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4. Highly Selective Nickel‐Catalyzed Isomerization‐Hydroboration of Alkenes Affords Terminal Functionalization at Remote C−H Position.

Author

Saunders, Tyler M., Shepard, Sydney B., Hale, Dylan J., Robertson, Katherine N., and Turculet, Laura

Subjects
ALKENES, DOUBLE bonds, HYDROBORATION, NICKEL, ISOMERIZATION
Abstract

We report herein the synthesis and characterization of nickel complexes supported by tridentate and bidentate phosphino(silyl) ancillary ligands, along with the successful application of these complexes as precatalysts for the hydroboration of terminal and internal alkenes using pinacolborane (HBPin). These reactions proceeded with low nickel loadings of 2.5‐5 mol % in the absence of co‐solvent, and in some cases at room temperature. Isomerization to afford exclusively the terminal hydroboration product was obtained across a range of internal alkenes, including tri‐ and tetra‐substituted examples. This reactivity is unprecedented for nickel and offers a powerful means of achieving functionalization at a C−H position remote from the C=C double bond. Nickel‐catalyzed deuteroboration experiments using DBPin support a mechanism involving 1,2‐insertion of the alkene and subsequent chain‐walking, which results in isotopic scrambling. [ABSTRACT FROM AUTHOR]

Published
2023
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6. Synthesis, structural characterization, and reactivity of Cp*Ru(N-phosphinoamidinate) complexes

Author

Kelly, Colin M., Ruddy, Adam J., Wheaton, Craig A., Sydora, Orson L., Small, Brooke L., Stradiotto, Mark, and Turculet, Laura

Subjects
Coordination compounds -- Chemical properties -- Research, Ruthenium -- Chemical properties -- Research, Chemical synthesis -- Methods -- Research, Chemistry
Abstract

We report herein on the synthesis and spectroscopic/crystallographic characterization of the first isolable, formally 16-electron Cp*Ru([κ.sup.2]-P~N) species, which are supported by N-phosphinoamidinate ligands. Despite the stability of such complexes, they have been shown to readily coordinate two-electron (L) donors including carbon monoxide and 2,6-xylylisocyanide, affording crystallographically characterized 18-electron Cp*Ru(L) ([κ.sup.2]-P~N) adducts. Preliminary reactivity studies confirm that such complexes are capable of extruding hydrogen from ammonia borane. Key words: N-phosphinoamidinate, ruthenium, ligand design, coordinative unsaturation. Nous decrivons la synthese et la caracterisation spectroscopique/cristallographique des premieres especes isolables Cp*Ru([κ.sup.2]-P~N) formellement a 16 electrons, qui sont supportees par des ligands N-phosphinoamidinate. Malgre leur stabilite, on a montre que ces complexes forment facilement une liaison de coordination avec des donneurs de doublet d'electrons (L), y compris le monoxyde de carbone et le 2,6-xylylisocyanure, pour donner des adduits Cp*Ru(L)([κ.sup.2]-P~N) a 18 electrons caracterises par cristallographie. Les etudes de reactivite preliminaires confirment que ces complexes sont capables d'extraire l'hydrogene de l'ammonia borane. [Traduit par la Redaction] Mots-cles: N-phosphinoamidinate, ruthenium, conception de ligands, insaturation coordinative., Introduction Coordinatively unsaturated Cp*Ru[L.sub.n] (Cp* = [η.sup.5]-[C.sub.5][Me.sub.5]) and related complexes have a well-established track record of exhibiting new and unusual metal-centered reactivity, (1, 2) with diverse applications in organic synthesis [...]

