Five‐Membered Ruthenacycles: Ligand‐Assisted Alkyne Insertion into 1,3‐N,S‐Chelated Ruthenium Borate Species

Zafar, Mohammad; Ramalakshmi, Rongala; Pathak, Kriti; Ahmad, Asif; Roisnel, Thierry; Ghosh, Sundargopal

doi:10.1002/chem.201902663

Cited by 20 publications

(28 citation statements)

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“…70 4). 2,71,73,74,76 These alkenylboranes are believed to be the intermediates in the formation of vinylborane species. The solid-state structure of 41b confirmed that the hydroboration of the alkyne occurred via Markovnikov addition in which the olefinic unit (MeO 2 C−CCH 2 ) is coordinated to the Ru center in an η 2 fashion (Figure 8a).…”

Section: Hydroboration Reactionsmentioning

confidence: 99%

“…The solid-state structures of 51a and 52a show five-membered metallacycles with exo CC double bonds, and the complexes can be considered structural isomers. 2 The five-membered ring in 51a contains a nonplanar Ru−C−N−C−S unit, while a planar Ru−C−S−C−N unit exists in 52a. Initial activation of the alkyne followed by proton transfer from the alkyne unit to an N,S-benzothiazolyl group likely resulted in the formation of 51a and 52a.…”

Section: Hydroboration Reactionsmentioning

confidence: 99%

“…In order to determine the role of ancillary ligands in the stability of the TM σ-borate complexes, the reaction of [( p -cymene)RuCl 2 (PR 3 )] with Na[H 2 B(C 7 H 4 NS 2 ) 2 ] ( p -cymene = η 6 -( p - i PrC 6 H 4 Me)) was performed, yielding the ruthenium σ-borate complexes [(κ N ,κ S -C 7 H 4 NS 2 )(R 3 P)RuH 2 B(L) 2 }] (R = Ph ( 33a ), OPh ( 33b )) and the bis(σ-borate) complex [Ru(H 2 B(C 7 H 4 NS 2 ) 2 ) 2 ] ( 34 ) (Scheme ). , The presence of upfield 1 H NMR chemical shifts at ca. −15 ppm suggested the presence of a Ru– H –B unit.…”

Section: Tetracoordinate σ-Borane/borate Complexesmentioning

confidence: 99%

“…The reaction of the ruthenium σ-borate complex [Cp*Ru(dppm)BH 2 (C 7 H 4 NS 2 ) 2 ] ( 40 ) with terminal alkynes RCCH (R = Ph, CO 2 Me) yielded the η 4 -σ,π-alkenylboranes [Cp*Ru{B(μ-H)(RCCH 2 )(C 7 H 4 NS 2 ) 2 }] (R = Ph ( 41a ), CO 2 Me ( 41b )) along with the η 2 -vinylborane complexes [Cp*Ru{BH(RCCH 2 )(C 7 H 4 NS 2 ) 2 }] , (R = Ph ( 42a ), CO 2 Me ( 42b )) (Table ). ,,,, These alkenylboranes are believed to be the intermediates in the formation of vinylborane species. The solid-state structure of 41b confirmed that the hydroboration of the alkyne occurred via Markovnikov addition in which the olefinic unit (MeO 2 C–CCH 2 ) is coordinated to the Ru center in an η 2 fashion (Figure a).…”

Section: Reactivity Of σ-Borane/borate Complexesmentioning

confidence: 99%

“…2019, 25, 13537−13546. 2 The synthesis of a series of ruthenium σborate complexes is described in this article along with the reaction of these complexes with alkynes, yielding f ive-membered ruthenacycles via 1,3-N,S-chelating ligand-assisted alkyne insertion.…”

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Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

et al. 2021

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Conspectus The coordination of an element–element σ bond to a transition metal (TM) is both a fundamentally intriguing binding mode and of critical importance to metal-mediated bond activation mechanisms and catalysis, particularly the hotly contested field of C–H activation. TM σ complexes of dihydrogen (i.e., H–H) and silanes (H–SiR3) have been extensively studied, the latter being of interest as models for the (generally unstable and unisolable) σ complexes of alkanes (i.e., H–CR3). TM σ complexes of hydroboranes and hydroborates (i.e., H–BR2, H–BR3, (H−)2BR2) are somewhat less well studied but similarly have relevance to catalytic borylation reactions that are of high current interest to organic synthesis. Our two research groups have made significant contributions to elaborating the family of σ-borane/-borate complexes using two distinct approaches: while the Ghosh group generally starts from hydrogen-rich tetracoordinate boron species such as borates, the Braunschweig group starts from hypovalent and/or hypocoordinate boron building blocks. Through these two approaches, a wide range of species containing one or two σ-bound B–H ligands have been prepared, some with additional chelating donor sites. Over the past 2 years, the body of work on σ-borane/-borate complexes from our two research groups has significantly expanded, with a combined nine published articles in 2019–2020 alone. Very recent work from the Braunschweig group has led to the synthesis of the first bis(σ)-borane complexes of group 6 metals, as well as the synthesis of a series of novel bis(σ)-borane and bis(σ)-borate complexes of ruthenium and iridium, the former being useful precursors for pentacoordinate borylene complexes of Ru. Recent work from the Ghosh group has uncovered a remarkable diversity of structures with σ(B–H)-bound ligands from the combination of borohydrides and nitrogen/chalcogen-containing groups and heterocycles. These reactions, while in some cases producing conventional scorpionate-type chelating products, more frequently undergo fascinating rearrangements with unpredictable outcomes. This Account aims to highlight this recent acceleration of research progress in this area, particularly the distinct but related approaches ofand complexes produced byour two research groups, in addition to relevant works from other groups where appropriate.

