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Cyclopentadienyl derivatives

The rotational motion of the C5H5 rings about their coordination axis in crystals of several metallocenes was suggested many years ago by Anderson [35] on the basis of the temperature dependence of the NMR second moment. Subsequently, several studies [36-43] have been devoted to the determination of the reorientational barrier of Cp and other ji-bonded cyclic ligands in organometallic systems. Actually the measurements of the temperature dependence of H T was preferred as it allows the exploitation of a wider temperature range with respect to the second moment [44]. [Pg.172]

The energy barrier opposing ring reorientation may have both intramolecular and intermolecular contributions. Those terms may be evaluated also by [Pg.172]

On the basis of the information gained from NMR spectroscopy we went [Pg.175]

This study has been extended to other metal carbonyl compounds containing permethylated cyclopentadienyl ligands [44]. These ligands display two distinct [Pg.175]

On these systems the C longitudinal relaxation times T of the C5Me5 moieties have been measured by means of the Torchia s pulse sequence [48]. The Ti( C) values obtained for ring carbons have been rationalized on the basis of two relaxation interactions (dipole-dipole and chemical shift anisotropy) modulated by the motions involving the permethylated cyclopentadienyl rings. Interestingly, a qualitative comparison between solution and solid state C relaxation data shows that the same relaxation mechanisms are operative in both physical states. [Pg.177]


Figure 5.10 Cyclopentadienyl derivatives of beryllium showing (a) the slruclure of fBe(ij -C5H5)Y] and (b) (he structure of crystalline IBe(/j -C5H5)(ij -C5H5)] at —120 (see text). Figure 5.10 Cyclopentadienyl derivatives of beryllium showing (a) the slruclure of fBe(ij -C5H5)Y] and (b) (he structure of crystalline IBe(/j -C5H5)(ij -C5H5)] at —120 (see text).
Cu ( j -C5H5)2] is not. Likewise, Fe and Ni carborane derivatives are extremely stable. Conversely, metallocarboranes tend to stabilize lower oxidation states of early transition elements and complexes are well established for Ti", Zr , Hf , V , Cr and Mn" these do not react with H2, N2, CO or PPh3 as do cyclopentadienyl derivatives of these elements. [Pg.195]

Conjugated diene (e.g. butadiene), cyclobutadiene derivatives Dienyl (e.g. cyclopentadienyl derivatives, cycloheptadienyl derivatives)... [Pg.925]

Cyclopentadienyl derivatives of divalent lanthanides are also known [Ln ( j -C5H5)2] (Ln = Sm, Eu, Yb) might be expected to be isostructural with ferrocene but are bent ie rather than the two rings being parallel they are tilted relative to each other. [Pg.1249]

Nontransition metal cyclopentadienyl derivatives of pyrrole are quite scarce (99CRV969). The derivatives M(2,5-C4H2 Bu2N)2 (M = Sn, Pb) were studied [92AG(E)778 92JCS(CC)760]. [Pg.117]

Table 2 Formation of cyclopentadienyl derivatives 75 via transmetallated alkyne-inserted rhodium-carbene complexes (see Scheme 15)... Table 2 Formation of cyclopentadienyl derivatives 75 via transmetallated alkyne-inserted rhodium-carbene complexes (see Scheme 15)...
Molecular compounds of bivalent tin are in all cases bent molecules, the angle between the substituents approaching 90°. Only the it-pseudo-bound cyclopentadienyl derivatives deviate considerably from this angle (120 and 144°, respectively) ... [Pg.30]

Noteworthy NMR studies involving nuclei other than phosphorus have been carried out for some P-chloro-NHPs where the possible occurrence of spontaneous P-Cl bond dissociation was probed by II NMR titrations and 35C1 NMR [20], and for P-cyclopentadienyl derivatives where measurement of solid-state 13C CP-MAS NMR spectra allowed one to substantiate the preservation of the circumambulatory ring migration of cyclopentadienyl groups in the solid state [47], Several neutral and cationic derivatives have also been studied by 15N NMR [20, 53],... [Pg.77]

Cyclopentadienyl derivatives of beryllium are described in reviews that include main-group,35 36 and specifically group 2, metallocenes.4 37... [Pg.72]

In the Group XIV compounds the two rings are not parallel, due to the influence of the metal lone pair, giving rise to a bent-sandwich molecular structure142 (C2V symmetry), different from that in other stable cyclopentadienyl derivatives, such as Fe(Cp)2, where the two rings are parallel (D5h symmetry in the eclipsed conformation and D5d symmetry in the staggered one). [Pg.329]

