Carbon-oxygen and related RX bond cleavages mediated by (silox)3Ti and other Group 4 derivatives (silox = tBu3SiO)

Covert, Katharine J.; Mayol, Ana-Rita; Wolczanski, Peter T.

doi:10.1016/s0020-1693(97)05651-x

Cited by 34 publications

(37 citation statements)

References 52 publications

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“…The zirconium center of this reactive intermediate could then oxidatively insert into a C-O bond of a coordinated molecule of THF. Similar THF insertion reactions involving low-valent group 4 metals have been reported on previous occasions [7,8]. It is of note that similar attempts to reduce the hafnium complex, 2, did not afford any tractable products.…”

Section: Resultssupporting

confidence: 80%

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

et al. 2012

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Reactions of in situ generated [Li(Giso)] (Giso = [(DipN) 2 CN(C 6 H 11 ) 2 ] -; Dip = C 6 H 3 Pr 2 i -2,6) with either ZrCl 4 or HfCl 4 led to the complexes [(Giso)MCl 3 ] (M = Zr 1 or Hf 2). Reduction of [(Giso)ZrCl 3 ] with an excess of magnesium metal in THF afforded a small isolated yield of the THF insertion product, [{(Giso)ZrCl(l-OC 4 H 8 )} 2 ]. The crystal structures of all complexes have been determined. The cell parameters of the compounds are 1 (toluene) 0.5 : P-1, a = 10.961(2), b = 11.046(2), c = 19.668 (4), a = 75.31(3), b = 76.69(3), c = 61.93(3); 2 (toluene) 0.5 : P-1, a = 10.949(2), b = 11.037(2), c = 19.621(4), a = 75.29(3), b = 76.80(3), c = 61.90(3); 3 (hexane) 2 : P2 1 /c, a = 14.424(3), b = 16.950(3), c = 20.330(4), b = 109.09(3). The crystal structures of 1 and 2 are the first for fivecoordinate, monomeric guanidinato group 4 metal trihalide complexes.

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Section: Resultssupporting

confidence: 80%

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

et al. 2012

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“…With the smaller metal yttrium, crystallographic confirmation of this product was elusive. Although THF can be ring-opened in many ways, − the two-electron ring-opening reduction in Scheme is unusual. The formal half-reaction is shown in eq .…”

Section: Discussionmentioning

confidence: 99%

Reactivity of Ln(II) Complexes Supported by (C₅H₄Me)^1– Ligands with THF and PhSiH₃: Isolation of Ring-Opened, Bridging Alkoxyalkyl, Hydride, and Silyl Products

2018

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Reduction of Cp Me 3 Ln(THF), 1-Ln (Ln = La and Gd; Cp Me = C 5 H 4 Me), with KC 8 in the presence of 2.2.2-cryptand (crypt) generates dark solutions, 2-Ln, with EPR spectra consistent with Ln(II) complexes: an eight-line hyperfine pattern for La at g = 1.971 and a broad single line for Gd at g = 1.988. The solutions decompose within minutes, and in the La system, a decomposition product was isolated in which a molecule of THF had been reduced by two electrons and ring-opened to generate an alkoxyalkyl-bridged bimetallic La(III) complex, [K(crypt)] 2 -[(Cp Me 3 La) 2 (μ-OCH 2 CH 2 CH 2 CH 2 )], 3-La. An analogous Pr complex, 3-Pr, was also crystallographically characterized. Since decomposition products were not readily isolated from the analogous yttrium Cp Me 3 Y(THF)/KC 8 /crypt reaction, the composition of the solution of 2-Y was probed by addition of the hydrogen delivery reagent, PhSiH 3 , which had previously been reported to form U(III) hydrides from tris(cyclopentadienyl) U(II) complexes. This generated an Y(III) silyl complex, [K(crypt)][Cp Me 3 Y(SiH 2 Ph)], 4, in addition to a hydride product, [K(crypt)][(Cp Me 3 Y) 2 (μ-H)], 5. The retention of three Cp Me ligands per metal in 3-Ln, 4, and 5 is consistent with the presence of a (Cp Me 3 Ln) 1− species in 2-Ln.

