| Increasing attention has been paid to dinuclear metal complexes, due to the significant cooperative effect of both metal centers on their reactivity and catalytic applications. Intensive study of these complexes will help to provide new catalysts with potential application prospects and expand organometallic chemical theory. In this dissertation, reactions of fulvenes and five-heterocyclic substituted cyclopentadienes with carbonyl complexes gave 12 corresponding dinuclear metal carbonyl complexes. 8 complexes of them were characterized by X-ray diffraction and their structures were also discussed. The main results are listed as following:In this dissertation, 6 five-heterocyclic substituted cyclopentadienyl ligands were designed and synthesized. Reactions of these ligands with metal carbonyl complexes in refluxing xylene gave the corresponding dinuclear metal carbonyl complexes [(η5-C5Me4C4H3S)M(CO)(μ-CO)]2 [M=Ru (6), M=Mo (7)],[(η5-C5H4)CR1R2(C4H3S)Ru (CO)2]2 [R1, R2=CH3 (8), R1=CH3, R2=C2H5 (9), R1, R2=(CH2)5 (10), R1, R2=C2H5 (11)], [(η5-C5Me4(2-CH3C4H2O))Ru(CO)(μ-CO)]2 (13) and [(η5-C5Me4(2-CH3C4H2O))Fe(CO) (μ-CO)]2 (14) which have been characterized by IR spectra, 1H NMR, and elemental analysis, and the molecular structures of the complexes 6, 8, 10, 11 and 13 were determined by X-ray diffraction. The structures of the complexes 6, 8, 10 and 13 are similar. They have two types of carbonyl ligands, namely terminal and bridging, in their molecular structures.However, the complex 11 has only four terminal carbonyls without bridging carbonyls, which has a much longer Ru-Ru bond distance than those in the complexes 6, 8, 10 and 13. The steric effects of the substituents had influence on the molecular structures, especially on the Ru-Ru bond distances. The Ru-Ru bond distance increases with the increasing of the steric effect of the substituent, on the contrary, the smaller. The five-heterocyclic furan or thiophene in these ligands did not coordinate with the metal centers. This is mainly attributable to the lone pair electrons in the furan and thiophene, which may be involved in the formation of aromatic systems.Reactions of fulvene ligandsC5H4CR1R2 [R1, R2=CH3 (15), R1, R2=C2H5 (16)] with Ru3(CO)12 were studied respectively, the corresponding fulvene-bridged complexes (η3:η5-C5H4C(CH2)2)Ru2(CO)5 (18) and (η3:η5-C5H4C(CHCH2)(C2H5))Ru2(CO)5 (19) were obtained which contain Ru-Ru bond. One Ru atom is coordinated with cyclopentadienyl ligand inη5 manner, the other Ru atom is coordinated with allyl group inη3 manner. It illustrates fulvenes undergo double bond isomerization, which coordinate with the Ru atom in reactions. At the same time, the 6, 6-tetramethylenefulvene was reacted with Ru3(CO)12 in refluxing xylene to give the new dinuclear complexes (η5-C5H4C5H7)2Ru2(CO)2(μ-CO)2 (20) and (η1:η5-C5H8C5H4)Ru2(CO)6 (21). By IR spectra, 1H NMR, and elemental analysis, complex 21 has been identified as the fulvene-bridged diruthenium complex and its structure reveals that an exocyclic double bond and two enocyclic double bonds in fulvene ligands have been bound to two Ru atoms in anη1:η5-mode. Complex 20 has been characterized by single crystal X-ray diffraction analysis and its crystal structure shows that the 6, 6-tetramethylenefulvene undergos double bond isomerization, which does not coorditate with the metal center in the reaction. These results suggest that when metal carbonyl complexes reacted with fulvenes, due to the different coordination modes, diversified product structures were obtained. Different coordination modes in molecular structures had a great influence on the Ru-Ru bond distance. The Ru-Ru bond distances of complexes inη3:η5 andη1:η5 fashions were longer than that of unbridged complexes inη5 fashion. This is mainly attributable to the existence of the C-bridge, which hindered further nearing between the two Ru atoms and made the Ru-Ru bond longer.
|
PDF Full Text Request