Synthesis and Characterization of Neutral and Cationic Magnesium Complexes Supported by NHC Ligands
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https://figshare.com/articles/dataset/Synthesis_and_Characterization_of_Neutral_and_Cationic_Magnesium_Complexes_Supported_by_NHC_Ligands/8636570
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资源简介：
A series
of neutral N-heterocyclic carbene (NHC) magnesium alkyl
complexes was synthesized by reaction of IMes (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene)
and IPr (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with
Grignard reagents. In the presence of THF, the mononuclear species
[Mg(IMes)(R)(Br)(THF)] (1, R = Me; 2, R
= Et) and [Mg(IPr)(R)(Br)(THF)] (3, R = Me; 4, R = Et) were isolated. Complex 4 was further methylated
to afford the Mg–THF adduct [Mg(IPr)(Me)2(THF)]
(5), which crystallizes as the dimer [{(Mg(IPr)(Me)}2(μ-Me)2] (5′), thus evidencing
the labile THF coordination in these systems. In contrast, in the
presence of Et2O, the dinuclear Mg(II) species [{(Mg(NHC)(Br)}2(μ-Me)2] (6, NHC = IMes; 7, NHC = IPr), [{(Mg(IMes)(Ph)}2(μ-Br)2] (8), [{(Mg(IMes)(CH2Ph)}2(μ-Cl)2] (9), and [{(Mg(IPr)(Ph)}2(μ-Br)2] (10) were isolated
and characterized. The protonolysis reaction between the protio ligand
[IMes-H]Cl and EtMgBr afforded the Mg(II) dihalido dimer [{(Mg(IMes)(Br)}2(μ-Cl)2] (11). The solid-state
molecular structures of species 5′ and 6–11 were established through X-ray crystallographic
studies. THF adducts 1 and 3 may be readily
ionized by a salt metathesis reaction with [BPh4]Na in
the presence of THF to yield NHC-supported Mg(II) alkyl cations [{Mg(NHC)(Me)(THF)2}]+ (12, NHC = IMes; 13, NHC = IPr) as BPh4– salts. Reflecting
the labile THF coordination to Mg(II) in these cations, the mononuclear
cation 12 crystallizes as the dication [{(Mg(IMes)(THF)}2(μ-Me)2]2+ (12′). Only partial ionization of the halido methyl dimer 6 was observed by reaction with [B(C6F5)4]Li in PhBr to afford the tetranuclear NHC–Mg(II) dicationic
aggregate [{[Mg(IMes)(Me)][Mg(IMes)]}(μ-Me)2]2(μ-Br)2]2+ (14) as
a B(C6F5)4 salt. Computational studies
were performed for selected neutral and cationic NHC–Mg(II)
derivatives, and all agree with the electronic structure and bonding
at Mg(II) being largely dominated by electrostatic interactions.
创建时间：
2019-07-03
