Crystal structure of the new palladium complexes tetrakis(1,3-dimethylimidazolium-2-ylidene)palladium(II) hexadecacarbonyltetrarhenium diethyl ether disolvate and octa-μ-carbonyl-dicarbonyltetrakis(triphenylphosphane)palladiumdirhenium (unknown solvate)

The investigation of the coordination chemistry of heterometallic transition-metal complexes of palladium (Pd) and rhenium (Re) led to the isolation and crystallographic characterization of tetrakis(1,3-dimethylimidazolium-2-ylidene)palladium(II) hexadecacarbonyltetrarhenium diethyl ether disolvate, [Pd(C5H8N2)4][Re4(CO)16]·2C4H10O or [Pd(IMe)4][Re4(CO)16]·2C4H10O, (1), and octa-μ-carbonyl-dicarbonyltetrakis(triphenylphosphane)palladiumdirhenium, [Pd4Re2(C18H15P)4(CO)10] or Pd4Re2(PPh3)4(μ-CO)8(CO)2, (2), from the reaction of Pd(PPh3)4 with 1,3-dimethylimidazolium-2-carboxylate and Re2(CO)10 in a toluene–acetonitrile mixture. In complex 1 the Re—Re bond lengths [2.9767 (3)–3.0133 (2) Å] are close to double the covalent Re radii (1.51 Å). The palladium–rhenium carbonyl cluster 2 has not been structurally characterized previously; the Pd—Re bond lengths [2.7582 (2)–2.7796 (2) Å] are about 0.1 Å shorter than the sum of the covalent Pd and Re radii (1.39 + 1.51 = 2.90 Å). One carbene ligand and a diethyl ether molecule are disordered over two positions with occupancy ratios of 0.5:0.5 and 0.625 (15):0.375 (15) in 1. An unidentified solvent is present in compound 2. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). The SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON was used to remove the contribution of the electron density in the solvent region from the intensity data and the solvent-free model was employed for the final refinement. The cavity with a volume of ca 311 Å3 contains approximately 98 electrons.

Adsorption behaviors of ether and aluminum surface: A molecular dynamics study

As a pre-study for ether-coated aluminum (Al) nanoparticles (ANPs), ReaxFF or reactive force field-based Molecular Dynamic (MD) Simulations are performed to uncover the mechanism of adsorption behaviors between the Aluminum surface and ether molecules. Meanwhile, part of the results has been verified by experiments. In this study, three different models have been employed with varying concentrations of ether molecules. The obtained results indicate that the adsorption of the ether molecule could be divided into four stages and each stage is associated with charge transfer between Hydrogen and Aluminum atoms. After that, adsorbed ether molecules keep a horizontal state above the Aluminum surface with a vacuum. By evaluating variable temperature conditions, it is concluded that the room-temperature is suitable for forming the ether coating on Aluminum surface. Besides, a higher ether concentration could also bring beneficial effects relating to adsorbing rates. While the disassociated ether solution is removed, it seems that some adsorbed ether molecules will be desorbed, which is similar to the volatilization effect in the filtering experiment. Finally, simulations for desorption show that 455 (K) is a critical point for the adsorbed ether layer.

Crystal structure of (diethyl ether-κO)[5,10,15,20-tetrakis(2-isothiocyanatophenyl)porphyrinato-κ4 N]zinc diethyl ether solvate

The crystal structure of the title compound, [Zn(C48H24N8S4)(C4H10O)]·C4H10O, consists of discrete porphyrin complexes that are located on a twofold rotation axis. The ZnII cation is fivefold coordinated by four N atoms of the porphyrin moiety and one O atom of a diethyl ether molecule in a slightly distorted square-pyramidal environment with the diethyl ether molecule in the apical position. The porphyrin backbone is nearly planar with the metal cation slightly shifted out of the plane towards the coordinating diethyl ether molecule. All four isothiocyanato groups of the phenyl substituents at the meso-positions face the same side of the porphyrin, as is characteristic for picket fence porphyrins. In the crystal structure, the discrete porphyrin complexes are arranged in such a way that cavities are formed in which additional diethyl ether solvate molecules are located around a twofold rotation axis. The O atom of the solvent molecule is not positioned exactly on the twofold rotation axis, thus making the whole molecule equally disordered over two symmetry-related positions.

