Synthesis and Reactivity of N‐Heterocyclic Silylene Stabilized Disilicon(0) Complexes

Du, Shaozhi; Jia, Hongwei; Hua, Rong; Song, Haibin; Cui, Chunming; Mo, Zhenbo

doi:10.1002/anie.202115570

Cited by 17 publications

(14 citation statements)

References 106 publications

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“…Accordingly, TD-DFT calculations show a transition at 626 nm, corresponding to the n → p excitation (Figures S50–S51 and Table S3). The molecular structure of 1 was determined by single crystal X-ray diffraction (SC-XRD) analysis (Figure ) and it represents a rare example of structurally defined NHI-silylenes. , The Si1–N1 distance of 1.665(2) Å is similar to previous imino(siloxy)silylene (1.661(2) Å), but much shorter than known acyclic aminosilylenes (1.720(1)–1.750(10) Å). ,, The N1–Si1–Si2 angle of 106.15(9)° is significantly more obtuse than the angles around the central Si atom typical for cyclic silylenes (86.94°–93.88(7)°), , implying higher reactivity, , but it is still more acute than acyclic aminosilylsilylene Si{Si(SiMe 3 ) 3 }{N(SiMe 3 )Dipp} (116.91(5)°)…”

Section: Resultsmentioning

confidence: 89%

Room Temperature Intermolecular Dearomatization of Arenes by an Acyclic Iminosilylene

et al. 2023

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A novel nontransient acyclic iminosilylene (1), bearing a bulky super silyl group (−Si t Bu 3 ) and N-heterocyclic imine ligand with a methylated backbone, was prepared and isolated. The methylated backbone is the feature of 1 that distinguishes it from the previously reported nonisolable iminosilylenes, as it prevents the intramolecular silylene center insertion into an aromatic C−C bond of an aryl substituent. Instead, 1 exhibits an intermolecular Buchner-ring-expansion-type reactivity; the silylene is capable of dearomatization of benzene and its derivatives, giving the corresponding silicon analogs of cycloheptatrienes, i.e. silepins, featuring seven-membered SiC 6 rings with nearly planar geometry. The ring expansion reactions of 1 with benzene and 1,4bis(trifluoromethyl)benzene are reversible. Similar reactions of 1 with N-heteroarenes (pyridine and DMAP) proceed more rapidly and irreversibly forming the corresponding azasilepins, also with nearly planar seven-membered SiNC 5 rings. DFT calculations reveal an ambiphilic nature of 1 that allows the intermolecular aromatic C−C bond insertion to occur. Additional computational studies, which elucidate the inherent reactivity of 1, the role of the substituent effect, and reaction mechanisms behind the ring expansion transformations, are presented.

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Section: Resultsmentioning

confidence: 89%

Room Temperature Intermolecular Dearomatization of Arenes by an Acyclic Iminosilylene

et al. 2023

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“…The second‐order perturbation analysis (SOPA) shows an electron delocalization from the Ge1−Ge2 π orbital to the formally vacant orbitals of Si1 and Al1 [27] . In sharp contrast, the alkynyl group of an alkynylaluminum complex PhCCAlCp*(Me)(THF) bears one C−C σ‐orbital and two C−C π‐orbitals with a high WBI (2.78) [26] . The natural population analysis (NPA) charges in 4 (Ge1: 0.38; Ge2: −0.81; Al1: +1.76) indicate the anionic character of the Ge=Ge moiety and the polarized Ge−Al bond.…”

Section: Methodsmentioning

confidence: 99%

A Silylene‐Stabilized Germanium Analogue of Alkynylaluminum

et al. 2022

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In contrast to the well-developed metal acetylides, the heavier analogues of the type REEM (E = Si, Ge, Sn, Pb; M = metals) have not been reported to date. Herein, we describe the synthesis of a silylenestabilized germanium analogue of alkynylaluminum ( 4) by the reaction of a silylene-stabilized digermavinylidene (3) with 0.25 equiv of (AlCp*) 4 in THF at 80 °C. The structure of 4 has been unambiguously characterized by spectroscopic analysis, X-ray diffraction analyses and DFT calculations, and features a linear AlGeGe skeleton with a Ge=Ge double bond and a polarized GeÀ Al bond. Complex 4 shows excellent reactivity towards small molecules such as H 2 , CS 2 and TolNCO, and this allows for the construction of the structurally intriguing germylenyl aluminum complex (5) and the germacycles (6, 7).

