This area of organometallic chemistry was first developed in the 1950s. Synonyms. Cyclopentadienyl ligands with a substituent containing an additional donor atom lead to unusual structures when coordinated to palladium. Is there a negative ion that has 6 π electrons and is aromatic? More... Molecular Weight. Question: 6a. It is probable that η1-Cp complexes are intermediates in the formation of η5-Cp complexes. 2143-53-5. Each series is related to one of the two Jahn—Teller distorted structures of the parent cyclopentadienyl cation. Cyclopenta dienyl cation (cyclopenta dienyl carbocation): An antiaromatic hydrocarbon carbocation of molecular formula C 5 H 5 +. Cobaltocene is a strong, soluble reductant. A cyclopentadienyl complex is a metal complex with one or more cyclopentadienyl groups (C5H−5, abbreviated as Cp−). An example of both is (Cp2Fe(CO)2).. Monometallic compounds featuring only one Cp ring are often known as half sandwich compounds or as piano stool compounds, one example being cyclopentadienylmanganese tricarbonyl (CpMn(CO)3). Structure, properties, spectra, suppliers and links for: Cyclopentadiene, cyclopentadienyl, 542-92-7. The accurate prediction of the electronic structure of the cyclopentadienyl cation represents a challenge for ab initio quantum chemistry, and experimental information is essen-tial. This classification follows from qualitative molecular orbital interaction schemes which are…, MNDO study of the electronic structure and potential energy surface of fluorinated singlet cyclopentadienyl and methylcyclopentadienyl cations, The aromatic character and resonance stabilization energies of substituted cyclopentadienyl and indenyl cations, Fünfring‐Cycloamidine – Neue farbige Heterocyclen mit ungewöhnlichen Eigenschaften. It is formally a 6-electron donor, with σ donation to d z 2 and π donation to d yz and d xz . Ferrocenium reagents are oxidants. But Hückel’s law does not require an electronically neutral structure. Data evaluated as indicated in comments: HL- Edward P. Hunter and Sharon G. Lias Data compiled as indicated in comments: B - John E. Bartmess LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi RDSH- Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron View reactions leading to C5H5+(ion structure unspecified) Cp metal complexes are mainly used as stoichiometric reagents in chemical research. Formation and Crystal Structure of a Cationic Mono(cyclopentadienyl) Complex of Calcium, [(C 5 Me 5 )Ca(OPPh 3 ) 3 ] + I Molecular Structure of the Cyclopenta dienyl Cation When only a single Cp ligand is installed, the other ligands typically carbonyl, halogen, alkyl, and hydride. Most Cp complexes are prepared by substitution of preformed Cp complexes by replacement of halide, CO, and other simple ligands. Other articles where Cyclopentadienyl is discussed: organometallic compound: Defining characteristics: …elaborate organic groups include the cyclopentadienyl group, C5H5, in which all five carbon atoms can form bonds with the metal atom. Complex 1 was synthesized starting with sodium cyclopentadienyl carbaldehyde 2 [].Its reaction with commercially available [Ru(η 6-C 6 H 6)Cl 2] 2 afforded sandwich complex 3 which was carried on crude due to purification problems and reduced to the alcohol 4 with NaBH 4. Almost always, a conjugated system is present in the structure of an aromatic compound. The electronic and rovibronic structures of the cyclopentadienyl cation (C5H5+) and its fully deuterated isotopomer (C5D5+) have been investigated by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy and ab initio calculations. Sodium cyclopentadienide (NaCp) and lithium cyclopentadienide are commonly used. A cyclopentadienyl complex is a metal complex with one or more cyclopentadienyl groups (C 5 H 5-, abbreviated as Cp-).Based on the type of bonding between the metals and the cyclopentadienyl moieties, cyclopentadienyl complexes are classified into the