1291-32-3Relevant articles and documents
Formation of metallaboranes from the group IV transition metals and pentaborane(9): Crystal and molecular structure of [(Cp2Zr)2B5H8] [B11H14]
Thomas, Rhodri Ll.,Rath, Nigam P.,Barton, Lawrence
, p. 67 - 75 (2002)
The reactions between [(C5H5)2MCl2] (where M = Ti, Zr, Hf) and Li[B5H8] in a variety of solvents have been investigated. In the case of Zr, a pale orange solid, μ-(Cp2ClZr)B5H8 (1), is formed in 70% yield. Compound 1 exists as a B5H9 cage with a Cp2ClZr moiety replacing a bridging H atom. The variable temperature NMR spectra of 1 reveal two fluxional processes, one (ΔG? = 54 kJ mol-1) which renders a plane of symmetry in the molecule and a higher temperature one (ΔG? = 48 kJ mol-1) which renders all the basal B atoms equivalent. Dynamic processes are suggested to account for these observations. Passage of a CH2Cl2 solution of 1 through silica gel affords 2, [(Cp2Zr)2B5H8] [B11H14], a yellow, air-stable, crystalline solid, in 14% yield. The cation in 2, [(Cp2Zr)2B5H8]+, consists of a distorted spiro[2.2]pentane-like B5 moiety comprising two B3 triangles sharing a naked boron vertex. The two triangles are twisted 73° with respect to each other, and the two [Cp2Zr] groups bond in a trihapto arrangement to the two opposite B-B-B edges. Each exterior B-Zr edge is H-bridged, and the B atoms possess terminal hydrogens. Reactions of Cp2HfCl2 with Li[B5H8 lead to the formation of the analogue of 2, [(Cp2Hf)2B5H8] [B11H14] (3). The precursor to 3, that is, the Hf analogue of 1, is not observed. Reaction between Li[B5H8] and Cp2TiCl2 afforded no identifiable products, but reaction with CpTiCl3 resulted in cage coupling and the formation of B1OH14.
Die Bildung von β-C-H agotischen Alkenylzirconocen-Komplexen bei der anormalen Hydrozirconierung von Alkinen
Erker, Gerhard,Zwettler, Roland,Krueger, Carl,Schlund, Rueger,Hyla-Kryspin, Isabella,Gleiter, Rolf
, p. C15 - C18 (1988)
Some alkynes R1CCR2 bearing bulky substituents undergo abnormal hydrozirconation reactions when treated with the reagent x (1).The products obtained do not contain newly formed C-H bonds.Dicyclopentadienylzirconacyclopentadiene systems (5) are formed instead.Extended Hueckel calculations as well as the isolation of the product (3b) in addition to Cp2ZrCl2 and (5b) from Me3SiCCPh and 1 indicate that β-C-H agostic alkenylmetallocene complexes may serve as important intermediates for this variant of hydrozirconation.The molecular structure of 3b was deterrmined by an X-ray diffraction study.Complex 3b crystallizes in space group P21/n with cell constants a 9.641(2), b 18.066(3), c 11.762(1) Angstroem, β= 92.122(7) deg, Z=4.The Zr-C(1)-C(2) angle is 89.9 deg and the Zr-H(2) distance is 2.29(2) Angstroem.
REACTIONS OF Cp2M(CO)2 AND Cp2M(CO)(PPh3) (M=Zr, Hf) WITH ACETYLENES: FORMATION OF SOME METALLACYCLOPENTADIENE COMPLEXES OF ZIRCONOCENE AND HAFNOCENE
Sikora, David J.,Rausch, Marvin D.
, p. 21 - 38 (1984)
The photolysis of Cp2Zr(CO)2 with diphenylacetylene or 3-hexyne yields, the respective zirconacyclopentadiene complexes Cp2Zr(C4R4) (R=Ph, Et).The thermolysis of Cp2Zr(CO)2 with 3-hexyne or bis(pentafluorophenyl)acetylene also leads to the formation of Cp2Zr(C4R4) (R=Et, C6H5).HCl degradation of Cp2Zr yields 1,2,3,4-tetrakis(pentafluorophenyl)-1,3-butadiene and Cp2ZrCl2.When Cp2Zr(CO)2 is heated with diphenylacetylene in a closed vessel, tetraphenylcyclopentadienone is formed along with Cp2Zr(C4Ph4).The hafnacyclopentadiene complexes Cp2Hf(C4R4) (R=Ph, C6G5, Et) are obtained when Cp2Hf(CO)2 is thermolyzed with the respective acetylene in refluxing octane.Complexes Cp2Hf(C4R4) (R=Ph, Et) are also formed when Cp2Hf(CO)2 is photolyzed with diphenylacetylene or 3-hexyne, respectively.The monocarbonyl-triphenylphosphine complexes Cp2M(CO)(PPh3) (M=Zr, Hf) can be prepared via the irradiation of hydrocarbon solutions of Cp2M(CO)2 and triphenylphosphine.These complexes react readily with diphenylacetylene and 3-hexyne at 55-60 deg C to afford the corresponding metallacyclopentadiene complexes Cp2M(C4R4) (M=Zr, Hf; R=Ph, Et).The metallocene dicarbonyls Cp2M(CO)2 (M=Zr, Hf) are readily prepared via the reduction of Cp2MCl2 (M=Zr, Hf) with amalgamated magnesium metal in THF solution under one atmosphere of carbon monoxide.
