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The formation of the iron species in FeaZSM-5 prepared by chemical vapour deposition (CVD) of FeCl 3 onto HaZSM-5 was monitored by characterising the catalyst after each step of its preparation by X-ray absorption, UV±VIS and atomic absorption spectroscopy (AAS), and by magnetic susceptibility measurements. Upon the CVD treatment, the iron ions are exchanged in the zeolite pores in the form of tetrahedrally coordinated [FeCl 2 ] species. During the subsequent washing of the zeolite most of these ions (ca. 80%) aggregate into small binuclear hydroxo-iron clusters with a structure similar to that of the binuclear units in a-FeOOH. The remaining ions are present as isolated species, while a minor fraction of multinuclear clusters may be present as well. Calcination in oxygen after the washing results mainly in the removal of the water molecules coordinatively bound to the iron species. Both the washing of the zeolite and its calcination in oxygen were found to be of fundamental importance for the formation of small clusters. When the washing is omitted, the calcination yields relatively large Fe 2 O 3 particles. If the thermal treatment after the washing is carried out in helium rather than in oxygen, partial autoreduction of the iron from Fe 3 to Fe 2 takes place together with the formation of Fe 3 O 4 clusters. The possible structure of the binuclear (hydr)oxo-iron clusters is discussed.

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UV-vis and FTIR spectroscopies and temperature-programmed decomposition were used for the identification and characterization of anionic Pt Chini complexes [Pt 3 (CO) 3 (µ-CO) 3 ] n 2-inside faujasite matrices of different Si/Al ratios (X, Y zeolites) and various character of the lattice charge-compensating cations (alkali metal + , Mg 2+ , Ca 2+ ). The ship-in bottle synthesis of these species from [Pt(NH 3 ) 4 ] 2+ was carried out by carbonylation at 90°C. It was found that Chini complexes of the nuclearities Pt 6 , Pt 9 , and Pt 15 are mostly formed in alkali metal faujasites, while the presence of Mg 2+ and Ca 2+ stimulates the formation of neutral Pt 0 particles. Larger Chini complexes are formed in Y zeolites rather than in X zeolites. Within the same zeolite type, the contribution of clusters with higher nuclearity increases in the sequence Cs + < K + < Na + < Li + . Generally, the smallest Chini clusters are preferred in zeolite matrices with the highest basicity and largest size of alkali metal cations. The finest cluster size distribution is achieved in K faujasites where Pt 6 and Pt 9 dominate. Water in zeolites is essential for the formation of Chini complexes; increasing the number of H 2 O molecules lowers the cluster nuclearity. Compared to solutions, the faujasite matrix affects the vibrational frequencies of CO ligands while electronic transitions are not changed significantly. The transformation of Chini complexes to other Pt species followed by a release of CO occurs above 90 and below 130°C for all the zeolite matrices studied.

Diffuse reflectance time-resolved UV-VIS spectroscopy has been used together with FTIR spectroscopy and ' 3CO-' 'CO isotopic exchange for the investigation of anionic Pt carbonyl complexes [Pt3(CO)3(p-CO)3],2 -formed in alkali-metal X zeolites (alkali metal = Li+, Na+, K + and Cs') from [Pt(NH,),]'+. It is shown that, compared with solutions, the zeolite matrix does not alter electronic transitions, while the vibrational frequencies of the C O ligands are appreciably changed. This latter effect is explained by the interaction of linear CO ligands with oxygen atoms of the zeolite lattice [an upward frequency shift of CO stretching vibration v(C0)J and the location of the bridging COs in the vicinity of alkali-metal cations [a downward frequency shift of CO stretching vibration v(CO),]. The effect of increasing the nuclearity of Chini complexes on the increase of v(CO), (at 2000-2100 cm-') is much higher than the influence of increasing the electropositivity of the alkali-metal cations in the X matrix. Inside all the alkali-metal X zeolites and under all carbonylation conditions used, Pt, species (n = 2) are formed. The decreasing size and electropositivity of alkali-metal cations in the sequence Cs+ > K + > Na+ > Li+ assist in stacking of more triangular units and the appearance of the Pt, and PtI5 (n = 3 and 5, respectively) carbonyl complexes.