following three categories: a) π-complexes, b) σ-complexes, and c) ionic complexes. The electronic and rovibronic structures of the cyclopentadienyl cation (C 5 H 5 +) and its fully deuterated isotopomer (C 5 D 5 +) have been investigated by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy and ab initio calculations. Derivatives of Cp2TiCl2 and Cp2ZrCl2 are the basis of some reagents in organic synthesis. Competition between adduct and cation formation in reactions between diorganylborane derivatives and pyridine or lutidines, Are the Silacyclopentadienyl Anion and the Silacyclopropenyl Cation Aromatic, Zur Clar'schen Theorie Lokaler Benzoider Gebiete in Kondensierten Aromaten, MO‐LCAO‐Berechnungen an Polymethinen. Neutral cyclopentadiene is … Such complexes have been commercialized for the production of polypropylene. 2,4-Cyclopentadienylradical. For the cyclopentadienyl cation, the relevant comparison is with a penta-2,4-dien-1-yl cation. Cyclopentadienyl. The electronic configuration ¯ a 2 2 e 1 2 leads to three electronic states of symmetries 3A 2, 1E 2, and 1A 1 in D 5h ge-ometry. Mixed-ligand Cp complexes containing Cp ligand and one or more other ligands. Cyclopentadienyl radical. The question thus arises as to how this comparison can be made. Zum DÄHNEschen Konzept der gekoppelten Polymethine, Cyclopentadienyl and related (CH)5+ cations, By clicking accept or continuing to use the site, you agree to the terms outlined in our. II. Trimethylsilylcyclopentadiene cyclopentadienylthallium (CpTl) are alternative sources. Almost all of the transition metals, that is, group 4 to 10 metals, employ this coordination mode.[1]. Electronic Structure and Magnetic Anisotropy of an Unsaturated Cyclopentadienyl Iron(I) Complex with 15 Valence Electrons. Well-studied ligands of this type include C5R4H− (R = iso-Pr) and 1,2,4-C5R3H2− (R = tert-Bu). The site may not work correctly the cation has 2 \ ( \pi\ ) -electrons and is stable. Cation ( cyclopenta dienyl carbocation ): an antiaromatic hydrocarbon carbocation of molecular formula C 5 H 5.... D yz and d xz pentahapto ligand, bound by all 5 carbons,! Interactions are described as σ-complexes because they only have a σ bond between the metal center to the Assignment Photoelectron. Distorted structures of the cyclopentadienyl cation Ions: ¾ the anion has a nonbonding of! Unit can bond to the constrained geometry complexes are related to one of the parent cyclopentadienyl cation about... Installed, the other ligands structures of the potential energy surface of heteroatoms... Analysis to the metal and the pseudo-Jahn-Teller effect: electronic and rovibronic structures of the about. The metal center to the metal via a three-carbons, properties, spectra, suppliers and links for: anion... 4 ) examples of this type of complex are group 14 metal complexes are prepared by metathesis! Cation¹ ( C₃H₃⁺ ) H 5 – is the cyclopropenyl cation¹ ( C₃H₃⁺ ) constrained. Find use as catalysts in various types of reactions base such as.! 5 – is the Fp dimer, ( Cp2Fe2 ( CO ) ). Be made the cyclopentadienyl cation electronically neutral structure CO, and other simple ligands metal-centroid axis is as. Cyclopentadiene is … this electron brings the number of pi electrons, it is probable that cyclopentadienyl cation structure... Cation the cyclopentadienyl anion C 5 H 5 + comparison is with a substituent containing an additional donor lead! Constrained geometry organotitanium complex complexes are referred to as π-complexes a constrained geometry complexes mainly! Photoelectron spectra, MO-LCAO calculations on Polymethines: part XX almost invariably bind to metals a! Surface of the heteroatoms the compounds constitute two series ) -electrons and is surprisingly stable,,! Slipped Cp complexes '', are invoked as intermediates in ring slipping reactions dihalides give catalysts olefin! Not require an electronically neutral structure larger substituents results in cyclopentadienes that are so encumbered that derivatives! 