60938-59-2Relevant articles and documents
METALLOCENE DERIVATIVES OF EARLY TRANSITION ELEMENTS. PART 4. SYNTHESIS AND CRYSTAL STRUCTURES OF A SERIES OF ZIRCONOCENE(IV) HALIDES (X = Cl OR Br) AND 2X2> ( X =F, Br, OR I)
Antinolo, Antonio,Lappert, Michael F.,Singh, Anirudh,Winterborn, Duncan J. W.,Engelhardt, Lutz M.,et al.
, p. 1463 - 1472 (1987)
A series of zirconocene(IV) halides, and 2X2> , has been prepared, either by (i) substitutive procedures from ZrCl4 , or (ii), for complexes (3), (5), or (6), by oxidative addition to 2(CO)2>.The only vasym(ZrX2) vibration to be assigned with confidence is for X = F at 563 cm-1, (1)H and (13)C n.m.r.data are unexceptional.X-Ray structure determinations of complexes (1)-(5) have been carried out.Their molecular symmetry is close to 2, or crystallographically imposed 2 in (3), with the stereochemistry about the metal centre best described as distorted tetrahedral.The angle X-Zr-X is 93.70(7), 94.2(1), 100.5(3), 100.25(5), and 100.37(4)deg for the halides (1)-(5), respectively; and the corresponding centroid-Zr-centroid angles are 129.1, 128.2, 131.4, 131.4, and 131.8 deg.Metalhalogen distances in (1) and (3) are significantly longer than in the parent zirconocene(IV) halides (cf. 2.44 Angstroem for X = Cl and 1.98 Angstroem for X = F) as are the metal-centroid distances in (3)-(5).
Synthesis, structural characterization and reactivity of new tin bridged ansa-bis(cyclopentadiene) compounds: X-ray crystal structures of Me2Sn(C5Me4R-1)2 (R = H, SiMe3)
Gómez-Ruiz, Santiago,Prashar, Sanjiv,Fajardo, Mariano,Anti?olo, Antonio,Otero, Antonio
, p. 3057 - 3064 (2008/02/02)
The organo-tin compounds, Me2Sn(C5H4R-1)2 (R = Me (1), Pri (2), But (3), SiMe3 (4)) and Me2Sn(C5Me4R-1)2 (R = H (5), SiMe3
The importance of cyclopentadienyl substituent effects in group 4 metallocene dinitrogen chemistry
Pool, Jaime A.,Chirik, Paul J.
, p. 286 - 295 (2007/10/03)
This article highlights some of our recent efforts and presents new data on the importance of cyclopentadienyl substituent effects on group 4 metallocene dinitrogen chemistry. Reactions such as the coordination of N2 to an isolated titanium sandwich complex, alkali-metal reductions of zirconocene dihalide complexes, alkane reductive elimination reactions, and the hydrogenation of zirconium dinitrogen complexes are all extremely sensitive to the groups present on the cyclopentadienyl rings. These results are promising for the future of N2 fixation, as the reactivity of a specific metallocene can be dramatically altered by subtle manipulations in ligand substituents.
CH-Aktivierungsreaktionen an substituierten Zirconocenkomplexen und deren Verwendung in der katalytischen Ethylenpolymerisation
Licht, Andrea I.,Alt, Helmut G.
, p. 91 - 104 (2007/10/03)
Zirconocene dichloride complexes with substituents containing aliphatic end groups at the aromatic ligands react with two equivalents of n-butyllithium to give metallacyclic zirconocene complexes via aliphatic CH-activation reactions. As well as ω-alkenyl substituted zirconocene dichloride complexes with terminal aliphatic groups as zirconocene dichloride complexes with purely aliphatic substituents are suitable for the synthesis of such metallacycles. In combination with methylalumoxane (MAO), these metallacycles are excellent catalysts for ethylene polymerization. Their activities can be three and a half times higher than the activities of the corresponding zirconocene dichloride educts. The catalyst 25/MAO is able to produce 2640 kg PE g-1 Zr h (60 deg C, pentane solution, 10 bar ethylene pressure).
