Addition and Coupling Reactions of Zirconocene Cation Complexes that Contain a Pendant η2-Formaldiminium Side Chain

Pflug, Jörg; Erker, Gerhard; Kehr, Gerald; Fröhlich, Roland

doi:10.1002/1099-0682(200008)2000:8<1795::aid-ejic1795>3.0.co;2-y

Cited by 17 publications

(3 citation statements)

References 12 publications

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“…As shown in Table , the differences in bond distances between 1 and 2 are within 0.02 Å, which is consistent with the difference between Shannon's ionic radii of Zr(IV) and Hf(IV) . The Zr−C(13) distance of 2.237(6) Å is very close to the Zr−C(15) distance of 2.242(6) Å, which compare well with the 2.246(3) Å found in tol [NCN]Zr(CH 2 SiMe 3 ) 2 , 2.273(3) Å in ( η 5 -C 5 Me 5 ) 2 Zr[CH 2 N(Me)CH 2 N(Me)CH 2 ], and 2.272(7) Å in [( η 5 -C 5 H 5 ){ η 5 : σ : σ -(C 5 H 4 )C(Me) 2 N(Me) CH 2 }Zr(Bu t NC)][MeB(C 6 F 5 ) 3 ] 7a. The average Zr−cage atom distance of 2.544(6) Å is close to that of 2.564(5) Å found in ( η 5 -C 2 B 9 H 11 )Zr(NEt 2 ) 2 (HNEt 2 ) 5a.…”

supporting

confidence: 83%

“…But they may serve as the intermediates and subsequently eliminate a SiMe 4 molecule via the rupture of a C−H bond at one of the N-methyl groups to give the final products. Such an internal C−H activation is normally observed at methylzirconocene cations or [(C 5 Me 5 )(C 2 B 9 H 11 )]TiCH 3 , 1b,g rather than neutral metallocene alkyls. Both complexes 1 and 2 were fully characterized by various spectroscopic techniques and elemental analyses…”

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confidence: 94%

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Highly Electrophilic Half-Sandwich Group 4 Metallacarborane Alkyls. C−H/C−O Activation and Alkyne Insertion Reactions at Neutral Metal Complexes

2005

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Treatment of 7-Me 2 N(H)CH 2 CH 2 -7,8-C 2 B 9 H 11 with M(CH 2 SiMe 3 ) 4 in toluene gave the C-H activation products [η 1 :σ:η 5 -{MeN(CH 2 )CH 2 CH 2 }C 2 B 9 H 10 ]M(CH 2 -SiMe 3 )(THF) (M ) Zr (1), Hf (2)). Insertion of diphenylacetylene into the azametallacyclopropane in 2 and subsequent elimination of SiMe 4 afforded a new metallacyclic complex, [σ:σ:η 1 :η 5 -{(CH 2 )[(CH 2 )PhCdCPh]N(CH 2 -CH 2 )C 2 B 9 H 10 }]Hf(THF) (3). Reaction of Zr(CH 2 Ph) 4 with 7-Me 2 N(H)CH 2 CH 2 -7,8-C 2 B 9 H 11 in DME generated a C-H/C-O activation product, [{η 1 :σ:η 5 -[MeN(CH 2 )CH 2 -CH 2 ]C 2 B 9 H 10 }Zr(µ:η 1 -OCH 2 CH 2 OCH 3 )] 2 (4). These results demonstrated that neutral half-sandwich metallacarborane alkyls have characteristics of electrophilic metal alkyls.

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confidence: 83%

mentioning

confidence: 94%

Highly Electrophilic Half-Sandwich Group 4 Metallacarborane Alkyls. C−H/C−O Activation and Alkyne Insertion Reactions at Neutral Metal Complexes

2005

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“…The 13 C NMR resonance of the Zr−CH 2 −N moiety is observed at 55.4 ppm, while the related 1 J CH coupling constant amounts to 150.3 Hz. This value is about 13 Hz larger than those observed for the N−CH 3 ( 1 J CH = 137.4 Hz) and N−CH 2 −R ( 1 J CH = 137.2 Hz) groups and is diagnostic of the heterocyclopropane character of the zirconaaziridinium framework. In analogy with η 2 -imine complexes of zirconium two extreme resonance structures may in principle contribute to the description of the iminium−Zr bond, but that involving the π coordination of the iminium double bond to a formally Zr(II) center is certainly less important due to the high π basicity of Zr(II) .…”