Published
2014
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17. Alkene Isomerization–Hydroboration Catalyzed by First-Row Transition-Metal (Mn, Fe, Co, and Ni) N-Phosphinoamidinate Complexes: Origin of Reactivity and Selectivity

Author

Macaulay, Casper M., primary, Gustafson, Samantha J., additional, Fuller, Jack T., additional, Kwon, Doo-Hyun, additional, Ogawa, Takahiko, additional, Ferguson, Michael J., additional, McDonald, Robert, additional, Lumsden, Michael D., additional, Bischof, Steven M., additional, Sydora, Orson L., additional, Ess, Daniel H., additional, Stradiotto, Mark, additional, and Turculet, Laura, additional

Published
2018
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18. Rhodium and iridium amido complexes supported by silyl pincer ligation: ammonia N-H bond activation by a [PSiP]Ir Complex

Author

Morgan, Erin, MacLean, Darren F., McDonald, Robert, and Turculet, Laura

Subjects
Aniline -- Chemical properties, Aniline -- Structure, Elimination reactions -- Analysis, Iridium -- Chemical properties, Organosilicon compounds -- Structure, Organosilicon compounds -- Chemical properties, Rhodium -- Chemical properties, Chemistry
Abstract

The Ir silyl pincer complexes are inserted into the N-H bonds of anilines and ammonia under mild conditions to obtain isolable [Cy-PSiP]Ir(H)(NHR) complexes. The obtained complexes are resistant to N-H bond reductive elimination at room temperature, even in the presence of arenes, alkenes, and phosphines.

Published
2009

25. Cobalt- and Iron-Catalyzed Isomerization–Hydroboration of Branched Alkenes: Terminal Hydroboration with Pinacolborane and 1,3,2-Diazaborolanes

Author

Ogawa, Takahiko, Ruddy, Adam J., Sydora, Orson L., Stradiotto, Mark, and Turculet, Laura

Abstract

The synthesis and characterization of a series of structurally varied N-phosphinoamidinate-ligated cobalt complexes is described, along with the successful application of these and a related iron complex as precatalysts in the isomerization–hydroboration of terminal, geminal, and internal alkenes. These reactions proceed under mild conditions (23–65 °C), at relatively low base-metal loadings (1–5 mol %), typically without cosolvent, and with high terminal hydroboration selectivity across a broad spectrum of branched alkenes. With some of the alkene substrates examined, the N-phosphinoamidinate-ligated precatalysts employed herein are shown to provide alternative terminal selectivity versus other previously reported precatalyst classes for such transformations. Reports of terminal-selective metal-catalyzed alkene isomerization–hydroboration disclosed thus far in the literature employ pinacolborane (HBPin); while effective in the system herein, we also report the first examples of such transformations employing either 1,3-dimethyl-1,3-diaza-2-boracyclopentane or benzo-1,3,2-diazaborolane. The application of these 1,3,2-diazaborolanes in place of HBPin in some instances enables novel terminal selectivity in the isomerization–hydroboration of branched alkenes.

Published
2024
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26. Selective Ni-Catalyzed Hydroboration of CO2to the Formaldehyde Level Enabled by New PSiP Ligation

Author

Murphy, Luke J., Hollenhorst, Helia, McDonald, Robert, Ferguson, Michael, Lumsden, Michael D., and Turculet, Laura

Abstract

The synthesis and characterization of group 10 metal pincer complexes supported by a new bis(indolylphosphino)silyl ligand are described, including the synthesis of Ni, Pd, and Pt hydride species. Solution NMR and single-crystal X-ray data revealed that a significant amount of structural variability is possible for such hydride complexes, particularly in the case of Ni, where terminal Ni-Has well as complexes involving η2-SiH coordination are both accessible and may even coexist, in ratios dependent on factors such as the nature of additional coligands, including N2from the reaction atmosphere, as well as solvent and temperature. Nickel and palladium hydride complexes of this new ligand were found to exhibit divergent selectivity in the catalytic hydroboration of CO2with pinacolborane (HBPin). While the Pd catalyst exhibited moderate activity for CO2hydroboration to the formate level, the analogous Ni species exhibited unprecedented selectivity (97%) for hydroboration of CO2to the formaldehyde level to provide the bis(boryl)acetal PinBOCH2OBPin in high yield, under mild conditions. The HBPin-derived bis(boryl)acetal can be successfully isolated and utilized as a source of methylene for the formation of C–N and C–P bonds.

