Fulvalene titanium and zirconium complexes: synthesis and NMR study of phosphanido-, alkyl-, and alkynyl-derivatives. X-ray crystal structures of [{Ti(η5−C5H5)(μ−PPH2)}2{μ−(η5−C5H4−η5−C5H4)}] and [{Zr(η5−C5H5)(μ−C≡CSiMe3)}2{μ−(η5−C5H4−η5−C5H4)}]

Cano, Ana; Cuenca, Tomás; Galakhov, Mikhail; Rodríguez, Gema M.; Royo, Pascual; Cardin, Christine J.; Convery, M.A.

doi:10.1016/0022-328x(94)05288-m

Cited by 25 publications

(8 citation statements)

References 30 publications

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“…Many dinuclear compounds containing bridging h 5 -h 1 cyclopentadienyl rings and h 5 -h 5 -fulvalene systems, resulting from ring C H activation in dicyclopentadienyl derivatives, have been reported [1,11]. However di-h 5 -cyclopentadienyl ligands singly bridged by various alkyl [2 -5] and silyl [6][7][8][9][10][11][12][13][14] groups are among the most frequently used systems to bridge dinuclear metal compounds.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Gómez‐García

Royo

1999

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 99%

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Gómez‐García

Royo

1999

Journal of Organometallic Chemistry

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“…In addition, it was shown that 3b can be obtained starting from PhC⋮CC⋮CPh. Dedicated efforts of several researchers over the years established the delicate balance that exists between the structures 2 and 3 for Ti as a function of the substituents on the bridging acetylides or butadiynes. − Naturally, curiosity in the C−C coupling and cleaving reactions mediated by Ti led to reactions involving Zr. ,− Early on Erker and co-workers showed by X-ray crystallography that the binuclear Zr complex with bridging alkynyl ligands has the structure 2h 11a. In fact, detailed studies showed that the structure is fluxional, but in no case was the Zr complex with the C−C coupled product 3h isolated 11c.…”

Section: Introductionmentioning

confidence: 99%

Novel Mechanism for Interesting C−C Coupling and Cleavage Reactions and Control of Thermodynamic Stability Involving [L₂M(μ-CCR)₂ML₂] and [L₂M(μ-RCC-CCR)ML₂] Complexes (M = Ti, Zr; L = η⁵-C₅H₅, Cl, H; R = H, F, CN): A Theoretical Study¹

Jemmis

Giju

1998

J. Am. Chem. Soc.

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Possible reaction mechanisms for C−C coupling and cleavage reactions involving [(η5-C5H5)M(μ-CCR)2M(η5-C5H5)2] and [(η5-C5H5)M(μ-RCC-CCR)M(η5-C5H5)2] (M = Ti, Zr) complexes are discussed on the basis of theoretical studies. A series of realistic and simplified model complexes, [L2M(μ-CCR)2ML2] 8 and [L2M(μ-RCC-CCR)ML2] 9 (M = Ti, Zr; L = η5-C5H5, Cl, H; R = H, F, CN) were calculated using ab initio MO and density functional methods. The formation of the bisacetylide bridging complex starting from either metal acetylides or butadiyne is explained by a mechanistic scheme involving metallacyclocumulenes (5), binuclear complexed metallacyclocumulenes (6), and the M+2−M+4 complexes (7). The latter rather than 6 led to the C−C coupled products 9 via 8. The experimentally observed unusual C−C coupling in the dimeric bis(η5-cyclopentadienyl)phenylethynyltitanium complex and the lack of it in the corresponding zirconium complex are influenced by substituents on the ethynyl group. Theoretical studies demonstrate that the electron-withdrawing substituent R = F drives the thermodynamic equilibrium distinctively towards the C−C coupled product, 9 both for M = Ti and Zr. An unusually short Zr−Zr interatomic distance in [(η5-C5H5)Zr(μ-CCR)2Zr(η5-C5H5)2] compared to Ti−Ti distance in the corresponding Ti complex is observed theoretically and from X-ray crystal structures of related complexes. Substitution of cyclopentadienyls by Cl and even H to obtain computationally viable models does not change the relative energies of the ground and transition states of the binuclear Zr complexes. The Ti complexes are affected somewhat more by these changes but the trends in relative energies between Ti and Zr isomers are retained. Geometric parameters and relative energies obtained at the B3LYP/LANL2DZ level are found to be better than those at the HF level.

