Dramatic enhancement of the stability of rare-earth metal complexes with α-methyl substituted N,N-dimethylbenzylamine ligands

Petrov, Alex R.; Thomas, Oliver; Harms, Klaus; Rufanov, Konstantin A.

doi:10.1016/j.jorganchem.2010.09.042

Cited by 10 publications

(33 citation statements)

References 26 publications

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“…32 For the rare-earth metals, only orthometalated N,N-dimethylbenzylamine complexes exist and, of these, only the middle and late lanthanides proved to be stable enough for isolation. 33,34 Herein, we report our findings of a new class of homoleptic trialkyl rare-earth-metal complexes using R-metalated N,N-dimethylbenzylamine ligands as stable benzyl ligand derivatives to form lanthanide complexes free of coordinating solvent.…”

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confidence: 99%

“…The N,N- dimethylbenzylamine ligand scaffold is not unknown in the literature; however, nearly all of its previous uses have been limited to ortho-metalated complexes. , There is only a single example of a crystallographically characterized α-metalated transition-metal complex, a zirconium species by Norton and co-workers . For the rare-earth metals, only ortho-metalated N,N -dimethylbenzylamine complexes exist and, of these, only the middle and late lanthanides proved to be stable enough for isolation. , Herein, we report our findings of a new class of homoleptic trialkyl rare-earth-metal complexes using α-metalated N,N- dimethylbenzylamine ligands as stable benzyl ligand derivatives to form lanthanide complexes free of coordinating solvent.…”

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Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Behrle

Schmidt

2011

Organometallics

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Experimental Section General Considerations. Compounds 1-17 were prepared using standard Schlenk and drybox techniques. Lanthanum(III) chloride, praseodymium(III) chloride, neodymium(III) chloride, and gadolinium(III) chloride were purchased from Strem and used without further purification. Cerium(III) chloride hexahydrate and samarium(III) chloride hexahydrate were purchased from Strem and dried as described previously. 1 N,N-Dimethylbenzylamine (DMBA-H), 2,6-di-tert-butylphenol, and p-tertbutylphenol were purchased from Acros and used without further purification. 2,6-Diisopropylaniline and 1,1,1,3,3,3-hexamethyl-disilazane were purchased from Acros and dried over calcium hydride, freeze-pump-thawed three times, distilled, and stored under nitrogen. Potassium tert-butoxide was purchased from Fisher and used without further purification. C 6 D 6 and C 7 D 8 were purchased from Cambridge Isotope Laboratories and were vacuum-transferred from sodium/benzophenone ketyl and degassed with three freeze-evacuate-thaw cycles. C 5 D 5 N was purchased from Cambridge Isotope Laboratories and was vacuum-transferred from calcium hydride and degassed with three freeze-evacuate-thaw cycles. All other solvents were purchased from either VWR or Fisher. Pentane and toluene were purified by passage through columns of alumina and activated 4 Å molecular sieves and degassed prior to use. Tetrahydrofuran was dried over a sodium/benzophenone ketyl and distilled prior to use. All 1 H and 13 C NMR data were obtained on a 400 MHz VXRS or a 600 MHz Inova spectrometer. 1 H NMR shifts given were referenced internally to the residual solvent peaks at δ 7.16 ppm (C 6 D 5 H), 2.08 ppm (C 7 D 7 H), and 8.74 ppm (C 5 D 4 HN). 13 C NMR shifts given were referenced internally to the residual peaks at δ 128.0 ppm (C 6 D 6), 20.4 ppm (C 7 D 8), and 150.3 ppm (C 5 D 5 N). IR samples were prepared as Nujol mulls and taken between KBr plates on a Perkin-Elmer XTL FTIR spectrophotometer. Melting points were observed on a capillary Mel-Temp apparatus in sealed capillary tubes under nitrogen and are uncorrected. Elemental analyses S-3 were determined by Galbraith Laboratories, Knoxville, TN or Atlantic Microlabs, Inc., Norcross, GA. Single-crystal X-ray structure determinations were performed at The University of Toledo. α-Potassiated-N,N-dimethylbenzylamine (α-K(DMBA)). Following a modified procedure from Sebastian, J.F. 2 an oven dried 100 mL flask was charged with potassium tert-butoxide (2.91 g, 25.9 mmol). THF (50 mL) was added in order to dissolve the potassium tert-butoxide completely. N,N-dimethylbenzylamine (3.90 g, 28.8 mmol) was added to the 100 mL flask to yield a yellow solution. The 100 mL flask was cooled to-78 °C and n-BuLi (25.3 mL, 1.14 M, 28.8 mmol) was added dropwise. The reaction was stirred at-78 °C for 1.5 h, removed from the cold bath, placed in an ice bath (0 °C) and the solvent removed under vacuum. The resulting sticky dark red solid was placed in the freezer (-25 °C) overnight. The solid was washed with copious amounts of pentan...

