Chiral annulated cyclopentadienyl ligands: Synthesis and crystal structure of both exo and endo Rh{η5-Cp′}(cod)} [Cp′=(4S,7R)-1,2,3-triphenyl-4,8,8-trimethyl-1H,4,5,6,7-tetrahydro-4,7-methanoindenyl]
1998; Elsevier BV; Volume: 551; Issue: 1-2 Linguagem: Inglês
10.1016/s0022-328x(97)00563-9
ISSN1872-8561
AutoresJames A. Ramsden, David J. Milner, Harry Adams, Neil A. Bailey, Paul D. Hempstead, Colin White,
Tópico(s)Ferrocene Chemistry and Applications
ResumoAbstract The title homochiral cyclopentadiene ligand C 31 H 30 (i.e., Cp′H, 5 ) has been synthesised from camphor in four steps. The lithium salt of this ligand reacted with [Rh(cod)Cl] 2 to give predominantly racemic ( η 4 -cycloocta-1,5-diene)[ η 5 -1,2,3-triphenyl-4-methyl-7-isopropyl-1H-indenyl]rhodium although the desired RhCp′(cod) complex was formed in 20% yield as an equal mixture of endo 7a and exo 7b isomers. The X-ray structures of 7a and 7b have been determined at room temperature with use of Mo-K α radiation ( λ =0.71069 A). Both compounds crystallise in the orthorhombic space group P 2 1 2 1 2 1 ( D 2 4 , No. 19); for compound 7a , a =13.549(23) A, b =14.490(25) A, c =15.909(14) A, V =3123(8) A 3 , Z =4 and D c =1.303 g cm −3 and the structure was refined to R =0.0488 on the basis of 2545 independent reflections. For the exo isomer 7b , a =13.301(18) A, b =15.599(32) A, c =14.436(19) A, V =2995(10) A 3 , Z =4 and D c =1.359 g cm −3 ; the structure was refined to R =0.0362 on the basis of 4620 independent reflections. Bromine reacts with the compounds 7a and 7b to give the corresponding [{Rh(Cp′)} 2 ( μ -Br 3 )]Br 3 .
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