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11 results on '"cyclopentadienyl"'

1. Stacking interactions of aromatic ligands in transition metal complexes

Author

Malenov, Dušan P., Zarić, Snežana D., Malenov, Dušan P., and Zarić, Snežana D.

Abstract

In this review article we present all the recent research on stacking interactions of aromatic ligands that coordinate to transition metals through their π-electrons (η-coordination). These studies were mostly based on searching the crystal structures from the Cambridge Structural Database (CSD) and on quantum chemical calculations. Stacking interactions between coordinated and uncoordinated benzene reach the energy of −4.40 kcal/mol, while the strongest calculated staking between two coordinated benzenes has the energy of −4.01 kcal/mol; this is significantly stronger than stacking between two uncoordinated benzenes (−2.73 kcal/mol). It was determined that in crystal structures both coordinated benzene and coordinated cyclopentadienyl anion form stacking interactions that dominantly have large horizontal displacements (more than 4.5 Å). This dominance is caused by the relatively strong stacking interactions at large displacements between benzene or Cp ligands in sandwich compounds, while for half-sandwich compounds they are supported by additional interactions of the other (usually branched) ligands. Larger aromatic ligands, tropylium and cyclooctatetraenide, almost exclusively form stacking interactions with large horizontal displacements. Methyl substituted benzene and Cp ligands dominantly form stacking interactions in combination with C–H/π interactions. Moreover, there is an interplay of stacking and aromatic C–H/π interactions in the CSD crystal structures, both interactions being important energy contributors to the stability of supramolecular systems. Stacking interactions of η-coordinated aromatic ligands are important in materials science, crystal engineering and medicinal chemistry, primarily in the application of ruthenium-arene complexes, where they determine the strength of bonding of these complexes to the DNA.

Published
2020

3. Synthesis and reactivity of di(silylamido)cyclopentadienyl titanium and zirconium complexes

Author

Jesús Cano, Pascual Royo, María Sudupe, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Science, chemistry.chemical_element, Biochemistry, Catalysis, Inorganic Chemistry, Cyclopentadienyl complex, CIENCIA, Polymer chemistry, Materials Chemistry, Organic chemistry, Reactivity (chemistry), Physical and Theoretical Chemistry, Cyclopentadienyl, Alkyl, chemistry.chemical_classification, Titanium, Zirconium, Ligand, Organic Chemistry, Cationic polymerization, SCIENCE, Silylamido, Química inorgánica, chemistry, Polymerization, Chemistry, inorganic
Abstract

We present in this account the synthesis and recent developments of a new class of group 4 metal complexes with the tridentate di(silylamido)cyclopentadienyl ligand. These doubly silyl-bridged group 4 metal amido chelates are receiving increasing interest as they are efficient catalysts for ethene polymerization when activated with MAO despite generating 14-electron d0 cationic species free of the alkyl group required for the first insertion reaction in the polymerization process., Programa Juan de la Cierva (Ministerio de Educación y Ciencia)

Published
2007

4. Synthesis and characterization of η5-cyclopentadienyl-silylallyl niobium and tantalum complexes

Author

Pilar Nicolás, Pascual Royo, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Niobium, Science, Inorganic chemistry, chemistry.chemical_element, Tantalum, Alkylation, Medicinal chemistry, Inorganic Chemistry, chemistry.chemical_compound, Transmetalation, Cyclopentadienyl complex, CIENCIA, Materials Chemistry, Physical and Theoretical Chemistry, Cyclopentadienyl, Alkyl, chemistry.chemical_classification, Imido, Nuclear magnetic resonance spectroscopy, SCIENCE, Química inorgánica, chemistry, Lithium, Metallocene, Derivative (chemistry), Chemistry, inorganic
Abstract

Reaction of the disilylcyclopentadiene 1,1-[SiMe2(CH2CHdouble bond; length as m-dashCH2)]2C5H4 with NbCl5 gave the new allylsilyl-substituted monocyclopentadienyl niobium complex [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4]. This compound was reacted with LiNHtBu or NH2tBu to give the imido derivative [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl2], which was further alkylated to the imido alkyl complexes [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)R2] (R = Me, CH2Ph) and [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl (CH2Ph)]. Reaction of the imido complexes with the corresponding lithium cyclopentadienides gave the dicyclopentadienyl-imido complexes [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl] (M = Nb, Ta; R = H, Me). Metallocene dichlorides [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl2] (M = Nb, Ta; R = H, Me) were easily prepared by reduction with Na/Hg and simultaneous transmetallation of [Ta(η5-C5R5)Cl4] with Li[C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)] and of [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4] with Li(C5R5). All of the new compounds have been characterized by elemental analysis, and IR and NMR spectroscopy., Financial support of our work by MCyT (Project MAT2001-1309) is gratefully acknowledged.