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“…[16] However, the bond-stretching frequency of the CC triple bond in the infrared spectrum at ñ = 1805 cm À1 is in the expected region of s,p-alkynyl-bridged complexes similar to 6. [17] The molecular structures of a few dimeric Group 4 acetylide complexes of type [Cp' 2 M(m-h 1 :h 2 -C < = 3 > CR)(m-Scheme 6. Synthesis of complex 6.…”

Section: Resultsmentioning

confidence: 99%

“…[14] h 1 :h 2 -CCR')MCp' 2 ] were described in the last years (M = Ti, Zr). [16,17] Thereby, Cp' represents substituted or unsubstituted cyclopentadienyl units and the substituents R and R' are alkyl, aryl, SiMe 3 , or SnMe 3 groups. The important bond lengths and angles of the symmetric zirconium complexes are similar to 6.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

Kaleta

Strehler

Hildebrandt

et al. 2012

Chemistry A European J

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The reaction of different metallocene fragments [Cp(2)M] (Cp=η(5)-cyclopentadienyl, M=Ti, Zr) with diferrocenylacetylene and 1,4-diferrocenylbuta-1,3-diyne is described. The titanocene complexes form the highly strained three- and five-membered ring systems [Cp(2)Ti(η(2)-FcC(2)Fc)] (1) and [Cp(2)Ti(η(4)-FcC(4)Fc)](2) (Fc=[Fe(η(5)-C(5)H(4))(η(5)-C(5)H(5))]) by addition of the appropriate alkyne or diyne to Cp(2)Ti. Zirconocene precursors react with diferrocenyl- and ferrocenylphenylacetylene under C-C bond coupling to yield the metallacyclopentadienes [Cp(2)Zr(C(4)Fc(4))](3) and [Cp(2)Zr(C(4)Fc(2)Ph(2))](5), respectively. The exchange of the zirconocene unit in 3 by hydrogen atoms opens the route to the super-crowded ferrocenyl-substituted compound tetraferrocenylbutadiene (4). On the other hand, the reaction of 1,4-diferrocenylbuta-1,3-diyne with zirconocene complexes afforded a cleavage of the central C-C bond, and thus, dinuclear [{Cp(2)Zr(μ-η(1):η(2)-C≡CFc)}(2)] (6) that consists of two zirconocene acetylide groups was formed. Most of the complexes were characterized by single-crystal X-ray crystallography, showing attractive multinuclear molecules. The redox properties of 3, 5, and 6 were studied by cyclic voltammetry. Upon oxidation to 3(n+), 5(n+), and 6(n+) (n=1-3), decomposition occured with in situ formation of new species. The follow-up products from 3 and 5 possess two or four reversible redox events pointing to butadiene-based molecules. However, the dinuclear complex 6 afforded ethynylferrocene under the measurement conditions.

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Fulvalene titanium and zirconium complexes: synthesis and NMR study of phosphanido-, alkyl-, and alkynyl-derivatives. X-ray crystal structures of [{Ti(η5−C5H5)(μ−PPH2)}2{μ−(η5−C5H4−η5−C5H4)}] and [{Zr(η5−C5H5)(μ−C≡CSiMe3)}2{μ−(η5−C5H4−η5−C5H4)}]

Cited by 25 publications

References 30 publications

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Novel Mechanism for Interesting C−C Coupling and Cleavage Reactions and Control of Thermodynamic Stability Involving [L₂M(μ-CCR)₂ML₂] and [L₂M(μ-RCC-CCR)ML₂] Complexes (M = Ti, Zr; L = η⁵-C₅H₅, Cl, H; R = H, F, CN): A Theoretical Study¹

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

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Fulvalene titanium and zirconium complexes: synthesis and NMR study of phosphanido-, alkyl-, and alkynyl-derivatives. X-ray crystal structures of [{Ti(η5−C5H5)(μ−PPH2)}2{μ−(η5−C5H4−η5−C5H4)}] and [{Zr(η5−C5H5)(μ−C≡CSiMe3)}2{μ−(η5−C5H4−η5−C5H4)}]

Cited by 25 publications

References 30 publications

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

Novel Mechanism for Interesting C−C Coupling and Cleavage Reactions and Control of Thermodynamic Stability Involving [L2M(μ-CCR)2ML2] and [L2M(μ-RCC-CCR)ML2] Complexes (M = Ti, Zr; L = η5-C5H5, Cl, H; R = H, F, CN): A Theoretical Study1

Synthesis and Characterization of Multiferrocenyl‐Substituted Group 4 Metallocene Complexes

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Novel Mechanism for Interesting C−C Coupling and Cleavage Reactions and Control of Thermodynamic Stability Involving [L₂M(μ-CCR)₂ML₂] and [L₂M(μ-RCC-CCR)ML₂] Complexes (M = Ti, Zr; L = η⁵-C₅H₅, Cl, H; R = H, F, CN): A Theoretical Study¹