Alkinol- und alkindiol-funktionalisierte zirconocen-verbindungen: Synthese, struktur und reaktionsverhalten 1
Lang, Heinrich,Weinmann, Susanne,Herres, Mathias,Weinmann, Markus,Walter, Olaf,Nuber, Bernhard,Zsolnai, Laszlo
, p. 49 - 61 (2007/10/03)
The reaction of [Zr]Cl2 (1) {[Zr] = (η5-C5H4SiMe3)2Zr} with HO(CR2)nC≡CH (2a: R = H, n = 2; 2b: R = H, n = 4; 2c: R = CH3, n = 1) or HOCH2C≡CCH2OH (2d) yields, depending on the nature of the bases used [1,4-diazabicyclo[2.2.2]octane (DABCO) or NEt3], different substitution products. On treatment of 1 with 2a or 2b in toluene in the presence of DABCO, the σ-alkynol-substituted zirconocenechlorides [Zr](Cl)[O(CH2)nC≡CH] (3a: n = 2; 3b: n = 4) are formed. Moreover, zirconocene σ-dialkynols [Zr][O(CR2)nC≡CH]2 (4a: R = H, n = 2; 4b: R = H, n = 4; 4c: R = CH3, n = 1) can be obtained by treatment of compounds 1, 3a or 3b with 2a-2c in NEt3. When 2d is reacted with two equivalents of 1 in the presence of DABCO, the product isolated is (Cl)[Zr](μ,-OCH2C≡CCH2O)[Zr](Cl) (5), while in NEt3 as solvent cyclic [Zr] (μ-OCH2C≡CCH2O)2[Zr] (6) is obtained. The chemical behaviour of compounds 3 and 4 is discussed. The reaction of [Zr](Cl)[O(CH2)2C≡CH] (3a) with [CuO2CMe]4 (7) yields [Zr](Cl)(μ,-O2CMe) (8) by elimination of [CuO(CH2)2C≡CH]n. Treatment of compounds 3a, 4a or 4c with Co2(CO)8 (9) affords [Zr](Cl){[η2-O(CH2)2C≡CH] Co2(CO)6} (10), [Zr]{[η2-O(CH2)2C≡CH] Co2(CO)6}2 (11a) or [Zr]{[η2-OCMe2C≡CH]Co2(CO)6}2 (11b) respectively. In each of these compounds the HC≡C building block is η2-coordinated to a Co2(CO)6 fragment. Treatment of complexes 3a, 4b, 10 or 11 with HCl(aq) produces [Zr]Cl2 (1) and 2a or 2b [reaction of 3 or 4 with HCl(aq)] or [Zr]Cl2 (1) and [η2-HO(CH2)2C≡CH]Co2(CO)6 (12a) or (η2-HOCMe2C≡CH)Co2(CO)6 (12b) [reaction of 10 or 11 with HCl(aq)]. The solid state structures of compounds [Zr](Cl)[O(CH2)2C≡CH] (3a), (Cl)[Zr](μ-OCH2C≡CCH2O)[Zr](Cl) (5) and [Zr]{[η2-OCMe2C≡CH]Co2(CO)6}2 (11b) are reported. 3a crystallizes in the rhombic space group Pnma with cell constants a = 813.1(3), b = 1523.7(5), c = 1850.0(6) pm, V = 2292.0(9) × 106 pm3 and Z = 4. Crystals of 5 and 11b are monoclinic. Compound 5: space group Pc with a = 1290.8(6), b - 2582(1), c - 760.1(3) pm, β = 73.15(3)°, V = 2424(2) × 106 pm3 and Z = 2. Compound 11b: space group P21/n with a = 1461.0(6), b = 2057(1), c = 1528.4(6) pm, β= 96.06(3)°, V = 4567(3) × 106 pm3 and Z = 4.
