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The new silanone complex is accessible in 82% yield and has undergone addition of ammonia under mild conditions, which has produced the sila-hemiaminal and its unique tautomer, the first silanoic amide. Single-crystal X-ray diffraction analysis has shown that the tautomers are in equilibrium in solution and can be cocrystallized in benzene or THF solutions having a SiOH-O[double bond]Si hydrogen bond.

Unique isolable silanone complex is prepared and isolated by the facile oxygenation of the NHC-silylene precursor featuring a Si(II) atom with unusually high nucleophilicity. The remarkably short Si[double bond]O distance in the complex has suggested the presence of a betaine-like Si[double bond]O [pi] system with balanced electrostatics.

The N-Si donor supported siloxysilylene is used as a precursor for gentle monooxygenation of the divalent silicon (Si) atom, which is then employed for the preparation of an isolable silanoic ester at room temperature. The generated compounds are very stable in dry-air and remain unchanged up to a high temperature in an anaerobic atmosphere.

Conspectus Monoatomic zerovalent main-group element complexes emerged very recently and attracted increasing attention of both theoretical and experimental chemists. In particular, zerovalent silicon complexes and their congeners (metallylones) stabilized by neutral Lewis donors are of significant importance not only because of their intriguing electronic structure but also because they can serve as useful building blocks for novel chemical species. Featuring four valence electrons as two lone pairs at the central atoms, such complexes may form donor-acceptor adducts with Lewis acids. More interestingly, with the central atoms in the oxidation state of zero, they could pave a way to new classes of compounds and functional groups that are otherwise difficult to realize. In this Account, we mainly describe our contributions in the chemistry of monatomic zerovalent silicon (silylone) and germanium (germylone) supported by a chelate bis-N-heterocyclic carbene (bis-NHC) ligand in the context of related species developed by other groups in the meantime. Utilizing the bis-NHC stabilized chlorosilyliumylidene [:SiCl]+ and chlorogermyliumylidene [:GeCl]+ as suitable starting materials, we successfully isolated silylone (bis-NHC)Si and germylone (bis-NHC)Ge, respectively. The electronic structures of the latter complexes established by theoretical calculations and spectroscopic data revealed that they are genuine metallylone species with electron-rich silicon(0) and germanium(0) centers. Accordingly, they can react with 1 molar equiv of GaCl3 to form Lewis adducts (bis-NHC)E(GaCl3) (E = Si, Ge) and with 2 molar equiv of ZnCl2 to furnish (bis-NHC)Si(ZnCl2)2. Conversion of the metallylones with elemental chalcogens affords isolable monomeric silicon(II) and germanium(II) monochalcogenides (bis-NHC)EX(GaCl3) (X = Se, Te), representing molecular heavier congeners of CO. Moreover, their reaction with elemental chalcogens can also yield monomeric silicon(IV) and germanium(IV) dichalcogenides (bis-NHC)EX2 (X = S, Se, Te) as the first isolable complexes of the molecular congeners of CO2. Moreover, (bis-NHC)Si could even activate CO2 to afford the monomolecular silicon dicarbonate complex (bis-NHC)Si(CO3)2 via the formation of SiO and SiO2 complexes as intermediates. Furthermore, starting with a chelate bis-N-heterocyclic silylene supported [:GeCl]+, we developed two bis-N-heterocyclic silylene stabilized germylone→Fe(CO)4 complexes. Our achievements in the chemistry of metallylones demonstrate that the characteristic of monatomic zerovalent silicon and its analogues can provide novel reaction patterns for access to unprecedented species and even extends the series of functional groups of these elements. With this, we can envision that more interesting zerovalent complexes of the main-group elements with unprecedented reactivity will follow in the near future. [ABSTRACT FROM AUTHOR]

Detection of proteins containing single amino acid polymorphisms (SAPs) encoded by nonsynonymous SNPs (nsSNPs) can aid researchers in studying the functional significance of protein variants. Most proteogenomic approaches for large-scale SAPs mapping require construction of a sample-specific database containing protein variants predicted from the next-generation sequencing (NGS) data. Searching shotgun proteomic data sets against these NGS-derived databases allowed for identification of SAP peptides, thus validating the proteome-level sequence variation. Contrary to the conventional approaches, our study presents a novel strategy for proteome-wide SAP detection without relying on sample-specific NGS data. By searching a deep-coverage proteomic data set from an industrial thermotolerant yeast strain using our strategy, we identified 337 putative SAPs compared to the reference genome. Among the SAP peptides identified with stringent criteria, 85.2% of SAP sites were validated using whole-genome sequencing data obtained for this organism, which indicates high accuracy of SAP identification with our strategy. More interestingly, for certain SAP peptides that cannot be predicted by genomic sequencing, we used synthetic peptide standards to verify expression of peptide variants in the proteome. Our study has provided a unique tool for proteogenomics to enable proteome-wide direct SAP identification and capture nongenetic protein variants not linked to nsSNPs. [ABSTRACT FROM AUTHOR]

