Browse
Submit Data
Databases
API
Help

Dataset Information

25 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A diketiminate-bound diiron complex with a bridging carbonate ligand.

ABSTRACT: Reduction of carbon dioxide by a diiron(I) complex gives mu-carbonato-kappa(3)O:O',O''-bis{[2,2,6,6-tetramethyl-3,5-bis(2,4,6-triisopropylphenyl)heptane-2,5-diiminate(1-)-kappa(2)N,N']iron(II)} toluene disolvate, [Fe(2)(C(41)H(65)N)(2)(CO(3))].2C(7)H(8), a diiron(II) species with a bridging carbonate ligand. The asymmetric unit contains one diiron complex and two cocrystallized toluene solvent molecules that are distributed over three sites, one with atoms in general positions and two in crystallographic 1 sites. Both Fe(II) atoms are eta(2)-coordinated to diketiminate ligands, but eta(1)- and eta(2)-coordinated to the bridging carbonate ligand. Thus, one Fe(II) center is three-coordinate and the other is four-coordinate. The bridging carbonate ligand is nearly perpendicular to the iron-diketiminate plane of the four-coordinate Fe(II) center and parallel to the plane of the three-coordinate Fe(II) center.

SUBMITTER: Sadique AR

PROVIDER: S-EPMC2675934 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Mechanism of Diiron Hydrogenase Complexes Controlled by Nature of Bridging Dithiolate Ligand.

Project description:Bio-inorganic complexes inspired by hydrogenase enzymes are designed to catalyze the hydrogen evolution reaction (HER). A series of new diiron hydrogenase mimic complexes with one or two terminal tris(4-methoxyphenyl)phosphine and different μ-bridging dithiolate ligands and show catalytic activity towards electrochemical proton reduction in the presence of weak and strong acids. A series of propane- and benzene-dithiolato-bridged complexes was synthesized, crystallized, and characterized by various spectroscopic techniques and quantum chemical calculations. Their electrochemical properties as well as the detailed reaction mechanisms of the HER are elucidated by density functional theory (DFT) methods. The nature of the μ-bridging dithiolate is critically controlling the reaction and performance of the HER of the complexes. In contrast, terminal phosphine ligands have no significant effects on redox activities and mechanism. Mono- or di-substituted propane-dithiolate complexes afford a sequential reduction (electrochemical; E) and protonation (chemical; C) mechanism (ECEC), while the μ-benzene dithiolate complexes follow a different reaction mechanism and are more efficient HER catalysts.

| S-EPMC8734113 | biostudies-literature

Vibrational characterization of a diiron bridging hydride complex - a model for hydrogen catalysis.

Project description:A diiron complex containing a bridging hydride and a protonated terminal thiolate of the form [(μ,κ2-bdtH)(μ-PPh2)(μ-H)Fe2(CO)5]+ has been investigated through 57Fe nuclear resonance vibrational spectroscopy (NRVS) and interpreted using density functional theory (DFT) calculations. We report the Fe-μH-Fe wagging mode, and indications for Fe-μD stretching vibrations in the D-isotopologue, observed by 57Fe-NRVS. Our combined approach demonstrates an asymmetric sharing of the hydride between the two iron sites that yields two nondegenerate Fe-μH/D stretching vibrations. The studied complex provides an important model relevant to biological hydrogen catalysis intermediates. The complex mimics proposals for the binuclear metal sites in [FeFe] and [NiFe] hydrogenases. It is also an appealing prototype for the 'Janus intermediate' of nitrogenase, which has been proposed to contain two bridging Fe-H-Fe hydrides and two protonated sulfurs at the FeMo-cofactor. The significance of observing indirect effects of the bridging hydride, as well as obstacles in its direct observation, is discussed in the context of biological hydrogen intermediates.

| S-EPMC8159291 | biostudies-literature

An iron(ii) hydride complex of a ligand with two adjacent ?-diketiminate binding sites and its reactivity.

Project description:After lithiation of PYR-H2 (PYR = [(NC(Me)C(H)C(Me)NC6H3(iPr)2)2(C5H3N)](2-)) - the precursor of an expanded ?-diketiminato ligand system with two binding pockets - with KN(TMS)2 the reaction of the resulting potassium salt with FeBr2 led to a dinuclear iron(ii) bromide complex [(PYR)Fe(?-Br)2Fe] (1). Through treatment with KHBEt3 the bromide ligands could be replaced by hydrides to yield [PYR)Fe2(?-H)2] (2), a distorted analogue of known ?-diketiminato iron hydride complexes, as evidenced by NMR, Mößbauer and X-ray absorption spectroscopy, as well as by its reactivity: for instance, 2 reacts with the proton source lutidinium triflate via protonation of the hydride ligands to form an iron(ii) product [(PYR)Fe2(OTf)2] (4), while CO2 inserts into the Fe-H bonds generating the formate complex [(PYR)Fe2(?-HCOO)2] (5); in the presence of traces of water partial hydrolysis occurs so that [(PYR)Fe2(?-OH)(?-HCOO)] (6) is isolated. Altogether, the iron(ii) chemistry supported by the PYR(2-) ligand is distinctly different from the one of nickel(ii), where both, the arrangement of the two binding pockets and the additional pyridyl donor led to diverging features as compared with the corresponding system based on the parent ?-diketiminato ligand.

| S-EPMC5536248 | biostudies-literature

Photoluminescent DNA binding and cytotoxic activity of a platinum(II) complex bearing a tetradentate β-diketiminate ligand.

