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Topic: Cyclopentadienyl

	The Organometallic HyperTextBook: Cyclopentadienyl Ligands
		The cyclopentadienyl (Cp) ligand is a monoanionic ligand with the formula C
		The first characterized example of a cyclopentadienyl complex was ferrocene, Cp Fe, which has an iron atom "sandwiched" between two planar Cp rings as shown on the left.
		For this reason, bis(cyclopentadienyl) complexes are sometimes called "sandwich compounds" or metallocenes.
	www.ilpi.com /organomet/cp.html (1428 words)

	Cyclopentadienyl complex - Wikipedia, the free encyclopedia
		Metals and cyclopentadienyl moieties connected by π-bonds are called π-complexes.
		Ionic complexes primarily occur with alkali metal cations and alkali earth metals cations connected to cyclopentadienyl anions.
		Ionic type complexes are synthesized generally by a reaction of cyclopentadiene with a metal in an non-aromatic solvent.
	en.wikipedia.org /wiki/Cyclopentadienyl_complex (314 words)

	[No title] (Site not responding. Last check: )
		isopropyl (cyclopentadienyl) (fluorenyl) hafnium dichloride, diphenylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride,
		(cyclopentadienyl) (fluorenyl) hafnium dichloride, diisobutylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride, ditertbutylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride, cyclohexylidene (cyclopentadienyl) (fluorenyl) hafnium dichloride, diisopropylmethylene (2,5-dimethylcyclopentadienyl) (fluorenyl)- hafnium dichloride, isopropyl (cyclopentadienyl) (fluorenyl) titanium dichloride, diphenylmethylene (cyclopentadienyl) (fluorenyl) titanium dichloride, diisopropylmethylene (cyclopentadienyl) (fluorenyl) titanium dichloride,
		(cyclopentadienyl) (fluorenyl) titanium dichloride, ditertbutylmethylene (cyclopentadienyl) (fluorenyl) titanium dichloride, cyclohexylidene (cyclopentadienyl) (fluorenyl) titanium dichloride, diisopropylmethylene (2,5 dimethylcyclopentadienyl fluorenyl) titanium dichloride, racemic-ethylene bis (1- indenyl) zirconium (IV) dichloride, racemic-ethylene bis (4,5,6,7-
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=99/31147.990624&ELEMENT_SET=DECL (4868 words)

	United States Patent Application: 0040152591
		A cyclopentadienyl group is defined as an aromatic ring system or fused ring system that contains at least one aromatic C5 structure.
		Substituted cyclopentadienyl structures are structures in which one or more hydrogen atoms are replaced by a hydrocarbyl, hydrocarbylsilyl, or similar heteroatom-containing structure.
		L is a substituted C5-ring-containing ligand such as cyclopentadienyl with an optional bridging group to connect both L ligands.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040152591".PGNR.&OS=DN/20040152591&RS=DN/20040152591 (10028 words)

	High pressure, high temperature polymerization of ethylene - US Patent 5084534 (Site not responding. Last check: )
		The process of claim 8 wherein the cyclopentadienyl transition metal compound is selected from one of bis(cyclopentadienyl) zirconium dimethyl, bis(cyclopentadienyl) ziconium dichloride, bis(cyclopentadienyl)titanium dichloride, bis(methylcyclopentadienyl) zirconium dichloride, bis(methylcyclopentadienyl) titanium dichloride, bis(n-butylcyclopentadienyl) zircnium dichloride, dimethylsilyldicyclopentadienyl zirconium dichloride, bis(trimethylsilylcyclopentadienyl)zirconium dichloride, dimethylsilyldicyclopentadienyl titanium dichloride or mixtures thereof.
		The cyclopentadienyl ring can be unsubstituted or contain one or more substituents such as, for example, a hydrocarbyl substituent or other substituents such as, for example, a trialkyl silyl substituent.
		Mono, di and tri-silyl substituted cyclopentadienyl compounds such as bis(trimethylsilylcyclopentadienyl)zirconium dichloride and dimethyl, bis(1,3 di-trimethylsilyl cyclopentadienyl) zirconium dichloride and dimethyl and bis(1,2,4-tri-trimethylsilylcyclopentadienyl)zirconium dichloride and dimethyl.
	www.patentstorm.us /patents/5084534.html (6302 words)

