Greengold, a giant cluster compound of unusual electronic structure

We report the isolation of a previously elusive giant gold-cluster compound with unusual electronic structure and excellent solid-state ordering prope rties. Greengold is a water-soluble Au:PR3 compound (R=p-C6H4-CONHCH3) form ed in high yield in the solution-phase reduction of R3PAuCl. Following chro matographic isolation, it has been investigated by electron microscopy (STE M), optical spectroscopy, mass spectrometry (MALDI), and X-ray diffraction, from which emerges a consistent picture of Greengold's intrinsic character istics as (i) a single compound of similar to 22 000 amu molecular weight, containing a strongly bound globular metal core of mass 14800 (AU(75), 1.3- nm equivalent diameter); (ii) a highly ordered solid, exhibiting diffractio n through 21 orders of a 2.47-nm spacing; and (iii) a carrier of a highly s tructured optical absorption across the entire visible and near-infrared sp ectrum (to similar to 1.0 eV), including relative transparency in the blue and yellow regions, giving rise to its eponymous green tint.