Bis[μ-2-(trimethylsilylamido)-6-(trimethylsilylamino)pyridine-κ3N1,N2:N2]bis[(diethyl ether-κO)lithium(I)]

The title complex, [Li2(C11H22N3Si2)2(C4H10O)2], crystallizes in theP-1 space group with one molecule of a centrosymmetric dimeric complex in the unit cell. The lithium cation is coordinated in a bidentate fashion by the pyridyl N atom and a silylamido N atom of one 2,6-bis(trimethylsilylamido)pyridine ligand and by a monodentate, bridging silylamido N atom of another. A diethyl ether molecule completes the tetrahedral coordination environment for each lithium atom. Neither intra- nor intermolecular hydrogen bonding nor π–π stacking are observed in the crystal, likely indicating that weak electrostatic interactions are the dominant feature leading to the supramolecular structure.

Crystal structure ofcis-anti-cis-dicyclohexane-18-crown-6 acetonitrile disolvate

The title compound (systematic name:cis-anti-cis-2,5,8,15,18,21-hexaoxatricyclo[20.4.0.09,14]hexacosane acetonitrile disolvate), C20H36O6·2CH3CN, crystallizes from an acetonitrile solution of dicyclohexane-18-crown-6 on evaporation. The molecule is arranged around a center of symmetry with half the crown ether molecule and one molecule of acetonitrile symmetry independent. All O—C—C—O torsion angles aregauchewhile all C—O—C—C angles aretrans. The sequence of torsion angles is [(tg+t)(tg−t)]3; the geometry of oxygen atoms is close to pseudo-D3dwith three atoms below and three atoms above the mean plane, with an average deviation of ±0.16 (1) Å from the mean plane. This geometry is identical to that observed in metal ion complexes of dicyclohexane-18-crown-6 but differs significantly from the conformation of a free unsolvated molecule. Each acetonitrile molecule connects to a crown ether moleculeviatwo of its methyl group H atoms (C—H...O). Weaker interactions exist between the third H atom of the acetonitrile methyl group and an O atom of a neighbouring crown ether molecule (C—H...O); and between the N atom of the acetonitrile molecule and a H atom of another neighbouring crown ether molecule. All these intermolecular interactions create a three-dimensional network stabilizing the disolvate.

[6,6′-Bis(1,1-dimethylethyl)-4,4′-dimethyl-2,2′-methylenediphenolato-κ2O,O′]dichlorido(9H-fluoren-9-ol-κO)titanium(IV)–fluorene–diethyl ether (1/0.5/1)

The title adduct, [TiCl2(C23H30O2)(C13H10O]·0.5C13H10·C4H10O, is a monomer with a trigonal–bypyramidal coordination sphere of the TiIVatom in which the ligand O atoms of the bidentate diphenolate anion are located in both apical and equatorial positions. Chloride ligands occupy the remaining two equatorial sites of the trigonal bypyramid with the fluoren-9-ol O atom occupying the other apical site. The hydroxy group H atom of this latter group is hydrogen bonded to an O atom of a non-coordinating diethyl ether molecule. The title compound also contains a further fluorene solvent molecule, which lies across a centre of symmetry and which is equally disordered over an inversion centre.

Formation of Organometallic Species, [M – H]+ Ions and Radical Cations upon Mass Spectrometric Fragmentation of Mercury–Crown Ether Complexes

Mass spectrometric fragmentation pathways of [M + HgClO4]+ (M – crown ether molecule), determined by tandem mass spectrometry experiments, are discussed in detail. The decomposition of [M + HgClO4]+ proceeds along three fragmentation pathways: formation of [M – H]+ ions, formation of organometallic species, namely [M – H + Hg]+ ions, and formation of radical cations [M]+•. The factors influencing these processes, namely crown ether cavities and the presence of electron withdrawing/electron donor groups, have been discussed.