Reactivity of Group 4 Metal Alkyl and Metallacyclic Compounds Supported by Aryloxide Ligands Toward Organic Isocyanides

Thorn, Matthew G.; Fanwick, Phillip E.; Rothwell, Ian P.

doi:10.1021/om990413c

Cited by 46 publications

(21 citation statements)

References 37 publications

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“…The corresponding values for the Ti (+1.78) and Zr (+1.62) complexes are also close to the U counterpart, in agreement with previous studies showing the ability of Group 4 transition metal complexes to participate in the substitution reactions with alkynes 44,55,56 . Similar to propenes, the NPA charge on the metal center of the Pa cumulene complex suggests that its reactivity towards alkynes should be comparable to that of the recently synthesized (η 5 -C 5 Me 5 ) 2 U[η 4 -C 4 (SiMe 3 ) 2 ], as well as Group 4 cumulenes, whereas the reactivity of the corresponding Np and Pu complexes should be similar to the Th complex 30,31 (Supplementary Fig.…”

Section: Resultssupporting

confidence: 90%

δ and φ back-donation in AnIV metallacycles

et al. 2020

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In all known examples of metal-ligand (M-L) δ and φ bonds, the metal orbitals are aligned to the ligand orbitals in a "head-to-head" or "side-to-head" fashion. Here, we report two fundamentally new types of M-L δ and φ interactions; "head-to-side" δ and "side-to-side" φ back-bonding, found in complexes of metallacyclopropenes and metallacyclocumulenes of actinides (Pa-Pu) that makes them distinct from their corresponding Group 4 analogues. In addition to the known Th and U complexes, our calculations include complexes of Pa, Np, and Pu. In contrast with conventional An-C bond decreasing, due to the actinide contraction, the An-C distance increases from Pa to Pu. We demonstrate that the direct L-An σ and π donations combined with the An-L δ or φ back-donations are crucial in explaining this nonclassical trend of the An-L bond lengths in both series, underscoring the significance of these δ/φ back-donation interactions, and their importance for complexes of Pa and U in particular.

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Section: Resultssupporting

confidence: 90%

δ and φ back-donation in AnIV metallacycles

et al. 2020

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“…The four‐membered rings exist as azatitanacyclobutanes IVa or ‐butenes IVb, which can be generated via [2+2] cycloaddition reactions of olefins or alkynes– and titanium imido species, or by employing titanium carbenes and carbodiimides . The family of the five‐membered rings is represented by insertion products of olefins and acetylenes into titanaaziridines, leading to azatitanacylopentanes Va and −3‐pentenes Vb ,. The isomeric azatitanacyclo‐2‐pentenes Vc are formed by complexation of 1‐azabutadiene ligands .…”

Section: Introductionmentioning

confidence: 99%

From Five to Seven: Ring Expansion of Monoazadiene Titanium Complexes by Insertion of Aldehydes, Ketones and Nitriles

Manßen

Kahrs

Töben

et al. 2017

Chemistry A European J

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The ring enlargement reactions at ambient temperatures of non C-terminus substituted monoazabutadiene (η -RN=CHCH=CH ) titanium complexes 2 are investigated. The insertion of aldehydes/ketones (five examples) and nitriles (four examples) into the Ti-C bonds result in expansion of the five-membered rings to uncommon seven-membered titanacycles 3 and 4 in good yields. These new compounds are fully characterized by NMR spectroscopy and single-crystal X-ray diffraction. In subsequent reactions, the seven-membered ring systems are protolyzed and the released organic fragments are isolated. Whereas the aldehyde/ketone insertion products 3 form substituted δ-amino alcohols 5 after reduction with NaBH CN, the nitrile insertion products 4 form substituted pyrroles 6 via cyclization.

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“…Thus, Bochmann et al reported that trimethylsilylnitrile isomerizes to the isocyanide and forms the η 2 -iminoacyl complex [Cp 2 Ti(Me 3 SiNCMe)(CNSiMe 3 )]BPh 4 , possibly due to the fact that, in these systems, the formation of titaniumcarbon bonds is favored with respect to titaniumnitrogen bonds . Furthermore, the double migratory insertions of two methyl groups to a coordinated isocyanide to give an azametallacyclopropane species are known for a few examples with early transition metals. − …”

Section: Results and Discussionmentioning

confidence: 99%

Structural Diversity in the Reactions of Dimetallic Alkyl Titanium Oxides with Isonitriles and Nitriles

et al. 2021

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A detailed study of the reaction of the dinuclear [{Ti(η5-C5Me5)R2}2(μ-O)] (R = Me 1, CH2Ph 2) compounds with a series of organic isonitriles (R′NC, R′ = tBu, iPr, CH2SiMe3, Xyl) (Xyl = 2,6-Me2C6H3) and nitriles (R′CN, R′ = tBu, iPr, SiMe3) has been carried out. Single-crystal X-ray structural studies revealed a variety of reactivity and structural moieties. Theoretical calculations (density functional theory, DFT) were used to understand the mechanism of some uncommon reactions observed experimentally. Reactions of 1 and 2 with isocyanides tBuNC, iPrNC, and Me3SiCH2NC led to the formation of dimetallic η2-iminoacyl species [{Ti(η5-C5Me5)(R′NCR)R}2(μ-O)] (R = Me, R′ = tBu 3, iPr 4, CH2SiMe3 5; R = CH2Ph, R′ = CH2SiMe3 6). Complex 4 underwent net rearrangements at room temperature to give the imido-vinylamido derivative [Ti2(η5-C5Me5)2(μ-O)(μ-NiPr) {N(iPr)CMeCMe2}Me] (7), whereas the reaction of complex 2 with XylNC rendered the NC bond cleavage product [{Ti(η 5 -C5Me5)(CHCHPh)}(μ-O)(μ-κ 2 -N,CN(MeC6H3)CH2){Ti(η 5 -C5Me5)}] (8). The reactions of 1 with nitriles tBuCN and iPrCN gave the ketimido products [{Ti(η 5 -C5Me5)Me(CN(Me)R′)}2(μ-O)] (R′ = tBu 9, iPr 10), whereas the analogous processes with 2 gave the alkenyl-imido complexes [{Ti(η 5 -C5Me5)(CH2Ph)2}(μ-O){Ti(η 5 -C5Me5)(NC(R′)C(H)Ph)(NCR′)}] (R′ = tBu 11, iPr 12) with the concomitant coordination of a nitrile molecule. Complex 1 reacts with Me3SiCN to afford the nitrile–isonitrile isomerization product [{Ti(η 5 -C5Me5)Me2}(μ-O){Ti(η5-C5Me5)(κ 2 -C,N-Me2CNSiMe3)(CNSiMe3)] (13).

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Reactivity of Group 4 Metal Alkyl and Metallacyclic Compounds Supported by Aryloxide Ligands Toward Organic Isocyanides

Cited by 46 publications

References 37 publications

δ and φ back-donation in AnIV metallacycles

δ and φ back-donation in AnIV metallacycles

From Five to Seven: Ring Expansion of Monoazadiene Titanium Complexes by Insertion of Aldehydes, Ketones and Nitriles

Structural Diversity in the Reactions of Dimetallic Alkyl Titanium Oxides with Isonitriles and Nitriles

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