Bimetallic Supported Catalysts from Single-source Precursors - Atomically-Precise Methods for Synthesis of Solid Catalysts - page 78

d n 9 r 4 n g | 5

.

Figure 3.11 TEM images after thermal activation of clusters (a) [Ru 5 PtC(CO) 14 (COD)]
and (b) [Ru 6 Au 2 C(CO) 16 (PPh 3 ) 2 ] immobilized on activated carbon via
chelating phosphine groups.
Reproduced with permission from ref. 81.

same steps than with clusters (see the scheme in Figure 3.5), i.e., (i) syn-
thesizing ligand-stabilized metal-containing species in solution (preferably
monodisperse in size), (ii) immobilizing them on a support and (iii) acti-
vating them by ligand removal in order to obtain heterogeneous catalysts.
This was coined the 'precursor' concept by H. Bonnemann and colleagues. 89
These authors quote that 'an obvious advantage of the precursor concept
over the conventional salt-impregnation method is that both the size and the
composition of the colloidal metal precursors may be tailored independently
of the support'. This is precisely the line of reasoning developed for cluster
compounds. As mentioned above, when small colloid metal nanoparticles