Synthesis and reactivity of N-heterocyclic carbene (NHC)-supported heavier nitrile ylides.

The synthesis and isolation of stable heavier analogues of nitrile ylide as N-heterocyclic carbene (NHC) adducts of phosphasilenyl-tetrylene [(NHC)(Ar)Si(H)PE(Ar)] (E = Ge 1, Sn 2; Ar = 2,6-MesCH, NHC = IMe) are reported. The delocalized Si-P-E π-conjugation was examined experimentally and computationally. Interestingly, the germanium derivative 1 exhibits a 1,3-dipolar nature, leading to an unprecedented [3 + 2] cycloaddition with benzaldehyde, resulting in unique heterocycles containing four heteroatoms from group 14, 15, and 16.

Potent Anticancer Activity of a Dinuclear Gold(I) bis-N-Heterocyclic Imine Complex Related to Thioredoxin Reductase Inhibition in Vitro.

A dinuclear gold(I) complex featuring a strongly donating bis-N-heterocyclic imine ligand was synthesised and characterised by different methods, including single crystal X-ray diffraction (SC-XRD) analysis. The compound has been tested for its antiproliferative effects in a panel of human cancer cell lines in vitro, showing highly selective anticancer effects, particularly against human A549 non-small cell lung cancer cells (NSCLC), with respect to non-tumorigenic cells (VERO). The accumulation of the compound in A549 and VERO cells was studied by high-resolution continuum source atomic absorption spectrometry (HRCS-AAS), revealing that the anticancer effects are not particularly related to the different amounts of gold taken up by the cells over 72 h.

Anions featuring an aluminium-silicon core with alumanyl silanide and aluminata-silene characteristics.

Molecular species containing multiple bonds to aluminium have long been challenging synthetic targets. Despite recent landmark discoveries in this area, heterodinuclear Al-E multiple bonds (where E is a group-14 element) have remained rare and limited to highly polarized π-interactions (Al=E ↔ Al-E). Here we report the isolation of three alumanyl silanide anions that feature an Al-Si core stabilized by bulky substituents and a Si-Na interaction.

Room Temperature Intermolecular Dearomatization of Arenes by an Acyclic Iminosilylene.

A novel nontransient acyclic iminosilylene (), bearing a bulky super silyl group (-SiBu) and -heterocyclic imine ligand with a methylated backbone, was prepared and isolated. The methylated backbone is the feature of 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, exhibits an intermolecular Büchner-ring-expansion-type reactivity; the silylene is capable of dearomatization of benzene and its derivatives, giving the corresponding silicon analogs of cycloheptatrienes, .

Room-Temperature-Observable Interconversion Between Si(IV) and Si(II) via Reversible Intramolecular Insertion Into an Aromatic C-C Bond.

An easily isolable silacycloheptatriene (silepin) 1 b was synthesized from the reaction of a N-heterocyclic imino (IPrN) substituted tribromosilane IPrNSiBr with the sterically congested bis(trimethylsilyl)triisopropylsilyl silanide KSi(TMS) Si( Pr) (BTTPS). In solution, the Si(IV) silepin 1 b is in a thermodynamic equilibrium with the acyclic Si(II) silylene 1 a. The relative concentration of the Si(II) or Si(IV) isomers can be controlled by temperature variation and observed by variable temperature NMR and UV/Vis spectroscopy.

Isolation and Reactivity of Tetrylene-Tetrylone-Iron Complexes Supported by Bis(N-Heterocyclic Imine) Ligands.

The germanium iron carbonyl complex 3 was prepared by the reaction of dimeric chloro(imino)germylene [IPrNGeCl] (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-iminato) with one equivalent of Collman's reagent (Na Fe(CO) ) at room temperature. Similarly, the reaction of chloro(imino)stannylene [IPrNSnCl] with Na Fe(CO) (1 equiv) resulted in the Fe(CO) -bridged bis(stannylene) complex 4. We observed reversible formation of bis(tetrylene) and tetrylene-tetrylone character in complexes 3 vs.

Isolation of Cyclic Aluminium Polysulfides by Stepwise Sulfurization.

Despite the notable progress in aluminium chalcogenides, their sulfur congeners have rarely been isolated under mild conditions owing to limited synthetic precursors and methods. Herein, facile isolation of diverse molecular aluminium sulfides is achievable, by the reaction of N-heterocyclic carbene-stabilized terphenyl dihydridoaluminium (1) with various thiation reagents. Different to the known dihydridoaluminium 1 , 1 features balanced stability and reactivity at the Al center.

Application of ferrocene-bridged N-heterocyclic carbene stabilised bis-phosphinidenes in Sn(II) complexation.

Two new bidentate ferrocene-bridged bis(-heterocyclic carbene-phospinidenes) (bisNHCPs) were successfully isolated by treating 1,1'-bis-(dichlorophosphine)ferrocene with -heterocyclic carbenes, followed by dechlorination using sodium naphthalenide. The bisNHCPs were used in complexation of various Sn(II) halides and Sn(II) bistriflate (SnX with X = Cl, Br, I, OTf). Transmetalation to a CuCl complex and Sn(II) transfer to a bisimine was performed to investigate the stannyliumylidenes' reactivity.

