Trapping an unprecedented octacoordinated iron(II) complex with neutral bis-tetrazolylpyridyl ligands and solvent molecules.

Iron(II) can show a very rich coordination chemistry with concomitant modulation of its properties as promising functional materials. Metalation of the neutral tridentate nitrogen-donor -coordinating ligand 2,6-bis(2-(methyl)-2-tetrazol-5-yl)pyridine (Mebtp) with Fe(ClO)·6HO through accurate solvent polarity control enables the selective crystallization of [Fe(Mebtp)](ClO)·MeCN·2.75HO (2·MeCN·2.

Molecular Ruthenium Cyclopentadienone Bifunctional Catalysts for the Conversion of Sugar Platforms to Hydrogen.

Molecular ruthenium cyclopentadienone complexes were employed for the first time as pre-catalysts in the homogeneously catalysed Aqueous Phase Reforming (APR) of glucose. Shvo's complex resulted the best pre-catalyst (loading 2 mol %) with H yields up to 28.9 % at 150 °C.

A proficient multivariate approach for iron(II) spin crossover behaviour modelling in the solid state.

Iron(II) -pyrazolilpyridyl (bpp-R) complexes [Fe(bpp-R)](X)·solvent, R = substituent and X = anion, can undergo a spin transition from high ( = 2, HS) to low spin ( = 0, LS), being spin crossover (SCO) in the solid state. The distortion of the octahedral coordination environment around the metal centre is governed by crystal packing, the intermolecular interactions among the substituent R of the bpp-R ligands, the anion X, and the co-crystallized solvent, and this modulates the SCO behaviour. In this work, an innovative multivariate approach, through the combination of the chemometric tools Principal Component Analysis and Partial Least Squares regression, was applied on the coordination bond distances and angles and selected torsional angles of the available HS structures.

Advances in Catalytic Routes for the Homogeneous Green Conversion of the Bio-Based Platform 5-Hydroxymethylfurfural.

5-Hydroxymethylfufural (HMF) is an intriguing platform molecule that can be obtained from biomasses and that can lead to the production of a wide range of products, intermediates, or monomers. The presence of different moieties in HMF (hydroxy, aldehyde, furan ring) allows to carry out different transformations such as selective oxidations and hydrogenations, reductive aminations, etherifications, decarbonylations, and acetalizations. This is a great chance in a biorefinery perspective but requires the development of active and highly selective catalysts.

Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization.

Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application.

Application of the SMALP technology to the isolation of GPCRs from low-yielding cell lines.

The ability of styrene-maleic acid (SMAc) co-polymers to spontaneously insert into biological membranes can be exploited to extract G protein-coupled receptors (GPCRs) embedded in styrene-maleic acid lipid particles (SMALPs), preserving the native environment around the protein and thus enhancing the feasibility of functional studies. So far, the SMALP technology has been primarily employed on non-mammalian cells and protocols are not optimized for adherent human cell lines, which cannot be harvested in large amounts. In this work, a fine investigation of key parameters affecting the formation of SMALPs was undertaken with the purpose of maximizing the yield of extraction of a recombinant form of human β-adrenergic receptor (rhβAR) from HEK293T cells.

Thermal Growth of Au-Fe Heterometallic Carbonyl Clusters Containing N-Heterocyclic Carbene and Phosphine Ligands.

The thermal reactions of [NEt][Fe(CO)(AuNHC)] [NHC = IMes ([NEt][]) or IPr ([NEt][]); IMes = CNH(CHMe); IPr = CNH(CHPr)], Fe(CO)(AuNHC) [NHC = IMes () or IPr ()], Fe(CO)(AuIMes)(AuIPr) (), and Fe(CO)(AuNHC)(AuPPh) [NHC = IMes () or IPr ()] were investigated in different solvents [CHCl, CHCN, dimethylformamide, and dimethyl sulfoxide (dmso)] and at different temperatures (50-160 °C) in an attempt to obtain higher-nuclearity clusters. and completely decomposed in refluxing CHCl, resulting in [Fe(CO)(AuNHC)] [NHC = IMes () or IPr ()]. Traces of [Fe(CO)(CCH)] () were obtained as a side product.