Published
2024
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30. Dehydrogenative B−H/C(sp3)−H Benzylic Borylation within the Coordination Sphere of Platinum(II).

Author

Kelly, Colin M., Fuller, Jack T., Macaulay, Casper M., McDonald, Robert, Ferguson, Michael J., Bischof, Steven M., Sydora, Orson L., Ess, Daniel H., Stradiotto, Mark, and Turculet, Laura

Subjects
BORYLATION, COORDINATION compounds, PLATINUM, DEHYDROGENATION, CHEMICAL reactions
Abstract

The first examples of stoichiometric dehydrogenative B−H/C(sp3)−H benzylic borylation reactions, which are of relevance to catalytic methylarene (di)borylation, are reported. These unusual transformations involving a (κ2-P,N)Pt(η3-benzyl) complex, and either pinacolborane or catecholborane, proceed cleanly at room temperature. Density functional calculations suggest that borylation occurs via successive σ-bond metathesis steps, whereby a PtII−H intermediate engages in C(sp3)−H bond activation-induced dehydrogenation. [ABSTRACT FROM AUTHOR]

Published
2017
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34. Synthesis and characterization of five-coordinate, 16-electron RuII complexes supported by tridentate bis(phosphino)silyl ligation.

Author

MacInnis, Morgan C., Ruddy, Adam J., McDonald, Robert, Ferguson, Michael J., and Turculet, Laura

Subjects
ALKYL compounds, DEHYDROGENATION, CYCLOHEXANONES, CRYSTAL defects, AZIDO group
Abstract

The synthesis of 16-electron complexes of the type (Cy-PSiP)RuX(L) (Cy-PSiP = κ3-(2-Cy2PC6H4)2SiMe) is reported. Treatment of (Cy-PSiP)H with one equiv. RuCl2(PPh3)3 in the presence of Et3N afforded a mixture of (Cy-PSiP)RuCl(PPh3) (1) and [(Cy-PSiP)RuCl]2 (2), which exists in a temperature-dependent equilibrium process involving reversible dissociation of PPh3 from 1 to form 2. While treatment of this equilibrium mixture with PMe3 afforded (Cy-PSiP)RuCl(PMe3) (3) cleanly, this product was more straightforwardly prepared by the addition of PMe3 to 2 (97% yield). Attempts to form an alkyl complex of the type (Cy-PSiP)RuMe(PMe3) via treatment of 3 with MeMgBr led to the dehydrogenation and cyclometalation of a cyclohexyl phosphino group to give the isolable 18-electron complex [MeSi(C6H4PCy2)(C6H4PCy(η3-C6H8))]RuPMe3 (4, 78% yield). The hydrido complex (Cy-PSiP)RuH(PMe3) (5) was identified as a minor by-product in this dehydrogenative process. Whereas simple 16-electron alkyl complexes of the type (Cy-PSiP)RuR(PMe3) remained elusive, the isolable allyl complex (Cy-PSiP)Ru(η3-C3H5) (9) was successfully prepared from 2 and (C3H5)MgCl (79% yield). Treatment of 3 with Me3SiN3 or NaN3 did not generate a five-coordinate azido species. However, the putative dinuclear complex [(Cy-PSiP)RuN3]2 (10) was observed to react with one equiv. of PMe3 to afford the isolable five-coordinate azido complex (Cy-PSiP)Ru(N3)(PMe3) (11; 94% yield). Crystallographic data for 3, 4, 5, 9 and 11 are presented. [ABSTRACT FROM AUTHOR]

Published
2016
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49. Synthesis, structural characterization, and reactivity of Cp*Ru( N-phosphinoamidinate) complexes.

Author

Kelly, Colin M., Ruddy, Adam J., Wheaton, Craig A., Sydora, Orson L., Small, Brooke L., Stradiotto, Mark, and Turculet, Laura

Subjects
RUTHENIUM compound synthesis, REACTIVITY (Chemistry), COMPLEX compounds, CRYSTALLOGRAPHY, CARBON monoxide, BORANES
Abstract

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2014
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