Cyclometalation of 2,6-di-tert-butylphenoxide ligands by tantalum aryl groups: aliphatic carbon-hydrogen bond activation and aryl isomerization via benzyne (o-phenylene) intermediates

Chamberlain, L. R.; Kerschner, Judith L.; Rothwell, Arlene P.; Rothwell, Ian P.; Huffman, John C.

doi:10.1021/ja00255a037

Cited by 43 publications

(22 citation statements)

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“…The Ta-O(I) distance is 1.971(3) ,~, in the normal range for this type of compound, and is longer than found in normal aryloxo derivatives (mean value 1.898 ~) [24].…”

Section: C(3 I)-ta(i)-c(28) ~4i)-ta(i)-o(i) Si(i)-c(3 L)-ta(i) Si(2)-mentioning

confidence: 56%

Pentamethylcyclopentadienyl halo- and alkyl-alkoxo tantalum(V) complexes. Crystal structure of

Castro

Galakhov

Gómez

et al. 1996

Journal of Organometallic Chemistry

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Reaction of TaCp" C! 4 with MOR (M -Li, Na) in different molar ratios gives halo alkoxides TaCp" CI,(OR)4_,, (n -3: R -tBu 1; $iPh 3 2; 2,6-Me2C6H 3 3; n --2: R -~Bu 4; SiPh 3 5; 2,6-Me2C6H3 6; a -!: R -SiMe 3 7) in good yields. The alkylidene complex TaCp'(CH2SiMe,02(CHSiMe ~) is hydrolyzed in the presence of traces of water to give the oxo dialkyl derivative [TaCp'(CH2SiM¢3)~O],, 8, and reacts with I equivalent of 2,6-MezC6H~NC affording a new 'q2-iminoacyi compound TaCp" (CH 2$iMe3XCHSiMe3){~ 2"C(CH 2SiMe3 ) = N(2,6"MeaC6 H 3)} 9. Reactions of TaCp "(CH 2SiMe3)a(CHSiMe3 ) with I equivalent of C6HsOH and 4-MeC6H3(OH) 2 result in the formation of the alkyl phenoxo TaCp'(CH2SiMe3)3(OC6Hs) 10 and 4-methyl pyrocatecholate TaCp'(CH2SiMe~)2(O2C6H3Me) 11, whereas the related re,",,:don with 2,6-Me2C6H 3OH leads to the cyclic alkyi-aikoxo compound TaCp (CH2SiMej)2(~2-O(2-CH2-6-MeC6H3)) 12. All the complexes were characterized by IR and NMR (tH and 13C) spectroscopy. The crystal and molecular structure of 12 has been determine~i. C~ystals of 12 are triclinic, space group P'[ with Z -2 in a unit cell of dimensions a-9.

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“…The Ta-O(I) distance is 1.971(3) ,~, in the normal range for this type of compound, and is longer than found in normal aryloxo derivatives (mean value 1.898 ~) [24].…”

Section: C(3 I)-ta(i)-c(28) ~4i)-ta(i)-o(i) Si(i)-c(3 L)-ta(i) Si(2)-mentioning

confidence: 56%

Pentamethylcyclopentadienyl halo- and alkyl-alkoxo tantalum(V) complexes. Crystal structure of

Castro

Galakhov

Gómez

et al. 1996

Journal of Organometallic Chemistry

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“…Seminal work by Rothwell and co‐workers detailed the synthesis and stabilization of metal aryloxides utilizing sterically demanding 2,6‐disubstituted phenoxides . More importantly, they managed to characterize a number of cyclometalation reactions involving the mild intramolecular C–H activation of ortho ‐ t Bu groups, resulting in chelating alkyl/phenoxide ligation with high‐valent, early‐transition‐metal centers (Scheme a) . In addition, C–H bond cleavage can also occur in some late‐transition‐metal complexes, affording bidentate alkyl/aryloxide ligands around the metal center (Scheme b) .…”

Section: Introductionmentioning

confidence: 99%

Metal Complexes Bearing Dianionic Trityl/Aryloxide Ligands: Rational Synthesis, Structural Diversity, and Redox Properties

et al. 2020

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Lithium complexes containing bidentate dianionic trityl/aryloxide ligands, Li2[ROC](Et2O)n ([ROC]2– = [κ2‐O,C‐OC6H2‐2‐C(3,5‐R2C6H3)2‐4,6‐tBu2]2–; 2a (R = H, n = 1) and 2b (R = Me, n = 0)) were synthesized through double metalation of ortho‐benzhydryl phenols with nBuLi. Similarly, sodium compound Na2[HOC](THF)2.5 (3a) was obtained when phenol H2[HOC] (1a) was treated with two equiv. of nBuLi/NaOtBu. The lithium compounds were employed for the preparation of other metal complexes supported by [ROC]2– ligands, i.e. {Zn[ROC](THF)}2 (R = H (4a) or Me (4b)), Sn[HOC]2 (5a) and Cp*Ir[MeOC] (6b, Cp* = η5‐C5Me5), by salt metathesis reactions with metal halides. The solid‐state structures of all metal complexes were established by X‐ray crystallography. The nuclearity of these metal complexes and the coordination fashion of the [ROC]2– ligands were found to be highly dependent on the identity of metal centers. Additionally, compound 2a was found to be facilely oxidized, as revealed by both electrochemical and reactivity study.

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“…substituents at 2, 4 and 6-positions [ 1,2]. In particular, Rothwell, Chamberlain and their coworkers [3,4] have reported several studies involving the large 2, 6-di-t-butylphenol ligand capable of bringing about intramolecular C-H activation via cyclometallation of a t-butyl group of the phenoxide, but no work on thermal behaviour of such complexes has been carried out. Scrutiny of literature has revealed that only scattered references are available on such properties of metal alkoxides and aryloxides especially those of group (IV) elements [5].…”

Section: Introductionmentioning

confidence: 99%

Thermal studies of some aryloxides of titanium(IV)

Malhotra

Sharma

Bhatt

et al. 1996

Journal of Thermal Analysis

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Thermal behaviour of aryloxides of titanium(IV) of composition TiCln(OArh-n (where n = 033 and OAr = OC6H4But-4, OC6H4OMe-4 and OC6H2-Bu~-2,6-Me-4) has been studied by DTA and TG analysis. Multiple decomposition steps have been indicated by thermal weight losses which are both exothermic and endothermic as shown by DTA curves. ' Based upon the total % loss in weighf during entire decomposition titanium dioxide has been found to be the final residue in each case.

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Cyclometalation of 2,6-di-tert-butylphenoxide ligands by tantalum aryl groups: aliphatic carbon-hydrogen bond activation and aryl isomerization via benzyne (o-phenylene) intermediates

Cited by 43 publications

References 0 publications

Pentamethylcyclopentadienyl halo- and alkyl-alkoxo tantalum(V) complexes. Crystal structure of

Pentamethylcyclopentadienyl halo- and alkyl-alkoxo tantalum(V) complexes. Crystal structure of

Metal Complexes Bearing Dianionic Trityl/Aryloxide Ligands: Rational Synthesis, Structural Diversity, and Redox Properties

Thermal studies of some aryloxides of titanium(IV)

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