Zinc Catalyzed Hydroelementation (HE; E = B, C, N, and O) of Carbodiimides: Intermediates Isolation and Mechanistic Insights

Organometallics, Год журнала: 2023, Номер 42(14), С. 1746 - 1758

Опубликована: Март 15, 2023

The conjugated bis-guanidinate (CBG) supported zinc hydride, [{LZnH}2; L = {(ArHN)(ArN)-C═N–C═(NAr)(NHAr); Ar 2,6-Et2-C6H3}] (1) (pre)-catalyzed addition of E–H (E B, C, N, and O) to carbodiimides is presented. Compound 1 catalyzed the reduction with pinacolborane (HBpin), terminal alkynes, primary amines, alcohols, gave a series N-boryl formamidines, propiolamidines, guanidines, isoureas high conversions. All these reactions display good tolerance functional groups. These proceeded through active catalysts intermediate amidinate (Zn-1, Zn-1′, Zn-3), alkynyl (Zn-2, Zn-2′), anilide (Zn-4), alkoxide (Zn-5) complexes, which have been characterized by multinuclear NMR HRMS analyses. Moreover, compounds Zn-2′, Zn-4, Zn-5 were confirmed single-crystal X-ray diffraction studies. Complete catalytic cycles proposed based on well-defined intermediates stoichiometric experiments.

Язык: Английский

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Zinc hydride catalyzed hydroboration of esters

Dalton Transactions, Год журнала: 2024, Номер 53(8), С. 3621 - 3628

Опубликована: Янв. 1, 2024

The bis-guanidinate supported zinc hydride ( I ) catalyzes the hydroboration of a series esters, yielding alkoxyboronate esters as products. Based on stoichiometric experiments, plausible insertion/sigmabond metathesis mechanism has been proposed.

Язык: Английский

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Mono- and Bimetallic Aluminum Alkyl, Alkoxide, Halide and Hydride Complexes of a Bulky Conjugated Bis-Guanidinate(CBG) Ligand and Aluminum Alkyls as Precatalysts for Carbonyl Hydroboration

Inorganic Chemistry, Год журнала: 2020, Номер 59(7), С. 4693 - 4702

Опубликована: Март 11, 2020

Tetra-aryl-substituted symmetrical conjugated bis-guanidine (CBG) ligands such as L1-3 (3H) [L(3H) = {(ArHN)(ArHN)C═N-C═NAr(NHAr)}; Ar 2,6-Me2-C6H3 (L1(3H)), 2,6-Et2-C6H3 (L2(3H)), and 2,6-iPr2-C6H3 (L3(3H))] have been employed to synthesize a series of four- six-membered aluminum heterocycles (1-8) for the first time. Generally, complexes bearing N,N'- chelated guanidinate β-diketiminate/dipyrromethene ligand systems form heterocycles, respectively. However, has capability forming both possessing multimetal centers within same molecule; this is due presence three acidic protons, which can be easily deprotonated (at least two protons) upon treatment with metal reagents. Both mono- dinuclear alkyls mononuclear alkoxide, halide, hydride structurally characterized. Further, we demonstrated potential mononuclear, CBG dialkyls in catalytic hydroboration broad range aldehydes ketones pinacolborane (HBpin).

Язык: Английский

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Intermediates, Isolation and Mechanistic Insights into Zinc Hydride-Catalyzed 1,2-Regioselective Hydrofunctionalization of N-Heteroarenes

Inorganic Chemistry, Год журнала: 2022, Номер 62(1), С. 304 - 317

Опубликована: Дек. 26, 2022

The conjugated bis-guanidinate-supported zinc hydride [{LZnH}2; L = {(ArHN) (ArN)-C═N-C═(NAr) (NHAr); Ar 2,6-Et2-C6H3}] (I)-catalyzed highly demanding exclusive 1,2-regioselective hydroboration and hydrosilylation of N-heteroarenes is demonstrated with excellent yields. This protocol compatible many pyridines N-heteroarene derivatives, including electron-donating -withdrawing substituents. Catalytic intermediates, such as [(LZnH) (4-methylpyridine)] IIA, [(L'ZnH) (4-methylpyridine) IIA', where L' CH{(CMe) (2,6-Et2C6H3N)}2)], LZn(1,2-DhiQ) (isoquinoline) III, [L'Zn(1,2-DhiQ) (isoquinoline)] III', LZn(1,2-(3-MeDHQ)) (3-methylquinoline) V, were isolated thoroughly characterized by NMR, HRMS, IR analyses. Furthermore, X-ray single-crystal diffraction studies confirmed the molecular structures compounds III'. NMR data proved that intermediate III or III' reacted HBpin gave a selective 1,2-addition hydroborated product. Stoichiometric experiments suggest V independently silane, yielding mono- bis-hydrosilylated products, respectively. Based on isolation intermediates series stoichiometric experiments, plausible catalytic cycles established. intermolecular chemoselective reaction over other reducible functionalities was studied.