	FERROCENE (BISCYCLOPENTADIENYL IRON)
		Ligand, in organometallic chemistry, is a molecule that donates or accepts a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complexes and organometallic compounds; can be further distinguished by the orbitals used in bond formation.
		There can be numerous organometallic coordination compounds distinguished by number of cyclopentadienyl rings (with or without substituents) bonded to a central transition-metal atoms and the types of transition-metals and the type of the bridge.
		The equivalent bonding of all 5 carbon atoms of each cyclopentadienyl ring in ferrocene is denoted as eta-5.
	www.chemicalland21.com /industrialchem/organic/FERROCENE.htm (445 words)

	Information Bridge: DOE Scientific and Technical Information (Site not responding. Last check: )
		Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes.
		The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography.
		The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals.
	www.osti.gov /bridge/product.biblio.jsp?osti_id=764394 (412 words)

	Cyclopentadiene - Wikipedia, the free encyclopedia
		The delocalisation energy gained by proton loss makes this compound weakly acidic, which is unusual for a hydrocarbon.
		Alkali metal bases can deprotonate cyclopentadiene to form the alkali metal derivatives of the cyclopentadienyl anion.
		When the Cp rings are mutually parallel the compound is known as a sandwich complex.
	en.wikipedia.org /wiki/Cyclopentadiene (400 words)

	[No title]
		The cyclopentadienyl ligand is even more reactive than benzene in the Friedel-Crafts situation.
		Structure of ferrocene: (n5 — C5 H5)2 Fe (Ferrocene) In the solide state the cyclopentadienyl rings of ferrocene are staggered.
		Of the 18 valence electrons in the ferrocene molecule six are from the iron and it has a formal oxidation state of Fe2+.
	www.maths.tcd.ie /~pwalsht/labs/Ferrocenere.doc (507 words)

	Media Portfolio
		The cyclopentadienyl anion (six pi electrons) can be easily formed by abstracting a proton from cyclopentadiene with a base.
		Cyclopentadiene is unusually acidic because loss of a proton converts the nonaromatic diene to the aromatic cyclopentadienyl anion.
		Huckel's rule predicts that the cyclopentadienyl cation, with four pi electrons, is antiaromatic.
	wps.prenhall.com /wps/media/objects/340/348272/wade_ch16.html (1354 words)

	Ferrocene
		This could only be possible with a structure such that as that on the right which has a single bond between the aromatic pi system of all five carbon atoms of the cyclopentadienyl ligand and the iron atom.
		The structure on the left that has a sigma type bond between a single carbon atom of the cyclopentadienyl ligand would result in more peaks in the IR and NMR spectra due to the lower symmetry of the structure creating different environments for the various atoms.
		This structure was the first assignment of a bond between ligand aromatic pi orbitals and metal d-orbitals of equivalent pi symmetry.
	antoine.frostburg.edu /chem/simon/chm411/lab/Ferrocene.htm (1201 words)

	Molecular Wheels on Surfaces
		Then we ask: what would happen if the cyclopentadienyl ring is bonded to an M atom, which is a part of an M surface?.
		Our calculations show that cyclopentadienyl, adsorbed to Si, Ge or Sn surfaces (co-adsorbed with H, so that all neighboring sites are blocked, can exhibit interesting spinning motion due to their fluxional behavior.
		A schematic diagram of cyclopentadienyl adsorbed on M surface.
	www.foresight.org /conference/MNT10/Abstracts/Das1 (353 words)

	Supported polymerization catalyst - Patent 4808561 (Site not responding. Last check: )
		The metal is selected from Group 4b, 5b and 6b metal, preferably 4b and 5b metals, preferably titanium, zirconium, hafnium, chromium, and vanadium, and especially titanium and zirconium.
		The cyclopentadienyl ring can be unsubstituted or contain substituents such as, for example, a hydrocarbyl substituent.
		wherein Cp is a cyclopentadienyl ring, M is a Group 4b, 5b, or 6b transition metal, R is a hydrocarbyl group or hydrocarboxy having from 1 to 20 carbon atoms, X is a halogen, and m=1-3, n=0-3, q=0-3 and the sum of m+n+q will be equal to the oxidation state of the metal.
	www.freepatentsonline.com /4808561.html (4984 words)

	Electron counting -- Facts, Info, and Encyclopedia article (Site not responding. Last check: )
		formally removing one of the cyclopentadienyl ligands from ferrocene and
		Using the ionic approach, removing one cyclopentadienyl anion yields a
		containing one cyclopentadienyl group, one iron atom, and 3 carbon monoxide
	www.absoluteastronomy.com /encyclopedia/e/el/electron_counting.htm (570 words)

