By stringent definition, organometallics encompasses the study of organic compounds that contain a carbon-metal bond. It remarkably combines organic and inorganic chemistry into one beautiful mesh where really cool chemistry can occur. The literature is replete with examples of reactions that employ organometallic chemistry, many of which have been taught to undergraduates in their early-on exploration of chemistry (the very familiar Grignard reaction, Gilman reagent, Grubbs’s catalyst for olefin metathesis). But there’s so much more about organometallics than meets the eye (Paulson-Khand, Heck, Suzuki, Chan-Lam, Ullmann)! A timeline of the history of organometallics is shown below (source: Wikipedia):
- 1760 Louis Claude Cadet de Gassicourt investigates inks based on Cobalt salts and isolates Cacodyl from cobalt mineral containing arsenic
- 1827 Zeise’s salt is the first platinum / olefin complex
- 1848 Edward Frankland discovers diethylzinc
- 1863 Charles Friedel and James Crafts prepare organochlorosilanes
- 1890 Ludwig Mond discovers Nickel carbonyl
- 1899 Introduction of Grignard reaction
- 1900 Paul Sabatier works on hydrogenation organic compounds with metal catalysts. Hydrogenation of fats kicks off advances in food industry, see margarine
- 1909 Paul Ehrlich introduces Salvarsan for the treatment of syphilis, an early arsenic based organometallic compound
- 1912 Nobel Prize Victor Grignard and Paul Sabatier
- 1930 Henry Gilman works on lithium cuprates, see Gilman reagent
- 1951 Walter Hieber was awarded the Alfred Stock prize for his work with metal carbonyl chemistry.
- 1951 Ferrocene is discovered
- 1963 Nobel prize for Karl Ziegler and Giulio Natta on Ziegler-Natta catalyst
- 1965 Discovery of cyclobutadieneiron tricarbonyl
- 1968 Heck reaction
- 1973 Nobel prize Geoffrey Wilkinson and Ernst Otto Fischer on sandwich compounds
- 1981 Nobel prize Roald Hoffman and Kenichi Fukui for creation of the Woodward-Hoffman Rules
- 2005 Nobel prize Yves Chauvin, Robert Grubbs, and Richard Schrock on metal-catalyzed alkene metathesis
- 2010 Nobel prize Richard F. Heck, Ei-ichi Negishi, Akira Suzuki
Our research group focuses on exploring organometallic methodologies, with special focus on metals like nickel, palladium, and copper (that mischievous blue fiend!). How I see our group’s study of organometallics is as a Nu-Nu cross coupling with the use of a lewis acid source to “connect” the two nucleophiles together.
What’s interesting about this concept is that it seems counter-intuitive because reactions occur usually between electrophiles and nucleophiles. But organometallics transcends this “normality” and introduces a whole area of confusion that’s both fascinating and headache-inducing. My current project deals with copper, which, on the spectrum of chemistry history, does some weird and unusual transformations (Gilman reactions, 1,4 additions, SN2` additions). Furthermore, its oxidation states completely covers the range of Cu(0) —> Cu(+1) —> Cu(+2) —> Cu(+3), which is not too similar to Palladium’s oxidation state profile (Pd(0) —> Pd(+2) —> Pd(+4) (rarely occurs)). Why am I using copper? I’m trying to form vinyl ethers through the coupling of a pseudo-halide (boronate ester) with alcohols, targeting that C-O bond formation:
Why am I doing this? Well, although literature is full of ways to make vinyl ethers, many of these methods need extreme conditions – strong bases, strong acids, incredibly (well, not too incredible) high temp (>220C), and reactive electrophiles. Just look back at Fritz Ullmann’s work on aryl halide coupling using copper and you’ll see how harsh the conditions were.
Fast-forward 97 years later to Chan, Lam, and Evans’s work on these copper-coupling reactions, and you’ll soon be stumbling into my research area, which is incredibly cool in my opinion.
Evans used Chan and Lam’s work to make thyroxine, a thyroid hormone agent.
I definitely need a greater foundation to shape up my misshapen understanding of organometallics, but I’m getting there.