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.
Highly fluorescent benzophosphole oxide block-copolymer micelles
Parke, Sarah M.,Tanaka, Susumu,Yu, Haoyang,Hupf, Emanuel,Ferguson, Michael J.,Zhou, Yuqiao,Naka, Kensuke,Rivard, Eric
, p. 7477 - 7488 (2019)
The efficient synthesis of highly fluorescent para-biphenyl-substituted benzophospholes via zirconium-mediated metallacycle transfer is reported. A norbornene-appended benzophosphole oxide monomer was found to readily undergo living ring-opening metathesis polymerization with the Grubbs third-generation catalyst to yield either a homopolymer or block copolymers. The resulting block copolymers consisting of lipophilic alkylated- or pinacolboronate-capped comonomers undergo self-assembly into spherical micelles in tetrahydrofuran/hexanes mixtures, as determined by dynamic light scattering and transmission electron microscopy. One hallmark of the benzophosphole-containing polymers is their greatly enhanced emission intensity in solution in relation to their monomers, presumably due to a restriction in molecular motion upon formation of homopolymers or assembled block-copolymer micelles. Evidence for "analyte amplified precipitation" was found, wherein addition of a substoichiometric amount of fluoride to a benzophosphole oxide-pinacolboronate block-copolymer spherical micelle leads to rapid precipitation of highly emissive aggregates. This observation should guide the development of related methods to visually detect (and sequester) analytes in solution.
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.
PREPARATION AND PROPERTIES OF (η-C5H5)2 ZrCl AND (η-C5H5)2Zr2; TRIMETHYLSILYL GROUP TRANSFER FROM MERCURY TO ZIRCONIUM
Blakeney, A. J.,Gladysz, J. A.
, p. 263 - 268 (1980)
Two silyl-zirconium compounds (η-C5H5)2ZrCl (I) and (η-C5H5)2-Zr2 (II), have been prepared by the reaction of η(C5H5)2ZrCl2 with Hg2 in refluxing benzene.While I is unreactive toward 1-hexyne (55-60 deg C) and CO (350 psi), t
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.
Insertion of sodium phosphaethynolate, Na[OCP], into a zirconium-benzyne complex
Kieser, Jerod M.,Gilliard, Robert J.,Rheingold, Arnold L.,Grützmacher, Hansj?rg,Protasiewicz, John D.
, p. 5110 - 5112 (2017)
Reaction of the zirconium-benzyne complex [Cp2Zr(PMe3)(C6H4)] with sodium phosphaethynolate, Na[OCP], affords a zircono-phosphaalkene complex. Notably, unlike reactions of other transition metal complexes with Na[OCP] that yield the products of simple salt metathesis, this transformation represents novel Na[OCP] insertion chemistry and formation of an unusual solid state coordination polymer. The polymer is disrupted upon addition of Me3SiCl to afford a silyl-capped dimer that retains the zirconophosphaalkene functionality. Protonation of either form of zirconophosphaalkenes results in the formation of benzoylphosphine, PhC(O)PH2.
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.
Investigation of the mechanism of alkane reductive elimination and skeletal isomerization in Tp′Rh(CNneopentyl)(R)H complexes: The role of alkane complexes
Northcutt,Wick,Vetter,Jones
, p. 7257 - 7270 (2001)
Experiments are described that provide indirect evidence for the involvement of alkane σ-complexes in oxidative addition/reductive elimination reactions of Tp′Rh(L)(R)H complexes (Tp′ = tris-3,5-dimethylpyrazolylborate, L = CNCH2CMe3). Reductive elimination rates in benzene-d6 were determined for loss of alkane from Tp′Rh(L)(R)H, where R = methyl, ethyl, propyl, butyl, pentyl, and hexyl, to generate RH and Tp′Rh(L)(C6D5)D. The isopropyl hydride complex Tp′Rh(L)(CHMe2)H was found to rearrange to the n-propyl hydride complex Tp′Rh(L)(CH2CH2CH3)H in an intramolecular reaction. The sec-butyl complex behaves similarly. These same reactions were studied by preparing the corresponding metal deuteride complexes, Tp′Rh(L)(R)D, and the scrambling of the deuterium label into the α- and ω-positions of the alkyl group monitored by 2H NMR spectroscopy. Inverse isotope effects observed in reductive elimination are shown to be the result of an inverse equilibrium isotope effect between the alkyl hydride(deuteride) complex and the σ-alkane complex. A kinetic model has been proposed using alkane complexes as intermediates and the selectivities available to these alkane complexes have been determined by kinetic modeling of the deuterium scrambling reactions.
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
