Search results for "ligand"

DOSY NMR, X-ray Structural and Ion-Mobility Mass Spectrometric Studies on Electron-Deficient and Electron-Rich M6L4 Coordination Cages.

2015

A novel modular approach to electron-deficient and electron-rich M6L4 cages is presented. From the same starting compound, via a minor modulation of the synthesis route, two C3-symmetric ligands L1 and L2 with different electronic properties are obtained in good yield. The trifluoro-triethynylbenzene-based ligand L1 is more electron-deficient than the well-known 2,4,6-tri(4-pyridyl)-1,3,5-triazine, while the trimethoxy-triethynylbenzene-based ligand L2 is more electron-rich than the corresponding benzene analogue. Complexation of the ligands with cis-protected square-planar [(dppp)Pt(OTf)2] or [(dppp)Pd(OTf)2] corner-complexes yields two electron-deficient (1a and 1b) and two electron-rich …

Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes

2015

Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)(3), with a lifetime of 70 +/- 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer ((MLCT)-M-3) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning similar to 1.6 eV from the (LC)-L-1 state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This …

Ligand exchange among iodine(I) complexes

2022

A detailed investigation of ligand exchange between iodine(I) ions in [N⋯I⋯N]+ halogen-bonded complexes is presented. Ligand exchange reactions were conducted to successfully confirm whether iodine(I) complex formation, via the classical [N⋯Ag⋯N]+ to [N⋯I⋯N]+ cation exchange reaction from their analogous Ag+ complexes, could be determined solely by using 1H NMR spectroscopy. In instances where the formation of the iodine(I) complex was unclear or in low yield by the traditional cation exchange reaction, a ligand exchange reaction was used to form the desired iodine(I) complexes in a quantitative manner. Mixing two homoleptic [N⋯I⋯N]+ iodine(I) complexes in 1 : 1 ratio was found to undergo a…

Polimeryzacja propylenu katalizowana metaloorganicznymi kompleksami z chiralnymi ligandami salenowymi

2007

Postęp badań w zakresie polimeryzacji olefin

2011

Na podstawie obszernego przeglądu literatury omówiono rozwój katalizatorów metaloorganicznych stosowanych w procesie polimeryzacji olefin z uwzględnieniem najnowszych badań w tym zakresie. Przedstawiono możliwości otrzymywania z ich udziałem produktów o różnej strukturze i właściwościach. Na tle postępu w technologii otrzymywania poliolefin scharakteryzowano wyniki najnowszych prac zespołu opolskiego, od wielu lat biorącego aktywny udział w badaniach nad opracowaniem i oceną właściwości katalitycznych kolejnych, nowych grup metaloorganicznych katalizatorów polimeryzacji i kopolimeryzacji olefin. Szczególną uwagę poświęcono katalizatorom zaliczanym do grupy układów postmetalocenowych z ligan…

Rapid self-healing and anion selectivity in metallosupramolecular gels assisted by fluorine-fluorine interactions.

2017

Simple ML2 [M = Fe(II), Co(II), Ni(II)] complexes obtained from a perfluoroalkylamide derivative of 4-aminophenyl-2,2′,6,2′-terpyridine spontaneously, yet anion selectively, self-assemble into gels, which manifest an unprecedented rapid gel strength recovery, viz. self-healing, and thermal rearrangement in aqueous dimethyl sulfoxide. The key factor for gelation and rheological properties emerges from the fluorine–fluorine interactions between the perfluorinated chains, as the corresponding hydrocarbon derivative did not form metallogels. The perfluoro-terpyridine ligand alone formed single crystals, while its Fe(II), Co(II) or Ni(II) complexes underwent rapid gelation leading to highly enta…

Dioxidomolybdenum(VI) and –tungsten(VI) complexes with tetradentate amino bisphenolates as catalysts for epoxidation

2017

Sixteen molybdenum and tungsten complexes with tripodal or linear tetradentate amino bisphenol ligands were studied as catalysts for the epoxidation of cis-cyclooctene, 1-octene, styrene, limonene and α-terpineol. These complexes can be divided into different categories upon key features, i.e. central metal (Mo versus W), side-arm donor (O versus N), hybridization of the N-donor (pyridine versus amine), ligand geometry (tripodal versus linear diamine) and sterical hindrance (Me versus tert-Bu substituents in the phenol part). All complexes can catalyse selectively the epoxidation of cis-cyclooctene by tert-butylhydroperoxide whereas the activities and selectivities towards other olefins (1-…

Synthesis and Solid-State X-ray Structure of the Mononuclear Palladium(II) Complex Based on 1,2,3-Triazole Ligand

2022

Herein, we described the synthesis and X-ray crystal structure of the new [Pd(3)2Cl2] complex with 1,2,3-triazole-based ligand (3). In the unit cell, there are two [Pd(3)2Cl2] molecules, and the asymmetric unit comprised half of this formula due to the presence of an inversion symmetry element at the Pd(II) center. The monoclinic unit cell volume is 1327.85(6) Å3, with crystal parameters of a = 10.7712(2) Å, b = 6.8500(2) Å, and c = 18.2136(6) Å, while β = 98.851(2)°. The structure comprised two trans triazole ligand units coordinated to the Pd(II) ion via one of the N-atoms of the triazole moiety. In addition, the Pd(II) is further coordinated with two tran…

Dynamics of weak interactions in the ligand layer of meta-mercaptobenzoic acid protected gold nanoclusters Au68(m-MBA)32 and Au144(m-MBA)40

2020

Atomically precise metal nanoclusters, stabilized and functionalized by organic ligands, are emerging nanomaterials with potential applications in plasmonics, nano-electronics, bio-imaging, nanocatalysis, and as therapeutic agents or drug carriers in nanomedicine. The ligand layer has an important role in modifying the physico-chemical properties of the clusters and in defining the interactions between the clusters and the environment. While this role is well recognized from a great deal of experimental studies, there is very little theoretical information on dynamical processes within the layer itself. Here, we have performed extensive molecular dynamics simulations, with forces calculated…

Redox-aktiiviset siltaavat ligandit lantanoidikomplekseissa

2017

Redox-aktiiviset siltaavat ligandit on mahdollista hapettaa tai pelkistää suhteellisen pysyviksi radikaaleiksi inertissä atmosfäärissä. Siltaavina ligandeina ne voivat koordinoitua kahden tai useamman metalli-ionin välille. Paramagneettiset siltaavat radikaaliligandit ja lantanoidit ovat lupaavia rakenneosia yksittäismolekyylimagneettien valmistuksessa, sillä radikaalien diffuusit spinorbitaalit voivat peittää lantanoidien 4f-orbitaaleja, jolloin muodostuu voimakas vaihtokytkentä lantanoidin ja radikaalin välille. Lantanoidikompleksien magneettisuus syntyy lantanoidi-ionin elektronien, spin-ratakytkennän ja kidekenttäympäristön vuorovaikutuksista ja siihen vaikuttaa ligandien ja metallin vä…