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Research Fellow WENG ZHIQIANG Postdoctoral Fellow, 2007, University of Illinois at Urbana-Champaign; Ph.D., 2003, National University of Singapore Contact Information:   Department of Chemistry, NUS 3 Science Drive 3 Singapore 117543 Office: S9-05-08 Tel: (65) 6516-2682 Fax: (65) 6779-1691 E-mail: chmwz@nus.edu.sg

Research Interests

• Organometallic Fluoride and Trifluoromethyl Complexes

Fluorine as the most electronegative atom plays a key role in pharmaceutical, agrochemical, and imaging agents. Incorporation of fluorine and/or fluorine-containing groups into an organic molecule can dramatically alter its chemical stability, lipophilicity and bioavailability. There is an incredible commercial driving force to develop fluorination reactions. Chem. Eng. News (2007, 85(49), 13-24) has reported that three of the top eight selling drugs in 2007 contained fluorine, including two out of the top three. However, only a handful fluoroorganic compounds exist naturally, the vast majority must be manmade. We will focus on synthesis of new late transition-metal complexes containing a M-F or M-CF3 bond, based on the reason that organometallic fluoride complexes have been proposed as key intermediates involved in the catalytic cycle for C-F bond formation; We then will examine the promising reactivity of these intermediates to release the target organofluorine compounds. Our final target is to find a practical method for metal catalyzed fluorination reactions.

• Heterobimetallic Catalyst for Hydrofunctionalization of Olefins

Heterobimetallic catalyst systems have been a topic of interest due to the potential cooperative interaction of two different metals as well as the possibility for each metal center to perform a separate and distinctive task. In this project, we will synthesize a series of heterobimetallic complexes incorporated late transition metal and Lanthanides metals. Some bifunctional ligands will be used to support the metal centre and bring the electron rich and electron deficient metals closely. The magnetic interactions and electronic cooperative effects in two different metals will probably make the complexes display unique reactivity pattern and unusual catalytic properties. We will examine the catalytic activity of these heterobimetallic complexes, for example, we will study the reactivity of these complexes in inter-and intra-molecular hydrofunctionalization of olefins.

Representative Publications

As "*" author:

• "Unusual Ligand Transformation Mediated by Cr(III): Hydrolytic Disintegration of a [PNP] Hybrid Ligand with CH₃CN Insertion". Teo, S.; Weng, Z.; Hor, T. S. A. Organometallics, 2008, in press.
• "Metal Unsaturation and Ligand Hemilability in Suzuki Coupling". Weng, Z. Teo, S.; Hor, T. S. A. Acc. Chem. Res. 2007, 40, 676.
• "A Strange Ni(I)-Ni(0) Binuclear Complex and Its Unexpected Ethylene Oligomerization".Weng, Z. Teo, S.; Liu, Z.-P.; Hor, T. S. A. Organometallics 2007, 26, 2950.
• "Chromium(III) Catalysed Ethylene Tetramerization Promoted by Bis(phosphino)amines with an N-Functionalised Pendant". Weng, Z. Teo, S.; Hor, T. S. A. Dalton Trans. 2007, 3493.
• "Suzuki Coupling Catalyzed by a Homoleptic Pd(I)-Pd(I) Solvento Complex". Han, X.; Weng, Z.; Hor, T. S. A. J. Organomet. Chem. 2007, 692, 5690.

• "Copper(I) Alkoxide Complexes in the Etherificatiion of Aryl Halides". Weng, Z.; Hartwig, J. F. To be submitted to Angew Chem. Int. Ed. 2008.
• "Copper Complexes of Anionic Nitrogen Ligands in the Amidation and Imidation of Aryl Halides." Tye, J. W.; Weng, Z. Johns, A. M.; Incarvito, C. D.; Hartwig, J. F. J. Am. Chem. Soc. 2008 in press.
• "Enantioselective a-Arylation of Ketones with Aryl Triflates Catalyzed by Difluorphos Complexes of Palladium and Nickel." Liao, X.; Weng, Z. Hartwig. J. F. J. Am. Chem. Soc. 2008, 130, 195.
• "Reductive Elimination of Ether from T-Shaped, Monomeric Arylpalladium Alkoxides". Stambuli, J. P.; Weng, Z.; Incarvito C. D. and Hartwig. J. F. Angew. Chem. Int. Ed. 2007, 46, 7674.
• "A Structurally Characterized Ni-Al Methyl-Bridged Complex with Catalytic Ethylene Oligomerization Activity". Weng, Z. Teo, S.; Koh, L. L.; Hor, T. S. A. Chem. Commun. 2006, 1319.
• "Stabilization of Nickel(0) by Hemilabile P,N-Ferrocene Ligands and Their Ethylene Oligomerization Activities". Weng, Z. Teo, S.; Hor, T. S. A. Organometallics 2006, 25, 4878.
• "1,1'-P/O-Ferrocenyl Ligands in Palladium-Catalyzed Suzuki Coupling of Aryl Chlorides". Teo, S.; Weng, Z.; Hor, T. S. A. Organometallics 2006, 25, 1199.
• "Ethylene Oligomerization of Coordinatively & Electronically Unsaturated Low-Valent Nickel". Weng, Z. Teo, S.; Koh, L. L.; Hor, T. S. A. Angew. Chem. Int. Ed. 2005, 44, 7560.
• "Homolytic Cleavage and Aggregation Processes in Cyclopentadienylchromium Chemistry". Weng, Z.; Goh, L. Y. Acc. Chem. Res. 2004, 37, 187.
• "Efficient Suzuki-Coupling of Aryl Chlorides Catalyzed by Palladium(0) with P,N-heteroligand and Isolation of Unsaturated Intermediates". Weng, Z. Teo, S.; Koh, L. L.; Hor, T. S. A. Organometallics 2004, 23, 4342.
• "Crystallographic Characterization of a Pd(II) Metallamacrocycle Supported by an Amino-Functionalized Ferrocene and Its Use as an Efficient Suzuki-Coupling Catalyst". Weng, Z. Teo, S.; Koh, L. L.; Hor, T. S. A. Organometallics 2004, 23, 3603.
• "Organometallic-Initiated Cleavage of the Metal Chelate and Thiazole Rings in a Cyclopentadienylchromium Complex". Goh, L. Y.*; Weng, Z.; Leong, W. K. Vittal, J. J. J. Am. Chem. Soc. 2002, 124, 8804.
• "C-S bond Cleavage and C-C Coupling in Cyclopentadienylchromium Complexes to Give the First Dithiooxamide-Bridged and Doubly Dithiocarbamate-Bridged Double Cubanes: [Cp₆Cr₈S₈{(C(S)NEt₂)₂}] and [Cp₆Cr₈S₈(S₂CNEt₂)₂]". Goh, L. Y.*; Weng, Z.; Leong, W. K.; Leung, P. H. Angew. Chem. Int. Ed. 2001, 40, 3236.