Ž . Materials Science and Engineering C 15 2001 207–209 www.elsevier.comrlocatermsec Preparation via solvated metal atoms and surface reactivity of homo and heteronanostructured metal particles: supported and unsupported Rh nanoaggregates G. Vitulli a, ) , E. Pitzalis a , P. Pertici a , P. Salvadori a , S. Coluccia b , G. Martra b , L. Lampugnani c , M. Mascherpa c a Centro del CNR per le Macromolecole Stereordinate ed Otticamente AttiÕe, Õia Risorgimento 35, 56126 Pisa, Italy b Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Õia P. Giuria 7, 10125 Torino, Italy c CNR, Ist. Chimica Analitica Strumentale, Area di Ricerca, Õia Alfieri 1, 56010 Ghezzano, Pisa, Italy Abstract Ž . Nanoscale Rh particles, 1.7–2.8 nm have been easily generated by clustering of Rh atoms from mesitylene solvated Rh atoms, obtained by reaction of Rh vapour and mesitylene. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Solvated Rh atoms; Clustering; Rh nanoparticles 1. Introduction The metal vaporization provides an efficient route to wx nanostructured homo and heterometallic particles 1 . Metal atoms, when reacted at low temperature with weakly com- plexing organic compounds, allow the formation of reac- tion products soluble in the excess of ligand and stable at Ž . low temperature solvated metal atoms . Such solutions, which contain solvent stabilized metal atoms andror metal microclusters, by further clustering at room temperature act as source of activated metal nanoparticles, which can w x be isolated as unsupported and supported aggregates 1–3 . Many metal–ligand combinations can be used and the choice of ligands can be rightly overseen in order to exert a valuable control over metal cluster size. We report here that mesitylene solvated Rh atoms, obtained by reaction of Rh vapour with mesitylene, are suitable starting material for the preparation of supported and unsupported Rh nanoparticles. The method ensures the generation of very small Rhodium particles in their reduced state and no activation steps are necessary. ) Corresponding author. Tel.: q 39-50-918224; fax: q 39-50-918260. Ž . E-mail address: pervit@dcci.unipi.it G. Vitulli . 2. Results and discussion The codeposition of Rh vapour with mesitylene at liquid nitrogen temperature in a glass reactor elsewhere wx described 2 affords a red brown matrix which gives on melting a brown solution, stable at y408C, containing reaction products which can be regarded as mesitylene wx stabilized Rh-hydrido microclusters 4 . Warming to room temperature results in a further clus- tering process with precipitation of Rh as ultrafine powder; in the presence of supports such as g-Al O or pumice, a 2 3 gentle deposition of well dispersed Rh nanoparticles on the Ž . support occurs Scheme 1 . The samples so obtained have been characterized by HRTEM at different magnification: the results are summa- rized in Table 1, compared with those obtained on a commercial 5% Rhrg-Al O . 2 3 It can be seen that all the metal vapour derived samples show a quite narrow particle size distribution, with mean Scheme 1. 0928-4931r01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0928-4931 01 00244-2