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Section: Hydroboration Reactionsmentioning

confidence: 99%

Section: Hydroboration Reactionsmentioning

confidence: 99%

Section: Tetracoordinate σ-Borane/borate Complexesmentioning

confidence: 99%

Section: Reactivity Of σ-Borane/borate Complexesmentioning

confidence: 99%

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Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

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Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.0^2,4.0^3,5]nonane

Joseph

Gomosta

Prakash

et al. 2020

Chemistry A European J

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Treatment of Li[BH3ER] (E=Se or Te, R=Ph; E=S, R=CH2Ph) with [Cp*CoCl]2 led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ‐EPh}{μ‐κ2‐E,H‐EBH3}], 1a and 1 b (1 a: E=Se; 1 b: E=Te) and a bis‐hydridoborate species [Cp*Co{μ‐κ2‐Se,H‐SeBH3}]2, 2. All the complexes, 1 a, 1 b and 2 are stabilized by β‐agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B−Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B‐chalcogen and Co‐chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ3‐E,H,H‐E(BH2)2‐C5Me5H3}], 3 a and 3 b (3 a: E=Se and 3 b: E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.02,4.03,5]nonane having identical structure and similar valence electron counts.

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Coordination and Hydroboration of Ru(II)‐Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Pathak

Gayen

Saha

et al. 2022

Chemistry A European J

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Treatment of [Cp*RuCl2]2, 1, [(COD)IrCl]2, 2 or [(p‐cymene)RuCl2]2, 3 (Cp*=η5‐C5Me5, COD= 1,5‐cyclooctadiene and p‐cymene=η6‐iPrC6H4Me) with heterocyclic borate ligands [Na[(H3B)L], L1 and L2 (L1: L=amt, L2: L=mp; amt=2‐amino‐5‐mercapto‐1,3,4‐thiadiazole, mp=2‐mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L1 and L2 afforded dihydridoborate species [LAM(μ‐H)2BHL] 4–6 (4: LA=Cp*, M=Ru, L=amt; 5: LA=Cp*, M=Ru, L=mp; 6: LA=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L2 yielded cis‐ and trans‐bis(dihydridoborate) species, [Ru{(μ‐H)2BH(mp)}2], cis‐7 and trans‐7. The isolation and structural characterization of fac‐ and mer‐[Ru{(μ‐H)2BH(mp)}{(μ‐H)BH(mp)2}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis‐and trans‐7, they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti‐Markovnikov addition products, 10 a–d.

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Five‐Membered Ruthenacycles: Ligand‐Assisted Alkyne Insertion into 1,3‐N,S‐Chelated Ruthenium Borate Species

Abstract: Buildingu pon previous work, the chemistry of [(h 6 -p-cymene)Ru{P(OMe) 2 OR}Cl 2 ], (R = Ho rMe)h as been extended with [H 2 B(mbz) 2 ] À (mbz = 2-mercaptobenzothiazolyl) using different Ru precursors and borate ligands. As ar esult,

Cited by 20 publications

References 99 publications

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.0^2,4.0^3,5]nonane

Coordination and Hydroboration of Ru(II)‐Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

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Five‐Membered Ruthenacycles: Ligand‐Assisted Alkyne Insertion into 1,3‐N,S‐Chelated Ruthenium Borate Species

Abstract: Buildingu pon previous work, the chemistry of [(h 6 -p-cymene)Ru{P(OMe) 2 OR}Cl 2 ], (R = Ho rMe)h as been extended with [H 2 B(mbz) 2 ] À (mbz = 2-mercaptobenzothiazolyl) using different Ru precursors and borate ligands. As ar esult,

Cited by 20 publications

References 99 publications

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

Recent Advances in the Synthesis and Reactivity of Transition Metal σ-Borane/Borate Complexes

Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.02,4.03,5]nonane

Coordination and Hydroboration of Ru(II)‐Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

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Chalcogen Stabilized bis‐Hydridoborate Complexes of Cobalt: Analogues of Tetracyclo[4.3.0.0^2,4.0^3,5]nonane