Crystal and molecualar structure of triscyclopentadienyltitanium: the cyclopentadienyl group as a two-centre three-electron ligand

Lucas, C. Robert; Green, Malcolm; Forder, R. A.; Prout, Keith

doi:10.1039/c39730000097

Cited by 33 publications

(13 citation statements)

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“…The binding energy BE, which is associated with the formation of a molecule from appropriate fragments, can be broken down into three major components [13] [9], and [ Zr(Cp) 3 ] (2b) [7]. In accord with the experiment, our calculations reveal that [ Zr(Cp) 3 ] prefers 3h 5 coordination, whereas [ Ti(Cp) 3 ] adopts the 2h 5 h 2 geometry.…”

Section: ( Me)]supporting

confidence: 86%

“…The zirconium( III ) system [ Zr(Cp) 3 ] (2b) has been shown to exhibit a 3h 5 structure (determined by X-ray diffraction) [7], whereas the related complex [ ZrBr{1,3-(t-Bu) 2 C 5 H 3 }(Cp) 2 ] (1f) has its bulky substituted cyclopentadienyl ligand slipped to the h 2 -bonding mode [8]. The analogous 2h 5 h 2 -type structure was also established by X-ray diffraction for the paramagnetic complex [ Ti(Cp) 3 ] (2a) [9].…”

Section: (Co)]mentioning

confidence: 95%

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Comparison of Characteristic Structural Features among the Triade of Tris(cyclopentadienyl)(Group-4 Metal) Complex Cations: a Combined Theoretical and Experimental Study

Jacobsen¹,

Berke²,

Brackemeyer³

et al. 1998

HCA

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A density functional theory computational chemistry study has revealed a fundamental structural difference between [Ti(Cp)3]+ and its congeners [Zr(Cp)3]+ and [Hf(Cp)3]+/(Cp=cyclopentadienyl). Whereas the latter two are found to contain three uniformely η5‐coordinated Cp ligands (3η5‐structural type), [Ti(Cp)3]+ is shown to prefer a 2η5η2 structure. [Ti(Cp)3]+[B(C6F5)3(Me)]− (10⋅[B(C6F5)3(Me)]−) was experimentally generated by treatment of [Ti(Cp)3(Me)] (7a) with B(C6F5)3 (Scheme 3). Low‐temperature 1H‐NMR spectroscopy in CDFCl2 (143 K, 600 MHz; Fig. 8) showed a splitting of the Cp resonance into five lines in a 2 : 5 : 2 : 5 : 1 ratio which would be in accord with the theoretically predicted 2η5η2‐type structure of [Ti(Cp)3]+. The precursor [Ti(Cp)3(Me)] (7a) exhibits two 1H‐NMR Cp resonances in a 10 : 5 ratio in CD2Cl2 at 223 K. Treatment of [HfCl(Cp)2(Me)] (6c) with sodium cyclopentadienide gave [Hf(Cp)3(Me)] (7c) (Scheme 1). Its reaction with B(C6F5)3 furnished the salt [Hf(Cp)3]+[B(C6F5)3(Me)]− (8⋅[B(C6F5)3(Me)]−), which reacted with tert‐butyl isocyanide to give the cationic complex [Hf(Cp)3(C=N−CMe3)]+ (9a; with counterion [B(C6F5)3(Me)]− (Scheme 2). Complex cation 9a was characterized by X‐ray diffraction (Fig. 7). Its Hf(Cp3) moiety is of the 3η5‐type. The structure is distorted trigonal‐pyramidal with an average D−Hf−D angle of 118.8° and an average D−Hf−C(1) angle of 96.5° (D denotes the centroids of the Cp rings; Table 6). Cation 9a is a typical d0‐isocyanide complex exhibiting structural parameters of the C≡N−CMe3 group (d(C(1)−N(2))=1.146 (5) Å; IR: v˜(C≡N) 2211 cm−1) very similar to free uncomplexed isonitrile. Analogous treatment of 8 with carbon monoxide yielded the carbonyl (d0‐group‐4‐metal) complex [Hf(Cp)3(CO)]+ (9b; with counterion [B(C6F5)3(Me)]−) (Scheme 2) that was also characterized by X‐ray crystal‐structure analysis (Fig. 6). Complex 9b is also of the 3η5‐structural type, similar to the peviously described cationic complex [Zr(Cp)3(CO)]+, and exhibits properties of the CO ligand (d(C−O)=1.11 (2) Å; IR: v˜(C≡O) 2137 cm−1) very similar to the free carbon monoxide molecule.

