TY - JOUR
T1 - Triosmium clusters on a support
T2 - Determination of structure by X-ray absorption spectroscopy and high-resolution microscopy
AU - Mehraeen, Shareghe
AU - Kulkarni, Apoorva
AU - Chi, Miaofang
AU - Reed, Bryan W.
AU - Okamoto, Norihiko L.
AU - Browning, Nigel D.
AU - Gates, Bruce C.
PY - 2011/1/17
Y1 - 2011/1/17
N2 - The structures of small, robust metal clusters on a solid support were determined by a combination of spectroscopic and microscopic methods: extended X-ray absorption fine structure (EXAFS) spectroscopy, scanning transmission electron microscopy (STEM), and aberration-corrected STEM. The samples were synthesized from [Os3(CO)12] on MgO powder to provide supported clusters intended to be triosmium. The results demonstrate that the supported clusters are robust in the absence of oxidants. Conventional high-angle annular dark-field (HAADF) STEM images demonstrate a high degree of uniformity of the clusters, with root-mean-square (rms) radii of 2.03±0.06Å The EXAFS Os-Os coordination number of 2.1±0.4 confirms the presence of triosmium clusters on average and correspondingly determines an average rms cluster radius of 2.02±0.04Å The high-resolution STEM images show the individual Os atoms in the clusters, confirming the triangular structures of their frames and determining Os-Os distances of 2.80±0.14Å, matching the EXAFS value of 2.89±0.06Å. IR and EXAFS spectra demonstrate the presence of CO ligands on the clusters. This set of techniques is recommended as optimal for detailed and reliable structural characterization of supported clusters.
AB - The structures of small, robust metal clusters on a solid support were determined by a combination of spectroscopic and microscopic methods: extended X-ray absorption fine structure (EXAFS) spectroscopy, scanning transmission electron microscopy (STEM), and aberration-corrected STEM. The samples were synthesized from [Os3(CO)12] on MgO powder to provide supported clusters intended to be triosmium. The results demonstrate that the supported clusters are robust in the absence of oxidants. Conventional high-angle annular dark-field (HAADF) STEM images demonstrate a high degree of uniformity of the clusters, with root-mean-square (rms) radii of 2.03±0.06Å The EXAFS Os-Os coordination number of 2.1±0.4 confirms the presence of triosmium clusters on average and correspondingly determines an average rms cluster radius of 2.02±0.04Å The high-resolution STEM images show the individual Os atoms in the clusters, confirming the triangular structures of their frames and determining Os-Os distances of 2.80±0.14Å, matching the EXAFS value of 2.89±0.06Å. IR and EXAFS spectra demonstrate the presence of CO ligands on the clusters. This set of techniques is recommended as optimal for detailed and reliable structural characterization of supported clusters.
KW - EXAFS spectroscopy
KW - HAADF-STEM
KW - MgO-supported clusters
KW - aberration-corrected STEM
KW - osmium carbonyls
UR - https://www.scopus.com/pages/publications/78651423336
U2 - 10.1002/chem.201000860
DO - 10.1002/chem.201000860
M3 - Article
AN - SCOPUS:78651423336
SN - 0947-6539
VL - 17
SP - 1000
EP - 1008
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 3
ER -