoscience Nanomaterials are finding increasing utility in a number of areas, including biomedical imaging and heterogeneous catalysis. Control of their size and composition are very important, and organometallic compounds, in particular organometallic clusters, are useful precursors for this purpose. Homogeneous catalysis and bond activation The link between organometallic chemistry and catalysis, especially homogeneous catalysis, is well established. Our current interest in homogeneous catalysis lies mainly in bond activation reactions and a detailed study of the reaction pathways utilising spectroscopic, kinetic and computational methods.

近期论文

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The room temperature reaction of Os3(CO)11(NCCH3) with BiPh3 afforded the substituted derivative Os3(CO)11(BiPh3), which has now been characterised by an X-ray crystallographic study. This completes the series of monosubstituted group 15 derivatives of triosmium carbonyl clusters. Suat Ping Oh, Ying-Zhou Li and Weng Kee Leong. J. Organomet. Chem., asap. [Cp*IrCl2]2 catalyses the cyclisation of 2-alkynylanilines into indoles. A wide variety of substrates is tolerated. A reaction pathway involving intramolecular hydroamination is proposed. Elumalai Kumaran and Weng Kee Leong. Tet. Letts.2014, 55, 5495-8. We show how a metal carbonyl functionalized nanostructured substrate can be used in a rapid and simple assay for the detection of A1AT, a potential biomarker for bladder cancer, in clinical urine samples. The assay involves monitoring changes in the carbonyl stretching vibrations of the metal carbonyl via surface-enhanced Raman spectroscopy (SERS). Kien Voon Kong, Weng Kee Leong, Zhiyong Lam, Tianxun Gong, Douglas Goh, Weber Kam On Lau and Malini Olivo. Small, 2014, 10, 5030-4. Binuclear oxidative addition of Sb-Cl bonds with the clusters Os3(CO)11(NCCH3) or Os3(CO)10(NCCH3)2 was found to be an effective synthetic route to organometallic clusters and rings containing m2-SbPh2 or m3-SbPh moieties. Isomeric products were observed, and pathways for the reactions have been proposed on the basis of experimental and computational evidence. Ying-Zhou Li, Rakesh Ganguly and Weng Kee Leong. Organometallics 2014, 33, 3867-76. The complete oxidation sequence of ruthenociphenol, a ruthenium analogue of ferrocifen, has been investigated by cyclic voltammetry. Distinct differences in behavior from the ferrocene derivatives may explain their different cytotoxic activities against hormone-independent breast cancer cells. Hui Zhi Shirley Lee, Olivier Buriez, Eric Labbe, Siden Top, Pascal Pigeon, Gerard Jaouen, Christian Amatore, and Weng Kee Leong. Organometallics 2014, 33, 4940-6. [Cp*IrCl2]2 catalyses the cyclization of 2-ethynylanilines to 2,2’-biindoles via intramolecular hydroamination. A reaction pathway has been proposed on the basis of deuterium labelling experiments and computational studies. Elumalai Kumaran, Wai Yip Fan and Weng Kee Leong. Organic Letts. 2014, 16, 1342-5. The water-soluble dimercaptopropanoate-bridged diiron hexacarbonyl complex Na2[(μ-SCH2CH2COO)Fe(CO)3]2 behaves as a photoCORM; all six CO ligands are released within 30 min of visible-light irradiation. The resulting product, tentatively assigned to an iron thiolate salt, is also water-soluble. Cell viability studies show that Na2[(μ-SCH2CH2COO)Fe(CO)3]2 is not cytotoxic toward normal epithelial cells. Hwa Tiong Poh, Bai Ting Sim, Tsz Sian Chwee, Weng Kee Leong and Wai Yip Fan. Organometallics 2014, 33, 959-63. The strong photoacoustic signal of a water soluble osmium carbonyl cluster allowed it to be employed as a contrast agent to image the cerebral vasculature of the rat. The high stability and low toxicity of such compounds make them excellent candidates in such biomedical applications. Kien Voon Kong, Lun-de Liao, Zhiyong Lam, Nitish V. Thakor, Weng Kee Leong and Malini Olivo. Chem. Commun. 2014, 50, 2601-3. The cluster Os3(CO)11(NCCH3) oxidatively adds across the Sb-H bond in SbPh2H to afford the clusters Os3(CO)11(H)(m-SbPh2) and Os3(CO)11(m-H)(m-SbPh2)Os3(CO)11. Similarly, its reaction with Sb2Ph4 afforded Os3(CO)11(m-SbPh2)2Os3(CO)11 as the major product. In both cases, the intermediate from the oxidative addition reaction was trapped as a W(CO)5 adduct. Ying-Zhou Li, Rakesh Ganguly and Weng Kee Leong. Organometallics 2014, 33, 823-8. The reaction of [Cp*MX2]2 (M = Rh or Ir, X = Cl, Br or I) with alkynylpyridines afforded halogen-substituted N-metallacyclic complexes. The reaction pathway has been examined through deuterium labeling and other experiments and computational studies, and is proposed to proceed via halide dissociation followed by attack at the alkyne. These N-metallacycles exhibit aromaticity, and undergo Sonogashira coupling reactions. Jing Wei Teo, Venugopal Shanmugham Sridevi and Weng Kee Leong. Organometallics 2014, 9, 1453-7. A structure-activity relationship study for