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Section: ( Me)]supporting

confidence: 86%

Section: (Co)]mentioning

confidence: 95%

Comparison of Characteristic Structural Features among the Triade of Tris(cyclopentadienyl)(Group-4 Metal) Complex Cations: a Combined Theoretical and Experimental Study

Jacobsen¹,

Berke²,

Brackemeyer³

et al. 1998

HCA

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“…Although there are known examples of mono-, di-and pentahapto bonding modes in cyclopentadienyl-metal complexes (Calderon, Cotton, De Boer & Takats, 1971;Lucas, Green, Forder & Prout, 1973), the present complex is the first with trihapto bonding in a planar n-bonded system and therefore requires reassessment of the comment by Cotton 0969) that trihapto bonding in such systems is 'mythical'.…”

Section: Discussionmentioning

confidence: 99%

The crystal and molecular structure of (pentahaptofluorenyl)(trihaptofluorenyl)dichlorozirconium(IV)

Kowala¹,

Wunderlich²

1976

Acta Crystallogr Sect B

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“…30 The structure of complex 1 provides the first example of q2 co-ordination of an indenyl ligand to a transition-metal centre, although such co-ordination of cyclopentadienyl has been observed in the neutral, paramagnetic compound [Ti(q-C,H,),(q2-C,H,)]. 33 The dilithium salt Li,[(CH,),C(C,H4)(C9H,)]~0.8Et20 was prepared as a pyrophoric pale yellow solid by treatment of 6,6pentamethylenefulvene with lithium indenide followed by nbutyllithium, in 92% yield. * Addition of toluene to a mixture of this salt and [Zr(q-C,H,)Cl,]-dme gave red needle crystals of the air-and moisture-sensitive ansa-bridged compound [zr(( CH,),C( q-C5H4)( q2-C9H 6) >( q-CSH ,)cl]*o.…”

Section: Resultsmentioning

confidence: 99%

New mono- and bi-nuclear ansa-metallocenes of zirconium and hafnium as catalysts for the polymerisation of ethene and propene

Diamond¹,

Chernega²,

Mountford³

et al. 1996

J. Chem. Soc., Dalton Trans.

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The new unsa-metallocenes [M(Me,C(q-C5H4)(q2-C9H6)}(q-C5H,)Cl] [M = Zr (crystal structure) or, Hf], [M ( ( C H , ) 5 C ( q -C 5 H 4 ) ( q 2 -~~~6 ) } ( q -~5~5 )~~]~~.~~6~5~e [M = Zr (crystal structure) or Hf], [Zr{Me,C(q-CSH4)(q3-C1 3H8)}(~-C5H5)Cl] (crystal structure), [M{Me,C(q-C5H4),)(q-C5H5)Cl] [M = Zr or Hf (crystal structures)], [X,(q-C5H5)M(C5H4(CMe,)C9H6))M*(q-C5H5)X2}] (X = C1, M, M* = Zr, Zr; Hf, Hf; Zr, Hf; or Hf, Zr; X = Me, M, M* = Zr, Zr; Zr, Hf; Hf, Zr; or Hf, Hf), [Cl,(q-C5H5)Zr{C5H4(CMe,)C9H6)-Zr(q-C5Mes)C12], [{M(C5H4CMe2(C9H,)}(q-C5H5)C12] (M = Zr or Hf) and [Zr{C,H,CMe,(C,H,}-(q-C,H,)Me,] have been prepared and characterised. The activity of the metallocenes as cocatalysts for the polymerisation of ethene and propene has been evaluated.

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Crystal and molecualar structure of triscyclopentadienyltitanium: the cyclopentadienyl group as a two-centre three-electron ligand

Cited by 33 publications

References 0 publications

Comparison of Characteristic Structural Features among the Triade of Tris(cyclopentadienyl)(Group-4 Metal) Complex Cations: a Combined Theoretical and Experimental Study

Comparison of Characteristic Structural Features among the Triade of Tris(cyclopentadienyl)(Group-4 Metal) Complex Cations: a Combined Theoretical and Experimental Study

The crystal and molecular structure of (pentahaptofluorenyl)(trihaptofluorenyl)dichlorozirconium(IV)

New mono- and bi-nuclear ansa-metallocenes of zirconium and hafnium as catalysts for the polymerisation of ethene and propene

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