Metallocene, An organo-metallic coordination compound, or more specifically a cyclopentadienyl derivative of a transition metal or metal halide. Metallocenes are best known as catalysts for polymerizing ethylene and propylene. [Pg.407]

My initial plan involved dehydrogenation of cyclic alkanes to give stable arenes, particularly of cyclopentane to give cyclopentadienyl derivatives. My own experimental efforts with Pt were unavailing, but Jeimifer Quirk, a graduate student of mine working on Ir, took an interest in the project and found a small yield of Cp... [Pg.7]

The broader subject of the interaction of stable carbenes with main-group compounds has recently been reviewed. Accordingly, the following discussion focuses on metallic elements of the s and p blocks. Dimeric NHC-alkali adducts have been characterized for lithium, sodium, and potassium. For imidazolin-2-ylidenes, alkoxy-bridged lithium dimer 20 and a lithium-cyclopentadienyl derivative 21 have been reported. For tetrahydropyrimid-2-ylidenes, amido-bridged dimers 22 have been characterized for lithium, sodium, and potassium. Since one of the synthetic approaches to stable NHCs involves the deprotonation of imidazolium cations with alkali metal bases, the interactions of alkali metal cations with NHCs are considered to be important for understanding the solution behavior of NHCs. [Pg.8]

Organometallic Titaniam(iv) Compounds.—Charge-transfer interactions between TiC and aromatic hydrocarbons and fluorocarbons have been characterized by spectrophotometric studies. " The other work described here will mainly be concerned with selected aspects of the chemistry of Ti -alkyl and -cyclopentadienyl derivatives. [Pg.17]

Indeed, cyclopentane formation during all cyclic alkane hydrogenolysis and cyclopentane transformation into a cyclopentadienyl derivative, inert in hydrogenolysis, explains the rapid deactivation process of this catalyst in the presence of cyclic alkanes. [Pg.87]

Fig. 27. Cyclopentadienyl derivatives of some main group metals. Fig. 27. Cyclopentadienyl derivatives of some main group metals.

See other pages where Cyclopentadienyl derivatives is mentioned: [Pg.223]    [Pg.265]    [Pg.981]    [Pg.1039]    [Pg.157]    [Pg.197]    [Pg.342]    [Pg.11]    [Pg.312]    [Pg.312]    [Pg.169]    [Pg.34]    [Pg.68]    [Pg.97]    [Pg.26]    [Pg.44]    [Pg.291]    [Pg.329]    [Pg.330]    [Pg.436]    [Pg.129]    [Pg.136]    [Pg.144]    [Pg.194]    [Pg.389]    [Pg.236]    [Pg.45]    [Pg.20]    [Pg.243]   
See also in sourсe #XX -- [ Pg.325 ]

See also in sourсe #XX -- [ Pg.293 , Pg.310 , Pg.314 ]

See also in sourсe #XX -- [ Pg.464 ]




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Alkoxides cyclopentadienyl derivatives

Bis-cyclopentadienyl Derivatives

Boron cyclopentadienyl derivatives

Bridging cyclopentadienyl derivative

Carbonyls, metal cyclopentadienyl derivatives

Cyclopentadiene, derivatives cyclopentadienyl metal complexes

Cyclopentadienyl Derivatives and Related Compounds

Cyclopentadienyl and Related Derivatives

Cyclopentadienyl complexes tris derivatives

Cyclopentadienyl derivatives bases

Cyclopentadienyl derivatives metal-coordinated cyclobutadienes

Cyclopentadienyl derivatives of hafnium

Cyclopentadienyl derivatives substitution polymerization

Cyclopentadienyl derivatives transition metal chemistry

Cyclopentadienyl iron dicarbonyl derivatives

Cyclopentadienyl manganese tricarbonyl, derivatives

Cyclopentadienyl titanium derivatives

INDEX cyclopentadienyl derivatives

Iron carbonyl complexes cyclopentadienyl derivatives

Lithium cyclopentadienyl derivatives

Manganese compounds cyclopentadienyl derivatives

Molybdenum cyclopentadienyl tricarbonyl derivatives

Polymeric lithium cyclopentadienyl derivatives

Potassium cyclopentadienyl derivatives

Silane, cyclopentadienyl derivatives

Silylation cyclopentadienyl derivatives

Sodium cyclopentadienyl derivatives

Stretching modes cyclopentadienyl derivatives

Tungsten cyclopentadienyl derivatives

Uranium cyclopentadienyls alkyl derivatives

Uranium cyclopentadienyls derivatives

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