Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand

Matthew P. Stevens; Emily Spray; Iñigo J. Vitorica-Yrezabal; Kuldip Singh; Vanessa M. Timmermann; Lia Sotorrios; Stuart A. Macgregor; Fabrizio Ortu

doi:10.1039/d2dt02012b

Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand

Matthew P. Stevens, Emily Spray, Iñigo J. Vitorica-Yrezabal, Kuldip Singh, Vanessa M. Timmermann, Lia Sotorrios, Stuart A. Macgregor^*, Fabrizio Ortu^*

^*Corresponding author for this work

School of Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, ⁿBu; Tptm = {C(S-C₅H₄N)₃}⁻) and [AE(Tptm)(N′′)] (AE = Mg-Ba; N′′ = {N(SiMe₃)₂}⁻) were targeted from the reaction of HTptm with R₂Mg or [AE(N′′)₂]₂. Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ³C,N,N-C{Bu}{S-C₅H₄N}₂)(μ-S-C₅H₄N)}₂] (1) and [{Mg(κ³C,N,N-C{Me}{S-C₅H₄N}₂)(μ-OSiMe₃)}₂] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N′′)] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)(ⁿBu)] (1m′) system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.

Original language	English
Pages (from-to)	11922-11936
Number of pages	15
Journal	Dalton Transactions
Volume	51
Issue number	31
Early online date	15 Jul 2022
DOIs	https://doi.org/10.1039/d2dt02012b
Publication status	Published - 21 Aug 2022

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@article{bfbe5273f6ac4dc58f82d41d2e5db94b,

title = "Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand",

abstract = "Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, nBu; Tptm = {C(S-C5H4N)3}−) and [AE(Tptm)(N′′)] (AE = Mg-Ba; N′′ = {N(SiMe3)2}−) were targeted from the reaction of HTptm with R2Mg or [AE(N′′)2]2. Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ3C,N,N-C{Bu}{S-C5H4N}2)(μ-S-C5H4N)}2] (1) and [{Mg(κ3C,N,N-C{Me}{S-C5H4N}2)(μ-OSiMe3)}2] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N′′)] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)(nBu)] (1m′) system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.",

author = "Stevens, {Matthew P.} and Emily Spray and Vitorica-Yrezabal, {I{\~n}igo J.} and Kuldip Singh and Timmermann, {Vanessa M.} and Lia Sotorrios and Macgregor, {Stuart A.} and Fabrizio Ortu",

note = "Funding: The authors thank the University of Leicester and the College of Life Science and Engineering for a PhD scholarship (M. P. S.), Royal Society (RGS\R2\202097) and Engineering and Physical Sciences Research Council (EP/W00691X/1 and EP/T019867/1) for funding. X-ray diffraction at Leicester was also supported by the Engineering and Physical Sciences Research Council (EP/V034766/1).",

year = "2022",

month = aug,

day = "21",

doi = "10.1039/d2dt02012b",

language = "English",

volume = "51",

pages = "11922--11936",

journal = "Dalton Transactions",

issn = "1477-9226",

publisher = "ROYAL SOC CHEMISTRY",

number = "31",

}

TY - JOUR

T1 - Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand

AU - Stevens, Matthew P.

AU - Spray, Emily

AU - Vitorica-Yrezabal, Iñigo J.

AU - Singh, Kuldip

AU - Timmermann, Vanessa M.

AU - Sotorrios, Lia

AU - Macgregor, Stuart A.

AU - Ortu, Fabrizio

N1 - Funding: The authors thank the University of Leicester and the College of Life Science and Engineering for a PhD scholarship (M. P. S.), Royal Society (RGS\R2\202097) and Engineering and Physical Sciences Research Council (EP/W00691X/1 and EP/T019867/1) for funding. X-ray diffraction at Leicester was also supported by the Engineering and Physical Sciences Research Council (EP/V034766/1).

PY - 2022/8/21

Y1 - 2022/8/21

N2 - Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, nBu; Tptm = {C(S-C5H4N)3}−) and [AE(Tptm)(N′′)] (AE = Mg-Ba; N′′ = {N(SiMe3)2}−) were targeted from the reaction of HTptm with R2Mg or [AE(N′′)2]2. Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ3C,N,N-C{Bu}{S-C5H4N}2)(μ-S-C5H4N)}2] (1) and [{Mg(κ3C,N,N-C{Me}{S-C5H4N}2)(μ-OSiMe3)}2] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N′′)] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)(nBu)] (1m′) system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.

AB - Herein we report the reactivity of the proligand tris(2-pyridylthio)methane (HTptm) with various Alkaline Earth (AE) reagents: (1) dialkylmagnesium reagents and (2) AE bis-amides (AE = Mg-Ba). Heteroleptic complexes of general formulae [Mg(Tptm)(R)] (R = Me, nBu; Tptm = {C(S-C5H4N)3}−) and [AE(Tptm)(N′′)] (AE = Mg-Ba; N′′ = {N(SiMe3)2}−) were targeted from the reaction of HTptm with R2Mg or [AE(N′′)2]2. Reaction of the proligand with dialkylmagnesium reagents led to formation of [{Mg(κ3C,N,N-C{Bu}{S-C5H4N}2)(μ-S-C5H4N)}2] (1) and [{Mg(κ3C,N,N-C{Me}{S-C5H4N}2)(μ-OSiMe3)}2] (2) respectively, as a result of a novel transfer of an alkyl group onto the methanide carbon with concomitant C-S bond cleavage. However, reactivity of bis-amide precursors for Mg and Ca did afford the target species [AE(Tptm)(N′′)] (3-AE; AE = Mg-Ca), although these proved susceptible to ligand degradation processes. DFT calculations show that alkyl transfer in the putative [Mg(Tptm)(nBu)] (1m′) system and amide transfer in 3-Ca is a facile process that induces C-S bond cleavage in the Tptm ligand. 3-Mg and 3-Ca were also tested as catalysts for the hydrophosphination of selected alkenes and alkynes, including the first example of mono-hydrophosphination of 4-ethynylpyridine which was achieved with high conversions and excellent regio- and stereochemical control.

U2 - 10.1039/d2dt02012b

DO - 10.1039/d2dt02012b

M3 - Article

C2 - 35876311

AN - SCOPUS:85135361823

SN - 1477-9226

VL - 51

SP - 11922

EP - 11936

JO - Dalton Transactions

JF - Dalton Transactions

IS - 31

ER -

Synthesis, characterisation and reactivity of group 2 complexes with a thiopyridyl scorpionate ligand

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