Accessing Homo- and Heterobimetallic Complexes with a Dianionic Pentadentate Ligand.

The tetrapyrazolylpyridyl diborate (BPzPy) ligand provides a suitable platform for the isolation of heterobimetallic main-group element compounds as well as homotetrametallic copper complexes. The heterobimetallic tin(II)-lithium(I) () and tin(II)-thallium(I) () complexes have been synthesized, isolated, and fully characterized including single-crystal X-ray diffraction analysis. When reacted with copper(I) sources, complex grants access to a homotetrametallic copper(I) complex ().

Novel triphenyltin(IV) compounds with carboxylato -functionalized 2-quinolones as promising potential anticancer drug candidates: and evaluation.

Three newly synthesized triphenyltin(IV) compounds, Ph3SnL1 (L1- = 3-(4-methyl-2-oxoquinolin-1(2)-yl)propanoato), Ph3SnL2 (L2- = 2-(4-methyl-2-oxoquinolin-1(2)-yl)ethanoato), and Ph3SnL3 (L3- = 2-(4-hydroxy-2-oxoquinolin-1(2)-yl)ethanoato), were characterized by elemental microanalysis, FT-IR spectroscopy and multinuclear (H, C and Sn) NMR spectroscopy. A single X-ray diffraction study indicates that compounds Ph3SnL1 and Ph3SnL2 exhibit a 1D zig-zag chain polymeric structure, which in the case of Ph3SnL2 is additionally stabilized by π-interactions. In addition, the synthesized compounds were further examined using density functional theory and natural bond orbital analysis.

Metal-metal cooperativity boosts Lewis basicity and reduction properties of the bis(gallanediyl) LGa.

The interplay of two proximate gallium centres equips the bimetallic complex LGa (1, L = 1,2--Cy[NC(Me)C(H)C(Me)N(Dip)], Dip = 2,6-i-PrCH) with increased Lewis basicity and higher reducing power compared to the monometallic gallanediyl LGa (2, L = HC[MeCN(Dip)]) as evidenced by cross-over experiments. Quantum chemical calculations were employed to support the experimental findings.

Anion-Dependent Reactivity of Mono- and Dinuclear Boron Cations.

The dinuclear bis(N-heterocyclic carbene) borane adduct 2 rapidly reacts with tritylium salts at room temperature but the outcome is strongly impacted by the respective counter-ion. Using tritylium tetrakis(perfluoro-tert-butoxy)aluminate affords - depending on the solvent - either the bis(boronium) ion 4 or the hydride-bridged dication 5. In case of tritylium hexafluorophosphate, however, H/F exchange occurs between boron and phosphorus yielding the dinuclear BF adduct 3 along with phosphorus dihydride trifluoride.

A molecular aluminium fulleride.

The reaction of alumylene [(nacnac)Al] (1) with C fashions the first example of a structurally characterised aluminium-fulleride complex, [{(nacnac)Al}C] (2), in which the Al centres are covalently bound to significantly elongated 6 : 6 bonds. Hydrolysis of 2 yields CH and the reaction of 2 with [{nacnac)Mg}] cleaved off the Al fragments by affording the fulleride [{nacnac)Mg}C].

A tetranuclear magnesium hydride cluster with a four-coordinate hydride in near square-planar geometry.

A tetranuclear magnesium hydride complex based on the β-oxo-δ-diiminate (BODDI) ligand was isolated. In the solid state, the complex features three bridging μ-hydrides and one unprecedented four-coordinate hydride in a nearly square-planar coordination environment. In the solid state, two different coordination polymers are observed depending on whether the axial or equatorial oxygen lone pairs of 1,4-dioxane are engaged in bonding to magnesium.

simpleISM-A straight forward guide to upgrade from confocal to ISM.

Resolution in a confocal laser scanning microscopes (CLSM) can be improved if the pinhole is closed. But closing the pinhole will deteriorate the signal to noise ratio (SNR). A simple technique to improve the SNR while keeping the resolution same by upgrading the system to an image scanning microscope.

Effective or predatory funding? Evaluating the hidden costs of grant applications.

Researchers are spending an increasing fraction of their time on applying for funding; however, the current funding system has considerable deficiencies in reliably evaluating the merit of research proposals, despite extensive efforts on the sides of applicants, grant reviewers and decision committees. For some funding schemes, the systemic costs of the application process as a whole can even outweigh the granted resources-a phenomenon that could be considered as predatory funding. We present five recommendations to remedy this unsatisfactory situation.