Published
2005

5. Synthesis and characterization of methyl-phenyl-substituted cyclopentadienyl zirconium complexes

Author

Eberhardt Herdtweck, Pascual Royo, Gema Martínez, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Science, chemistry.chemical_element, Alkylation, Biochemistry, Medicinal chemistry, Polymerization, Inorganic Chemistry, Propene, Transmetalation, chemistry.chemical_compound, Cyclopentadienyl complex, CIENCIA, Materials Chemistry, Organic chemistry, Physical and Theoretical Chemistry, Cyclopentadienyl, Metallocene, Zirconium, Organic Chemistry, Silyl-amido, SCIENCE, Nuclear magnetic resonance spectroscopy, Química inorgánica, chemistry, Chemistry, inorganic
Abstract

The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C5H3(SiMe2X)] (X = Me, Cl, NHt-Bu) and [(Me-Ph-C5H3)2SiMe2] and the lithium salts Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] and Li2[(Me-Ph-C5H2)2SiMe2] have been isolated by conventional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C5H3(SiMe3)] with ZrCl4(SMe2)2 gave the monocyclopentadienyl complex [Zr(η5-1-Ph-3-Me-C5H3)Cl3]. The ansa-metallocene [Zr{(η5-2-Me-4-Ph-C5H2)SiMe2(η5-2-Ph-4-Me-C5H2)}Cl2] was obtained from the mixture of isomers formed by transmetallation of Li2[(Me-Ph-C5H2)2SiMe2] to ZrCl4 and characterized as the meso-diastereomer by X-ray diffraction methods. Similar transmetallation of Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] gave the silyl-η-amido complex [Zr{η5-2-Me-4-Ph-C5H2(SiMe2-η-Nt-Bu)}Cl2] that was further alkylated to give [Zr{η5-2-Me-4-Ph-C5H2(SiMe2-η-Nt-Bu)}R2] (R = Me, CH2Ph) and used as a catalyst precursor, activated with MAO, for ethene and propene polymerization. All of the new compounds were characterized by elemental analysis and NMR spectroscopy., Ministerio de Educación, Cultura y Deporte

Published
2005

6. Regioselective formation of [2-(η5-cyclopentadienyl)-2-fluorenylpropane]-titanium complexes: precursors, synthesis, structure and reactivity

Author

Juan C. Flores, Mijail Galakhov, Pilar Gómez Sal, Pascual Royo, Avelino Martín, Iván Dorado, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Trimethylsilyl, Stereochemistry, Fluorenyl, Science, Crystal structure, Alkylation, Biochemistry, Medicinal chemistry, Inorganic Chemistry, chemistry.chemical_compound, Cyclopentadienyl complex, CIENCIA, Materials Chemistry, Reactivity (chemistry), Physical and Theoretical Chemistry, Cyclopentadienyl, Chemistry, Ligand, Organic Chemistry, Center (category theory), Regioselectivity, SCIENCE, Química inorgánica, Bridged ligands, Titanium complexes, Chemistry, inorganic
Abstract

