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  • 08/08/17

    Research from Professor Ellis designated 'Very Important Paper'

A research article by Professor John Ellis and his colleagues has been designated as a Very Important Paper, which is a distinction given to less than five percent of the manuscripts published in Angewandte Chemie.

The article, "Ta(CNDipp)6, Dipp = 2,6-diisopropylphenyl: An Isocyanide Analog of Hexacarbonyltantalum(0),” was written by Khetpakorn Chakarawet, Zachary W. Davis-Gilbert, Stephanie R. Harstad, Victor G. Young Jr., Ph.D., Professor Jeffrey R. Long, and Professor Ellis. Chakarawet and Long are from the Department of Chemistry at the University of California, Berkeley.

The abstract reads: “Hexakis(2,6-diisopropylphenylisocyanide)tantalum is the first isocyanide analogue of the highly unstable Ta(CO)6 and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta0 complexes are known, Ta(benzene)2 and Ta(dmpe)3, dmpe = 1,2-bis(dimethylphos-phano)ethane, but these have only been accessed via ligand co-condensation with tantalum vapor in a sophisticated metal-atom reactor. Consistent with its 17-electron nature, Ta-(CNDipp)6 undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, it qualitatively resembles V(CO)6, the only paramagnetic homoleptic metal carbonyl isolable under ambient conditions.”

One of the reviewers wrote: “This is a beautiful piece of work describing the synthesis and structure of an isocyanide analog of the elusive Ta(CO)6. John Ellis has made a career out of making highly novel compounds of the early transition metals in ‘impossible’ oxidation states, which require outstanding experimental skill, and this paper is no exception.” 

Another reviewer commented that this research builds on an older observation that the disproportionation product [Ta(CNDipp)7][Ta(CNDipp)6] could be isolated in crystalline form. Here, several purposeful syntheses of the Ta(0) complex, Ta(CNDipp)6, are along with some fascinating reactivity studies of it and it's 1e-reduced analogue, the anion [Ta(CNDipp)6]-. 

“The results and detailed characterization of the compounds are beyond reproach. Moreover, this will inspire others to potentially investigate the chemistry of Ta(0) compounds, of which there are few,” wrote the reviewer.