A Planar Five-Membered Aromatic Ring Stabilized by Only Two π-Electrons.

Many chemicals known today are partially or fully aromatic, since a ring framework experiences additional stabilization through the delocalization of π-electrons. While aromatic rings with equal numbers of π-electrons and ring atoms such as benzene are particularly stable, those with the minimally required two π-electrons are very rare and yet remain limited to three- and four-membered rings if not stabilized in the coordination sphere of heavy metals. Here we report the facile synthesis of a dipotassium cyclopentagallene, a unique example of a five-membered aromatic ring stabilized by only two π-electrons.

A Highly Fluorescent Dinuclear Aluminium Complex with Near-Unity Quantum Yield.

The high natural abundance of aluminium makes the respective fluorophores attractive for various optical applications, but photoluminescence quantum yields above 0.7 have yet not been reported for solutions of aluminium complexes. In this contribution, a dinuclear aluminium(III) complex featuring enhanced photoluminescence properties is described.

Synthesis, characterization, and reactivity of group 13 hydride complexes based on amido-amine ligands.

The preparation of group 13 hydride complexes supported by N,N',N'-substituted 1,2-ethanediamines is reported. Dihydridoalanes LAlH2, for which the aggregation behaviour in solution and in the solid state is modulated by the steric bulk of the aryl substituent, readily react with elemental sulphur affording dinuclear aluminium sulphide complexes. Chloridohydrido trielanes LEHCl (E = B, Al, Ga) have been synthesized as well starting from the hydrochloride salts of the protio-ligands and the chlorido substituent within LAlHCl is readily replaced using Li[N(SiMe3)2].

Calcium and Magnesium Bis(β-diketiminate) Complexes: Impact of the Alkylene Bridge on Schlenk-Type Rearrangements.

Dinuclear heteroleptic alkaline-earth-metal complexes are interesting synthetic targets because the close proximity of two metals allows for cooperative effects. However, these complexes are also prone to undergoing Schlenk-type rearrangements, affording less-active homoleptic complexes. Here we present the metalation of bis(β-diketimine) ligands possessing flexible bridging groups, i.

Cooperative Bond Activation by a Bimetallic Main-Group Complex.

Inspired by natural metalloenzymes that efficiently catalyze a variety of transformations, chemists have developed large numbers of dinuclear transition-metal complexes with extraordinary properties and reactivity patterns. For main-group element compounds, however, metal-metal cooperativity is much less explored. Here we present the synthesis and characterization of a room-temperature-stable compound with two separated two-coordinated gallium(I) centers possessing both a lone pair of electrons and a vacant orbital, reminiscent of singlet carbenes.

Ditopic bis(,','-substituted 1,2-ethanediamine) ligands: synthesis and coordination chemistry.

The synthesis of two different types of bis(N,N',N'-substituted 1,2-ethanediamine)s, bridged either through the secondary (type 1) or tertiary (type 2) amine groups is reported. Selected protio-ligands have been applied in subsequent metallation reactions using aluminium, magnesium, tin, and zinc sources allowing to isolate five mononuclear and eight dinuclear complexes. All complexes have been fully characterized and their solid-state structures have been studied by means of single-crystal X-ray diffraction analysis.

Magnesium bis(amidinate) and bis(guanidinate) complexes: impact of the ligand backbone and bridging groups on the coordination behaviour.

A library of ten dinucleating bis(amidine) and bis(guanidine) ligands, in which the bridging groups, terminal rests, and backbone substituents were systematically altered, has been synthesized and subsequently applied in metallation reactions using three different magnesium sources. Eight Mg complexes could be isolated and fully characterized, and in seven cases their solid-state structure could be determined by means of single crystal X-ray diffraction analysis. The results evidence a versatile coordination behaviour, which ranges from the first dinuclear heteroleptic magnesium iodide complex to dinuclear homoleptic complexes.

Nucleophilic Magnesium Silanide and Silaamidinate Derivatives.

Density functional theory (DFT) calculations demonstrate that the previously reported reaction of [(BDI)Mg--Bu] (BDI = HC{(Me)CN-Dipp}; Dipp = 2,6-diisopropylphenyl) with the silaborane MePhSi-Bpin provides the magnesium silanide derivative [(BDI)MgSiMePh], through the intermediacy of a short-lived silyl-pinacolato-organoborate species. The nucleophilic character of the resultant silanide anion is assayed through a series of reactions with RN═C═NR (R = i-Pr, Cy, -Bu) and -tolN═C═N--tol. When they are performed in a strict 1:1 stoichiometry, all four reactions result in silyl addition to the carbodiimide carbon center and formation of the corresponding β-diketiminato magnesium silaamidinate complexes.