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“…Since Denk and West described the first bottleable N -heterocyclic silylene (NHSi) in 1994, several series of (NHSi)s have been reported. , Owing to the intramolecular imino- N donor interaction with the empty 3p orbital at the central silicon atom (Scheme , H ), the chelating N -heterocyclic amidinato (NHSi)s are considered to be more electron-rich ligands compared with NHCs and can serve as versatile strong donating ligands in main-group and transition-metal coordination chemistry . After Kira and co-workers reported the heavy allenes D with a SiESi moiety (E = Si, Ge), , which could also be viewed as silylene-supported E 0 complexes, several novel low-valent main-group complexes such as E – F have been realized using NHSi ligands. − …”

Section: Introductionmentioning

confidence: 99%

Chelating Bis-silylenes As Powerful Ligands To Enable Unusual Low-Valent Main-Group Element Functions

et al. 2023

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Metrics & More Article Recommendations CONSPECTUS: Silylenes are divalent silicon species with an unoccupied 3p orbital and one lone pair of electrons at the Si II center. Owing to the excellent σ-donating ability of amidinatobased silylenes, which stems from the intramolecular imino-N donor interaction with the vacant 3p orbital of the silicon atom, Nheterocyclic amidinato bis(silylenes) [bis(NHSi)s] can serve as versatile strong donating ligands for cooperative stabilization of central atoms in unusually low oxidation states. Herein, we present our recent achievement on the application of bis(NHSi) ligands with electronically and spatially different spacers to main-group chemistry, which has allowed the isolation of a variety of low-valent compounds consisting of monatomic zero-valent group 14 E 0 complexes (named "metallylones", E = Si, Ge, Sn, Pb); monovalent group 15 E I complexes (E = N, P, isoelectronic with metallylones); and diatomic low-valent E 2 complexes (E = Si, Ge, P) with intriguing electronic structures and chemical reactivities. The role of the Si II •••Si II distance was revealed to be crucial in this chemistry. Utilizing the pyridine-based bis(NHSi) (Si•••Si distance: 7.8 Å) ligand, germanium(0) complexes with additional Fe(CO) 4 protection at the Ge 0 site have been isolated. Featuring a shorter Si•••Si distance of 4.3 Å, the xanthene-based bis(NHSi) has allowed the realization of the full series of heavy zero-valent group 14 element E 0 complexes (E = Si, Ge, Sn, Pb), while the o-carborane-based bis(NHSi) (Si•••Si distance: 3.3 Å) has enabled the isolation of Si 0 and Ge 0 complexes. Remarkably, reduction of the o-carborane-based bis(NHSi)-supported Si 0 and Ge 0 complexes induces the movement of two electrons into the o-carborane core and provides access to Si I −Si I and Ge I −Ge I species as oxidation products. Additionally, the o-carborane-based bis(NHSi) reacts with adamantyl azide, leading to a series of nitrogen(I) complexes as isoelectronic species of a carbone (C 0 complex). Moreover, cooperative activation of white phosphorus gives bis(NHSi)-supported phosphorus complexes with varying and unexpected electronic structures when employing the xanthene-, o-carborane-, and anilinebased bis(NHSi)s. With the better kinetic protection provided by the xanthene-based bis(NHSi), small-molecule activation and functionalization of the bis(NHSi)-supported central E or E 2 atoms (E = Si, Ge, P) are possible and furnish several novel functionalized silicon, germanium, and phosphorus compounds.With knowledge of the ability of chelating bis(NHSi)s in coordinating and functionalizing low-valent group 14 and 15 elements, the application of these ligand systems to other main-group elements such as group 2 and 13 is quite promising. To fully understand the role of the NHSi in a bis(NHSi) ligand, introducing a mixed ligand, i.e., the combination of an NHSi with other functional groups, such as Lewis acidic borane or Lewis basic borylene, in one chelating ligand could lead to new types of low-valent main-...

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Synthesis and Reactivity of N‐Heterocyclic Silylene Stabilized Disilicon(0) Complexes

Cited by 17 publications

References 106 publications

Room Temperature Intermolecular Dearomatization of Arenes by an Acyclic Iminosilylene

Room Temperature Intermolecular Dearomatization of Arenes by an Acyclic Iminosilylene

A Silylene‐Stabilized Germanium Analogue of Alkynylaluminum

Chelating Bis-silylenes As Powerful Ligands To Enable Unusual Low-Valent Main-Group Element Functions

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