Wuzong Zhou, ^* John Meurig Thomas, ^* Douglas S. Shephard, Brian F. G. Johnson, Don Ozkaya, Thomas Maschmeyer, Robert G. Bell, Qingfeng Ge

The anionic ruthenium cluster carbonylates [Ru₆C(CO)₁₆]^2- or [H₂Ru₁₀(CO)₂₅]^2- interspersed with bis(triphenylphosphino)iminium counterions (PPN⁺) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and computer simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gentle thermolysis, the cluster carbonylates yield nanoparticles of ruthenium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cyclooctene. In both their as-prepared and denuded states, these encapsulated clusters are likely to exhibit interesting electronic and other properties.

W. Zhou, D. S. Shephard, B. F. G. Johnson, Q. Ge, University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK.
J. M. Thomas, Davy-Faraday Research Laboratories, Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UK, and Department of Materials Science, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
D. Ozkaya, Department of Materials Science, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, UK.
T. Maschmeyer, University Chemical Laboratories, Lensfield Road, Cambridge CB2 1EW, UK, and Davy-Faraday Research Laboratories, Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UK.
R. G. Bell, Davy-Faraday Research Laboratories, Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UK.
^*   To whom correspondence should be addressed. E-mail: wz100{at}cus.cam.ac.uk (W.Z.)