Chemistry

Eight COs for U

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Science  05 Nov 2010:
Vol. 330, Issue 6005, pp. 733
DOI: 10.1126/science.330.6005.733-c

Although many transition metals readily form stable complexes with multiple carbonyl (CO) groups, uranium carbonyls have proven to be exceptionally difficult to synthesize and characterize. Ricks et al. studied the coordination of CO to U+ and UO2+ cations generated in the gas phase by laser-induced vaporization. The vibrational spectra of mass-selected clusters were determined by exciting the complexes in the infrared and measuring photodissociation yields. Although larger clusters with weakly bound CO molecules were observed, the core coordination complexes were U(CO)8+ and UO2(CO)5+. Aided by quantum chemical calculations, the authors assigned the former complex as a square antiprism with appreciable back-donation of metal electrons to CO and the latter as a pentagonal bipyramid with little back-donation. These results extend the range of metal complexes exclusively binding CO to coordination number 8.

J. Am. Chem. Soc. 132, 10.1021/ja1077365 (2010).

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