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“…Starting materials Zr(CH 2 Ph) 4 and N(CH 2 CH 2 NHSiMe 3 ) 3 were prepared according to literature procedures. 35,36 All other chemicals were obtained from commercial suppliers and dried by appropriate means.…”

Section: Methodsmentioning

confidence: 99%

General Preparation of (N₃N)ZrX (N₃N = N(CH₂CH₂NSiMe₃)₃³⁻) Complexes from a Hydride Surrogate

et al. 2008

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A homoleptic triamidoamine zirconium complex featuring a metalated trimethylsilyl substituent, [κ 5 -(Me 3 SiNCH 2 CH 2 ) 2 NCH 2 CH 2 NSiMe 2 CH 2 ]Zr (1), was synthesized by reaction of Zr(CH 2 Ph) 4 with N(CH 2 CH 2 NHSiMe 3 ) 3 followed by sublimation. Complex 1 is a general precursor to a family of complexes with the formulation (N 3 N)ZrX (N 3 N ) N(CH 2 CH 2 NSiMe 3 ) 3 3-, X ) anionic ligand) by reactions that parallel expected reactivity of a hydride derivative. Treatment of 1 with phosphines, amines, thiols, alkynes, and phenol resulted in the formation of new, pseudo-C 3V -symmetric (N 3 N)ZrX complexes (X ) phosphido, amido, alkynyl, thiolate, or phenoxide) via element-H bond activation. Thus, the reactivity of complex 1 is that best described as a hydride surrogate. For example, complex 1 reacted with PhPH 2 at ambient temperature to provide (N 3 N)ZrPHPh (2) in 86% yield. Density functional theory studies and X-ray crystal structures provide a general overview of the bonding in these complexes, which appears to be highly ionic. In general, there is little evidence for ligand-to-metal π-bonding for the pseudoaxial X ligand in these complexes except for strongly π-basic terminal amido ligands. The limited π-bonding appears to be the result of competitive π-donation by the pseudoequatorial amido arms of the triamidoamine ancillary ligand. Thus, the relative Zr-X bond energies are governed by the basicity of the anionic ligand X. Solid-state structures of phosphido (3, 4, 5), amido (10), and thiolate (15) complexes support the computational results.

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Carbon-oxygen and related RX bond cleavages mediated by (silox)3Ti and other Group 4 derivatives (silox = tBu3SiO)

Cited by 34 publications

References 52 publications

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

Reactivity of Ln(II) Complexes Supported by (C₅H₄Me)^1– Ligands with THF and PhSiH₃: Isolation of Ring-Opened, Bridging Alkoxyalkyl, Hydride, and Silyl Products

General Preparation of (N₃N)ZrX (N₃N = N(CH₂CH₂NSiMe₃)₃³⁻) Complexes from a Hydride Surrogate

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Carbon-oxygen and related RX bond cleavages mediated by (silox)3Ti and other Group 4 derivatives (silox = tBu3SiO)

Cited by 34 publications

References 52 publications

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

Synthesis and Crystal Structures of Bulky Guanidinato Zirconium(IV) and Hafnium(IV) Chloride Complexes

Reactivity of Ln(II) Complexes Supported by (C5H4Me)1– Ligands with THF and PhSiH3: Isolation of Ring-Opened, Bridging Alkoxyalkyl, Hydride, and Silyl Products

General Preparation of (N3N)ZrX (N3N = N(CH2CH2NSiMe3)33−) Complexes from a Hydride Surrogate

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Reactivity of Ln(II) Complexes Supported by (C₅H₄Me)^1– Ligands with THF and PhSiH₃: Isolation of Ring-Opened, Bridging Alkoxyalkyl, Hydride, and Silyl Products

General Preparation of (N₃N)ZrX (N₃N = N(CH₂CH₂NSiMe₃)₃³⁻) Complexes from a Hydride Surrogate