Titanium(IV) Cations with Trigonal Monopyramidal Geometry: Unusual Lewis Acids Supported by a Triaryl Triamidoamine Ligand

Ghana, Priyabrata; Krüchten, Franziska D. van; Spaniol, Thomas P.; Okuda, Jun

doi:10.1002/chem.201901796

Cited by 4 publications

(2 citation statements)

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“…While the central metal is mostly confined to a C 3 -symmetrical N 3 N ligand set with five-coordinate trigonal bipyramidal geometry, expansion to a six-coordinate distorted octahedral geometry would be possible for larger metal centers . While this N 3 N ligand system has been proven to be effective in stabilizing reactive organometallic complexes with unusual bonding and electronic structures, , isolated examples of TREN ligated group 4 metal hydrides are still unknown. Schrock et al.…”

Section: Introductionmentioning

confidence: 99%

“…Following our studies on titanium and reduced arene hafnium complexes supported by the bulky aryl-substituted triamidoamine ligand Xy-TREN (Xy-TREN = {(3,5-Me 2 C 6 H 3 )NCH 2 CH 2 } 3 N 3– ), ,, we report here on the synthesis, characterization, and reactivity of an isolable monomeric hydride of hafnium that undergoes reversible bimolecular metalation and readily reacts with α-olefins.…”

Section: Introductionmentioning

confidence: 99%

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A Terminal Hydride of Hafnium Supported by a Triamidoamine Ligand

et al. 2023

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A mononuclear hafnium hydride supported by an aryl-substituted triamidoamine ligand [HfH(thf)(Xy-N3N)] (Xy-N3N = {(3,5-Me2C6H3)NCH2CH2}3N3–) was synthesized by either hydrogenolysis of the hydrocarbyl complex [Hf(R)(thf)(Xy-N3N)] (R = Me, CH2SiMe3, η3-C3H5, CH2Ph) in tetrahydrofuran (THF) or, more conveniently, by salt metathesis of the chloro precursor [HfCl(thf)(Xy-N3N)] with NaBEt3H in methylcyclohexane. The structure of a terminal hydride with a distorted capped trigonal bipyramidal geometry was characterized by single crystal X-ray diffraction (d(Hf–H): 1.83(3) Å) and by 1H NMR spectroscopy. The unusually low field shifted 1H chemical shift for the hydride ligand was detected at δ 18.28 ppm. Dehydrogenative thermolysis of the hydride complex at 25 °C in benzene or toluene resulted in deprotonation of the α-hydrogen of one of the three XyNCH2CH2 groups in the ligand by the hydride, followed by the combination of this deprotonated anionic complex with cationic complex [Hf(Xy-N3N)]+ to give an unsymmetric dinuclear complex bridged by μ-H, μ-NXy, and μ,κN,κC-XyNCHCH2 groups. This decomposition product was characterized by single crystal X-ray diffraction and by 1H and 13C NMR spectroscopy and analyzed by density functional theory (DFT) calculations. Hydrogenation in THF at 25 °C reformed the hydride complex over a period of 48 h. The hydride complex reacted with olefins RHCCH2 (R = H, Et, nHex, cHex, Ph) to give the corresponding anti-Markovnikov insertion products [Hf(CH2CH2R)(thf)n(Xy-N3N)]. Catalytic hydrogenation of olefins was achieved with 5 mol % of the hydride complex at 70 °C in THF or benzene.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Terminal Hydride of Hafnium Supported by a Triamidoamine Ligand

et al. 2023

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Bridging Titanium Nitrido Complexes Containing A Linear Ti−N−Ti Core with A Two‐Coordinate Nitrido Ligand

Okumura,

Ghana,

Spaniol

et al. 2024

Chemistry A European J

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A series of titanium m2‐nitrido complexes supported by the triamidoamine ligand Xy‐N3N (Xy‐N3N = {(3,5‐Me2C6H3)NCH2CH2}3N3–) is reported. The titanium azido complex [(Xy‐N3N)TiN3] (1‐N3), prepared by salt metathesis of the chloride complex [(Xy‐N3N)TiCl] (1‐Cl) with NaN3, reacted with lithium metal or with alkali metal naphthalenides (alkali metal M = Na, K, and Rb) in THF to give the corresponding dinuclear m2‐nitrido complexes M[(Xy‐N3N)Ti=N‐Ti(Xy‐N3N)] (2‐M; M = Li, Na, K, Rb). Single crystal X‐ray diffraction studies of 2‐Li, 2‐Na, and 2‐K revealed alkali metal dependent structures in the solid state. While 2‐Li and 2‐K contain a m2‐nitrido ligand with a linear Ti–N–Ti core, 2‐Na includes a m3‐nitrido ligand as part of a T‐shape Ti2NaN fragment with the sodium cation weekly coordinated to the nitrido nitrogen atom. When the synthesis of the nitrido complexes was carried out in the presence of excess alkali metals, selective decomposition of the nitrido complexes was observed affording some intractable titanium species along with the trialkali metal salts [M3(Xy‐N3N)] (3‐M) (M = Li, Na, K, and Rb). These salts were also prepared by deprotonation of (Xy‐N3N)H3 with the corresponding alkali metal hexamethyldisilazide and characterized by multinuclear NMR spectroscopy as well as single crystal X‐ray diffraction.

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