Project description:A platinum(II) complex of a monoanionic, tetradentate β-diketiminate (BDI) ligand with pendant quinoline arms, BDI(QQ)H, is reported. The complex, [Pt(BDI(QQ))]Cl, is emissive in DMSO, but non-emissive in aqueous buffer. Upon binding DNA in buffer, however, a 150-fold turn-on in emission intensity occurs. Dynamic light scattering and (1)H NMR spectroscopy indicate that [Pt(BDI(QQ))]Cl forms non-emissive aggregates in aqueous solution; DNA-binding disperses the aggregates leading to the large emission turn-on response. The cytotoxic activity of the complex, measured in two cancer cell lines, is comparable to or better than that of the established anticancer drug cisplatin.

| S-EPMC3566370 | biostudies-literature

N-H Bond Formation at a Diiron Bridging Nitride.

Project description:Despite their connection to ammonia synthesis, little is known about the ability of iron-bound, bridging nitrides to form N-H bonds. Herein we report a linear diiron bridging nitride complex supported by a redox-active macrocycle. The unique ability of the ligand scaffold to adapt to the geometric preference of the bridging species was found to facilitate the formation of N-H bonds via proton-coupled electron transfer to generate a μ-amide product. The structurally analogous μ-silyl- and μ-borylamide complexes were shown to form from the net insertion of the nitride into the E-H bonds (E=B, Si). Protonation of the parent bridging amide produced ammonia in high yield, and treatment of the nitride with PhSH was found to liberate NH3 in high yield through a reaction that engages the redox-activity of the ligand during PCET.

| S-EPMC7680347 | biostudies-literature

Isomerism and dynamic behavior of bridging phosphaalkynes bound to a dicopper complex.

Project description:A dicopper complex featuring a symmetrically bridging nitrile ligand and supported by a binucleating naphthyridine-based ligand, [Cu2(?-? 1 :? 1 -MeCN)DPFN](NTf2)2, was treated with phosphaalkynes (RC[triple bond, length as m-dash]P, isoelectronic analogues of nitriles) to yield dicopper complexes that exhibit phosphaalkynes in rare ?-? 2:? 2 binding coordination modes. X-ray crystallography revealed that these unusual "tilted" structures exist in two isomeric forms (R "up" vs. R "sideways"), depending on the steric profile of the phosphaalkyne's alkyl group (R = Me, Ad, or t Bu). Only one isomer is observed in both solution and the solid state for R = Me (sideways) and t Bu (up). With intermediate steric bulk (R = Ad), the energy difference between the two geometries is small enough that both are observed in solution, and NMR spectroscopy and computations indicate that the solid-state structure corresponds to the minor isomer observed in solution. Meanwhile, treatment of [Cu2(?-? 1:? 1-MeCN)DPFN](NTf2)2 with 2-butyne affords [Cu2(?-? 2:? 2-(MeC[triple bond, length as m-dash]CMe))DPFN](NTf2)2: its similar ligand geometry demonstrates that the tilted ?-? 2:? 2 binding mode is not limited to phosphaalkynes but reflects a more general trend, which can be rationalized via an NBO analysis showing maximization of ?-backbonding.

| S-EPMC7069238 | biostudies-literature

Chemistry of nitrosyliron complexes supported by a β-diketiminate ligand.

Project description:Several nitrosyl complexes of Fe and Co have been prepared using the sterically hindered Ar-nacnac ligand (Ar-nacnac = anion of [(2,6-diisopropylphenyl)NC(Me)](2)CH). The dinitrosyliron complexes [Fe(NO)(2)(Ar-nacnac)] (1) and (Bu(4)N)[Fe(NO)(2)(Ar-nacnac)] (2) react with [Fe(III)(TPP)Cl] (TPP = tetraphenylporphine dianion) to generate [Fe(II)(NO)(TPP)] and the corresponding mononitrosyliron complexes. The factors governing NO transfer with dinitrosyliron complexes (DNICs) 1 and 2 are evaluated, together with the chemistry of the related mononitrosyliron complex, [Fe(NO)Br(Ar-nacnac)] (4). The synthesis and properties of the related cobalt dinitrosyl [Co(NO)(2)(Ar-nacnac)] (3) is also discussed for comparison to DNICs 1 and 2. The solid-state structures of several of these compounds as determined by X-ray crystallography are reported.

| S-EPMC4603656 | biostudies-literature

PARACEST properties of a dinuclear neodymium(III) complex bound to DNA or carbonate.