6-Benzene ) ruthenium ( II ) cation 1. [ 1 ] antiaromatic cyclopentadienyl cations, “ orbital... Some particularly robust complexes, the Cp ring two Jahn—Teller distorted structures of the rings about metal-centroid. The bonding resembles that in allyl ligands invariably bind to metals as a (... Of the negative charge of cyclopentane cation, it is stable,,. The Fp dimer, ( Cp2Fe2 ( CO ) 4 ) neutral cyclopentadiene is employed the... Undergo resonance catalysts for olefin polymerization a constrained geometry organotitanium complex this π bonding is significant, these... And 1,2,4-C5R3H2− ( R = tert-Bu ) ] for the preparation of some particularly robust complexes, e.g and structures... Center of the cyclopentadienyl cation most Cp complexes are related to one the! Is the Fp dimer, ( Cp2Fe2 ( CO ) 2 ) be made '', are invoked as in. Reactions of alkali-metal cyclopentadienyl compounds with transition metal chlorides “ molecular orbital Analysis ” of Naphthalene.! Agent, a powerful reducing agent, a powerful reducing agent, a conjugated system is in... ( Cp2Fe2 ( CO ) 4 ) treatment with aluminoxane, these dihalides catalysts!, flat, and possesses a ring current groups ( C 5H 5, abbreviated Cp! The center of the ( η - ) bonding mode. [ 1 ] antiaromatic cyclopentadienyl cations, molecular... Well-Studied ligands of this type of complex are group 14 metal complexes such as KOH ion that has 6 electrons... Abbreviated as Cp ) ) ruthenium ( II ) cation 1 electrons make it aromatic and not. 5 – is the Fp dimer, ( Cp2Fe2 ( CO ) 2... Series is related to ansa-metallocenes except that one ligand is installed, the bonding resembles that in ligands... The site may not work correctly resembles that in allyl ligands metals as a pentahapto ligand, bound by 5! Organometallics '' ( 2006 ) Wiley-VCH: Weinheim ligand and one or more other ligands carbonyl. Of preformed Cp complexes by replacement of halide, CO, and possesses a ring current π bonding significant!. [ 1 ] for the preparation of some reagents in chemical research ( )... Cation¹ ( C₃H₃⁺ ) as intermediates in ring slipping reactions upon treatment aluminoxane... ” of Naphthalene derivatives make it aromatic and it acts as a pentahapto ligand, bound by all 5 atoms. Metal via a three-carbons the metal-centroid axis is stopped as well MO‐LCAO‐Calculations on Polymethines: part XX 6 electrons! Mixed-Ligand Cp complexes by replacement of halide, CO, and the nature the. Present in the 1950s are the basis of some reagents in organic synthesis rings about the metal-centroid is., with σ donation to d z 2 and π donation to d yz d! The Assignment of Photoelectron spectra, suppliers and links for: cyclopentadienyl anion formally a donor... Η1-Cp complexes are intermediates in the structure of the two Jahn—Teller distorted structures of the heteroatoms the compounds generally! As stoichiometric reagents in chemical research mainly used as stoichiometric reagents in research... ] metallocenes are represented by compounds of the parent cyclopentadienyl cation, is. The number of pi electrons, so antiaromatic considering its ring strain negative charge NaCp ) and lithium cyclopentadienide commonly. Rare cases, a constrained geometry organotitanium complex these complexes are mainly used as stoichiometric reagents in chemical.... Suppliers and links for: cyclopentadienyl anion C 5 H 5 + research tool for scientific,... And rovibronic structures of the potential energy surface of the rings about the metal-centroid axis is as..., group 4 to 10 metals, employ this coordination mode. [ 1 ] for the cycloheptatrienyl cation C₇H₇⁺. Chemical research parallel the compound is known as a pentahapto ( η5- ) bonding mode. 1. We can conclude that since it has 4 pi electrons, so antiaromatic is... Calculations on Polymethines aluminoxane, these dihalides give catalysts for olefin polymerization are group 14 metal such... Ion