Cyclopentadienylmetal trichloride formation versus metallocene dichloride formation in the reactions of silylated cyclopentadienes with zirconium and hafnium chlorides. Crystal structure of (1,3-bis- (trimethylsilyl)cyclopentadienyl)titanium trichloride
Winter,Zhou,Dobbs,Heeg
, p. 210 - 214 (2008/10/08)
The reaction of zirconium and hafnium tetrachlorides with tris(trimethylsilyl)cyclopentadiene affords the monocyclopentadienyl complexes (1,3-bis(trimethylsily)cyclopentadienyl)zirconium trichloride (1, 73%) and (1,3-bis(trimethylsilyl)cyclopentadienyl)hafnium trichloride (2, 76%) in good isolated yields. The reaction of 1 with (1,3-bis(trimethylsilyl)cyclopentadienyl)lithium affords 1,1′,3,3′-tetrakis(trimethylsilyl)zirconocene dichloride (74%). In contrast to the preparations of 1 and 2, reaction of bis(trimethylsilyl)cyclopentadiene with zirconium and hafnium tetrachlorides affords 1,1′-bis- (trimethylsilyl)zirconocene dichloride (5, 73%) and 1,1′-bis(trimethylsilyl)hafnocene dichloride (6, 76%). The reaction of (trimethylsilyl)cyclopentadiene with zirconium and hafnium tetrachlorides affords zirconocene dichloride (7, 91%) and hafnocene dichloride (8, 90%). The intermediacy of monocyclopentadienyl species in the preparation of the metallocene dichlorides is supported by the reaction of cyclopentadienylzirconium trichloride with (trimethylsilyl)cyclopentadiene to afford 7 (85%). Reaction of zirconium tetrachloride with 1 equiv of (trimethylsilyl)cyclopentadiene at 0 °C for 0.5 h affords 7 and cyclopentadienylzirconium trichloride in a (69 ± 2):(31 ± 2) ratio. The silyl group regiochemistry in 1 and 2 was established through an X-ray crystal structure determination of the titanium analogue (1,3-bis(trimethylsilyl)cyclopentadienyl)titanium trichloride (3). Complex 3 crystallizes in the orthorhombic space group Pbnm with a = 7.459 (3) angstrom, b = 11.799 (3) angstrom, c = 20.535 (3) angstrom, V = 1807.1 (9) angstrom3, and Z = 4.
METALLOCENE DERIVATIVES OF EARLY TRANSITION METALS. PART 2. SUBSTITUTED CYCLOPENTADIENYL GROUP 4A DICHLORO-METALLOCENE COMPLEXES (M=Zr OR Hf; R=Me, Et, Pri, But, OR SiMe3), THEIR MONO- AND DI-ALKYL DERIVATIVES (X=Cl OR R';R'= CH2SiMe3 OR CH2CME3...
Lappert, Michael F.,Pickett, Christopher J.,Riely, Paul I.,Yarrow, Paul I. W.
, p. 805 - 813 (2007/10/02)
The substituted d0 metallocene dichloro-complexes 2 (M = TiIV, ZrIV, or HfIV; R = Me, Et, Pri, But, or SiMe3), (1)-(11), have been prepared from MCl4 and 2Li in tetrahydrofuran (thf).From the appropriate dichloride and either(i) MgR'Cl in CH2Cl2 there was obtained the chloro(alkyl) (R = CH2SiMe3) or , or (ii) akyl-lithium in OEt2 the dialkyl (M'= Zr or Hf; R'' = H, Me, Et, Pri or But; X = C or Si), (13)-(16), was produced; treatment of t)2Cl2> with BBr3 in CH2Cl2 gave t)2Br2>.The 1H n.m.r. spectra of each of the dichlorides (1)-(11) show the ring protons of the C5H4R group as an AA'BB' or A2B2 (R = SiMe3) signal; the dialkyls (13)-(16) show this feature as an A2X2 pattern, whereas in t)2SiMe3)Cl> it appears as ABCD.The 13C n.m.r. spectra show three signals for the corresponding carbon atoms (C5H4R) and the chemical shift data are compared with results on substituted ferrocenes or benzenes, or C6H5R.Treatment of the complex with an equimolar portion of Na in thf at 20 deg C yields an appropriate d1 dialkylmetal(III) complex, which is persistent for M = Ti or Zr but not for M = Hf, and is characterised by its e.s.r. spectrum av., 1.984-1.993; a(1H), 0.175-0.360 mT; a(47/49Ti), 0.720-1.05. mT;a(91Zr),1.000-2.410 mT> showing coupling with the α protons of the alkyl group R'.As each of these (Zr) dialkyls undergoes irreversible one-electron reduction at a Pt electrode in 0.2 mol dm-3 in thf the above d1 complexes are formulated as .Cyclic voltammetry data are provided for several metallocene(IV) complexes: (i) dichlorides -(M = Zr), and E1/2red is nearly 1 V more negative than for Ti>; (ii) chloro(alkyls) (irreversible reduction); and (iii) dialkyls (irreversible reduction).