	Linked Cyclopentadienyl Sulfonamido Complexes (Site not responding. Last check: )
		There is an increasing interest in bidentate ligands for early transition metals in which the ligand contains a cyclopentadienyl group and another anionic ligand group.
		This has promted us to investigate the synthesis and chemistry of ligands in which a cyclopentadienyl group is linked to a sulfonamido group.
		Our aim was to develop a ligand synthesis strategy which was (a) simple and (b) uses starting materals which are readily available and for which (c) modification of the ligand structure were simple to implement.
	www.ch.ic.ac.uk /ectoc/ectoc-3/pub/011 (213 words)

	[No title] (Site not responding. Last check: )
		4,673,714 certain bis (cyclopentadienyl) titanium compounds were found not to require lithium compounds as cocatalysts.
		Either adjacent R groups, or adjacent R'groups or both optionally together constitute a divalent substituent which form a cyclic structure with the carbon atoms on the cyclopentadienyl group to which they are attached.
		trans, trans-1,4-diphenyl-1,3-butadiene), [dimethylsilanediyl (9-fluorenyl)- (cyclopentadienyl)]- zirconium (trans, trans-1,4-diphenyl-1,3-butadiene), [dimethylsilanediyl (9-fluorenyl)- (cyclopentadienyl)]- zirconium (trans, trans-1,4-diphenyl-1,3-butadiene), [dimethylsilanediyl-bis (cyclopentadienyl)]-zirconium (trans, and mixtures thereof and the corresponding titanium and hafnium compounds.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=01/04164.010118&ELEMENT_SET=DECL (5866 words)

	Session 7
		When simple cyclopentadienyl ligands are used in the catalyst, atactic polypropylene is produced because the methyl substituent on propylene has no preference for being oriented up or down.
		However, chemists can modify the cyclopentadienyl ligands in ways that force the propylene methyl group to orient in a particular way.
		Shown in Figure 6 is an example of a zirconium complex with modified cyclopentadienyl (cp) ligands.
	www.chemistry.wustl.edu /~edudev/Designer/session7.html (769 words)

	AllRefer.com - Sir Geofferey Wilkinson (Chemistry, Biography) - Encyclopedia
		He shared the 1973 Nobel Prize in Chemistry with Ernst Otto Fischer for their independent research on the organometallic compounds of the transitions metals.
		At Harvard, Wilkinson theorized that certain transition metals, such as iron and ruthenium, combine with cyclopentadienyl carbon rings to form organometallic compounds.
		This theory initiated a vast amount of research, not only on cyclopentadienyl derivatives but on similar systems with four-, six-, seven-, and even eight-membered carbon rings.
	reference.allrefer.com /encyclopedia/W/WilknsnG.html (196 words)

	Richard D. ErnstChemistry, University of Utah (Site not responding. Last check: )
		Nevertheless, this compound reacts readily with a wide variety of unsaturated organic molecules (e.g., imines, ketones, alkynes, nitriles, and isonitriles), leading to selective coupling between the unsaturated molecule and the open pentadienyl ligand.
		Thus not only is pentadienyl more strongly bound than cyclopentadienyl, it is also more reactive.
		In essence, the aromaticity of a cyclopentadienyl ligand leads both to weaker bonding to a metal as well as a greater reluctance to undergo coupling reactions, through which it would lose much resonance delocalization energy.
	courses.chem.utah.edu /faculty/ernst (716 words)

	New Page 1
		Here, Cp is a cyclopentadienyl group or a substituted cyclopentadienyl ring.
		Specifically, the present invention is a novel transition metal compound represented by general formula (I).
		within the formula for the transition metal compound (I) of the present invention is a cyclopentadienyl group.
	ourworld.compuserve.com /homepages/StevenWJohnston/04069394.htm (586 words)

	Titanocenes and their use - Patent 4963470 (Site not responding. Last check: )
		A titanocene according to claim 1, in which one radical R.sup.1 is a-cyclopentadienyl anion substituted by a group of the formula IV or V and the other radical R.sup.1 has the same meaning or is a cyclopentadienyl or methylcyclopentadienyl anion.
		Another preferred sub-group are those titanocenes in which one radical R.sup.1 is a cyclopentadienyl anion which is substituted by groups of the formula IV or V and the other radical R.sup.1 has the same meaning or is a cyclopentadienyl or methylcycloplentadienyl anion.
		The compounds of the formula VI are known in some cases or can be prepared by analogous processes, by reacting sodium cyclopentadienyl with compounds of the formula (R.sup.6).sub.3 ZCl or R.sup.6 (SiOR.sub.2.sup.6).sub.x SiR.sub.2.sup.6 Cl, reacting the resulting substituted cyclopentadienes with sodium again and then reacting 2 mol thereof with 1 mol of Ti(Hal).sub.4.
	www.freepatentsonline.com /4963470.html (4920 words)