Bis(perfluoropinacolato)silane: A Neutral Silane Lewis Superacid Activates Si-F Bonds.

Despite the earth abundance and easy availability of silicon, only few examples of isolable neutral silicon centered Lewis superacids are precedent in the literature. To approach the general drawbacks of limited solubility and unselective deactivation pathways, we introduce a Lewis superacid, based on perfluorinated pinacol substituents. The compound is easily synthesized on a gram-scale as the corresponding acetonitrile mono-adduct 1⋅(MeCN) and was fully characterized, including single crystal X-ray diffraction analysis (SC-XRD) and state-of-the-art computations.

An Isolable Three-Coordinate Germanone and Its Reactivity.

A rare three-coordinate germanone [IPrN] Ge=O (IPrN=bis(2,6-diisopropylphenyl)imidazolin-2-imino) was successfully isolated. The germanone has a rather high thermal stability in arene solvent, and no detectable change was observed at 80 °C for at least one week. However, high thermal stability of [IPrN] Ge=O does not prevent its reactivity toward small molecules.

A Zwitterionic Heterobimetallic Gold-Iron Complex Supported by Bis(N-Heterocyclic Imine)Silyliumylidene.

The facile synthesis of the first bis-N-heterocyclic imine-stabilized chlorosilyliumylidene 1 is reported. Remarkably, consecutive reaction of 1 with PPh AuCl and K Fe(CO) gives rise to the unique heterobimetallic complex 1,2-( NHI) -C H -ClSiAuFe(CO) (4). The overall neutral complex 4 bears an unusual linear Si-Au-Fe structure and a rare anagostic interaction between the d -configured gold atom and a CH bond of the mesityl ligand.

Recent advances of group 14 dimetallenes and dimetallynes in bond activation and catalysis.

Since the first heavy alkene analogues of germanium and tin were isolated in 1976, followed by West's disilene in 1981, the chemistry of stable group 14 dimetallenes and dimetallynes has advanced immensely. Recent developments in this field veered the focus from the isolation of novel bonding motifs to mimicking transition metals in their ability to activate small molecules and perform catalysis. The potential of these homonuclear multiply bonded compounds has been demonstrated numerous times in the activation of H, NH, CO and other small molecules.

Dialumenes - aryl silyl stabilisation for small molecule activation and catalysis.

Main group multiple bonds have proven their ability to act as transition metal mimics in the last few decades. However, catalytic application of these species is still in its infancy. Herein we report the second neutral NHC-stabilised dialumene species by use of a supporting aryl ligand ().

An Air-Stable Heterobimetallic Si M Tetrahedral Cluster.

Air- and moisture-stable heterobimetallic tetrahedral clusters [Cp(CO) MSiR] (M=Mo or W; R=SitBu ) were isolated from the reaction of N-heterocyclic carbene (NHC) stabilized silyl(silylidene) metal complexes Cp(CO) M=Si(SitBu )NHC with a mild Lewis acid (BPh ). Alternatively, treatment of the NHC-stabilized silylidene complex Cp(CO) W=Si(SitBu )NHC with stronger Lewis acids such as AlCl or B(C F ) resulted in the reversible coordination of the Lewis acid to one of the carbonyl ligands. Computational investigations revealed that the dimerization of the intermediate metal silylidyne (M≡Si) complex to a tetrahedral cluster instead of a planar four-membered ring is due to steric bulk.

NHC-Stabilized Silyl-Substituted Chlorosilylene.

The first N-heterocyclic carbene (NHC) stabilized silyl-substituted chlorosilylene () was isolated via selective dehydrochlorination by NHC from silyl-based Si(IV) precursor BuSiSiHCl. Compound can form an iron chlorosilylene complex () with an iron carbonyl dimer and undergoes chloride/hydride metathesis to yield a stable NHC-silylene hydride borane adduct (). Upon treatment with additional NHC, chlorosilylene was converted into silyl-substituted silyliumylidene ions ().

N-Heterocyclic Carbene-Stabilized Germanium and Tin Analogues of Heavier Nitriles: Synthesis, Reactivity, and Catalytic Application.

The synthesis of stable heavier analogues of nitriles as monomeric tetrylene-phosphinidenes TerEP(IDipp) (E = Ge, Sn; Ter = 2,6-MesCH, IDipp = C([N-(2,6-PrCH)CH]) was achieved by taking advantage of NHC (N-heterocyclic carbene, here IDipp) coordination to the low-valent phosphorus center. Multiple bonding character of the E-P bonds was examined experimentally and computationally. Both germanium and tin compounds undergo [2+2] cycloaddition with diphenylketene, whereas reaction of the tin derivative with (pentafluorophenyl)borane provided unique "push-pull" phosphastannene (Ter)(Ar)Sn = P(IDipp) (Ar = CF[B(F)(CF)]).

Sleep quality in patients with primary aldosteronism.

Objective: In subjects at high risk for sleep apnea (SA), aldosterone concentrations correlate with severity of SA and primary aldosteronism (PA) is very often diagnosed. Patients with PA show a high prevalence of SA. Treatment of PA either by adrenalectomy (ADX) or mineralocorticoid receptor (MR) blockade is thought to abolish the increased comorbidities.