Metalations with group 4 alkylmetal(IV) halides: Expeditious route to metallocene and nonmetallocene procatalysts
Eisch, John J.,Owuor, Fredrick A.,Otieno, Peter O.
, p. 4132 - 4134 (2001)
Group 4 alkylmetal(IV) halides of the type Bu2MtCl2, generated in hydrocarbon media at -78°C by treating MtCl4 with 2 equiv of n-butyllithium, function as strong bases toward a variety of Br?nsted acids, E-H, where E = cyclopentadienyl or substituted cyclopentadienyl, 1-alkynyl, indenyl, alkoxy, aryloxy, and disubstituted amino, to form metallocene and nonmetallocene procatalysts, E2MCl2, expeditiously and generally in high yield.
Carbon-carbon bond formation reaction of zirconacyclopentadienes with alkynes in the presence of Ni(II)-complexes
Takahashi, Tamotsu,Tsai, Fu-Yu,Li, Yanzhong,Nakajima, Kiyohiko,Kotora, Martin
, p. 11093 - 11100 (1999)
Zirconacyclopentadienes, prepared from two alkynes or a diyne, reacted with the alkyl-, trimethylsilyl-, or alkoxy-substituted third alkyne as well as an alkyne with an electron-withdrawing group in the presence of a stoichiometric amount of NiBr2(PPh3)2 to give benzene derivatives in good yields. Heteroatom-containing diynes such as dipropargylbenzylamine and propargyl-homopropargylbenzylamine gave isoindoline and tetrahydroisoquinoline derivatives in good to high yields. This procedure was also used for the selective preparation of benzene derivatives from three different alkynes. The use of trimethylsilyl-substituted alkyne as the first, second or third alkyne afforded desilylated benzene derivatives. The reaction of zirconacyclopentadienes with allenes gave benzene derivatives as a mixture of two isomers.
Heterometallic (ZrIII)2-Al hydrides [(Cp 2Zr)2(μ-H)](μ-H)2AlX2 (X = Cl or Br): Preparative synthesis and reactivity. Molecular structure of [(Cp 2Zr)2(μ-Cl)](μ-H)
Sizov,Zvukova,Khvostov,Gorkovskii,Starikova,Bulychev
, p. 2496 - 2501 (2005)
A procedure was developed for the synthesis of trinuclear cyclic (Zr III)2-Al hydrides [(Cp2Zr)2(μ-H)] (μ-H)2AlX2 (X = Cl (1a) or Br (1b)). These complexes were prepared in 60-65% yields by
Electrochemical reduction of zirconocene dihalides and dialkyls studied by electron spin resonance
Samuel, Edmond,Query, Dominique,Vedel, Jacques,Basile, Fran?oise
, p. 1073 - 1077 (1985)
An electrochemical cell designed to work in the cavity of an ESR spectrometer at variable temperatures was used to study the electrochemical reduction of zirconocene compounds Cp2ZrX2 (X = halogen (hal); Cp = η5-C5/s
Synthesis and catalytic activity of group 4 metallocene containing silsesquioxanes bearing functionalized silyl groups
Wada, Kenji,Itayama, Naohiko,Watanabe, Naoki,Bundo, Masaki,Kondo, Teruyuki,Mitsudo, Take-Aki
, p. 5824 - 5832 (2004)
A series of metallocene-containing silsesquioxanes with alkenylsilyl and trimethylsilyl groups, Cp′2M[(c-C5H 9)7Si7O11](OSiMe2R) (2b-d, 3b-d, 4d, 5d: Cp′ = Cp (cyclopentadienyl), Cp* (pentamethylcyclopentadienyl); M = Ti, Zr, Hf, R = methyl, vinyl, allyl), have been synthesized. The structures of the complexes Cp2M[(c-C 5H9)7Si7O11](OSiMe 2CH2CH=CH2) (M = Zr (3d), Hf (5d)) have been unambiguously established by single-crystal X-ray diffraction analyses. Silylation or germylation of the zirconocene-containing silsesquioxane monosilanol Cp2Zr[(c-C5H9)7Si 7O11](OH) (3a) or its hafnocene derivative Cp 2Hf[(c-C5H9)7-Si7O 11](OH) (5a), which can be prepared by the careful reaction of the silsesquioxane trisilanol (c-C5H9)7Si 7O9(OH)3 (1a) with zirconocene dichloride or hafnocene dichloride, yields the new series of metallocene-containing