A Study On Structural Stability Of Ferracyclopentadienone Carbonyl Iron Clusters

Ferracyclopentadienone carbonyl compounds play an important role on construction of functional organic compounds, which are the catalytic intermediates of many cycloaddition and alkyne coupling reactions. This aspect of work is a research hot spot of chemical workers. The ferracyclopentadienone carbonyl compounds were synthesized by homogeneous catalytic reaction of metal carbonyl clusters and alkynes. A lot of knowledge and experience have accumulated for the research, and its reaction mechanism is still a hot research topic. Tetraphenyl cyclopentadienone is the important raw materials and intermediates of many organic reactions and can be designed for building aromatic compounds, which was obtained by thermal decomposition of ferracyclopentadienone carbonyl compounds.In this dissertation, ferracyclopentadienone carbonyl compounds C4Ph4Fe2(CO)6(1)and C4H2Fc2Fe2(CO)6(3) and tetraphenyl cyclopentadienone C4Ph4(CO)(2) were obtained by the thermal reaction of Fe3(CO)12 with diphenylacetypene and ferrocenylacetylene,respectively. Their molecular and crystal structures have been determined by our group. On this basis, the structural stability of ferrole compounds was studied under the presence of light, heat and Br2. The experimental results show that compound 2 is the product of three decomposition reactions of cluster 1.The main works in the dissertation are as follows:1. Ferracyclopentadiene carbonyl compound C4Ph4Fe2(CO)6(1) and tetraphenyl substituted cyclopentadienone compound(Ph4C4CO)(2) were simultaneously obtained by cyclization reaction of Fe3(CO)12 with diphenylacetypene using toluene as solvent. Ferracyclopentadiene carbonyl compound C4H2Fc2Fe2(CO)6(3) was synthesized by cyclization reaction of Fe3(CO)12 with ferrocenylacety lene using toluene as solvent.2. Cluster 1 was dissolved in CH2Cl2, and then the solution was placed under sunlight. The change of the carbonyl stretching vibration absorption peaks for cluster 1 with time was monitored by FTIR. After shined for 4 hours, cluster 1was completely decomposited. The shined solution was separated by column chromatography and the purple product of light decomposition was gotten. This compound(Ph4C4CO)(2) has been proved by MP, FTIR, NMR and MS.3. Clusters 1 was dissolved in CH2Cl2, and then the solution was irradiated by Xe lamp as light source selecting VISREF(320-780 nm), UVREF(250-380 nm),UVCUT420(420-780 nm) and single wavelength(405nm) as filters, respectively.The change of the carbonyl stretching vibration absorption peaks for cluster 1with time was detected by FTIR. After the solution shined for 24 h, 32 h, 52 h, 64 h,respectively, cluster 1 was completely decomposited. The shined solution was separated by column chromatography and the purple product of light decomposition was gotten, respectively. The purple product is compound(Ph4C4CO)(2) that have been proved by MP, FTIR, NMR and MS.4. The CH2Cl2 solution of clusters 1 kept in dark place was exposed to the air for64 h,and the change of the carbonyl stretching vibration absorption peaks for cluster 1 with time was monitored by FTIR. The results show the carbonyl stretching vibration absorption peaks for cluster 1 were not obviously altered.Cluster 1 in CH2Cl2 solution is not decomposed.5. The purple solid powder of cluster 1 was exposed to air under sunlight for 64 h,and the change of the carbonyl stretching vibration absorption peaks for cluster 1with time was monitored by FTIR. The results show the carbonyl stretching vibration absorption peaks of cluster 1 were not obviously altered,and cluster 1in solid exposed to the air is stable.6. Cluster 1 was dissolved in DMF, and the reflux reaction was carried out at140 ℃ for 4h. The solvent from the reaction solution was removed in vacuum,and the residues were separated by column chromatography. The purple product is compound(Ph4C4CO)(2) that have been proved by MP, FTIR, NMR and MS.7. Cluster 1 was dissolved in acetic acid and brominated at room temperature in bromine solution of acetic acid. The reaction solution was dealed with, and the residues were separated by column chromatography. The purple product is compound(Ph4C4CO)(2) that have been proved by MP, FTIR, NMR and MS.8. Cluster 3 was dissolved in CH2Cl2, and then the solution was placed under sunlight. The change of the carbonyl stretching vibration absorption peaks of cluster 3 with time was monitored by FTIR. After the solution shined for 48 hours, cluster 3 was completely decomposited. The shined solution was separated by column chromatography, however, the pure product has not been obtained due to complicated products of light decomposition. The separation experiment for the shined solution has still been continued.