RESUMO
Here, we show for the first time that main-chain organometallic polymers (MCOPs) can be prepared from Janus N-heterocyclic carbene (NHC) linkers and polynuclear cluster nodes. The crosslinked framework Co4S4-MCOP is synthesized via ligand displacement reactions and undergoes reversible electron transfer in the solid state. Discrete molecular cluster species can be excised from the framework by digesting the solid in solutions of excess monocarbene. Finally, we demonstrate a synthetic route to monodisperse framework particles via coordination modulation.
RESUMO
The title compounds, [Mo(C5H5)(COCH3)(C6H12N3P)(CO)2], (1), and [Mo(C5H5)(COCH3)(C9H16N3O2P)(C6H5)2))(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. The mol-ecular structures of these complexes are quite similar, exhibiting a four-legged piano-stool geometry with trans-disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substanti-ally. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the mol-ecules into centrosymmetrical dimers through C-Hâ¯O inter-actions with a cyclo-penta-dienyl ligand of a neighboring mol-ecule, and these dimers are linked into layers parallel to (100) by C-Hâ¯O inter-actions between the molybdenum acetyl and the cyclo-penta-dienyl ligand of another neighbor. The extended structure of (2) is dominated by C-Hâ¯O inter-actions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the mol-ecules into centrosymmetrical dimers and link them into chains along [010]. Additional C-Hâ¯O inter-actions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101).
RESUMO
Negatively substituted trimethylenecyclopropane dianions, a subclass of hexasubstituted [3]radialenes, are candidates for use as active species in redox flow batteries (RFBs) due to their stability in water, reversible electrochemistry, and tailorable synthesis. Hexacyano[3]radialene disodium is investigated as a pH 7 aqueous organic catholyte. The dianion and radical anion are stable in air and aqueous solutions at neutral pH. Systematic introduction of asymmetry via step-wise synthesis leads to enhanced solubility and higher capacity retention during galvanostatic cycling. An aqueous flow cell comprising a diester-tetracyano[3]radialene catholyte, sulfonated-methyl viologen as the anolyte, and a cation exchange membrane provides an operating Vcell = 0.9 V, 99.609% coulombic efficiency, and minimum capacity fade over 50 cycles.
RESUMO
In the title compound, C40H36B2N4O5, the B-O-B bond angle is 132.75â (13) and the dihedral angle between the benzodiazborole rings is 73.02â (5)°. In the crystal, weak C-Hâ¯O inter-actions link the mol-ecules.
RESUMO
In the crystalline state of the title solvate, C18H13NO3·C4H8O, hydrogen-bonding inter-actions between hydroxyl groups on a phenoxazine backbone and the tetra-hydro-furan solvent are observed that suggest the ability for this compound to act as a chelating ligand. The Oâ¯O donor-acceptor distances for this hydrogen bonding are 2.7729â (15) and 2.7447â (15)â Å. The three-ring backbone of the phenoxazine bends out of planarity by 18.92â (3)°, as computed using mean planes that encompass each half of the three-ring structure, with the central N and O atoms forming the line of flexion. In the crystal, a π-π stacking arrangement exists between inversion-related mol-ecules, with a centroid-to-centroid distance of 3.6355â (11)â Å. In the disordered tetra-hydro-furan solvate, all atoms except oxygen were modeled over two positions, with occupancies of 0.511â (8) and 0.489â (8).
RESUMO
The first synthesis of anion capped cerium corrole complexes is reported. Unusual clustering of the lanthanide corrole units has been found and the degree of aggregation can be controlled by the choice of the capping ligand. A polymeric structure 1a, with the general formula [Cor-Ce(THF)-Cp-Na]n (Cor = 5,15-bis(2,4,6-trimethylphenyl)-10-(4 methoxyphenyl)-corrole, THF = tetrahydrofuran), is formed using sodium cyclopentadienide (NaCp) and a dimeric structure 2a, with the general formula [Cor-Ce-Tp]2, is formed when potassium tris(pyrazolyl)borate (KTp) is used. Encapsulation of the counter-cation leads to the isolation of the monomeric structures 1b and 2b, with the general formulas [AM(2.2.2-cryptand)][Cor-Cp-X] (AM = Na or K, X = Cp or Tp). The structural and spectroscopic properties of the complexes have been investigated.
RESUMO
The redox-active bis(imino)acenapthene (BIAN) ligand was used to synthesize homoleptic aluminum, chromium, and gallium complexes of the general formula (BIAN)3M. The resulting compounds were characterized using X-ray crystallography, NMR, EPR, magnetic susceptibility and cyclic voltammetry measurements and modeled using both DFT and ab initio wavefunction calculations to compare the orbital contributions of main group elements and transition metals in ligand-based redox events. Complexes of this type have the potential to improve the energy density and electrolyte stability of grid-scale energy storage technologies, such as redox flow batteries, through thermodynamically-clustered redox events.
RESUMO
The first examples of lanthanide corroles are prepared by two synthetic routes. (Mes2(p-OMePh)corrole)La·4.5DME (1·4.5DME) and (Mes2(p-OMePh)corrole)Tb·4DME (2·4DME) are prepared from the free base corrole and Ln((NSiMe3)2)3, while (Mes2(p-OMePh)corrole)Gd·TACNMe3 (3·TACNMe3) is prepared by metathesis of the recently reported Li3 corrole and GdCl3.
Assuntos
Elementos da Série dos Lantanídeos/química , Compostos Macrocíclicos/síntese química , Porfirinas/química , Cristalografia por Raios X , Compostos Macrocíclicos/química , Modelos Moleculares , Estrutura MolecularRESUMO
A synthesis of the bis(borano)hypophosphite anion with various counterions has been developed to make use of more benign and commercially available reagents. This method avoids the use of potentially dangerous reagents used by previous methods and gives the final products in good yield. Details of the crystal structure determination of the sodium salt in space group Ama2 are given using a novel computational technique combined with Rietveld refinement.