Bis(4‐methylbenzoxazol‐2‐yl)methanide in s‐Block Metal Coordination

Koehne, Ingo; Herbst‐Irmer, Regine

doi:10.1002/ejic.201700501

Cited by 15 publications

(12 citation statements)

References 49 publications

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“…The ATR-IR spectrum of 4 shows two vibrational bands vH −Al = 1876 and 1783 cm −1 . Additionally, the synthesis of 4a and 4b was proven by LIFDI [+] mass spectrometry, which revealed signals at m/z 610.1 (34) [M] + and 626.1 (100) [M + O] + , respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

“…A different approach to activate this alane was accomplished by a reaction with MeOTf, leading to [ Dipp NacNacAlH(OTf)] (Chart , V ) . Alumoxanes [RAlO] n and [R 2 Al–O–AlR 2 ] n are another class of aluminum compounds, which are widely used as cocatalysts for metallocene-based olefin polymerization. , A number of synthetic routes toward the preparation of molecular alumoxanes with a well-defined association, especially dialuminoxanes ([RAl] 2 (μ-O)) (Chart , VI ), were investigated by a variety of working groups. − Over the past decade, various bis(benzheterocyclo)methane ligand platforms were developed in our group to mimic the coordination features of the well-established NacNac systems. − …”

Section: Introductionmentioning

confidence: 99%

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Mixed Low-Valent Alanes from the Bis(4-methyl-benzoxazol-2-yl)methanide Ligand

et al. 2020

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Within this work, an aluminum dihydride complex ([(4‑MeBox2CH)AlH2]) (1) based on the bis(4-methyl-benzoxazol-2-yl)methanide ligand was synthesized and characterized by spectroscopic methods (NMR, ATR-IR, and fluorescence), DSC (differential scanning calorimetry), mass spectrometry (LIFDI), and single crystal X-ray diffraction. The reactivity of alane 1 was investigated toward the reducing agents [DippNacNacAlI] and [(MesNacNacMgI)2], which gave the dialane compounds [(4‑MeBox2CH)HAlII–AlIIH(DippNacNac)] (2) and [{(4‑MeBox2CH)AlIIH}2] (4a), respectively. Furthermore, dialuminoxanes [{(4‑MeBox2CH)AlH}2(μ-O)] (4b) and [({(MesNacNac)Mg}2(μ-H)){H3AlII–AlIIH(4‑MeBox2CH)}] (4c) were isolated as byproducts, with 4b co-crystallizing with 4a. The hydricity of both hydrides in the mixed-ligated dialane 2 were examined by a reaction with 1 equiv of trityl borate ([Ph3C][B(C6F5)4]), which resulted in [(4‑MeBox2CH)HAlII–AlII(DippNacNac)][B(C6F5)4] (3). Due to the formation of 4b, complex 1 was reacted with 0.5 equiv of water, which causes the likely synthesis of insoluble oligomeric alumoxanes. To prevent this reaction and support the formation of well-defined dialumoxanes, 1 was initially converted to [(4‑MeBox2CH)(DippO)AlH] (5) by the deprotonation of 2,6-diisopropylphenol (propofol). This sterically encumbered compound 5 was subsequently reacted with 0.5 equiv of water, which resulted in defined molecules of [{(4‑MeBox2CH)(DippO)Al}2(μ-O)] (6). All these compounds exemplify the versatility of the 4‑MeBox2CH ligand in low-valent aluminum chemistry.

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Section: ■ Results and Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Mixed Low-Valent Alanes from the Bis(4-methyl-benzoxazol-2-yl)methanide Ligand

et al. 2020

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“…With bis(indaoxazol-2-yl)methane and its derivatives ( B in Chart ), also chiral ligand platforms comprising an extended ring system were accessed, promoting metal-mediated catalytic applications. − In the field of ligand systems that display an extended π system within the ligand periphery, our group was able to establish bis(benzoxazol-2-yl)methanides and their higher benzothiazole homologues as promising platforms in group 1, 2, and 13 chemistry ( C in Chart ). − Furthermore, the corresponding nitrogen-bridged derivatives as well as the bis(1-methylbenzimidazol-2-yl)methanide and asymmetrically substituted congeners were extensively investigated with respect to their metal coordination.…”

