Synthesis and Structures of Dinuclear Aluminum Complexes Based on Bis(β‐diketiminate) Ligands

Desat, Marcella E.; Kretschmer, Robert

doi:10.1002/zaac.201900193

Cited by 8 publications

(5 citation statements)

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“…The γ-CH proton of the β-diketiminate resonates as a singlet at 4.95 ppm, i.e., shifted upfield compared to its mononuclear relative 3 (5.19 ppm, both in C 6 D 6 ) . Such a pattern of resonances has been observed before in the case of Al(III), Cu(I), and Tl(I) complexes of the protio-ligand 1 , and indicates hindered conformational exchange at room temperature.…”

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confidence: 61%

Cooperative Bond Activation by a Bimetallic Main-Group Complex

2020

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Inspired by natural metalloenzymes that efficiently catalyze a variety of transformations, chemists have developed large numbers of dinuclear transition-metal complexes with extraordinary properties and reactivity patterns. For main-group element compounds, however, metal–metal cooperativity is much less explored. Here we present the synthesis and characterization of a room-temperature-stable compound with two separated two-coordinated gallium(I) centers possessing both a lone pair of electrons and a vacant orbital, reminiscent of singlet carbenes. This species displays enhanced reactivity compared to its mononuclear counterpart due to bimetallic cooperativity that allows for the facile activation of strong C–F bonds across the gallium–gallium bond. Two mechanistic scenarios of the cooperative bond activation have been identified by DFT and DLPNO-CCSD(T) calculations.

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confidence: 61%

Cooperative Bond Activation by a Bimetallic Main-Group Complex

2020

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“…The ethylene-bridged β-diketiminate ligand H 2 L (H 2 L = N-(−4-((2-((4-((2,6-diisopropylphenyl)imino)pent-2-en-2-yl)amino)ethyl)imino)pent-2-en-2-yl)-2,6-diiso-propylaniline) has been synthesized according to the literature procedure. − The H 2 L ligand was characterized by 1 H/ 13 C NMR spectroscopy and X-ray single crystal diffraction. An ORTEP drawing of the molecular structure of the H 2 L ligand is shown in Figure S1.…”

Section: Resultsmentioning

confidence: 99%

Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

Dang

et al. 2021

Organometallics

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A dinucleating bis(β-diketiminate) ligand with a flexible bridge has been employed to synthesize zinc complexes. The ligand, abbreviated H2L (H2L = N-(4-((2-((4-((2,6-diisopropylphenyl)imino)pent-2-en-2-yl)amino)ethyl)imino)pent-2-en-2-yl)-2,6-diisopropylaniline), was deprotonated with ZnEt2 to afford [LZn2Et2] (1). Reactions of 1 with 2 equiv of BnOH and nBuOH, respectively, gave access to [LZn2(OBn)2]·C6H14 (2·C6H14) and [LZn2(OnBu)2] (3). Treatment of 1 with 2 equiv of I2 in THF produced [LZn2I2(THF)2]·2THF (4·2THF). X-ray single-crystal diffraction analyses revealed that they are all heteroleptic bimetallic compounds with two metal centers being chelated by one ligand set. The structurally similar compounds 1 and 4·2THF possess approximate C 2 symmetry, with two β-diketiminate units being arrayed in head-to-tail antiparallel mode. Thus, the molecular structures of 1 and 4·2THF exhibit a seesaw-like topology. The structures of 2·C6H14 and 3 are almost identical, in which two zinc atoms are shared by two ZnN2C3 six-membered rings, two Zn2ON2C2 seven-membered rings, and one Zn2O2 four-membered ring. Therefore, the metal cores of 2·C6H14 and 3 display a crownlike topology. All complexes are catalytically active for the borylation of aryl iodides with B2Pin2 (B2Pin2 = 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bis(1,3,2-dioxaborolane). Complex 1 shows higher activity in comparison to 2, 3, and 4·2THF. The borylation reactions catalyzed by 1 could proceed under mild conditions and can be applied to a series of substrates with high functional group generality. This methodology thus represents a novel use of β-diketiminate zinc complexes for C–I borylation.

