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 - Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022/7/15
Y1 - 2022/7/15
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.
UR - http://www.scopus.com/inward/record.url?scp=85135361823&partnerID=8YFLogxK
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 -