Polymerization Isomerism in [{MFe(CO)} ] (M = Cu, Ag, Au; n = 3, 4) Molecular Clusters Supported by Metallophilic Interactions.

Triangular clusters [{MFe(CO)}] (M = Cu, 4; Ag, 5; Au, 6) were selectively obtained by heating Fe(CO)(MIMes) (M = Cu, 1; Ag, 2; Au, 3; IMes = CNH(CHMe)). 1-3 were synthesized by reacting Na[Fe(CO)]·2thf with 2 equiv of M(IMes)Cl. As previously described, the direct reactions of Na[Fe(CO)]·2thf with one equivalent of M(I) salts resulted in the triangular cluster [{CuFe(CO)}] for Cu, whereas the square clusters [{MFe(CO)}] were formed for Ag and Au.

Click-Derived Triazolylidenes as Chelating Ligands: Achievement of a Neutral and Luminescent Iridium(III)-Triazolide Complex.

Versatility in the synthesis of triazole derivatives was exploited to obtain convenient mesoionic carbenes working as chelating or cyclometalating ligands for the preparation of cationic or neutral iridium(III) complexes. We present the synthesis and characterization of three new cationic cyclometalating iridium(III) complexes (1-3-BF) and a neutral one (4), equipped with functionalized triazolylidene ligands. All the complexes are obtained in good yields, present irreversible or quasi-reversible oxidation and reduction processes, and display good photophysical stability.

Mechanistic Insight into Electrocatalytic H Production by [Fe(CN){μ-CN(Me)}(μ-CO)(CO)(Cp)]: Effects of Dithiolate Replacement in [FeFe] Hydrogenase Models.

DFT has been used to investigate viable mechanisms of the hydrogen evolution reaction (HER) electrocatalyzed by [Fe(CN){μ-CN(Me)}(μ-CO)(CO)(Cp)] (1) in AcOH. Molecular details underlying the proposed ECEC electrochemical sequence have been studied, and the key functionalities of CN and amino-carbyne ligands have been elucidated. After the first reduction, CN works as a relay for the first proton from AcOH to the carbyne, with this ligand serving as the main electron acceptor for both reduction steps.

Negatively charged Ir(iii) cyclometalated complexes containing a chelating bis-tetrazolato ligand: synthesis, photophysics and the study of reactivity with electrophiles.

The bis-tetrazolate dianion [1,2 BTB](2-), which is the deprotonated form of 1,2 bis-(1H-tetrazol-5-yl)benzene [1,2-H2BTB], is for the first time exploited as an ancillary N^N ligand for negatively charged [Ir(C^N)2(N^N)](-)-type complexes, where C^N is represented by cyclometalated 2-phenylpyridine (ppy) or 2-(2,4-difluorophenyl)pyridine (F2ppy). The new Ir(iii) complexes [Ir(ppy)2(1,2 BTB)]- and [Ir(F2ppy)2(1,2 BTB)]- have been fully characterised and the analysis of the X-ray structure of [Ir(ppy)2(1,2 BTB)]- confirmed the coordination of the [1,2 BTB](2-) dianion in a bis chelated fashion through the N-atoms adjacent to each of the tetrazolic carbons. Both of the new anionic Ir(iii) complexes displayed phosphorescence in the visible region, with intense sky-blue (λmax = 460-490 nm) or aqua (λmax = 490-520 nm) emissions originating from [Ir(F2ppy)2(1,2 BTB)]- and [Ir(ppy)2(1,2 BTB)]-, respectively.

Straightforward synthesis of iron cyclopentadienone N-heterocyclic carbene complexes.

Novel iron complexes bearing both cyclopentadienone and N-heterocyclic carbene ancillary ligands were obtained by a straightforward synthesis from Fe2(CO)9. The preparation represents a rare example of silver transmetallation involving iron. The reaction is general and occurs in the presence of variously functionalized NHC and cyclopentadienones.