the triosmium carbonyl cluster Os3(CO)10(NCCH3)2 has been carried out with a series of clusters of the general formulae Os3(CO)12-nLn, a cationic osmium cluster and a hemi-labile maltolato-Os cluster. The SAR results show that good solubility in DMSO and at least one vacant site are required for cytotoxicity. Some of these new compounds are found to be more active against hormone-independent breast cancer MDA-MB 231 than hormone-dependent breast cancer MCF 7, suggesting a different target that is specific to MDA-MB-231. Hui Zhi Shirley Lee, W.K. Leong, S. Top and A. Vessières. ChemMedChem, 2014, 33, 1453-7. The room temperature reaction of [Os3(CO)12] with [PdCl(allyl)(NHC)], where NHC = SIPr {N,N'-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene} or IPr {N,N'-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene}, afforded Pd-Os mixed metal clusters with the formulae [PdnOs3(CO)12(NHC)n] (n = 1-3). These are the first examples of Pd-Os heterometallic clusters containing NHC ligands, and they have all been structurally characterized. In all these clusters, the metal cores are raft-like, with carbonyl ligands bridging all the Os-Pd edges. Yu Liu, Rakesh Ganguly, Han Vinh Huynh, Weng Kee Leong. Organometallics 2013, 32, 7559-63. A triosmium carbonyl cluster-boronic acid conjugate is used as a secondary carbohydrate probe in a SERS-based assay. The assay does not require conjugation of the metal carbonyl probe to a SERS-active species and it utilizes the CO stretching vibrations of the metal carbonyl, which lies in a silent region of the SERS spectrum (1800-2200 cm-1), for quantification. High selectivity for glucose over fructose and galactose is obtained, and a human urine sample doped with glucose is detected accurately. Kien Voon Kong, Zhiyong Lam, Weber Kam On Lau, Weng Kee Leong, Malini Olivo. J. Amer. Chem. Soc. 2013, 135, 18028-31. The initial site of attack of a free N-heterocyclic carbene (NHCs) on the triosmium carbonyl cluster [Os3(CO)12] is a carbonyl ligand, to form a stable zwitterionic species. This species is the intermediate for CO substitution, which results after loss of a CO and migratory deinsertion. It is the first time that such an acyl intermediate has been crystallographically characterized. Y. Liu, R. Ganguly, H.V. Huynh and W.K. Leong. Angew. Chem. Int. Ed. 2013, 52, 12110-3. A synthetic route to cationic aminocarbene complexes of iridium(III) by the reaction of {Cp*IrCl2]2 with aminopyridines and terminal alkynes is described. These complexes can undergo reversible deprotonation at the NH moiety, and those containing a benzylic group at the metallacycle can readily undergo aerial oxidation. These are characteristic of electron delocalisation within, and hence aromaticity in, the metallacycle. E. Kumaran, K.T.S. How, R. Ganguly, Y. Li and W.K. Leong. Organometallics 2013, 32, 4149-52. Aldol-type condensation of L- and D-[Cu(phen)(threo)(H2O)]NO3 yielded their respective products with retention of chirality. Crystal structure analyses show each of the products existing as a pair of stereoisomers with the same chirality. The effect of chirality on their DNA binding recognition, BSA interaction and anticancer property is examined. C.-H. Ng, W.-S. Wang, K.-V. Chong, Y.-F. Win, K.-E. Neo, H.-B. Lee, S.-L. San, R.N.Z.R.A. Rahman and W.K. Leong. Dalton Trans. 2013, 42, 10233-43. Cp*Ir(CO)2 reacts with C6F5CN in the presence of a base to give the diaryl complex Cp*Ir(CO)(p-C6F4CN)2. K.H.G. Mak, P.K. Chan, W.Y. Fan, W.K. Leong and Y. Li. J. Organomet. Chem. 2013, 741-2, 176-180. Reaction of the dimeric species [Cp*IrCl2]2 with terminal alkynes containing a conjugated carbonyl group results in C-C bond formation between two or three alkyne molecules, depending on the polarity of the reaction medium. K.N. Wong, K.H.G. Mak, W.Y. Fan, V.S. Sridevi and W.K. Leong. J. Organomet. Chem. 2013, 741, 40-6. The reaction of [Cp*IrCl2]2 with 2-methyl-1-butene-3-yne results in the formation of a complex containing a h3-tetraenyl ligand, resulting from the head-to-head C-C coupling between the alkyne functionalities of two conjugated enyne molecules. K.H.G. Mak, W.Y. Fan, V.S. Sridevi and W.K. Leong. J. Organomet. Chem. 2013, 739, 52-6. Visible light irradiation of Cp*Ir(CO)2, 1, in pentafluorobenzontrile resulted in the formation of two isomeric diiridium(II) complexes [Cp*Ir(µ-CO)(C6F4CN)]2, 3, and [Cp*Ir(CO)(C6F4CN)]2, 4, while the analogous reaction of 1 in hexafluorobenzene to give [Cp*Ir(µ-CO)(C6F5)]2, 3a, required UV irradiation. Complex 4 isomerizes to 3 under visible light irradiation. A reaction pathway to 4 involving aromatic nucleophilic substitution has been proposed on the basis of experimental and computational data. The isomerisation of 4 to 3 is believed to proceed via a radical species resulting from homolytic fission of the Ir-Ir bond. K.H.G. Mak, P.K. Chan, W.Y. Fan, R. Ganguly, W.K. Leong. Organometallics 2013, 32, 1053-9.