New Vistas in N‐Heterocyclic Silylene (NHSi) Transition‐Metal Coordination Chemistry: Syntheses, Structures and Reactivity towards Activation of Small Molecules

Blom, Burgert; Stoelzel, Miriam; Drieß, Matthias

doi:10.1002/chem.201203072

Cited by 271 publications

(120 citation statements)

References 109 publications

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“…The related Si(I) dimer (12) (for an excellent, detailed and up-to-date review on the reactivity of interconnected bis-silylenes such as 12, see [33]) can also activate We have recently (2012) comprehensively reviewed all NHSi transition metal complexes, where we showed that a large array of NHSi complexes from group 4 to group 10 now exist [38,39]. In this section we will limit the discussion to recent and representative examples of NHSi complexes that have been implicated in catalytic transformations, or interesting small molecule activation reactions over the last few years.…”

Section: Free N-heterocyclic Silylenes (Nhsis) and Their Reactivity Tmentioning

confidence: 98%

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

Blom

Drieß

2013

Structure and Bonding

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*2 Si: (Cp* ¼ η 5 -C 5 Me 5 ), the first isolable Si(II) compound, and later in 1994 with the discovery of the first N-heterocyclic silylene by West and Denk, heralding the beginning of a bourgeoning era in low-valent silicon chemistry. Since these and other key discoveries, massive advances have been made in understanding and elucidating the nature of these reactive compounds, and their ability, for example, to activate small molecules, or behave as ligands in transition metal complexes which can perform a variety of catalytic or stoichiometric transformations. In this chapter, recent advances in silylene chemistry will be presented, with a particular focus on developments in the last 10 years approximately. A key emphasis will rest on the reactivity of isolable silylenes, including their coordination towards metals, with respect to small molecule bond activation, and potential catalytic transformations. Although metalcoordinated silylene complexes have been shown to be catalytically useful in a variety of transformations, metal-free catalysis with silylenes is still a target.

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Section: Free N-heterocyclic Silylenes (Nhsis) and Their Reactivity Tmentioning

confidence: 98%

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

Blom

Drieß

2013

Structure and Bonding

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“…4 σ-Stabilized metallylene (silylene or germylene) donor ligands also have given rise to unique properties and reactivities. 5,6 It is noteworthy that bis-silylene and -germylene pincer moieties are more σ-donating than P III -based ligands.…”

Section: And [Pcp]mentioning

confidence: 99%

From Bis(silylene) and Bis(germylene) Pincer-Type Nickel(II) Complexes to Isolable Intermediates of the Nickel-Catalyzed Sonogashira Cross-Coupling Reaction

et al. 2013

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The first [ECE]Ni(II) pincer complexes with E = Si(II) and E = Ge(II) metallylene donor arms were synthesized via C-X (X = H, Br) oxidative addition, starting from the corresponding [EC(X)E] ligands. These novel complexes were fully characterized (NMR, MS, and XRD) and used as catalyst for Ni-catalyzed Sonogashira reactions. These catalysts allowed detailed information on the elementary steps of this catalytic reaction (transmetalation → oxidative addition → reductive elimination), resulting in the isolation and characterization of an unexpected intermediate in the transmetalation step. This complex, {[ECE]Ni acetylide → CuBr} contains both nickel and copper, with the copper bound to the alkyne π-system. Consistent with these unusual structural features, DFT calculations of the {[ECE]Ni acetylide → CuBr} intermediates revealed an unusual E-Cu-Ni three-center-two-electron bonding scheme. The results reveal a general reaction mechanism for the Ni-based Sonogashira coupling and broaden the application of metallylenes as strong σ-donor ligands for catalytic transformations.

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“…Obviously, the heavier analogues possess distinct electronic features compared to the NHCs, and hence exhibit different reactivities [3,4]. While N-heterocyclic silylenes (NHSi) have been engaged as ancillary ligands in numerous homogeneous catalysis [5][6][7], N-heterocyclic germylenes (NHGe) serve as a precursor for polymerization chemistry [8][9][10] and also for chemical vapour depositions [11].…”

Section: Introductionmentioning

confidence: 99%

One-Pot Synthesis of Heavier Group 14 N-Heterocyclic Carbene Using Organosilicon Reductant

et al. 2018

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Syntheses of heavier Group 14 analogues of "Arduengo-type" N-heterocyclic carbene majorly involved the use of conventional alkali metal-based reducing agents under harsh reaction conditions. The accompanied reductant-derived metal salts and chances of over-reduced impurities often led to isolation difficulties in this multi-step process. In order to overcome these shortcomings, we have used 1,4-bis-(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene as a milder reducing agent for the preparation of N-heterocyclic germylenes (NHGe) and stannylenes (NHSn). The reaction occurs in a single step with moderate yields from the mixture of N-substituted 1,4-diaza-1,3-butadiene, E(II) (E(II) = GeCl 2 ·dioxane, SnCl 2 ) and the organosilicon reductant. The volatile byproducts trimethylsilyl chloride and pyrazine could be removed readily under vacuum. No significant over reduction was observed in this process. However, N-heterocyclic silylene (NHSi) could not be synthesized using an even stronger organosilicon reductant under thermal and photochemical conditions.

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New Vistas in N‐Heterocyclic Silylene (NHSi) Transition‐Metal Coordination Chemistry: Syntheses, Structures and Reactivity towards Activation of Small Molecules

Cited by 271 publications

References 109 publications

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

From Bis(silylene) and Bis(germylene) Pincer-Type Nickel(II) Complexes to Isolable Intermediates of the Nickel-Catalyzed Sonogashira Cross-Coupling Reaction

One-Pot Synthesis of Heavier Group 14 N-Heterocyclic Carbene Using Organosilicon Reductant

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