Synthesis and Dynamic Behavior of (Pentamethylcyclopentadienyl)azatantalacyclopropane Complexes. Crystal Structures of TaCp*Cl4[C(Me)(NHR)] and TaCp*Me2(.eta.2-Me2CNR)

Galakhov, Mikhail; Gómez, Manuel; Jiménez, Gerardo; Royo, Pascual; Pellinghelli, Maria Angela; Tiripicchio, António

doi:10.1021/om00004a050

Cited by 58 publications

(42 citation statements)

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“…The inside coordination of the N(1) iminocarbamoyl nitrogen atom located between C(12) and C(11) is similar to that found for similar (chloro)(iminoacyl)(imido)(pentamethylcyclopentadienyl)-or (iminoacyl)(imido)(methyl)(pentamethylcyclopentadienyl)tantalum complexes [11,12,14,27] in which the N(1) iminoacyl nitrogen atom is located between the iminoacyl carbon atom and the chlorine atom or the methyl carbon atom. The values of the TaϪN(3) bond length, consistent with triple bond character, and of the nearly linear TaϪN(3)ϪC(23) bond angle of 176.8(4)°are as expected for an imido ligand and compare well with those found in other (imido)(pentamethylcyclopentadienyl)-tantalum complexes.…”

Section: Resultssupporting

confidence: 67%

“…The Cp* (C 5 Me 5 ) ring is bound to the Ta atom in a nearly symmetric η 5 -fashion; a slight trend towards η 3 -coordination is observed, as indicated by three short [TaϪC(2) ϭ 2.485(6), TaϪC(3) ϭ 2.441(6), TaϪC(4) ϭ 2.406(6) Å ] and two long TaϪC Cp* ring carbon distances [TaϪC(1) ϭ 2.567(5) and TaϪC(5) ϭ 2.503(6) Å ], involving the C(1)ϪC(5) bond nearly trans to the imido group [30] (1) (1) and TaϪC (12) bond lengths are similar to those found in (η 2 -C,N-iminoacyl)Ta complexes. [11,12,14,27] The N(1)ϪC (12) The close similarity between the symmetry properties of the frontier orbitals of (cyclopentadienyl)(imido)metal [Ta(η 5 -C 5 Me 5 )(NtBu)] and the metallocene [Ti(η 5 -C 5 Me 5 ) 2 ] fragments [30] suggests that the 1a 1 metal orbital is used for π-bonding by the NMe 2 ligand. The dynamic behaviour observed for 2 at room temperature indicates that this 1a 1 orbital is energetically accessible for ligand binding, allowing the isocyanide to be located at any of the two positions appropriate for insertion into either the TaϪMe or TaϪNMe 2 bonds.…”

Section: Resultsmentioning

confidence: 99%

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Competitive Insertion of Isocyanide into Tantalum−Amido and Tantalum−Methyl Bonds

Amor¹,

Sánchez‐Nieves²,

Royo³

et al. 2002

Eur. J. Inorg. Chem.

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The (amido)methyl complexes [Ta(η 5 -C 5 Me 5 )(NtBu)-Me(NR 2 )] [R = Ph (3), SiMe 3 (4)] were prepared by reaction of [Ta(η 5 -C 5 Me 5 )(NtBu)ClMe] (1) with the appropriate lithium amides. Attempts to isolate the analogous NHMe derivative afforded a mixture of complexes [Ta(η 5 -C 5 Me 5 )(NtBu)-Me(NHMe)] (5) and [Ta(η 5 -C 5 Me 5 )(NMe)Me(NHtBu)] (6), resulting from hydrogen exchange between the amido and imido ligands. Insertion of CN(2,6-Me 2 C 6 H 3 ) into the Ta−Me bond of complexes 3 and 4 gave the η 1 -iminoacyl derivatives [Ta(η 5 -C 5 Me 5 )(NtBu)(NR 2 ){η 1 -C(Me)=N(2,6-Me 2 C 6 H 3 )}] [R = Ph (7), SiMe 3 (8)], while insertion into the Ta−NRMe (R = H,

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Competitive Insertion of Isocyanide into Tantalum−Amido and Tantalum−Methyl Bonds

Amor¹,

Sánchez‐Nieves²,

Royo³

et al. 2002

Eur. J. Inorg. Chem.

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“…The angle Cp*–Ta–Cl is 176.84° and confirms the apical position of the chlorine atom. This pentacoordination is unusual, and to the best of our knowledge, no other group 5 metal (alkyl)chlorido(cyclopentadienyl) derivative has this trigonal bipyramidal configuration; all other examples have a four‐legged piano‐stool arrangement 11b–d,17,18. In this case, such an arrangement is very unfavourable because of the important steric requirement of the trimethylsilylmethyl substituent.…”