Employing the potassium salt of the monoanionic bis(NHC)borate 1 (NHC = N-Heterocyclic Carbene) enables the synthesis and isolation of the bis(NHC)borate-stabilized chlorogermyliumylidene precursor 2 in 61% yield. A Cl/H exchange reaction of 2 using potassium trisec.-butylborhydride as a hydride source leads to the isolation of the first germyliumylidene hydride [HGe:+] complex 3 in 91% yield. The Ge(II)-H bond in the latter compound has an unexpected reactivity as shown by the reaction with the potential hydride scavenger [Ph3C]+[B(C6F5)4]-, furnishing the corresponding HGe: → CPh3 cation in the ion pair 4 as initial product. Compound 4 liberates HCPh3 in the presence of 3 to give the unusual dinuclear HGe: → Ge: cation in 5. The latter represents the first three-coordinate dicationic Ge(II) species stabilized by an anionic bis(NHC) chelate ligand and a Ge(II) donor. All novel compounds were fully characterized, including X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

By employing the chelate dicarbene 1, the new chlorogermyliumylidene complex 2 could be synthesized and isolated in 95% yield. Dechlorination of 2 with sodium naphthalenide furnishes the unique cyclic germadicarbene 3 which could be isolated in 45% yield. Compound 3 is the first isolable Ge(0) complex with a single germanium atom stabilized by a dicarbene. Its molecular structure is in accordance with DFT calculations which underline the peculiar electronic structure of 3 with two lone pairs of electrons at the Ge atom. [ABSTRACT FROM AUTHOR]

The insertion of the thermally stable ylide-like silylene LSi: (1) {L = CH[(CCH2)CMe][N(Ar)]2], Ar = 2,6-iPr2C6H3} into C−X and Si−X bonds of various small haloalkanes and halosilanes (MeI, PhCH2Br, CH2Cl2, CH2ClI, CH2Br2, CHCl3, MeCCl3, HSiCl3, and MeSiCl3) has been investigated. Surprisingly, the outcome of the reactions is in marked contrast to previous results employing related isolable silylenes. Exclusive formation of 1,1-insertion products LSi(R)X is observed, in a few cases along with a small amount of dihalosilane LSiX2or monohalosilane LSi(H)X. It is proposed that the reaction occurs via polar 1,4-addition and subsequent rearrangement of the latter kinetic (initial) product to give the 1,1-insertion product. The new compounds have been characterized by 1H, 13C, and 29Si NMR spectroscopy and by single-crystal X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the first heterobinuclear tetraphosphorous complexes 3a and 3b with a [Si(μ,η2:2-P4)-Ni] core are reported. The latter result from conversion of the sitylene-activated P4 ligand LSiP4 (; L= CH[(C=CH2)CMe][N-(2,6-Pr2C6H3)]2) with the β-diketiminatonickel(I) complexes [(L'Ni)2∙toluene] (L'= CH[CMeN(2,6-/Pr2C6H3)]2) and [(L"Ni)2 ∙ toluence] (L"= CH[CMeN(2,6-Et2C6H3)]2), respectively. Unexpectedly, the complexes 3a and 3b feature a [Si(μ,η2:2-P4)Ni] core with nickel(I) centers as shown by X-ray diffraction analysis, electron paramagnetic resonance, and magnetic measurements. The latter prove that the products are paramagnetic both in the solid state and in solution because of the presence of tetrahedral nickel(I) sites. [ABSTRACT FROM AUTHOR]

Addition of equimolar amounts of B(C6F5)3to the N-heterocyclic silacyclopropenes [LSi(C2H2)] (2; L = CH{(CCH2)(CMe)(2,6-iPr2C6H3N)2}) affords the first isolable, zwitterionic silacyclopropenylium−boranide compounds 3. Protonation of 2with the convenient Brønsted acid H(OEt2)2+B(C6F5)4−leads to quantitative formation of the corresponding silacyclopropenylium salt [4-B(C6F5)4]. [ABSTRACT FROM AUTHOR]

The article discusses the addition of ammonia to the SiO double bond of three to form a pair of sila-hemiaminal and silanoic amide tautomers. It uses density functional theory (DFT) calculations for activation of ammonia through compound three to assess the thermodynamic features of the systems. It highlights the capability of p-dimethylaminopyridine (DMAP)-stabilized SiO precursor three to activate ammonia under mild extrusion of the DMAP ligand.

The article describes the synthesis of the NHC-silylene adduct 2 containing a highly nucleophilic Si(II) site, which undergoes remarkably facile oxygenation with N2O to yield the first isolable NHC-supported silanone 3. According to the authors, the Si NMR spectrum 2 exhibits a significant shielding for the donor-supported Si(II) nucleus. Moreover, it reveals that Si NMR spectrum also exhibits a remarkable shift for the Si nucleus in 3.