Search results for "Cyclopentadienyl complex"
showing 10 items of 86 documents
Conformational Control of Metallocene Backbone by Cyclopentadienyl Ring Substitution: a New Concept in Polyphosphane Ligands Evidenced by “Through-Sp…
2009
The present study deals with the conformational control of the metallocene backbone within ferrocenyl polyphosphane ligands and their performance in the highly topical palladium-catalyzed heteroaromatics arylation by direct C−H activation. New substituted cyclopentadienyl rings were synthesized, which allowed the assembling of original tri- and diphosphanes. The bulky cyclopentadienyl lithium salts diphenylphosphino-3-(triphenyl)methylcyclopentadienyllithium (4) and 1,2-bis(diphenylphosphino)-4-(triphenyl)methylcyclopentadienyllithium (5) were prepared in excellent yield. The assembling of these new hindered cyclopentadienyl salts (Cp) with other Cp fragments was performed in order to prepa…
Experimental and Theoretical Studies of Nonclassical d 0 Cyclopentadienyl Polyhydride Complexes of Molybdenum and Tungsten
1998
Low-temperature protonation of compounds Cp{sup *}MH{sub 5}(PMe{sub 3}) (M = Mo, 1; W, 2) by HBF{sub 4}{center_dot}Et{sub 2}O in CD{sub 2}Cl{sub 2} or CDFCl{sub 2} affords the thermally unstable hexahydride derivatives [Cp{sup *}MH{sub 6}(PMe{sub 3})]{sup +} (M = Mo, 3; W, 4). The corresponding protonation of 1- and 2-d{sup 5} affords 3- and 4-d{sup 5}, respectively. The {Delta}{delta} on going from H{sub 6} to HD{sub 5} is small for both compounds, but positive for 3 and negative for 4, and no isotopic perturbation of resonance (IPR) is observed. The T{sub 1min} at 400 MHz for [Cp{sup *}MH{sub 6}(PMe{sub 3})]{sup +} apparently doubles on going from Mo to W (52 ms for 3 and approximately 10…
Effects of substitutions on cyclopentadienyl rings in complexes with molybdenum-mercury bonds. 95Mo and 199Hg NMR studies
1995
NMR data for 95Mo and 199Hg nuclei have been obtained for new di- and trimetallic complexes Cp′(CO)3MoHgX containing molybdenum-mercury bonds and bulky and/or potentially bifunctional substituted cyclopentadienyl ligands; Cp′=C5HMe2Ph2, C5Me4Bz, C5Bz5, C5H4PPh2 and C5Me4PPh2 (Bz=CH2C6H5; Me =CH3; Ph=C6H5); X=Cp′(CO)3Mo, Cl, Br, 1, SCN. They are discussed within the context of our earlier results reported for analogous complexes with the cyclopentadienyl ligands bearing methyl groups. With the exception of phenyl substituted rings, a rather narrow range of 95Mo chemical shifts is found for the compounds with the same number of different substituents on cyclopentadienyl ligands. An outstandin…
Chlorodicyclopentadienyloxoniobium(V) complexes revisited: The origin of the asymmetry in the 1H- and 13C-NMR spectra, X-ray crystal structures and a…
2000
Abstract 1H- and 13C-NMR spectra of chlorodicyclopentadienyloxoniobium(V) complex I and its four 1,1′-dialkyl substituted derivatives II–V have been recorded and assigned based on DQF 1H,1H-COSY and PFG 1H,13C-HMQC and HMBC experiments. Non-equivalences of all cyclopentadienyl protons and carbons in II–V (as reflected by their different 1H- and 13C-NMR chemical shifts) are explained by synchronous and out-of-phase rotations of the substituted cyclopentadienyl rings. A non-equivalence of the methyls in III (1,1′-di-isopropyl) is explained by a detailed inspection of the rotamers of the isopropyl groups. The X-ray structural data show that III and IV (1-methyl-1′-tert-butyl) crystallize in th…
Syntheses, Structure, and Reactivity of Chiral Titanium Compounds: Procatalysts for Olefin Polymerization
2001
Titanium complexes with chelating alkoxo ligands have been synthesised with the aim to investigate titanium active centres in catalytic ethylene polymerisation. The titanium complexes cis-[TiCl2(η2-maltolato)2] (1, 89 %), and cis-[TiCl2(η2-guaiacolato)2] (2, 80 %) were prepared by direct reaction of TiCl4 with maltol and guaiacol in toluene. The addition of maltol to [Ti(OiPr)4] in THF results in the formation of species [Ti(OiPr)2(maltolato)2] (3, 82 %). The titanium compound cis-[Ti(OEt)2(η2-maltolato)2] (4, 74 %) was obtained by the transesterification reaction of species 3 with CH3CO2Et. When compound 4 is dissolved in THF a dinuclear species [Ti2(μ-OEt)2(OEt)4(η2-maltolato)2] (5, 45 %)…
Tantalocenehydridephosphorus chemistry.
