个人简介

B.Sc., Carleton (1964); Ph.D., M.I.T., (F.A. Cotton, 1968); Postdoctoral, Imperial College (G. Wilkinson, 1968-69); Fellow, Chemical Institute of Canada; Killam Senior Fellow (1986-87); Alcan Lecture Award, Canadian Society for Chemistry (1989); UBC Killam Research Prize (1993); Japan Society for the Promotion of Science Fellow (1996); Canada Council Killam Research Fellow (2002-2004).

研究领域

Inorganic Chemistry

Research in the Legzdins group involves the study of transition-metal organometallic and coordination compounds that contain bound nitric oxide (i.e. nitrosyl ligands). NO is a versatile and important molecule that is gaining ever-increasing recognition. While in the atmosphere it is a noxious and toxic chemical, within the human body it is extraordinarily beneficial as the principal regulator of blood pressure and as a neurotransmitter. As a ligand, NO provides a unique electronic environment at metal centres. When attached in a linear fashion, NO represents one of the strongest p-acids known, and it is capable of stabilizing rare, low-valent organometallic complexes that do not obey the familiar 18-electron rule. This feature gives rise to unusual and fascinating chemical properties for these distinctive compounds, properties and reactivity that the Legzdins group continues to explore. The principal goal of our research program is the development of organometallic nitrosyl complexes as specific reactants or selective catalysts for chemical transformations of practical significance. Typically, the attainment of this goal involves a three-step process. First, methods for synthesizing new complexes are developed. Then the newly prepared compounds are isolated and characterized fully by conventional spectroscopic means (including NMR and IR spectra and single-crystal X-ray crystallography of representative compounds). Finally, their characteristic chemical properties are established, and those that are unique to them are productively exploited. Two families of compounds that we have investigated in this regard recently are described in the following paragraphs. Cp*M(NO)(alkyl)2 [M = Mo, W; Cp* = η5-C5Me5] Complexes. These compounds may be synthesized from Cp*M(NO)Cl2precursors via metatheses reactions, and they are rare examples of electronically and coordinatively unsaturated transition-metal alkyls that can be isolated under ambient conditions. The solid-state molecular structure of one of these remarkable complexes, namely Cp*W(NO)(CH2CMe3)2, has been established by a neutron-diffraction analysis, and it is shown in Figure 1. Figure 1 During our investigations of the characteristic chemistry of these complexes, we have discovered that they react with a variety of small molecules, often in an unprecedented manner. We have also found that their chemical properties are often dependent on the metal and the nature of the alkyl group. Two particularly interesting aspects of their chemistry are illustrated below. (1) Treatment of Cp*M(NO)(alkyl)2 with dihydrogen generates transient Cp*M(NO)(alkyl)(H) intermediates that exhibit a rich derivative chemistry. This is illustrated in Scheme 1 for Cp*W(NO)(CH2SiMe3)2. Scheme 1 (1) Furthermore, thermal activation of the Cp*M(NO)(alkyl)2 complexes in neat hydrocarbon solutions generates highly reactive alkylidene complexes that can be trapped by PMe3. This is illustrated for Cp*W(NO)(CH2CMe3)2 in Scheme 2, and the neopentylidene complex thus formed can effect both single (Scheme 2) and multiple (Scheme 3) activations of solvent C-H bonds even in the presence of excess PMe3. Scheme 2 Scheme 3 Cp*W(NO)(η3-allyl)(CH2CMe3) Complexes. These compounds may also be synthesized from Cp*M(NO)Cl2 precursors via metatheses reactions. Gentle thermolyses of these complexes result in the loss of neopentane and the transient formation of the 16-electron intermediate species, Cp*W(NO)(η2-allene) and/or Cp*W(NO)(η2-diene). These transient intermediates first effect the selective single activation of hydrocarbon C-H bonds intermolecularly via the reverse of the transformations by which they were generated and form new Cp*W(NO)(η3-allyl)(η1-hydrocarbyl) complexes. This thermal chemistry is illustrated for Cp*W(NO)(η3-CH2CHCHMe)(CH2CMe3) in Schemes 4 and 5. Scheme 4 The solid-state molecular structure of the PMe3-trapped diene complex is shown in Figure 2. Figure 2 Scheme 5 The solid-state molecular structure of one of the chloroalkyl complexes is shown in Figure 3. Figure 3 Most interestingly, exposure of the newly formed Cp*W(NO)(η3-allyl)(η1-hydrocarbyl) product complexes to pressures of CO gas generally results in the migratory insertion of the CO into the metal-alkyl linkages to form acyl compounds, as illustrated for a representative reactant in Scheme 6 Scheme 6 We are currently investigating the chemical properties of the new Cp*W(NO)(η3-allyl)(η1-acyl) compounds resulting from these carbonylation reactions, with particular emphasis being placed on those reactions that result in the selective conversion of the original hydrocarbon substrate into oxygen-containing organics that can be released from the metal’s coordination sphere. These types of transformations mediated by our tungsten complexes are of considerable current interest, primarily due to their potential for eventual conversion of readily available hydrocarbons into a plethora of value-added products. These studies in metal-nitrosyl chemistry are excellent for the training of highly qualified personnel since they require the individuals involved to become proficient with concepts in inorganic, organometallic, organic, and physical chemistry. During the course of her/his work, each individual in our group develops into a proficient synthetic chemist, fully familiar with the latest methodologies for the manipulation, isolation, and characterization of reactive compounds. Furthermore, mechanistic investigations train the individual to think critically during experimental design and the evaluation and interpretation of experimental data. Finally, every member of our research group is required to be familiar with the relevant chemical literature so that the oral and written presentations of their research results are always at the cutting edge of the field.

