| Popis: |
The mechanism of the synthesis of platinum carbonyl clusters Pt-3(CO)(6)](n)(2-) (n=3, 4) in cages of NaY was studied by IR, EXAFS (CO)-C-13 exchange reaction and NO interaction. The results suggest that oxidized Pt species in NaY cages reacts with CO at 304-373K to form PtO(CO) (sigma(CO)-2110cm(-1)) which aggregates into "Pt-3(CO)(6)" (sigma(CO)-2112, 1896 and. 1841cm(-1)) and eventually converts into dark-green carbonyl cluster (Pt-12(CO)(24)](2-). The carbonyl "Pt-3(CO)(6)" can exchange with (CO)-C-13 very quickly at 298K init the exchange reaction between (CO)-C-13 and intrazeolite Pt carbonyl clusters [Pt-3(CO)(0)](n)(2-) (n=3, 4) proceeds slowly even, at enhanced temperature such as 343K. It is interesting to find that NO breaks successively the intra and inter-trigonal lit lit bonds of the Pt-12 carbonyl clusters (even at 298 K) and the "Pt-3(CO)(6)" formed is further reacted to give PtO(CO) with the formation of N2O and CO2 in the gas phase. Pt-2(CO)(24)](2-) can be reversibly regenerated from the Pt subcarbonyls such as PtO(CO) and "Pt-3(CO)(6)" inside NaY by reacting wich CO at 300-353K. |