The 2-cyclopentadienyl-2-fluorenylpropane ligand has been converted into the monometalated derivatives M[CMe2(C5H4)(C13H9)] (MLi, Tl,) and CMe2[C5H4(SiMe3)](C13H9). These alkylating reagents have been characterized, and used to synthesize a new series of organotitanium (IV) complexes. The trimethylsilyl derivative was treated with TiCl4 to give the monocyclopentadienyl compound [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl3]. Reaction of the thallium derivative with [Ti(h 5 -C5R5)Cl3] afforded the ‘mixed-ring’ dicyclopentadienyl complexes [Ti{CMe2(h 5 -C5H4)(C13H9)}(h 5 -C5R5)Cl2 ]( R H, Me), whereas the reaction of TiCl4 with two equivalents of the lithium compound led to the dicyclopentadienyl complex [Ti{CMe2(h 5 C5H4)(C13H9)}2Cl2]. The monocyclopentadienyl compound [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl3] was readily hydrolyzed to give [Ti{CMe2(h 5 -C5H4)(C13H9)}Cl2]2(m-O) in wet acetone (0.5% H2O). The dicyclopentadienyl derivative [Ti{CMe2(h 5 C5H4)(C13H9)}(h 5 -C5Me5)Cl2] was further converted into [Ti{CMe2(h 5 -C5H4)(C13H9)}(h 5 -C5Me5)Me2] by alkylation with LiMe. Structural data of the titanium complexes demonstrate the h 5 -coordination of the cyclopentadienyl ring of the ancillary ligand, whereas the fluorenyl ring is not coordinated to the metal center. This mode of coordination is confirmed by the X-ray crystal structure analysis of [Ti{CMe2(h 5 -C5H4)(C13H9)}2Cl2]. © 1998 Elsevier Science S.A. All rights reserved.

Published
1998

7. Mixed-dicyclopentadienyl niobium and tantalum complexes: synthesis and reactivity X-ray molecular structures of Ta(η-C5Me5)(η5-C5H4SiMe3)Cl2 and Ta(η5-C5Me5){η5-C5H3(SiMe3)2}H3

Author

Castro Correro, Aurora, Gómez Rubio, Manuel, Gómez Sal, Pilar, Manzanero Castillo, Antonio, Royo Gracia, Pascual, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Oxo-chloro mixed species, Group 5, Science, Niobium, Hydrides, Tantalum, SCIENCE, Química inorgánica, Silyl, CIENCIA, Cyclopentadienyl, Chemistry, inorganic
Abstract

MCp* Cl,, (Cp* = $-C,Me,) reacts with LiCp (Cp = C,H,(SiMe,) (Cp’); C,H,(SiMe,), (Cp”)) and sodium amalgam, in I : I : 1 molar ratio to give the paramagnetic dicyclopentadienyl niobium and tantalum(W) complexes, MCp * CpCI,, (M = Nb, Cp = Cp’ 1; Cp” 2; M = Ta, Cp = Cp’ 3; Cp” 4). Reactions of 3 and 4 with l/2 equivalent of PCl, afford the diamagnetic trichlorocomplexes TaCp* CpCI,, (Cp = Cp’ 5; Cp” 6). while oxidation with dry 0, gives the diamagnetic dinuclear complexes [TaCp* CpCI,],( p-O>, (Cp = Cp’ 7; Cp” S), and with air are transformed into the corresponding oxoderivatives TaCp * CpCl(O), (Cp = Cp’ 9; Cp” 10). Treatment of compounds 3 and 4 with a slight excess of lithium aluminium hydride affords the trihydrido complexes TaCp” CpH, (Cp = Cp’ 11; Cp” 12). The trihydrido complex 12 reacts with two-electron donor ligands on heating to yield the hydrido tantalum(II1) compounds TaCp* Cp”H(L) (L = CO 13, C,H, 14, RNC 15). All the new complexes were characterized by usual IR and NMR spectroscopic methods. The crystal structures of 3 and 12 were determined by X-ray diffraction studies. Crystals of 3 are orthorhombic, space group P2,2,2,, with Z= 4 in a unit cell of dimensions a = 11.775(5) A, b = 12.821(l) A, c = 13.037(7) A. Crystals of 12 are triclinic, space group Pi with Z = 2 in a unit cell of dimensions a = 7.384(4) A, b = 10.861(2) A, c = 16.731(3) A, LY = 75.94(2)“, p = 84.75(3)” and y = 72.57(4)‘. Both structures were solved from diffractometer data by a combination of direct and Fourier methods and refined by full-matrix least squares fit on the basis of 4088 (3) and 4594 (12) observed reflections to R and R,. values of 0.040 and 0.064 (3) and 0.022 and 0.033 (12) respectively., We are grateful to DGICYT (Project PB-92-0178-C) for financial support of this research.