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“…Since the late 1960s, b-diketiminates (commonlyk nown as NacNac) have been extensively studied and widely appliedf or the synthesis and stabilization of metala nd non-metalc ompounds across the periodic table, [1][2][3] ranging from main group elements [4][5][6][7] to transitionm etals [8][9][10] as wella sf -block elements. [11,12] b-Diketiminates are an omnipresentl igand system in coordination chemistry, mainly due to their convenient synthetic accessibility ande asily adjustable scaffold, allowing a fine tuning of the electronic and sterice nvironment.…”

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confidence: 99%

A Phosphine Functionalized β‐Diketimine Ligand for the Synthesis of Manifold Metal Complexes

Zovko

Bestgen

Schoo

et al. 2020

Chemistry A European J

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Ab is(diphenyl)-phosphine functionalized b-diketimine (PNac-H) was synthesizeda saflexible ligand for transition metal complexes.T he newly designed ligand features symmetrically placed phosphine moieties around a b-diketimine unit, forming aP NNP-type pocket. Due to the hard and soft donora toms (N vs. P) the ligand can stabilize various coordination polyhedra.Acomplete series rangingf rom coordination numbers2to 6w as realized. Linear,t rigonal planar,s quare planar,t etrahedral, square pyramidal,a nd octahedral coordination arrangements containing the PNacligand around the metal centerw ere observed by using suitable metal sources. Hereby, PNac-H or its anion PNac À acts as mono-, bi-and tetradendate ligand. Such ab road flexibility is unusualf or ar igid tetradentate system.T he structural motifs were realized by treatment of PNac-H with as eries of late transitionm etal precursors, for example, silver,g old, nickel, copper, platinum, and rhodium. The new complexes have been fully characterizedb ys ingle crystal X-ray diffraction, NMR,I R, UV/Vis spectroscopy,m ass spectrometry as well as elemental analysis. Additionally,s elected complexes were investigated regarding their photophysical properties. Thus,P Nac-H provedt ob ea ni deal ligand platform for the selectivec oordination and stabilization of variousm etal ions in diversepolyhedra and oxidation states. sis [8, 19-23] as well as the activation of small molecules. [13, 24-26] In this regard, b-diketiminate ligandsh ave been proven capable of supporting metal ions in an umber of oxidation states as well as chemical environments. [27] Especially,t he stabilization of sub-valent andu ncommon oxidation states,f or example, Fe I , [26] Al I , [24, 27, 28] Ga I , [27] Si II , [29] Ge I , [30] and Mg I species, [31, 32] has been an achievement of supporting b-diketiminatel igand systems. Hereby,t he scaffold can be easily modified by varying the corresponding N-substituents,w hicha re adjustable regarding their steric demand, electronic properties as well as the introductiono fa dditional functionalities. [15] Thiso ffers ah igh degreeo fc ontrol for task-specific adjustments, for example, the kinetic stabilization of sub-valent and reactive metal species via sterically demanding substituents, [31, 33, 34] or an enhanced reactivity of the resulting metal complexes. [35, 36] In general,ab-diketiminate ligand provides am onoanionic, bidentate support for metal ions, [15] yet the introduction of additional heteroatom donor sites to the b-diketiminate scaffold allowst he extension to more complex coordination motifs,a higherd egree of metal stabilization as wella st he potential formation of heterobimetallicc omplexes.H erein, the design of the ligand plays ac rucial role in promoting or enforcingspecific arrangements. The introduction of additional side groups to a b-diketimines ystemh as already been investigatedapplying O-donora nd S-donorf unctionalities (Figure1), enabling the formation of multidentate ONNO and SNNS pockets, respectively.T hese bifunctionall ...

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Synthesis and Structures of Dinuclear Aluminum Complexes Based on Bis(β‐diketiminate) Ligands

Cited by 8 publications

References 48 publications

Cooperative Bond Activation by a Bimetallic Main-Group Complex

Cooperative Bond Activation by a Bimetallic Main-Group Complex

Zinc Complexes with an Ethylene-Bridged Bis(β-diketiminate) Ligand: Syntheses, Structures, and Applications as Catalysts in the Borylation of Aryl Iodides

A Phosphine Functionalized β‐Diketimine Ligand for the Synthesis of Manifold Metal Complexes

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