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"Baillie, R. A. ; Legzdins, P. Distinctive Activation And Functionalization Of Hydrocarbon C–H Bonds Initiated By Cp*w(No)(Η3-Allyl)(Ch2Cme3) Complexes. Accounts of Chemical Research 2014, 47, 330-340.BibTex Lefèvre, G. P. ; Baillie, R. A. ; Fabulyak, D. ; Legzdins, P. Insights Into The Intermolecular C–H Activations Of Hydrocarbons Initiated By Cp*w(No)(Η3-Allyl)(Ch2Cme3) Complexes. Organometallics 2013, 32, 5561-5572.BibTex Chow, C. ; Patrick, B. O. ; Legzdins, P. Thermal Chemistry Of A Tungsten Trimethylsilylallyl Complex In Benzene And Fluorobenzenes. Organometallics 2012, 31, 8159–8171.BibTex Baillie, R. A. ; Tran, T. ; Lalonde, K. M. ; Tsang, J. Y. K. ; Thibault, M. E. ; Patrick, B. O. ; Legzdins, P. Factors Influencing The Outcomes Of Intermolecular C–H Activations Of Hydrocarbons Initiated By Cpw(No)(Ch2Cme3)(Η3-Allyl) Complexes (Cp = Η5-C5Me5 (Cp*), Η5-C5Me4H (Cp')). Organometallics 2012, 31, 1055–1067.BibTex Chow, C. ; Patrick, B. O. ; Legzdins, P. Intermolecular C–H Activations Of Hydrocarbons Initiated By A Tungsten Trimethylsilylallyl Complex. Organometallics 2012, 31, 7453–7466.BibTex Baillie, R. A. ; Man, R. W. Y. ; Shree, M. V. ; Chow, C. ; Thibault, M. E. ; W. McNeil, S. ; Legzdins, P. Intermolecular C–H Activations Of Hydrocarbons Initiated By Cp*m(No)(Ch 2 Cme 3 )(Η 3 -Ch 2 Chchph) Complexes (M = Mo, W). Organometallics 2011, 30, 6201 - 6217.BibTex Tran, T. ; Chow, C. ; Zimmerman, A. C. ; Thibault, M. E. ; W. McNeil, S. ; Legzdins, P. Differing Reactions Of Functionalized Hydrocarbons With Cp*m(No)(Alkyl)(η3-Allyl) Complexes Of Molybdenum And Tungsten. Organometallics 2011, 30, 738-751.BibTex Baillie, R. A. ; Tran, T. ; Thibault, M. E. ; Legzdins, P. A Beneficial Kinetic Effect Of An Η5-C5Me4H Ligand. Journal of the American Chemical Society 2010, 132, 15160 - 15161.BibTex Baillie, R. A. ; Tran, T. ; Thibault, M. E. ; Legzdins, P. A Beneficial Kinetic Effect Of An Η5-C5Me4H Ligand. [Erratum To Document Cited In Ca153:555294]. Journal of the American Chemical Society 2010, 132, 17973.BibTex Semproni, S. P. ; W. McNeil, S. ; Baillie, R. A. ; Patrick, B. O. ; Campana, C. F. ; Legzdins, P. Ground-State Electronic Asymmetry In Cp*w(No)(Η1-Isonitrile)2 Complexes. Organometallics 2010, 29, 