Reactions Of Cyclopentadiene And Benzocyclopentadiene Derivatives With Metal Carbonyl

In recent years, because of the metal carbonyl compounds could activate multiplechemical bonds such as C-H bond, C-C bond, C=C bond etc., they have been broadly utilizedin organic synthesis. With further research, we found that hetero atoms were more likely tolead to the presence of C-H activation reactions. Based on it, in this paper we studiedreactions of the pyridyl-side-chain cyclopentadiene, N-heterocycle-substituted indene andfluorene derivatives,2-chloropyrazine and2-chloropyrimidine with metal carbonylcompounds.(1) The ligand of1,2,4,5-tetramethyl-3-(2-pyridyl)methyl cyclopentadienyl wasdesigned and synthesized. It reacted with Ru3(CO)12、Fe(CO)5、Mo(CO)6in refluxing xylene,respectively. Then three kinds of common binuclear metal compounds were isolated:[(η5-C5Me4)CH2(C5H4N)]2Ru2(CO)2(μ-CO)2(2)、[(η5-C5Me4)CH2(C5H4N)]2Fe2(CO)2(μ-CO)2(3)、[(η5-C5Me4)CH2(C5H4N)]2Mo3(CO)6(4), expect these we did not obtain any C-H bondactivated product. With the similar compounds by M-M bonds length comparison, we foundthat the steric effect of the substituent on the M-M bond length did have a certain influence.With increasing substituents, the steric effect became greater and the length of M-M bond waslonger.(2) The ligand of3-(2-pyrazinyl) indene was designed and synthesized, then reactedwith Ru3(CO)12、Fe(CO)5、Mo(CO)6, respectively. The results showed that the reactivity of theligand with Fe(CO)5、Mo(CO)6on the experimental conditions was very poor, yet quite goodwith Ru3(CO)12. Reaction of the ligand with Ru3(CO)12in refluxing xylene afforded atrinuclear ruthenium complex [μ2-η5:η1-(C4H3N2)(C9H5)]Ru3(CO)9(8). The molecularstructure of8was determined by X-ray diffraction. Result showed that the C-H activated toform C-Ru bond since the N atom coordinated with Ru atom. We also discussed the influenceof different solvents on the product. The reaction time was greatly reduced when heptane ortoluene was chosen as solvent instead of xylene, but product’s yield did not have significantchange.(3) We studied the reactions of Ru3(CO)12with fluorene,9-(2-pyrazinyl)fluorene and9-(2-pyridyl)fluorene. The results indicated that fluorene did not react with Ru3(CO)12on the experimental conditions. But N-heterocyclic substituted fluorene reacted with Ru3(CO)12inrefluxing xylene and afforded products:(C13H9)(C4H2N2)Ru3(CO)10(9) and(C13H9)(C5H3N)Ru3(CO)10(10). The probably reason was that adjacent C atom occured C-Hactivation for C-Ru bond formation due to N atom coordinated with Ru atom.(4) We also studied reactions of Ru3(CO)12with2-chloropyrazine and2-chloropyrimidine, and obtained two new compounds. The molecular structure of theproduct which was obtained by reaction of Ru3(CO)12with2-chloropyrazine was determinedby X-ray diffraction. It showed that the compound was a three-core clustersRu3(μ-C4H2NCl)(CO)10(11): N atom coordinated with Ru atom and caused its adjacent Catom to occur C-H activation for C-Ru bond formation.The composition and structure of compounds were characterized by means of1HNMR,IR spectra and elemental analysis. The crystal structures of five compounds were determinedvia X-ray diffraction analysis.