Polycarbonyls of Rh+ formed after interaction of CO with Rh–MFI: an FTIR spectroscopic study
Polycarbonyls of Rh+ formed after interaction of CO with Rh–MFI: an FTIR spectroscopic study
复制标题
DOI：
10.1039/b210711b
复制
发表时间：
2003-01
影响因子：
3.3
通讯作者：
E. Ivanova;K. Hadjiivanov
中科院分区：
文献类型：
--
作者：
E. Ivanova;K. Hadjiivanov
Rh+ ions in Rh–MFI are able to coordinate simultaneously three CO molecules at 293 K, the Rh+(CO)3 species formed being characterized by IR bands at 2181, 2118 and 2084 cm−1. During evacuation at 293 K the tricarbonyls are converted to Rh+(CO)2 geminal dicarbonyls (2114 and 2048 cm−1). The latter are quite stable and are decomposed at 673 K. Negligible amounts of Rh+–CO linear species (ca. 2114 cm−1) are produced during the decomposition of the dicarbonyls. At 100 K in the presence of gaseous CO the tricarbonyls can attach one more CO molecule. The proved frequencies of the Rh+(CO)4 species obtained are at 2164–2159 and 2112 cm−1. The results are explained by the high coordinative unsaturation of Rh+ in Rh–MFI. Experiments on CO–H2O coadsorption show formation of mixed Rh+(H2O)x(CO)2 complexes (2108 and 2040 cm−1) and also evidence that the relatively high CO frequencies of the gem-dicarbonyls are a result of the high coordinative unsaturation of Rh+ in Rh–MFI and the enhancement of the σ-component of the Rh+–CO bond as compared to Rh+(CO)2 species formed on oxide supports. NO replaces CO from the Rh+ cations producing Rh+(NO)2 dinitrosyls (1881 and 1786 cm−1). No evidence of mixed carbonyl–nitrosyl species has been found.
