Research in our group lies within the general realm of synthetic Inorganic and Polymer Chemistry, with particular focus given to addressing important challenges in the fields of solar energy, catalysis and chemical sensing. In addition, through our chemical explorations, we hope to gain fundamental insight into the nature of bonding and reactivity across the Period Table. Consequently, researchers in the Rivard group will be exposed to a number of advanced synthesis and characterization techniques, including quantum mechanical (DFT) methods.
Donor-acceptor Stabilization of Reactive Inorganic Species: From Chemical Curiosities to the Synthesis of Advanced Materials
The discovery of new compounds that exhibit unique or unusual bonding and chemical reactivity is what motivates many researchers who study Inorganic Chemistry. This research ensures the future growth of Chemistry as a discipline, and can often lead to the development of new advanced materials and technologies that benefit society as a whole. Along these lines, we have been exploring a donor-acceptor approach towards isolating a wide range of species that were either completely unknown before, or were only present as fleeting intermediates in chemical processes. One such example is GeH2, which is a key intermediate in the synthesis of semiconducting Ge metal from GeH4:
We have also extended our donor-acceptor (LB-LA) protocol to include the isolation of heavy methylene and ethylene analogues, such as SiH2, SnH2, H2SiGeH2 and H2SiSnH2, in the form of stable adducts. We are currently exploring the efficient conversion of these hydrides into functional nanoparticles, including the highly desirable thermoelectric material SiGe.
Functional Inorganic Polymers: From Solar Cells to Chemical Sensors
Polymers are a ubiquitous and essential part of modern living, and as a result, brand-name polymers such as Nylon, Teflon, Latex and Kevlar are now entrenched in our vocabulary. However, as impressive as these materials are, their utility is largely based upon their physical properties rather than their ability to undergo chemical reactions or interact with external stimuli such as light. Functional Polymers combine the desirable physical properties inherent to polymers with the added advantage of pre-designed chemical reactivity.
The field of polymer-based solar cells (or photovoltaics: creating electricity from light) has profited tremendously from the synthesis of new functional polymers bearing inorganic elements. This research domain is of profound importance in advancing/promoting new methods of cleanly harnessing energy, as Solar radiation represents a largely untapped renewable resource; for example, 1 hour of incident Solar light contains enough power to satisfy the energy needs of the entire planet for 1 year (!). We are utilizing an organometallic approach to prepare new polymers of tunable electronic and physical properties in order to maximize their ability to capture Solar radiation and convert it into useful forms of energy. A key aspect of our synthetic route is the ability to generate a library of new polymeric species from a single precursor via metallacycle transfer (or atom replacement) chemistry. Thus we are able to hone in on the most suitable materials for polymeric solar cells with unparalleled speed and efficiency. Moreover our chemical syntheses allows us to also prepare polymers with light emitting behavior (for polymer light emitting devices) and should give us materials that act as chemical sensors for various electron rich analytes such as halides
Ligand Design/Coordination Chemistry: From Umbrellas to Catalysis
Recently we have developed a series of bidentate ligands featuring sterically tunable, “umbrella-shaped” triarylsilyl (-SiAr3) groups. By increasing the size of the aryl groups at silicon, unprecedented levels of steric bulk should be achieved. This principle should give us access to complexes with very low coordination numbers and enhanced reactivity. We are currently exploring these ligands to access new examples of multiple bonding in involving inorganic elements, and to prepare the next generation of highly active transition metal catalysts for the activation of small molecule substrates such as N2.
S. M. I. Al-Rafia, M. J. Ferguson and E. Rivard “Interaction of Carbene and Olefin Donors with [Cl2PN]3: Exploration of a Reductive Pathway toward (PN)3”, Inorg. Chem. 2011, 50, 10543-10545.
S. M. I. Al-Rafia, A. C. Malcolm, R. McDonald, M. J. Ferguson and E. Rivard “Trapping the Heavy Inorganic Ethylenes, H2SiGeH2 and H2SiSnH2, in the form of Stable Adducts at Ambient Temperature”, Angew. Chem. Int. Ed. 2011, 50, 8354-8357.
S. M. I. Al-Rafia, A. C. Malcolm, S. K. Liew, M. J. Ferguson, R. McDonald and E. Rivard “Intercepting Low Oxidation State Main Group Hydrides with a Nucleophilic N-Heterocyclic Olefin” Chem. Commun. 2011, 6987-6989.
S. M. I. Al-Rafia, A. C. Malcolm, S. K. Liew, M. J. Ferguson, R. McDonald and E. Rivard, “Stabilization of the Heavy Methylene Analogues, GeH2 and SnH2, within the Coordination Sphere of a Transition Metal”, J. Am. Chem. Soc. 2011, 133, 777-779.
S. M. I. Al-Rafia, P. A. Lummis, M. J. Ferguson, R. McDonald and E. Rivard “Low-coordinate Germylene and Stannylene Heterocycles featuring Sterically Tunable Bis(amido)silyl Ligands”, Inorg. Chem. 2010, 49, 9709-9717.
K. Thimer, I. Al-Rafia, M. J. Ferguson, R. McDonald and E. Rivard "Donor/acceptor Stabilization of Germanium(II) Dihydride" Chem. Commun. 2009, 7119-7122.
E. Rivard and P. P. Power, “Multiple Bonding in Heavier Element Compounds Stabilized by Bulky Terphenyl Ligands”, Inorg. Chem., 2007, 46, 10047-10064.