Section: Introductionmentioning

confidence: 99%

Introducing NacNac-Like Bis(4,6-isopropylbenzoxazol-2-yl)methanide in s-Block Metal Coordination

et al. 2017

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Within this work, the field of bulky methanides in metal coordination is exceeded by the synthesis of the versatile and promising bis(4,6-isopropylbenzoxazol-2-yl)methane (7) ligand platform. As an enhancement in this class of ligands, isopropyl (iPr) substituents as steric-demanding groups have been successfully introduced in proximity to the coordination pocket, mimicking the shielding abilities of the ubiquitous NacNac ligand scaffold to improve the steric protection of a coordinated s-block metal cation. A percent buried volume (% V) calculation as well as an electronic structure analysis shades light onto the shielding and electronic abilities of the ligand in comparison to other selected methanides and diketiminates. Upon deprotonation with a variety of different group 1 and 2 metalation agents, a row of novel s-block metal complexes of the parent deprotonated monoanionic ligand 7 was obtained and structurally, as well as spectroscopically, characterized. In particular, in this context, the alkali-metal precursor complexes [Li(THF){(4,6-iPr-NCOCH)CH}] (8) and [K{μ-(4,6-iPr-NCOCH)CH}] (9) as well as the alkaline-earth-metal compounds [MgCl(THF){(4,6-iPr-NCOCH)CH}] (10) and [M(THF){(4,6-iPr-NCOCH)CH}] [M = Mg, n = 0 (11); M = Ca, n = 1 (12); M = Sr, n = 1 (13); M = Ba, n = 1 (14)] were successfully synthesized. Especially, the latter four exhibit interesting trends in the solid state as well as in solution within the metal series.

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“…Moreover, ligand C was successfully introduced to s‐block metal coordination, giving access to a variety of potassium, magnesium and calcium compounds …”

Section: Highlights Of Bis(benzoxazol‐2‐yl)methanes C‐e In Main‐groupmentioning

confidence: 99%

“…Moreover, ligand C was successfully introduced to s-block metal coordination, giving access to a variety of potassium, magnesium and calcium compounds. [40] However, it had been mandatory to introduce bulkier substituents adjacent to the C 3 N 2 coordination pocket, to promote the formation of stable heteroleptic metal complexes. As a consequence, ligand scaffolds D and E were prepared, featuring isopropyl and tert-butyl substituents, respectively.…”

Section: Group 1 and 2 Complexesmentioning

confidence: 99%

Bis(benzoxazol‐2‐yl)methanes Hounding NacNac: Varieties and Applications in Main Group Metal Coordination

et al. 2019

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Inspired by the well‐established class of β‐diketiminate or NacNac ligand scaffolds, the systematic building of ligand platforms mimicking its structural features and shielding abilities represents an exciting challenge. One of our focuses in the past decade has been the development of bis(benzheterocyclo)methanes, ‐amines and –phosphanes featuring additional donor‐sites in the ligand backbone as well as increasing steric bulk adjacent to the coordination pocket. This article addresses the variety of obtained ligand scaffolds, highlights some applications in 1, 2 and 13 metal coordination and looks to future developments of even more steric demanding systems to finally complement the famous Dipp‐substituted NacNac system.

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Bis(4‐methylbenzoxazol‐2‐yl)methanide in s‐Block Metal Coordination

Cited by 15 publications

References 49 publications

Mixed Low-Valent Alanes from the Bis(4-methyl-benzoxazol-2-yl)methanide Ligand

Mixed Low-Valent Alanes from the Bis(4-methyl-benzoxazol-2-yl)methanide Ligand

Introducing NacNac-Like Bis(4,6-isopropylbenzoxazol-2-yl)methanide in s-Block Metal Coordination

Bis(benzoxazol‐2‐yl)methanes Hounding NacNac: Varieties and Applications in Main Group Metal Coordination

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