Published
1996

8. Synthesis and characterization of new alkoxide and aryloxide derivatives of titanium and zirconium. X-ray molecular structure of [ZrCp2(OC6F5)2]

Author

Amor Chico, José Ignacio, Burton, N.C., Cuenca Agreda, Tomás, Gómez Sal, Pilar, Royo Gracia, Pascual, and Universidad de Alcalá. Departamento de Química Inorgánica

Subjects
Ciencia, Titanium, Group 4, Science, CIENCIA, Zirconium, Alkoxides, SCIENCE, Cyclopentadienyl, Química inorgánica, Chemistry, inorganic, X-ray diffraction
Abstract

Lithium or sodium alkoxides MOR (R double bond; length as m-dashCH2CHdouble bond; length as m-dashCMe2; M double bond; length as m-dash Li1; Na2; R double bond; length as m-dash C6F5; M double bond; length as m-dash Li3 were prepared by reaction of the alcohols with n-butyl lithium or sodium metal in hexane. Reaction of a hexane suspension of3 with SiClMe, afforded SiMe3(OC6F5)4, whereas the reaction of 3 equivalents of C6F5OH with AlMe3 in hexane led to Al(OC6F5)35. Compounds1 or2 react with one equivalent of [TiCp*Cl2Me] (Cp*double bond; length as m-dash C5Me5) in toluene to give [TiCp*ClMe(OCH2CHdouble bond; length as m-dashCMe2)]6. Complex6 reacts with AlEtCl2 to give quantitatively [TiCp*Cl3]. In the presence of water, the hydrolysis of6 takes palce giving the μ-oxo compound [{(TiCp*Cl)(μ − O)}3]. [TiCp*Cl2Me] reacted with an excess of the alcohol C6F5OH to give [TiCp*(OC6F5)3]7. [ZrCp2Cl2] reacted with two equivalents of pentaflurophenol in the presence of aniline to give the dialkoxide [ZrCp2(OC6F5)2]8. When the same reaction was carried out in a 1:1 molar ratio, a mixture of8 and the chloroalkoxide [ZrCp2Cl(OC6F5)]9 was obtained. A cleac reaction takes place when the μ-oxo compound [(ZrCp2Me)2(μ-O)] is treated with two equivalents of pentaflurophenol, leading to the isolation of the alkoxo complex [{ZrCp2(OC6F5)}2(μ-O)]10. The methylalkoxo derivative [ZrCp2Me(OC6F5)]11, was obtained by rection of [ZrCp2ClMe] with one equivalent of3. Alternative methods can be also be followed to synthesize8 and11. The crystal and molecular structure of8 has been determined by X-ray diffraction methods. The most interesting feature of this structure is the disposition of the (C6F5) ring planes, which are located practically on the reflection plane defined by O(1), Zr(1) and O(1)′.

Published
1995

9. The key role of coligands in novel ruthenium(II)-cyclopentadienyl bipyridine derivatives: Ranging from non-cytotoxic to highly cytotoxic compounds.

Author

Côrte-Real L, Robalo MP, Marques F, Nogueira G, Avecilla F, Silva TJ, Santos FC, Tomaz AI, Garcia MH, and Valente A

Subjects
2,2'-Dipyridyl chemical synthesis, 2,2'-Dipyridyl chemistry, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Cell Line, Tumor, Electrochemical Techniques, Humans, Ligands, Magnetic Resonance Spectroscopy, Models, Chemical, Organometallic Compounds chemical synthesis, Organometallic Compounds chemistry, Serum Albumin chemistry, Spectrometry, Fluorescence, Tryptophan chemistry, 2,2'-Dipyridyl analogs & derivatives, 2,2'-Dipyridyl pharmacology, Antineoplastic Agents pharmacology, Organometallic Compounds pharmacology, Ruthenium chemistry
Abstract

A new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [5: HSA] and [6: HSA] adducts (HSA=human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(η(5)-C5H5)(bipy)(PPh3)][PF6] (7; bipy=bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(η(5)-C5H5)(bipy)(PPh3)](+) cation complex in the racemic crystal packing., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Published
2015
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10. New water-soluble ruthenium(II) cytotoxic complex: biological activity and cellular distribution.