silsesquioxanes Cp2Zr[(c-C5H9) 7Si7O11](OSiMe2H) (3e), Cp 2-Zr[(c-C5H9)7Si7O 11](OGeMe3) (3f), and Cp2Hf[(c-C 5H9)7Si7O11](OSiMe 2H) (5e). The reaction of 3e with 2 equiv of hydrogen chloride results in the formation of the dimethylsilyl-containing silsesquioxane disilanol (c-C5H9)7Si7O 9(OH)2(OSiMe2H) (1e), indicating the applicability of metallocene moieties as protecting groups of two adjacent silanol groups. Silsesquioxanes bearing alkenylsilyl groups can be easily converted to derivatives with ethoxysilyl groups, Cp2M[(c-C 5H9)7Si7O11] [OSiMe 2(CH2)3SiMe2(OEt)] (M = Ti (2g), Zr (3g)), by the hydrosilylative reaction. The preliminary examination of the catalytic activity of these metallocene-containing silsesquioxanes toward the epoxidation of cyclohexene by tert-butyl hydroperoxide revealed that titanocene-containing silsesquioxanes (2b-d) show modest catalytic activity. The presence of alkenylsilyl groups has been found to accelerate the reactions, especially in the case of titanium-bridged silsesquioxanes.
Novel dimeric ring systems containing gallium
Cowley, Alan H.,Brown, David S.,Decken, Andreas,Kamepalli, Smuruthi
, p. 2425 - 2426 (1996)
A gallole (gallacyclopentadiene) is found to dimerise in a different fashion than boroles; the corresponding diazabutadiene complex is also dimeric.
Brainina, E. M.,Minacheva, M. Kh.
, (1984)
1H and 13C NMR evidence for the intermediate species 1:η5-C5H4)>2. Cyclopentadienyl C-H bond activation by thermolysis of n, Cp2Zr(R)Cl, and 2
Choukroun, Robert,Raoult, Yveline,Gervais, Daniele
, p. 189 - 194 (1990)
Thermal decomposition at 80 deg C of n (1) (Cp = η5-C5H5), Cp2Zr(R)Cl (2b) (R = cyclohexyl) and (Cp2ZrCl)2 gives the fulvalenide dizirconium complex 5 : η5-C5H4-C5H4)> (4) via the intermediate 1 : η5-C5H4)>2 (5).Complex (5) can also be prepared by treating Cp2ZrCl2 with sodium amalgam (1.5 eq) in refluxing toluene.In the presence of cyclic polyenes, such as 1,5-cyclooctadiene (1,5-COD) thermolysis of 1 takes place at room temperature probably to give initially a labile ? allyl species, which can be formulated in the case of the reaction with 1,5-COD as Cp2Zr(η3-C8H11)Cl.This is the first example in zirconium(IV) chemistry of cyclopentadienyl C-H bond activation resulting in hydrogenation of unsaturated substrates.
Selective tin-carbon bond cleavage reactions of trimethylstannylzirconocene dichloride with electrophiles
Cheng,Slebodnick,Deck,Billodeaux,Fronczek
, p. 4921 - 4926 (2000)
The reaction of 5,5-bis(trimethylstannyl)cyclopentadiene with CpZrCl3 (Cp = η5-C5H5) affords the monostan-nylated metallocene complex (η5-Me3SnC5H4)CpZrCl2 (1), accompanied by variable amounts of (η5-ClMe2-SnC5H4)CpZrCl2 (2). The complex (1) reacts with BCl3 or with ICl to afford 2 (Sn-CH3 cleavage), but with HCl, Cp2ZrCl2 is obtained instead (Sn-Cp cleavage). Depending on the reaction conditions, treatment of either 1 or 2 with BBr3 affords (η5-BrMe2SnC5H4)CpZrBr2 (3) or (η5-Br2MeSnC5H4)CpZrBr2 (4). The reaction of 1 with excess I2 affords the iodostannylated complex (η5-IMe2SnC5H4)CpZrCl2 (5). Two of the complexes (2·2C6H5CH3 and 4·THF) are crystallographically characterized. The adduct 4·THF has a distorted trigonal bipyramidal geometry about tin with a long O-Sn distance of 2.655 A. We find overall that Me3Sn substituents undergo electrophilic halodemethylation much more readily than corresponding Me3Si substituents, whereas the reactivities of the halostannylated complexes toward nucleophiles such as airborne moisture are much lower than those of their halosilylated counterparts.