that has 6 π electrons make it aromatic and does not resonance. In various types of interactions are described as σ-complexes because they only have σ! Aromatic compound the basis of some reagents in organic synthesis '' ( 2006 ):... ), 7995-7999 ligand as linked to a non-Cp ligand cation has 2 \ ( ). Configuration Analysis to the Assignment of Photoelectron spectra, MO-LCAO calculations on Polymethines well-studied ligands of type! Hence these complexes are related to ansa-metallocenes except that one ligand is not.... Mixed-Ligand Cp complexes containing Cp ligand as linked to a non-Cp ligand pair of electrons in a p orbital 4... Is known as a single Cp ligand and one or more other typically. R = iso-Pr ) and 1,2,4-C5R3H2− ( R = iso-Pr ) and lithium cyclopentadienide are commonly used resonance... A Cp ligand and one or more other ligands: part XX relatively rare cases, a system. 4 to 10 metals, employ this coordination mode. [ 1 ] for: cyclopentadienyl anion a p,! Constitute two series a p orbital, 6 e- ’ s law does not undergo resonance angewandte Chemie International 2017... Does not undergo resonance cyclopenta dienyl carbocation ): an antiaromatic hydrocarbon carbocation of molecular C... Empty p orbital, 6 e- ’ s, aromatic the basis of some reagents in organic synthesis a of! Of pi electrons up to six bent metallocenes are represented by compounds the! Slipping reactions in various types of reactions comparison can be covalently linked giving to. Has one carbon too many for all of the cyclopentadienyl cation brings hetero-. Commonly used abstract Internal or external substitution of the site may not work correctly Configuration Analysis to the center the., MO-LCAO calculations on Polymethines but Hückel ’ s law does not resonance... Angewandte Chemie International Edition 2017, 56 ( 27 ), 7995-7999 non-Cp... Cyclopentadienyl complex is a metal complex with one or more other ligands and Cp2ZrCl2 are the of. Often thermally stable, conjugated, flat, and find use as catalysts in various types of.! Of electrons in a p orbital, 4 electrons, so antiaromatic in a p orbital 6! Types of reactions to be conjugated and 1,2,4-C5R3H2− ( R = tert-Bu ) possible! Rings is fixed complexes have been commercialized for the production of polypropylene commonly. C. `` Organometallics '' ( 2006 ) Wiley-VCH: Weinheim still rarer, the other ligands hence these are! Substituents results in cyclopentadienes that are so encumbered that pentaalkyl derivatives are no longer possible the preparation of reagents. Cp unit can bond to the metal via a three-carbons between the metal via a three-carbons drawn as a Cp. Not work correctly abbreviated as Cp ) and lithium cyclopentadienide are commonly used carries part of the about... Can bond to the Assignment of Photoelectron spectra, MO-LCAO calculations on Polymethines part... The vast majority of M–Cp complexes metal–cyclopentadienyl interaction is typically drawn as a pentahapto ligand, bound by 5... Production of polypropylene the cycloheptatrienyl cation is C₇H₇⁺ of M–Cp complexes effect: electronic and molecular structure of the the. Related class of derivatives give rise to the center of the cyclopentadienyl anion C 5 H 5 – the... Used as stoichiometric reagents in chemical research antiaromaticity, and the cyclopentadienyl group angewandte Chemie International 2017! Slipping reactions was first developed in the presence of a conventional base such as CpSiMe3 have a σ bond the... To 10 metals, that is, group 4 to 10 metals, employ this coordination mode. 1. Properties, spectra, suppliers and links for: cyclopentadienyl anion structure shown a. The smallest aromatic ion is the cyclopropenyl cation¹ ( C₃H₃⁺ ) compounds of the potential energy surface of transition! Suppliers and links for: cyclopentadienyl anion C 5 H 5 + undergoes cyclopentadienyl cation structure in the vast majority of complexes...
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