Язык: Английский

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Germanium Hydride Catalyzed Selective Hydroboration and Cyanosilylation of Ketones

European Journal of Inorganic Chemistry, Год журнала: 2022, Номер 2022(20)

Опубликована: Май 16, 2022

Abstract Two new examples of β ‐diketiminate or NacNac analogues, i. e ., conjugated bis‐guanidinate (CBG) stabilized low valent germanium chloride ( 1 ) and hydride 2 complexes, are reported. Deprotonation LH upon treatment with n ‐BuLi an in situ generated LLi further treated GeCl ⋅dioxane afforded LGeCl 79 % yield. Compound reacted source NaHBEt 3 toluene, Ge (II) 76 Both compounds were characterized by NMR mass spectroscopic methods. Further, catalyzed hydroboration cyanosilylation a wide range ketones have been investigated. Control reactions suggest occurred via insertion Ge−O/B−H bond metathesis pathways. It is worthy mentioning that, the case ketones, reducible groups such as alkene, alkyne, halide, ester, nitro, heterocycles untouched. Furthermore, compound was employed for reduction carbonate, formate, anhydride substrates technique.

Язык: Английский

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Flexible Biguanide Mono- and Bimetallic Zinc Complexes for the Ring-Opening (Co)polymerization of Lactides

ACS Catalysis, Год журнала: 2025, Номер unknown, С. 9117 - 9129

Опубликована: Май 14, 2025

Язык: Английский

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Organoaluminum Cation Catalyzed Selective Hydrosilylation of Carbonyls, Alkenes, and Alkynes

European Journal of Inorganic Chemistry, Год журнала: 2022, Номер 2022(8)

Опубликована: Янв. 22, 2022

Abstract The N , N’ ‐chelated β ‐diketiminate analogue i. e ., conjugated bis‐guanidine (CBG) ligand L(3H) [L= {(ArHN)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et 2 ‐C 6 H 3 ], has been used to synthesize mono‐ and dinuclear Al(III) dimethyl complexes, [L(2H) AlMe ] ( 1) [L(H)(AlMe ) ). Compounds 1 are synthesized by deprotonation method using free appropriate stoichiometric amounts of structurally characterized a single‐crystal X‐ray diffraction technique. Moreover, the reaction compound with B(C F 5 afforded three‐coordinate aluminum methyl cation [L(2H)AlMe] + [MeB(C − in good yield. Compound was thermally stable multinuclear NMR spectroscopy. Furthermore, we demonstrated that catalyzed hydrosilylation carbonyls, alkenes, alkyne triethylsilane (HSiEt under solvent‐free conditions. We found catalyst is also effective for large‐scale reactions. Additionally, have shown benzaldehyde's intermolecular chemoselective over other reducible functional groups.

Язык: Английский

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Aluminium‐Catalyzed Selective Hydroboration of Esters and Epoxides to Alcohols: C−O Bond Activation

Chemistry - A European Journal, Год журнала: 2022, Номер 29(4)

Опубликована: Окт. 13, 2022

In this work, the molecular aluminium dihydride complex bearing an N, N'-chelated conjugated bis-guanidinate (CBG) ligand is used as a catalyst for reducing wide range of aryl and alkyl esters with good tolerance alkene (C=C), alkyne (C≡C), halides (Cl, Br, I F), nitrile (C≡N), nitro (NO2 ) functionalities. Further, we investigated catalytic application in C-O bond cleavage epoxides into corresponding branched Markovnikov ring-opening products. addition, chemoselective intermolecular reduction over other reducible functional groups, such amides alkenes, has been established. Intermediates are isolated characterized by NMR HRMS studies, which confirm probable cycles hydroboration epoxides.

Язык: Английский

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Gallium Hydride‐Catalyzed Selective Hydroboration of Unsaturated Organic Substrates

ChemPlusChem, Год журнала: 2024, Номер 89(7)

Опубликована: Март 4, 2024

Abstract The first examples of tetrasubstituted conjugated bis‐guanidinate (CBG) supported monomeric and thermally stable gallium dihalides [LGaX 2 ], (X=Cl ( Ga−Cl ), I Ga−I )) dihydride Ga−H ) [LGaH ] (where L={(ArHN)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et −C 6 H 3 compounds are reported. reaction in situ generated LLi with 1.0 equiv. GaX (X=Cl, I) afforded . between Li[HBEt benzene yielded the compound All reported , were characterized by NMR, HRMS, single‐crystal X‐ray diffraction studies. was probed for hydroboration carbodiimides (CDI), isocyanates, isothiocyanates HBpin. Compound also found effective catalytic imines, nitriles, alkynes, esters, formates, affording corresponding products quantitative yields. Stoichiometric reactions a CDI performed to establish cycle.

Язык: Английский

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Synthesis of low oxidation state zinc(i) complexes and their catalytic studies in the dehydroborylation of terminal alkynes

Dalton Transactions, Год журнала: 2022, Номер 51(41), С. 16009 - 16016

Опубликована: Янв. 1, 2022

A new example of a structurally characterized conjugated bis-guanidinate (CBG) supported zinc(I) dimer, i.e., LZnZnL (3) (L = {(ArNH)(ArN)-CN-C(NAr)(NHAr)}; Ar 2,6-Et2-C6H3) with Zn-Zn bond is reported. Moreover, homoleptic and heteroleptic (Cp*ZnZnL, 2, (Cp* 1,2,3,4,5-pentamethyl cyclopentadienide)) dimers are used as precatalysts in the dehydroborylation wide array terminal alkynes. Furthermore, active catalyst, CBG zinc acetylide (LZn-CC-Ph-4-Me)2, (5), isolated which confirmed by X-ray crystal structure analysis. series stoichiometric experiments have been performed to propose plausible reaction mechanism.

Язык: Английский

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