Author

Morais TS, Santos FC, Jorge TF, Côrte-Real L, Madeira PJ, Marques F, Robalo MP, Matos A, Santos I, and Garcia MH

Subjects
Antineoplastic Agents pharmacokinetics, Cell Line, Tumor, Coordination Complexes pharmacokinetics, Cytochromes c chemistry, Cytochromes c metabolism, Drug Screening Assays, Antitumor, Electrochemical Techniques, Endocytosis drug effects, Fluorescence, Golgi Apparatus drug effects, Humans, Organometallic Compounds chemical synthesis, Organometallic Compounds pharmacokinetics, Serum Albumin chemistry, Serum Albumin metabolism, Solubility, Temperature, Ubiquitin chemistry, Ubiquitin metabolism, Warfarin chemistry, Warfarin metabolism, Water, Antineoplastic Agents pharmacology, Coordination Complexes chemistry, Coordination Complexes pharmacology, Organometallic Compounds chemistry, Organometallic Compounds pharmacology, Ruthenium chemistry
Abstract

A novel water soluble organometallic compound, [RuCp(mTPPMSNa)(2,2'-bipy)][CF3SO3] (TM85, where Cp=η(5)-cyclopentadienyl, mTPPMS=diphenylphosphane-benzene-3-sulfonate and 2,2'-bipy=2,2'-bipyridine) is presented herein. Studies of interactions with relevant proteins were performed to understand the behavior and mode of action of this complex in the biological environment. Electrochemical and fluorescence studies showed that TM85 strongly binds to albumin. Studies carried out to study the formation of TM85 which adducts with ubiquitin and cytochrome c were performed by electrospray ionization mass spectrometry (ESI-MS). Antitumor activity was evaluated against a variety of human cancer cell lines, namely A2780, A2780cisR, MCF7, MDAMB231, HT29, PC3 and V79 non-tumorigenic cells and compared with the reference drug cisplatin. TM85 cytotoxic effect was reduced in the presence of endocytosis modulators at low temperatures, suggesting an energy-dependent mechanism consistent with endocytosis. Ultrastructural analysis by transmission electron microscopy (TEM) revealed that TM85 targets the endomembranar system disrupting the Golgi and also affects the mitochondria. Disruption of plasma membrane observed by flow cytometry could lead to cellular damage and cell death. On the whole, the biological activity evaluated herein combined with the water solubility property suggests that complex TM85 could be a promising anticancer agent., (© 2013.)

Published
2014
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11. Important cytotoxicity of novel iron(II) cyclopentadienyl complexes with imidazole based ligands.

Author

Gonçalves AC, Morais TS, Robalo MP, Marques F, Avecilla F, Matos CP, Santos I, Tomaz AI, and Garcia MH

Subjects
Cell Line, Tumor, Humans, Neoplasms pathology, Antineoplastic Agents chemical synthesis, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacology, Cyclopentanes chemical synthesis, Cyclopentanes chemistry, Cyclopentanes pharmacology, Cytotoxins chemical synthesis, Cytotoxins chemistry, Cytotoxins pharmacology, Imidazoles chemistry, Imidazoles pharmacology, Iron Compounds chemical synthesis, Iron Compounds chemistry, Iron Compounds pharmacology, Neoplasms drug therapy
Abstract

Four new compounds of general formula [FeCp(dppe)L][CF3SO3] with L=imidazole substituted ligands, and dppe=ethylenebis(diphenylphosphane) have been synthesized and characterized with the aim to evaluate their anticancer properties. The new compounds were fully characterized by spectroscopic and electrochemical methods and the structure of [Fe(η(5)-C5H5)(dppe)(1-BuIm)] [CF3SO3] (1), [Fe(η(5)-C5H5)(dppe) (ImH)][CF3SO3] (3) and [Fe(η(5)-C5H5)(dppe)(1HmIm)][CF3SO3] (4) (where 1-BuIm=1-butylimidazole, and 1HmIm=N-hydroxymethylimidazole) was determined by X-ray diffraction studies. Apparently, these compounds are the first reported 'Fe(η(5)-C5H5)' half sandwich derivatives presenting high cytotoxic activity against a set a human tumor cell lines predicting their potential value as antitumor drugs., (© 2013.)

Published
2013
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