2002
Abstract The aim of this paper is to look for a better knowledge of the behaviour of bent tantalocenes that bear hydrides, phosphorus PR2X (R=Me, Ph; X=H, lone pair) and cyclopentadienyl (Cp=C5H5, Cp′=C5H2tBu(Me)2, Cp*=C5Me5) ligands. An orbital control of regioselectivity of insertion of the PR2 phosphide fragment of chlorophosphines PR2Cl into the central TaH bond of trihydrides Cp2TaH3 leading to the formation of metallophosphonium cations is discussed. Neutralisation of cationic complexes with strong bases leads either to the Ta(V)–phosphide or to the Ta(III)–phosphine species depending on the nature of the cyclopentadienyl ligand; good electron donor Cp′ and Cp* rings favour the forma…
Iron(II) complexes of naphthalenes. X-ray structure of [cyclopentadienyl-iron(II)-η6-octamethylnaphthalene]PF6
1992
Abstract Complex ions [cyclopentadienyl-Fe(methylnaphthalene)]+ with 4 to 8 methyl substituents have been prepared from [CpFe(o-dichlorobenzene)]+ by a photochemical ligand exchange. Complexation shifts have been determined for 1H and 13C resonances of the η6-bonded naphthalenes. The X-ray structure of [CpFe(octamethylnaphthalene)]PF6 0.5 acetone has been determined. Crystals are monoclinic, the space group C2/c with unit-cell dimensions a = 10.689(4), b = 22.391(5), c = 20.550(4)A, β = 93.41(2)°, Z = 8. The structure determination established a distorted molecular geometry of the octamethylnaphthalene that is different from the free arene and its Cr(CO)3 complex.
Mono(cyclopentadienyl)titanium complexes containing a sulfide-bridged bis(phenolato) ligand. Molecular structure of Ti{2,2′-S(OC6H2-4-Me-6-tBu)2}(η5-…
2001
A series of titanium complexes containing a sulfur-bridged chelating bis(phenolato) ligand, Ti{2,2′-S(OC 6 H 2 -4-Me-6- t Bu) 2 }(η 5 -C 5 R 5 )Cl (R=H, Me; R 5 =1,3-(SiMe 3 ) 2 H 3 ), were prepared by the reaction of the dilithium derivative Li 2 [2,2′-S(OC 6 H 2 -4-Me-6- t Bu) 2 ] with Ti(η 5 -C 5 R 5 )Cl 3 . Alkylation of the chloro complexes gave complexes of the type Ti{2,2′-S(OC 6 H 2 -4-Me-6- t Bu) 2 }(η 5 -C 5 R 5 )R′ (R′=Me, CH 2 Ph). The crystal structure of the chloro complex Ti{2,2′-S(OC 6 H 2 -4-Me-6- t Bu) 2 }(η 5 -C 5 H 5 )Cl has been determined by X-ray diffraction and shows a monomeric four-legged piano-stool structure with the sulfur and chlorine atoms in trans positions. …
Chelated η5-cyclopentadienyl-η-ethyl complexes of molybdenum and tungsten; molecular structure of W(η5-C5H4CH2-η-CH2)(CO)3
2000
Abstract Molybdenum and tungsten complexes M(η5-C5H4CH2-η-CH2)(CO)3 (M=Mo, W) containing the bidentate ethyl-functionalized cyclopentadienyl ligand C5H4CH2CH2 have been synthesized by the reaction of spiro[2.4]hepta-4,6-diene with M(CO)3L3 (M=Mo; L3=1,3,5-C6H3Me3; M=W; L=NCMe). Reaction of the more stable tungsten complex with C6H5ICl2 and HBF4 gave complexes of the type W(η5-C5H4CH2CH2Cl)(CO)3Cl, W(η5-C5H4CH2CH3)(CO)3Cl and W(η5-C5H4CH2CH3)(CO)3(FBF3), respectively. The crystal structure of the tungsten tricarbonyl complex W(η5-C5H4CH2-η-CH2)(CO)3 has been determined by X-ray crystal diffraction on a single crystal and shows a four-legged piano stool structure.
Synthesis and characterization of titanium(IV) complexes containing the diphenylphosphino- and diphenylthiophosphoryl-functionalized cyclopentadienyl…
2000
The trimethylsilyl cyclopentadiene derivative C5H4(SiMe3)PPh2 (1) was treated with TiCl4 to give the air- and moisture-sensitive mono(cyclopentadienyl) compound Ti(η5-C5H4PPh2)Cl3 (4). Reaction of 4 with Mg(CH2C6H5)2(THF)2 gave Ti(η5-C5H4PPh2)(CH2C6H5)3 (5). Reactions of the lithium and thallium derivatives M{C5H4P(S)Ph2} (M=Li (2), Tl (3)) with one equiv. of TiCl4 afforded the mono(cyclopentadienyl) complex Ti{η5-C5H4P(S)Ph2}Cl3 (6), whereas reaction with 0.5 equiv. of TiCl4 gave the bis(cyclopentadienyl) complex Ti{η5-C5H4P(S)Ph2}2Cl2 (8). Compound 6 was also isolated as a minor product from the reaction of Ti{η5-C5H4P(S)Ph2}2Cl2 (8) with one equiv. of TiCl4. The major product was identif…