Cyclopentadienylrhodium Coordination to Alkenylarenes

Wadepohl, Hubert; Metz, A.; Pritzkow, Hans

doi:10.1002/1521-3765(20020402)8:7<1591::aid-chem1591>3.0.co;2-0

Cited by 18 publications

(8 citation statements)

References 60 publications

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“…Three possible interactions were envisaged between the palladium and the aromatic ring; a face‐on interaction with the aromatic ring 6 a (involving two palladium centres), an η 4 interaction 6 b ,17 or an agostic interaction 6 c (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

Wright

Gaunt

Spencer

2006

Chemistry A European J

102

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The Wacker reaction is one of the longest known palladium-catalysed organic transformations, and in the vast majority of cases proceeds with Markovnikov regioselectivity. Palladium(II)-mediated oxidation of styrenes was examined and in the absence of reoxidants was found to proceed in an anti-Markovnikov sense, giving aldehydes. Studies on the mechanism of this unusual transformation were carried out, and indicate the possible involvement of a eta(4)-palladium-styrene complex. With a heteropolyacid as the terminal oxidant, oxidation of styrene to give the anti-Markovnikov aldehyde as the major product was found to be catalytic.

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Section: Resultsmentioning

confidence: 99%

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

Wright

Gaunt

Spencer

2006

Chemistry A European J

102

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“…In most cases the former exhibits almost perfect η 5 coordination. For example, Δ is 0.018 Å in [Rh(CO)(Cp)(PPh 3 )] (PIFREB),28 0.033 Å in ( η 5 ‐cyclopentadienyl)( η 2 ‐ethene)( η 2 ‐1,2‐diphenylethene)rhodium (XISYUT),38 0.039 Å in ( η 5 ‐cyclopentadienyl)( η 2 ‐ethene)( η 2 ‐tetrafluoroethylene)rhodium (CPEFRH),39 and 0.011 Å in ( η 5 ‐cyclopentadienyl)( η 2 ‐ethene)( η 2 ‐sulphur dioxide)rhodium (CPSXER) 40. A search of rhodium indenyl complexes gave 79 structures, for which the slip distortion parameter can vary by about 0.08 Å.…”

Section: Resultsmentioning

confidence: 99%

¹⁰³Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

Orian

Bisello

Santi

et al. 2004

Chemistry A European J

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Experimental 103Rh NMR chemical shifts of mono- and binuclear rhodium(I) complexes containing s- or as-hydroindacenide and indacenediide bridging ligands with different ancillary ligands (1,5-cyclooctadiene, ethylene, carbonyl) are presented. A protocol, based on density functional theory calculations, was established to determine 103Rh NMR shielding constants in order to rationalise the effects of electronic and structural variations on the spectroscopic signal, and to gain insight into the efficiency of this computational method when applied to organometallic systems. Scalar and spin-orbit relativistic effects based on the ZORA (zeroth order regular approximation) level have been taken into account and discussed. A good agreement was found for model compounds over a wide range of chemical shifts of rhodium (approximately 10,000 ppm). This allowed us to discuss the experimental and calculated delta(103Rh) in larger complexes and to relate it to their electronic structure.

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“…Such species are unknown experimentally. However, related metallacyclopentadiene rings are found in Fe, , Co, − Ni, − Ru, − Rh, , and Ir derivatives. Such metallacyclopentadiene derivatives include the metallametallocenes CpM(C 4 H 4 M′)Cp (M, M′ = Fe, Co, Ni) and dinickelametallocenes (η 5 -CpNiC 4 H 4 ) 2 M (M = Fe, Co, Ni) that have been the subjects of recent theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Metallocene versus Metallabenzene Isomers of Nickel, Palladium, and Platinum

et al. 2014

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The relative energies of singlet and triplet metallocene, metallabenzene, and metallacyclopentadiene C10H10M isomers (M = Ni, Pd, Pt) have been examined using density functional theory. For the C10H10Ni system, the experimentally known triplet nickelocene (η5-Cp)2Ni is the lowest energy isomer by ∼17 kcal/mol with respect to singlet nickelocene. For the C10H10Pd system, the triplet and singlet palladocene structures have similar energies within ∼2 kcal/mol. However, the singlet palladocene has a “slipped ring” (η3-Cp)2Pd structure with two trihapto Cp rings. The C10H10Pt system is different since the platinabenzene CpPtC5H5 isomer is the lowest energy structure. This is in accord with the synthesis of stable substituted CpPtC5H3R2 platinabenzenes by Haley and co-workers [ Haley M. M. Haley M. M. Organometallics2004231174]. However, the slipped ring singlet platinocene (η3-Cp)2Pt to the isomeric platinocene lies only ∼2 kcal/mol above the platinabenzene global minimum, so the energy barrier for conversion of the platinabenzene must be substantial. The following general observations can be made regarding the relative stabilities of isomeric C10H10M (M = Ni, Pd, Pt) structures: (1) Triplet structures become less favorable energetically than isomeric singlet structures in the sequence Ni < Pd < Pt. (2) Slipped metallocene structures with trihapto η3-Cp rather than pentahapto η5-Cp rings leading ultimately to 16- rather than 18-electron metal configurations become increasingly favorable energetically in the sequence Ni < Pd < Pt. (3) Metallabenzene (η5-Cp)MC5H5 structures with pentahapto Cp rings are always more favorable energetically than isomeric metallacyclopentadiene (η6-C6H6)MC4H4 structures with hexahapto benzene rings.

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Cyclopentadienylrhodium Coordination to Alkenylarenes

Cited by 18 publications

References 60 publications

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

¹⁰³Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

Metallocene versus Metallabenzene Isomers of Nickel, Palladium, and Platinum

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Cyclopentadienylrhodium Coordination to Alkenylarenes

Cited by 18 publications

References 60 publications

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

Novel Anti‐Markovnikov Regioselectivity in the Wacker Reaction of Styrenes

103Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study

Metallocene versus Metallabenzene Isomers of Nickel, Palladium, and Platinum

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Product

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¹⁰³Rh NMR Chemical Shifts in Organometallic Complexes: A Combined Experimental and Density Functional Study