Section: Resultsmentioning

confidence: 84%

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

et al. 2006

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Alkylation of [TaCp*Cl4] (Cp* = η5‐C5Me5) with 3 equiv. of MgCl(CH2SiMe3) gives the chloridotris(trimethylsilylmethyl) complex [TaCp*Cl(CH2SiMe3)3] (1). TaCp*Cl2Me2 reacts with 2 equiv. of LiR (R = CH2Ph, CH2SiMe3) to give the mixed alkyl derivatives [TaCp*Me2R2] (R = CH2Ph, 2; CH2SiMe3, 3). The dimethyldineopentyl complex [TaCp*Me2(CH2CMe3)2] (4) was obtained by reaction of TaCp*Cl2(CH2CMe3)2 with 2 equiv. of LiMe. The treatment of a toluene solution of TaCp*Cl2Me2 with 2 equiv. of neophyllithium in a standard vacuum line gave a mixture of three compounds, [{TaCp*Me2(CH2CMe2Ph)}2(μ‐O)] (5), [TaCp*Me2(CH2CMe2–o‐C6H4‐κ2C,C)] (6) and [TaCp*Me(CH2CMe2Ph)(CH2)] (7), which were identified by NMR spectroscopy. However, when the reaction was carried out under rigorously anhydrous conditions, only complexes 6 and 7 were isolated. A chlorido(trimethylsilylmethyl)(trimethylsilylmethylidene) complex [TaCp*Cl(CH2SiMe3)(CHSiMe3)] (8) was prepared by heating 1 at 60 °C, or by leaving it at room temperature for a long time. A 3:2 (9/10) mixture of [TaCp*MeR(CHSiMe3)] (R = CH2SiMe3, 9; Me, 10) was obtained by thermal treatment of 3, which was accompanied by the evolution of CH4 and SiMe4. However, irradiation of a [D6]benzene solution of 3 with a sun lamp gave a mixture of 9 and [TaCp*(CH2SiMe3)R(CH2)] (R = Me, 11; CH2SiMe3, 12) in a 2:1:1 (9/11/12) ratio. When a [D6]benzene solution of 4 was heated at 60 °C, a mixture of the (alkyl)(neopentylidene) derivatives [TaCp*MeR(CHCMe3)] (R = Me, 13; CH2CMe3, 14) in a 4:1 (13/14) ratio was detected by NMR spectroscopy, while irradiation with a sun lamp produced a mixture ofalkylidene complexes [TaCp*(CH2CMe3)R(CH2)] (R = Me, 15; CH2CMe3, 16) in a 3:1 (15/16) ratio. On the other hand, the alkylation of TaCp*Cl2(CH2CMe3)2 with 2 equiv. of LiCH2SiMe3 gave the (alkyl)(alkylidene) complex [TaCp*(CH2CMe3)(CH2SiMe3)(CHCMe3)] (17) with the elimination of SiMe4, whereas the treatment of TaCp*Cl2(CH2SiMe3)2 with the appropriate reagent gave [TaCp*(CH2R)(CH2SiMe3)(CHR′)] (R = R′ = Ph, 18; R = CMe2Ph, R′ = SiMe3, 19) with the elimination of SiMe4 and CMe3Ph, respectively. All compounds were studied by IR and NMR spectroscopy, and the molecular structures of complexes 1, 4 and 5 were determined by X‐ray diffraction methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…On the other hand, azaniobacyclopropane complex 8 is obtained upon reaction of 2 equiv. of isocyanide with the dimethyl derivative 4 , in contrast to that observed in the case of the azatantalacyclopropane species [TaCp*{η 2 ‐(ArN)CMe 2 }]35b (Ar = 2,6‐Me 2 C 6 H 3 ; 2,4,6‐Me 3 C 6 H 2 ), which in the presence of isocyanides gives the corresponding dichloro(imido) complexes [TaCp*Cl 2 (NAr)] with elimination of the arylimine ketene Ar−N=C=CMe 2 . However, the oxaniobacyclopropane complex 7 reacts with 1 or 2 equiv.…”

Section: Resultsmentioning

confidence: 88%

Synthesis and Reactivity of Ene-Diamido and Ene-Diolato [(Trimethylsilyl)cyclopentadienyl]niobium(V) Complexes and a Comparative DFT Study of the Bonding Capabilities of Diazabutadiene and Butadiene Ligands

Galindo

Gómez

Rı́o

et al. 2002

Eur. J. Inorg. Chem.

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The reactions of [NbCpЈCl 2 (Me 3 SiCCSiMe 3 )] (CpЈ = η 5 -C 5 H 4 SiMe 3 ) with 2,3-dimethyl-1,4-diphenyl-1,4-diazabuta-1,3-diene (Me,Ph-DAD) and diketones R−CO−CO−R (R = Me, Ph) gave ene-diamido complexes [NbCpЈCl 2 (Me,Ph-DAD)] (1) and ene-diolato complexes [NbCpЈCl 2 {O(R)CC(R)O}] (R = Me, 2; Ph, 3), respectively, with simultaneous elimination of bis(trimethylsilyl)acetylene. The NMR spectroscopic data of these compounds are in agreement with a supine conformation, with respect to the CpЈ ring, of the ene-diamido and ene-diolato ligands. In order to gain further information concerning the bonding capabilities of the ene-diamido ligand, a DFT study of the model complex [NbCpCl 2 (HNCHCHNH)] (I) was performed. For comparison, a DFT analysis of the model compound [NbCpCl 2 (η 4 -CH 2 CHCHCH 2 )] (II) was also carried out. Differences in the bonding description of the diazabutadiene and butadiene ligands bonded to a common [NbCpCl 2 ] moiety are discussed. A detailed analysis of the fragment orbital

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Synthesis and Dynamic Behavior of (Pentamethylcyclopentadienyl)azatantalacyclopropane Complexes. Crystal Structures of TaCpCl4[C(Me)(NHR)] and TaCpMe2(.eta.2-Me2CNR)

Cited by 58 publications

References 0 publications

Competitive Insertion of Isocyanide into Tantalum−Amido and Tantalum−Methyl Bonds

Competitive Insertion of Isocyanide into Tantalum−Amido and Tantalum−Methyl Bonds

(Alkyl)‐ and (Alkyl)(alkylidene)(pentamethylcyclopentadienyl)tantalum Complexes

Synthesis and Reactivity of Ene-Diamido and Ene-Diolato [(Trimethylsilyl)cyclopentadienyl]niobium(V) Complexes and a Comparative DFT Study of the Bonding Capabilities of Diazabutadiene and Butadiene Ligands

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