A paper by Philip Coppens et al. in the Royal Society of Chemistry (RSC) Journal Chemical Communications is featured on the “RSC Hot Papers Web Page.” The work was performed at ChemMatCARS, APS sector 15. The group has developed several novel methods and is one of the very few research groups in the world routinely doing high-resolution, small-molecule, time-resolved crystallography.

A very large Rh-Rh bond shortening on excitation of the [Rh 2(1,8-diisocyano-p-menthane) 4] 2+ ion by time-resolved synchrotron X-ray diffraction
Philip Coppens , Oksana Gerlits , Ivan I. Vorontsov , Andrey Yu. Kovalevsky , Yu-Sheng Chen , Tim Graber , Milan Gembicky and Irina V. Novozhilova

Philip Coppens and his colleagues at SUNY at Buffalo, Toledo and Chicago describe in this communication a dramatic shortening of metal-metal distance, seen upon excitation of a dinuclear transition metal complex. We have already seen that the Rh-Rh bond length in ground state complexes varies tremendously depending upon the counterion. The use of time resolved X-ray techniques here reveals the unusually large contraction of the intermetallic distance on excitation of the ion to its triplet state. This represents the first experimental verification of Rh-Rh shortening in the solid state. (SA)