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confidence: 54%

Synthesis, Characterization, Interionic Structure, and Self-Aggregation Tendency of Zirconaaziridinium Salts Bearing Long Alkyl Chains

et al. 2010

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Zirconaaziridinium inner sphere ion pairs (ISIPs) bearing alkyl chains of different lengths, [Cp2Zr(eta(2)-(CH2NRR2)-R-1)(+)center dot center dot center dot X-] (R-1 = Me, R-2 = C2H5, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC2; R-1 = me, R-2 = C16H33, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC16; R-1 = R-2 = C18H37, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC18; R-1 = Me, R-2 = Ph, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NPh; R-1 = R-2 = C18H37, X- = B(C6F5)(4)(-), (ZrBT)-B-NC18; R-1 = Me, R-2 = Ph, X- = B(C6F5)(4)(-), (ZrBT)-B-NPh), have been synthesized by the reaction of [Cp2ZrMe+center dot center dot center dot MeB(C6F5)(3)(-)] or [CP2ZrMe+center dot center dot center dot B(C6F5)(4)(-)] with the suitable tertiary amine followed by selective C-H activation of one Me group of the coordinated amine and methane elimination. Subsequent reaction of ISIPs with THF afforded the corresponding outer-sphere ion pairs (OSIPs) ([(ZrTHF)-T-NC2][BN], [(ZrTHF)-T-NC16][BN], [(ZrTHF)-T-NC18][BN], [(ZrTHF)-T-NPh][BN], [(ZrTHF)-T-NC18][BT], [(ZrTHF)-T-NPh][BT]) in which the anion has been displaced into the second coordination sphere. The interionic structure in solution (i.e., the relative cation-anion position) and the self-aggregation level of both ISIPs and OSIPs have been investigated by means of H-1 NOESY, F-19, H-1 HOESY, and diffusion PGSE NMR methods, in low polar solvents. It is found that, independent of the nature or length of the alkyl chains, the anion prefers to pair with the cation from the side of the nitrogen atom and THF in ISIPs and OSIPs, respectively. Self-aggregation of ion pairs into higher aggregates is also weakly influenced by the nature of the alkyl chains, but it is strictly connected with the nature of the counterion: ISIPs and OSIPs bearing B(C6F5)(4)(-) showed an increased tendency to form higher aggregates with respect to those containing MeB(C6F5)(3)(-). The level of the self-aggregation in benzene-d(6) and cyclohexane-d(12) has been quantified by fitting the hydrodynamic volumes obtained from NMR diffusion experiments with several models of indefinite self-association. The IK model, in which the equilibrium constants slightly increase on increasing the aggregation step, best describes the experimental trends in all cases. The standard Gibbs free energy of self-association at 297 K (Delta G(0)) for (ZrBN)-B-NC18 is -6.7 +/- 0.2 kJ mol(-1) and -12.6 +/- 0.7 kJ mol(-1) in benzene-d(6) and cyclohexane-d(12), respectively. In the same solvents, the values of Delta G(0) are -17.9 +/- 0.5 kJ mol(-1) and -25.0 +/- 0.3 kJ mol(-1) for [(ZrTHF)-T-NC18][BT]. At room temperature, 80% and 4% of [(ZrTHF)-T-NC18][BT]are present in the form of ion pairs in cyclohexane-d(12) at analytical concentrations of 10(-5) and 10(-3) M, respectively. The self-aggregation of [(ZrTHF)-T-NC18][BN] in cyclohexane-d(12) is strongly depressed by increasing the temperature

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Formation of Dinuclear Titanium and Zirconium Complexes by Olefin Metathesis—Catalytic Preparation of Organometallic Catalyst Systems

Cano

Hüerländer

Hill

et al. 2003

Chemistry A European J

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The titanium complex [(C(5)H(4)bond;allyl)TiCl(3)] (2) undergoes olefin metathesis coupling when treated with 3 mol % of [Cl(2)(L(1))(L(2))Ru=CHPh] (L(1)=L(2)=PCy(3), 4 a; L(1)=PCy(3), L(2)=(H(2)IMes), 4 b) to yield the dimetallic complex [Cl(3)Ti(C(5)H(4))-CH(2)CH=CHCH(2)-(C(5)H(4))TiCl(3)] (5). The allyl-substituted titanocene complex [Cp(C(5)H(4)bond;allyl)TiCl(2)] (3) analogously yields the dimetallic system 6 when treated with 4. The ansa-zirconocene complex [Me(2)Si(C(5)H(4))(C(5)H(3)bond;allyl)ZrCl(2)] (7) cleanly yields the analogous dimetallic coupling product 8 (>95 % isomerically pure), when treated with catalytic amounts of 4 b in toluene. Complex 8 gives an active homogeneous ethene or propene polymerization catalyst, especially at elevated temperatures, when treated with excess methylalumoxane.

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Addition and Coupling Reactions of Zirconocene Cation Complexes that Contain a Pendant η2-Formaldiminium Side Chain

Cited by 17 publications

References 12 publications

Highly Electrophilic Half-Sandwich Group 4 Metallacarborane Alkyls. C−H/C−O Activation and Alkyne Insertion Reactions at Neutral Metal Complexes

Highly Electrophilic Half-Sandwich Group 4 Metallacarborane Alkyls. C−H/C−O Activation and Alkyne Insertion Reactions at Neutral Metal Complexes

Synthesis, Characterization, Interionic Structure, and Self-Aggregation Tendency of Zirconaaziridinium Salts Bearing Long Alkyl Chains

Formation of Dinuclear Titanium and Zirconium Complexes by Olefin Metathesis—Catalytic Preparation of Organometallic Catalyst Systems

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