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Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Behrle

Schmidt

2011

Organometallics

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“…2 Since that time, a large number homoleptic Ln−aryl complexes have been reported in the literature. Many of these complexes utilize pendant donor groups to stabilize the Ln−C aryl bonds, 1,3,4 such as [Ln(η 2 -N,C-C 6 H 4 -ortho-CH 2 NMe 2 ) 3 ] (Ln = Er, Yb, Lu, Y), 4 [Ln(η 2 -N,C-C 6 H 4 -ortho-CH(Me)NMe 2 ) 3 ] (Ln = Y, Dy, Nd, Sm), 1 [Sm(η 2 -N,C-C 6 H 4 -ortho-C(Me) 2 NMe 2 ) 3 ], 1 and [La{(S,S,)-Phebox-i Pr} 3 ], 3 among others. 1,4,6−8 However, many solventstabilized Ln−aryl complexes without stabilizing pendant donor groups are also known.…”

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Assessing the 4f Orbital Participation in the Ln–C Bonds of [Li(THF)₄][Ln(C₆Cl₅)₄] (Ln = La, Ce)

Ordoñez

Autschbach

et al. 2022

Inorg. Chem.

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The reaction of [Ln(NO 3 ) 3 (THF) 4 ] (Ln = La, Ce) with 4 equiv of LiC 6 Cl 5 in Et 2 O resulted in the formation of the homoleptic lanthanide-aryl "ate" complexes [Li(THF) 4 ][La(C 6 Cl 5 ) 4 ] ([Li][1]) and [Li(THF) 4 ][Ce(C 6 Cl 5 ) 4 ] ([Li][2]). These complexes represent the first isolated homoleptic perchlorophenyl complexes for the lanthanides. In the solid state, both [Li][1] and [Li][2] exhibit octa-coordinate lanthanide centers, with four Ln−C σ-bonds and four Cl → Ln dative interactions involving the ortho-Cl atoms of the C 6 Cl 5 ligands. Despite this apparent steric saturation, both [Li][1] and [Li][2] are highly temperature sensitive and quickly decompose in solution at room temperature. Density functional calculations show that the Ln−C ipso donation bonds feature only weak 4f participation (e.g., ∼1% 4f weight for [1] − ). Nonetheless, the 13 C chemical shift of the C ipso nuclei of [1] − includes ca. 8 ppm of deshielding from the spin−orbit interaction due to the participation of the 4f (and 5d) orbitals in the La−C bonds.

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“…42,43 This tert-amine was also used as the directing group to ortho-functionalizations such as, ortho arylation, 44 ortho olefination, 45 borylation of arenes, 46 ortho carbonylation, 47 and ortho-silylation. 44 It is noteworthy to mention that the N,N-dimethylaminomethyl group present in the functionalized N,N-dimethylbenzylamines can be easily converted to various and useful functional groups including, amide, 48 aldehyde, 49 alkene, 50 as well as chloromethyl substituent.…”

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confidence: 99%

Facile and Efficient Access to Tetrahydrobenzo[b]pyrans Catalyzed by N,N-Dimethylbenzylamine

Kiyani¹,

Jalali²

2016

HETEROCYCLES

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The N,N-dimethylbenzylamine (DMBA) has been used as an efficient, inexpensive, and commercially available organocatalyst for the one-pot, three-component synthesis of tetrahydrobenzo [b]pyrans in good to high yields. It was found that the one-pot Knoevenagel-Michael-Thorpe-Ziegler cyclization sequence of dimedone, malononitrile/ethyl cyanoacetate, and various aldehydes was efficiently implemented in ethanol at 45 °C. This procedure offers attractive several features: mild reaction conditions, use of ethanol as a green solvent, reusability the reaction media, shorter reaction times, and the ease of the work-up.

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Dramatic enhancement of the stability of rare-earth metal complexes with α-methyl substituted N,N-dimethylbenzylamine ligands

Cited by 10 publications

References 26 publications

Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Assessing the 4f Orbital Participation in the Ln–C Bonds of [Li(THF)₄][Ln(C₆Cl₅)₄] (Ln = La, Ce)

Facile and Efficient Access to Tetrahydrobenzo[b]pyrans Catalyzed by N,N-Dimethylbenzylamine

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Dramatic enhancement of the stability of rare-earth metal complexes with α-methyl substituted N,N-dimethylbenzylamine ligands

Cited by 10 publications

References 26 publications

Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Synthesis and Reactivity of Homoleptic α-Metalated N,N-Dimethylbenzylamine Rare-Earth-Metal Complexes

Assessing the 4f Orbital Participation in the Ln–C Bonds of [Li(THF)4][Ln(C6Cl5)4] (Ln = La, Ce)

Facile and Efficient Access to Tetrahydrobenzo[b]pyrans Catalyzed by N,N-Dimethylbenzylamine

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Assessing the 4f Orbital Participation in the Ln–C Bonds of [Li(THF)₄][Ln(C₆Cl₅)₄] (Ln = La, Ce)