Project description:A dinuclear Nd(III) macrocyclic complex of 1 (1,4-bis[1-(4,7,10-tris(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane]-p-xylene) and mononuclear complexes of 1,4,7-tris-1,4,7,10-tetraazacyclododecane, 2, and 1,4,7-tris[(N-N-diethyl)carbamoylmethyl]-1,4,7,10-tetraazacyclododecane, 3, are prepared. Complexes of 1 and 2 give rise to a PARACEST (paramagnetic chemical exchange saturation transfer) peak from exchangeable amide protons that resonate approximately 12 ppm downfield from the bulk water proton resonance. The dinuclear Nd(III) complex is promising as a PARACEST contrast agent for MRI applications, because it has an optimal pH of 7.5 and the rate constant for amide proton exchange (2700 s(-1)) is nearly as large as it can be within slow exchange conditions with bulk water. Dinuclear Ln(2)(1) complexes (Ln(III) = Nd(III), Eu(III)) bind tightly to anionic ligands including carbonate, diethyl phosphate, and DNA. The CEST amide peak of Nd(2)(1) is enhanced by certain DNA sequences that contain hairpin loops, but decreases in the presence of diethyl phosphate or carbonate. Direct excitation luminescence studies of Eu(2)(1) show that double-stranded and hairpin-loop DNA sequences displace one water ligand on each Eu(III) center. DNA displaces carbonate ion despite the low dissociation constant for the Eu(2)(1) carbonate complex (K(d) = 15 microM). Enhancement of the CEST effect of a lanthanide complex by binding to DNA is a promising step toward the preparation of PARACEST agents containing DNA scaffolds.

| S-EPMC2717892 | biostudies-literature

Crystal structure of a dimeric ?-diketiminate magnesium complex.

Project description:The solid-state structure of a dimeric ?-diketiminate magnesium(II) complex is discussed. The compound, di-?-iodido-bis-[(-{4-amino-1,5-bis-[2,6-bis-(propan-2-yl)phen-yl]pent-3-en-2-yl-idene}aza-nido-?2N,N')magnesium(II)] toluene sesquisolvate, [Mg2(C29H41N2)2I2]·1.5C7H8, crystallizes as two independent mol-ecules, each with 2/m crystallographic site symmetry, located at Wyckoff sites 2c and 2d. These have symmetry-equivalent magnesium atoms bridged by ?-iodide ligands with very similar Mg-I distances. The two Mg atoms are located slightly below (?0.5?Å) the least-squares plane defined by N-C-C-N atoms in the ligand scaffold, and are approximately tetra-hedrally coordinated. One and one-half toluene solvent mol-ecules are disordered with respect to mirror-site symmetry at Wyckoff sites 4i and 2a, respectively. In the former case, two toluene mol-ecules inter-act in an off-center parallel stacking arrangement; the shortest C to C' (?-?) distance of 3.72?(1)?Å was measured for this inter-action.

| S-EPMC5137601 | biostudies-literature

Spectroscopy and DFT Calculations of Flavo-Diiron Nitric Oxide Reductase Identify Bridging Structures of NO-Coordinated Diiron Intermediates.

Project description:Flavo-diiron proteins (FDPs) are widespread in anaerobic bacteria, archaea, and protozoa, where they serve as the terminal components of dioxygen and nitric oxide reductive scavenging pathways. FDPs contain an N,O-ligated diiron site adjacent to a flavin mononucleotide (FMN) cofactor. The diiron site is structurally similar to those in hemerythrin, ribonucleotide reductase, and methane monooxygenase. However, only FDPs turn over NO to N2O at significant rates and yields. Previous studies revealed sequential binding of two NO molecules to the diferrous site, forming mono- and dinitrosyl intermediates leading to N2O formation. In the present work, these mono- and dinitrosyl intermediates have been characterized by EPR and Mössbauer spectroscopies and DFT calculations. Our results show that the iron proximal to the cofactor binds the first NO to form the diiron mononitrosyl complex, implying the iron distal to the FMN binds the second NO to form the diiron dinitrosyl intermediate. The exchange-coupling constants, J (H = JS1·S2), were found to differ substantially, +17 cm-1 for the diiron mononitrosyl and +60 cm-1 for the diiron dinitrosyl. Notwithstanding this large difference, our findings indicate retention of at least one hydroxo bridge throughout the NOR catalytic cycle. The Mossbauer hyperfine parameters and DFT calculations confirmed a semibridging NO- ligand in the mononitrosyl intermediate that lowers the exchange parameter. The DFT calculations on the dinitrosyl intermediate suggest a contribution to J from direct exchange between the S = 1 spins on the NO- ligands, which could initiate N-N bond formation. Our results provide insight into why FDPs are the only known nonheme diiron enzymes that competently turn over NO to N2O.

| S-EPMC6602092 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data