Salt metathesis as an alternative approach to access aluminium(i) and gallium(i) β-diketiminates.

Salt metathesis, i.e. the reaction of sodium β-diketiminate with (AlCp*)4 and GaCp*, respectively, is a valuable pathway to access the respective aluminium(i) and gallium(i) β-diketiminates I and II.

Synthesis and Coordination Chemistry of 3,4-Ethylene-Bridged 1,1,2,5-Tetrasubstituted Biguanides.

The synthesis of 3,4-ethylene-bridged 1,1,2,5-tetrasubstituted biguanides is reported, which are accessible by three alternative routes. Exemplary molecular structures of the ligand and an observed side product have been elucidated by X-ray diffraction analysis. Mono- and dinuclear complexes of the biguanide in both its neutral and monoanionic forms were obtained, including examples of aluminum, copper, magnesium, potassium, tin, and zinc, indicating a versatile coordination behavior, as evidenced by means of single-crystal X-ray diffraction analysis.

C-F bond activation by pentamethylcyclopentadienyl-aluminium(i): a combined experimental/computational exercise.

The reaction of (Cp*Al) with a series of fluoro(hetero)arenes has been investigated and C-F bond activation was observed with perfluorotoluene, pentafluoropyridine as well as 1,2,3,4-tetrafluoro-, pentafluoro- and hexafluorobenzene. The reaction mechanism has been probed by means of DFT calculations and the computational findings are in good agreement with the experimental observations.

Facile oxidative addition of O and S by an indium bis(carbene) analogue.

The oxidative addition of oxygen towards an indium bis(carbenoid) yields an almost planar InO ring, an isovalence-electronic analogue of dioxane, in which the indium is in the formal oxidation state +ii. The weaker oxidant sulfur, however, yields an eight-membered ring in a deck-chair conformation containing four indium(iii) centres and four sulfides in an alternating fashion. According to DFT calculations, this reactivity difference originates from kinetic rather than thermodynamic reasons.

Ligands with Two Monoanionic N,N-Binding Sites: Synthesis and Coordination Chemistry.

Polytopic ligands have become ubiquitous in coordination chemistry because they grant access to a variety of mono- and polynuclear complexes of transition metals as well as rare-earth and main-group elements. Nitrogen-based ditopic ligands, in which two monoanionic N,N-binding sites are framed within one molecule, are of particular importance and are therefore the primary focus of this review. In detail, bis(amidine)s, bis(guanidine)s, bis(β-diimine)s, bis(aminotroponimine)s, bis(pyrrolimine)s, and miscellaneous bis(N,N-chelating) ligands are reviewed.

Dinuclear Aluminum Halide Complexes Based on Bis(β-diketiminate) Ligands: Synthesis, Structures, and Electrochemical Characterization.

Twenty-three dinuclear aluminum halide complexes based on bis(β-diketiminate) ligands with various flexible and rigid bridging groups have been synthesized and fully characterized by NMR and IR spectroscopy, cyclic voltammetry, and elemental analysis. In addition, nine complexes were structurally characterized by means of single-crystal X-ray diffraction. Attempts to reduce the dinuclear species using CK remained unsuccessful, but the reduction potentials investigated by cyclic voltammetry indicate the principle feasibility.

Speech-Language Clinicians Working with Deaf Children: A Qualitative Study in Context.

Students who are deaf or hard of hearing (DHH) increasingly attend local public schools, in which speech and language clinicians (SLCs) may lack experience with the individualized needs of a heterogeneous student population. This study explored the experiences of SLCs with students who are DHH in three different types of educational settings. Fourteen SLCs were interviewed and discussed a case study.

En Route to Bis-Carbene Analogues of the Heavier Group 13 Elements: Consideration of Bridging Group and Metal(I) Source.

With the aim of exploring the effect of steric constraints imposed on the metal-metal interaction of bis-carbene analogues of thallium by the linking scaffold, seven dinuclear thallium diyls with a series of rigid, semirigid, and flexible bridging scaffolds were synthesized. The solid-state molecular structures were determined for four of these compounds by single-crystal XRD and compared with the results of DFT calculations, which were performed for all substances. These compounds serve as models to investigate the metal-metal distance in the absence of co-coordinated molecules (additional ligands, solvent molecules).