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Type: Artigo de periódico
Title: First Evidence For Two Different μ-η1-η1- And μ-η1-η2- Co-ordination Modes Of The P3c2but 2 Ring Of [fe(η5-p3c2but 2)(η5-c5h5)] To A Same Cluster Fragment.
Author: Araujo M.H.
Hitchcock P.B.
Nixon J.F.
Vargas M.D.
Abstract: Investigation of the solution structures of [Ir4(CO)11L] (L = [Fe(η5-P3C2But 2)(η5-C5H5)] (1) and [Fe(η5-P3C2But 2)(η5-P2C3But 3)] (2) by 13C and 31P NMR spectroscopy showed that, at 163K, 1 exists in the form of two isomers with bridged and non-bridged structures, in a 1:0.15 ratio, respectively, whereas 2 exists only in the bridged form. At RT, 1,2 shift of η5-P3C2But 2 ring was only observed for compound 2. Where as 2 loses CO readily in solution to give [Ir4(CO)10{μ-η1-η 1-[Fe(η5-P3C2But 2)(η5-P2C3But 3)}] (3), activation with Me3NO was necessary to produce [Ir4(CO)10{[Fe(η5-P3C 2But 2)(η5-C5H 5)}] (4), obtained in the form of two non-interconverting isomers 4a and 4b, which were not able to be separated. A single crystal X-ray diffraction study of isomer4a established that the [Fe(η5-P3C2But 2)(η5-C5H5)] ligand bridges one of the edges of the Ir4 tetrahedron, interacting via the lone electron pair of one of the adjacent P atoms and in an η2- mode via the P-P double bond of the η5-P3C2But 2 ring and that all CO ligands arc terminally bonded. Variable temperature31P{1H} NMR spectroscopy evidenced a fluxional process involving interactions between the Ir1 and Ir2 atoms and the lone pair on P1, the P1-P2 bond, and the lone pair on P2. According to multinuclcar NMR, cluster 4b has similar structure to compound 3, with the η5-P3C2But 2 ring co-ordinated in aη1-η1- mode via the two adjacent P atoms, and all CO ligands bonded terminally.
Rights: aberto
Identifier DOI: 
Date Issue: 2000
Appears in Collections:Unicamp - Artigos e Outros Documentos

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