Reversible σ‐Borane‐to‐Borylene Transformation: A Little Something For Everyone

Braunschweig, Holger; Dewhurst, Rian D.

doi:10.1002/anie.200805248

Cited by 28 publications

(19 citation statements)

References 46 publications

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“…A wide variety of coordination modes of these complexes have been structurally characterized and theoretically examined [4] that led to the progress of new subclasses such as sigma, agostic, boryl, borylene, boratrane and more [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Hill, Parkin, Bourissou, Sabo-Etienne, Braunschweig, Weller, Aldridge, and others have synthesized a number of such novel complexes by substitution and addition reactions of boron containing ligands at an electronically unsaturated metal centre [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Transition-metal-boryl, borylene, σ-borane and agostic complexes have been extensively used in hydroboration reactions to generate organoboron compounds such as vinylboranes [5][6][35][36][37][38][39][40].…”

Section: Introductionmentioning

confidence: 99%

Chemistry of ruthenium σ-borane complex, [Cp∗RuCO(μ-H)BH2L] (Cp∗= η5-C5Me5; L = C7H4NS2) with terminal and internal alkynes: Structural characterization of vinyl hydroborate and vinyl complexes of ruthenium

et al. 2017

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The chemistry of ruthenium-borane complex, [Cp*RuCO(µ-H)BH 2 L] (Cp* = η 5-C 5 Me 5 ; L = C 7 H 4 NS 2), 1 with various alkynes has been explored. Photolysis of 1 with alkynyl-Grignard, [HC≡CMgBr] in toluene led to the isolation of vinyl hydroborate complex [Cp*Ru(µ-H)BH{HC=CH 2 }L], 2a as a sole product. Compound 2a can be viewed as a ruthenium-borate complex with an ethylene moiety. Further, the chemistry of 1 with various internal and terminal alkynes has been performed in photolytic conditions. Photolysis of 1 with [RC≡CR] (R = CO 2 Me) yielded vinyl hydroborate complex [Cp*Ru(µ-H)BCl{RC=CR}L], 2b. Terminal alkynes [HC≡CR] (R = Ph or CO 2 Me) under the same reaction conditions led to the isolation of metal vinyl complexes [Cp*Ru(CO)(C 2 HR)(L)], 3a and 3b (3a: R = Ph; 3b: R = CO 2 Me). In addition, DFT calculations were carried out to analyze the bonding and electronic structures of these new compounds.

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Section: Introductionmentioning

confidence: 99%

Chemistry of ruthenium σ-borane complex, [Cp∗RuCO(μ-H)BH2L] (Cp∗= η5-C5Me5; L = C7H4NS2) with terminal and internal alkynes: Structural characterization of vinyl hydroborate and vinyl complexes of ruthenium

et al. 2017

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“…Conceivably, single dehydrocoupling of two dihydroboranes would yield highly useful, but otherwise difficult to prepare, dihydrodiboranes(4) (B 2 H 2 R 2 ), from which a series of consecutive intermolecular dehydrocoupling processes could lead to oligo- or polymeric species of the form H(BR) n H. Alternatively, intramolecular dehydrocoupling of B 2 H 2 R 2 would provide a base-free diborene (RBBR) that may be detected if unstable or stabilized by the use of large steric bulk or metal π coordination (a coordination mode observed previously via a different synthetic route) . The use of dehydrocoupling to form E–E multiple bonds has limited precedence in the literature, notably dehydrocoupling of a dihydroarsine to form a diarsene (RAsAsR) by Waterman et al, and the dehydrogenation of a hydroborane to form a RuB double bond by Sabo-Etienne et al However, dehydrogenation has never been used to generate B–B multiple bonds.…”

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confidence: 99%

Unprecedented Borane, Diborane(3), Diborene, and Borylene Ligands via Pt-Mediated Borane Dehydrogenation

et al. 2015

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Reactions of an aryldihydroborane with a Pt(0) complex lead to a range of novel products, including complexes with bridging diborene and diborane(3) ligands and a complex with both borylene and borane (M → B) ligands. The products imply varying degrees of dehydrogenation of the boron centers with concomitant formation of boron-boron bonds, which in one case is later broken. These reactions show that although the dehydrocoupling of dihydroboranes is not a straightforward process in this case, the reactions are capable of connecting boron atoms in unusual ways, leading to unprecedented bonding motifs.

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“…In recent work, we have investigated the steric and electronic factors required to generate borylene complexes from the corresponding bis(σ)-borane species via dehydrogenation. 54 A range of dihydridobis(σ)-borane complexes [(Cy 3 P) 2 Ru(H) 2 (η 2 -H 2 BR)] (12a−16a) were isolated from the reactions of [(Cy 3 P) 2 RuHCl(H 2 )] and lithium trihydroborates (Scheme 4…”

Section: Late Transition Metalsmentioning

confidence: 99%

“…The regular occurrence of σ-borane complexes with late TMs is possibly due to the higher electron density and enhanced metal-to-ligand back-donation abilities of the metals, which are essential requirements for this type of bonding. In recent work, we have investigated the steric and electronic factors required to generate borylene complexes from the corresponding bis(σ)-borane species via dehydrogenation . A range of dihydridobis(σ)-borane complexes [(Cy 3 P) 2 Ru(H) 2 (η 2 -H 2 BR)] ( 12a – 16a ) were isolated from the reactions of [(Cy 3 P) 2 RuHCl(H 2 )] and lithium trihydroborates (Scheme and Figure ), while the reactions with dihydroboranes yielded the bis(σ)-borane complexes [(Cy 3 P) 2 RuHCl(η 2 -H 2 BR)] ( 12b – 16b ) .…”

Section: Tricoordinate σ-Borane Complexesmentioning

confidence: 99%

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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Reversible σ‐Borane‐to‐Borylene Transformation: A Little Something For Everyone

Cited by 28 publications

References 46 publications

Chemistry of ruthenium σ-borane complex, [Cp∗RuCO(μ-H)BH2L] (Cp∗= η5-C5Me5; L = C7H4NS2) with terminal and internal alkynes: Structural characterization of vinyl hydroborate and vinyl complexes of ruthenium

Chemistry of ruthenium σ-borane complex, [Cp∗RuCO(μ-H)BH2L] (Cp∗= η5-C5Me5; L = C7H4NS2) with terminal and internal alkynes: Structural characterization of vinyl hydroborate and vinyl complexes of ruthenium

Unprecedented Borane, Diborane(3), Diborene, and Borylene Ligands via Pt-Mediated Borane Dehydrogenation

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

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