Wilkinson, G.,Birmingham, J. M.
, p. 4281 - 4284 (1954)
Gelmini, Lucio,Stephan, Douglas W.
, p. L17 - L18 (1986)
Williams, Gregory M.,Schwartz, Jeffrey
, p. 1122 - 1124 (1982)
Nucleophilic reactivity of 1-zirconacyclopent-3-ynes: Carbon-carbon bond formation with aldehydes
Suzuki, Noriyuki,Watanabe, Takaaki,Hirose, Takuji,Chihara, Teiji
, p. 5317 - 5321 (2007)
Nucleophilic reactions of 1,1-bis(η5-cyclopentadienyl)-1-zirconacyclopent-3-yne (1) with proton and aldehydes were studied. The reaction with HCl gave a mixture of 2-butyne and 1,2-butadiene. Complex 1 reacted with benzaldehyde to give 1-phenyl-2-methyl-2,3-butadien-1-ol (3) in moderate yields in the presence of a proton source such as triethylammonium hydrochloride, while it gave 2-methylene-1-phenyl-3-buten-1-ol (4) on using triethylammonium tetraphenylborate.
A polyoxometalate transfer reagent: Synthesis, structure, and reactivity of zirconocene polyoxometalate [(PNbW11O40)2ZrCp2]6- [7]
Radkov, Emil V.,Young Jr., Victor G.,Beer, Robert H.
, p. 8953 - 8954 (1999)
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HYDROZIRCONIERUNG VON NITRILEN: DIE BILDUNG EIN- UND ZWEIKERNIGER (ALKYLIDENAMIDO)ZIRCONOCEN-KOMPLEXE
Froemberg, Wolfgang,Erker, Gerhard
, p. 343 - 354 (1985)
Cp2Zr(-N=CHR)Cl compounds (9a-9c: R=CH3, C6H5, CH2Ph, respectively) are formed upon hydrozirconation of nitriles.Subsequent reaction with an aryllithium reagent yields Cp2Zr(-N=CHR)Ar (14).The (alkylidene amido)zirconocene complexes are characterized by a
SYNTHESIS AND CHEMICAL PROPERTIES OF DICYCLOPENTADIENYLZIRCONIUM BIS(DIPHENYLARSENIDE) AND BIS(DIPHENYLANTIMONIDE), (E = As OR Sb)
Wade, Steven R.,Wallbridge, Malcolm G. H.,Willey, Gerald R.
, p. 271 - 276 (1984)
Treatment of Cp2ZrCl2 (Cp = η-C5H5) with LiEPh2 (E = As or Sb) affords the corresponding pentelide complexes Cp2Zr(EPh2)2.In the particular case of the Cp2TiCl2/LiAsPh2 system there is evidence for reduction to Cp2TiAsPh2.The spectral and elemental charac
Competitive Oxidation Processes in the Reaction between (Dicyclopentadienyl)zirconium Bis(phosphine) Complexes and Alkyl Halides
Williams, Gregory M.,Gell, Kerrie I.,Schwartz, Jeffrey
, p. 3660 - 3662 (1980)
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Four homologous zirconium 2,2′-biphenyldiyls: Synthesis, structure, and reactivity
Hilton, Cameron L.,King, Benjamin T.
, p. 4058 - 4061 (2006)
A homologous family of zirconohydrocarbons bearing the 2,2′-biphenyldiyl ligand (biphe) has been prepared. One of the homologues is a tetraanionic zirconate, two are examples of homoleptic σ-bound zirconohydrocarbons, and three are anionic ate complexes.
Palladium-Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans-Alkenes
Takahashi, Keita,Ogiwara, Yohei,Sakai, Norio
supporting information, p. 809 - 814 (2018/03/13)
Herein, we describe a reductive cross-coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp2HfF2, Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one-pot preparation of trans-alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans-alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.