Substrate and product role in the Shvo's catalyzed selective hydrogenation of the platform bio-based chemical 5-hydroxymethylfurfural.

The bio-based substrate and target product 2,5-bishydroxymethylfuran (BHMF) demonstrated to influence the reaction kinetics in the homogeneous reduction of 5-hydroxymethylfurfural (HMF) catalyzed by the Ru-based Shvo's catalyst. A combined experimental and computational study supports an important role of the -CH2OH moiety which may be involved in the catalytic cycle toward the formation of different intermediates from HMF and BHMF. The reaction is selective and leads to quantitative formation of BHMF working under mild conditions.

C-C bond formation in diiron complexes.

The growing effort to design new sustainable synthetic methodologies, based on readily available and environmentally friendly transition metals, has boosted research on iron complexes. This review article focuses on C-C-bond-forming reactions occurring at bridging ligands in diiron complexes, aimed at evidencing distinctive aspects and advantages associated with the presence of two adjacent iron centres. A number of diiron-mediated C-C-bond-forming reactions reported in the literature, including nucleophilic and electrophilic additions and insertion and cycloaddition reactions, have been accumulated over the years, which, together with more recent developments, indicate that diiron complexes might provide promising alternatives to precious metals in the challenging field of metal-promoted C-C bond formation.

[3+2+1] cycloaddition involving alkynes, CO and bridging vinyliminium ligands in diiron complexes: a dinuclear version of the Dötz reaction?

The vinyliminium complex [Fe2{mu-eta(1):eta(3)-C(SiMe3)=CHC=N(Me)2}(mu-CO)(CO)(Cp)2][SO3CF3] reacts with HC[triple bond]CR (R = CPh2OH), affording a mixture of the 2,4,6-trisubstituted oxo-eta(5)-cyclohexadienyl complex [Fe{eta(5)-C6H2O(NMe2)(SiMe3)(R)}(Cp)], the 2,6-disubstituted phenol C6H3R(NMe2)OH (R = CHPh2) and 1,2,4-trisubstituted ferrocene [1-NMe2-2-R-4-SiMe3-Fc]. The corresponding reaction with HC[triple bond]CR (R = CMe2OH) yields analogous products: [Fe{eta(5)-C6H2O(NMe2)(SiMe3)(R')}(Cp)] (R' = CMe=CH2), the phenol C6H3R'(NMe2)OH together with [1-NMe2-2-R-4-SiMe3-Fc].

Enzyme electrodes based on sono-gel containing ferrocenyl compounds.

An amperometric-mediated glucose sensor has been developed by employing a silica sono-gel carbon composite electrode (SCC). The chosen mediators, ferrocene (Fc) and 1,2-diferrocenylethane (1), have been immobilized in the sono-gel composite matrix. The complex 1 has been employed for the first time as an electron transfer mediator for signal transduction from the active centre of the enzyme to the electrode conductive surface.

Synthesis of new poly(propylenimine) dendrimers DAB-dendr-[NH(O)COCH2CH2OC(O)C5H4Rh(NBD)](n) [n=4, 8, 16, 32, 64] functionalized with alkoxycarbonylcyclopentadienyl complexes of rhodium(I).

The reaction between [Rh[C5H4CO2(CH)2OH](NBD)] (1) and 1,1'-carbonyldiimidazole (CDI) leads to the new CO2-imidazole functionalized alkoxycarbonylcyclopentadienyl complex [Rh[C5H4CO2(CH2)2O2C-Im](NBD)] (2) (Im=imidazole). The latter was treated with five generations of poly(propylenimine) dendrimers DAB-dendr-(NH2)(n) [n=4, 8, 16, 32, 64] (DAB=diaminobutane) to accomplish the synthesis of the new organometallic dendritic macromolecules DAB-dendr-[NH(O)COCH2CH2OC(O)C5H4Rh(NBD)](n) [n=4 (4), 8 (5), 16 (6), 32 (7), 64 (8)] based on flexible poly(propylenimine) dendrimer cores, built up to the fifth generation. Spectroscopic characterization of all the new compounds will be presented and discussed.