867 - 875.BibTex Graham, P. M. ; Buschhaus, M. S. A. ; Baillie, R. A. ; Semproni, S. P. ; Legzdins, P. Hydroperoxide-Initiated Intramolecular Insertions Of No Into Metal-Carbon Bonds. Organometallics 2010, 29, 5068 - 5072.BibTex Semproni, S. P. ; Legzdins, P. Unprecedented Reactivity Initiated By Insertion Of 2,6-Xylylisonitrile Into The W-Alkyl Linkages Of Cp*w(No)(N-Alkyl)(Eta(3)-Ch2Chchme) Complexes. Organometallics 2009, 28, 6139-6141.BibTex Buschhaus, M. S. A. ; Semiao, C. J. ; Legzdins, P. Reactions Of Two Cp*w(No) Complexes With Heterocyclic Olefins. Organometallics 2009, 28, 1122-1126.BibTex Semproni, S. P. ; Graham, P. M. ; Buschhaus, M. S. A. ; Patrick, B. O. ; Legzdins, P. Toward Alkane Functionalization Effected With Cp*w(No)(Alkyl)(Eta(3-)Allyl) Complexes. Organometallics 2009, 28, 4480-4490.BibTex Buschhaus, M. S. A. ; Pamplin, C. B. ; Blackmore, I. J. ; Legzdins, P. Transformations Of Cyclic Olefins Mediated By Tungsten Nitrosyl Complexes. Organometallics 2008, 27, 4724-4738.BibTex Tsang, J. Y. K. ; Buschhaus, M. S. A. ; Graham, P. M. ; Semiao, C. J. ; Semproni, S. P. ; Kim, S. J. ; Legzdins, P. Facile And Selective Aliphatic C-H Bond Activation At Ambient Temperatures Initiated By Cp*w(No)(Ch2Cme3)(Eta(3)-Ch2Chchme). Journal of the American Chemical Society 2008, 130, 3652-3663.BibTex Graham, P. A. ; Buschhaus, M. S. A. ; Pamplin, C. B. ; Legzdins, P. Reactivity Of Cp*mo(No)(= Chcme3) With Olefins And Dienes: C-H Activation Reactions Of Molybdenacyclobutanes. Organometallics 2008, 27, 2840-2851.BibTex Tsang, J. Y. K. ; Buschhaus, M. S. A. ; Fujita-Takayama, C. ; Patrick, B. O. ; Legzdins, P. Different Modes Of Reactivity Of Cp*w(No)(Alkyl)(Eta(3)-Allyl) Complexes With Cyclic Amines: The Influence Of The Allyl Ligands. Organometallics 2008, 27, 1634-1644.BibTex Blackmore, I. J. ; Semiao, C. J. ; Buschhaus, M. S. A. ; Patrick, B. O. ; Legzdins, P. Investigations Directed At Catalytic Carbon-Carbon And Carbon-Oxygen Bond Formation Via C-H Bond Activation. Organometallics 2007, 26, 4881-4889.BibTex Tsang, J. Y. K. ; Buschhaus, M. S. A. ; Legzdins, P. Selective Activation And Functionalization Of Linear Alkanes Initiated Under Ambient Conditions By A Tungsten Allyl Nitrosyl Complex. Journal of the American Chemical Society 2007, 129, 5372-+.BibTex