	Research in the Deck Group at Virginia Tech
		) as a substituent for the ubiquitous cyclopentadienyl (Cp) ligand.
		The pentafluorophenyl group is highly electron-withdrawing, yet chemically stable, especially toward strong electrophiles that would disrupt other groups such as -CO, or CF Substituted cyclopentadienyl ligands are readily incorporated into several established synthetic approaches to metallocenes and other organometallic complexes.
		In particular, we have found that multiply pentafluorophenyl-substituted cyclopentadienyl ligands can stabilize 19-electron complexes toward oxidation by air and even mineral acids.
	www.chem.vt.edu /chem-dept/deck/research.html (1285 words)

	Web page (Site not responding. Last check: )
		Cyclopentadienyl thallium complex (Cp-Tl) is an example of a 'half-sandwich' complex that is stable at room temperature.
		Cyclopentadienyl thallium (Cp-Tl) structure has been measured here in our laboratory using a Fourier transformed microwave spectrometer (5).
		The thallium-carbon(Cp) is increased to 2.764 A with the acetylene present.
	www.chem.arizona.edu /~lichtend/c518.dir/s2001.dir/finals.dir/tanjaroon.dir/PROJECT/final.html (2034 words)

	The design, synthesis, and application to catalysis of chiral 5-cyclopentadienyl complexes (Site not responding. Last check: )
		The planar chirality should be induced from a chiral substituent on the cyclopentadiene (enantiofacially directed metallation).
		All the elements needed for asymmetric induction should be incorporated into one cyclopentadiene making the ligands applicable to mixed metallocenes (two different cyclopentadienyl ligands) and monocyclopentadienyl complexes.
		The design principles were first realised in the zirconium complex 2, the synthesis of which was optimised to reliably produce 10g batches (68% yield from 1).
	www.soton.ac.uk /~rjw1/Reports/K71127/K71127sum.html (357 words)

	Untitled Document
		Titanium is bonded to six sulfur donor atoms and also to the cyclopentadienyl ring.
		Contacts from cobalt to the 5 C atoms in the cyclopentadienyl anion ring are essentially the same (~2.05 Angstroms).
		One nitrosyl group (NO) and the amine N are bonded to both Cr atoms (i.e., bridging), and each Cr is also bonded to a terminal nitrosyl group.
	www.luc.edu /faculty/spavko1/c340/gallery/gallery.htm (1121 words)

	Silyl Substituted Ferrocenes: An Illustration of an Electronically Derived Steric Saturation.
		With such advantages of cyclopentadienyl substitution, numerous other alkyl-substituted cyclopentadienyl derivatives have been reported.
		The main limitation of metallocene derivatives of this bulky cyclopentadienyl ligand is their extremely low solubility in almost all common organic solvents, e.g.
		The introduction of five CH Ph groups onto the cyclopentadienyl ring results in an extremely bulky cyclopentadienyl ligand, but due to the flexibility of the CH Ph groups arising from the -CH - moiety, a ligand that is not as sterically demanding as the
	www.ch.ic.ac.uk /ectoc/ectoc-3/pub/034/970703/E-intro.html (1262 words)

	cyclopentadienyl complexes (Site not responding. Last check: )
		The first ever cyclopentadienyl organometallic was synthesised by K. Thiele in 1901.
		In 1948 3 scientists J.F. Tremaine, J.A. Tebboth and S.A. Miller were attempting to synthesise amines form olefins using and iron catalyst.
		The ligands in sanwich compounds do not nescesarily have to be equal and often we get a variety of different types.
	easyweb.easynet.co.uk /~miky/projtpag/intpent.htm (290 words)

	Generation and Observation of the Cyclopentadienyl Anion: A Negatively Charged Aromatic Molecule
		The study of charged aromatic species greatly enhances discussions of the theory of aromaticity.
		= 15) affords the opportunity to generate the aromatic cyclopentadienyl anion in an organic laboratory class.
		This experiment describes the preparation of a solution of deuterated dimethylsulfinyl anion in an NMR tube, followed by the addition of freshly prepared cyclopentadiene.
	chemeducator.org /bibs/0002006/00020152.htm (120 words)

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