Search results for "Intermolecular force"
showing 10 items of 366 documents
Synthesis, crystal structures and magnetic properties of picolinate-bridged copper(II) chains
2018
The paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) coordination polymers, Cu2(L1)4 (1) and Cu3(L2)6 (2), based on rigid ethynylene-bridged ditopic ligands containing one picolinate subunit (L1 = 5-(pyridin-3-ylethynyl)picolinate anion; L2 = 5-((4-(methoxycarbonyl)phenyl)ethynyl)picolinate anion). Both 1 and 2 have a chain structure. In 1, the repeating unit in the chain is a doubly bridged picolinate dicopper(II) complex, whereas 2 is built upon trimeric units where the Cu2+ ions are also connected by double picolinate bridges. Both compounds exhibit antiferromagnetic interactions in the solid state. The magnetic properties of 1 and 2 were analyze…
Enhancement of the Intermolecular Magnetic Exchange through Halogen···Halogen interactions in Bisadeninium Rhenium(IV) Salts
2017
Two novel ReIV salts of general formula [H2ade]2[ReIVX6]X2·4H2O [H2ade2+ = 9H-adenine-1,7-diium; X = Cl(1) and Br(2)] have been synthesized and magneto-structurally characterized. 1 and 2 are isostructural salts that crystallize in the orthorhombic system with space group Fdd2. Both compounds are made up of discrete mononuclear [ReIVX6]2- and X- anions and doubly protonated adenine cations. The six-coordinate rhenium(IV) ion is bonded to six halide ligands [X = Cl (1) and Br (2)] in an octahedral geometry. Short intermolecular ReIV−X···X−ReIV interactions, as well as ReIV−X···H−N(H2ade) and ReIV−X···H−Ow hydrogen bonds, are present in the crystal lattice of 1 and 2. Magnetic suscep-tibility…
Insights into the crystal packing of phosphorylporphyrins based on the topology of their intermolecular interaction energies
2014
Four metal complexes of 5,15-bis(diethoxyphosphoryl)-10,20-diphenylporphyrin 1M (M = Cd(II), Ni(II), Pd(II), and Pt(II)) were synthesized and crystallographically characterized. The crystal organization patterns were analyzed using DFT (B97-D3/def2-SVP) calculations of the intermolecular interaction energies between complexes in the crystals. For the systematic analysis of crystal packing, the calculations were extended to previously reported compounds 1M (M = H2, Cu(II), and Zn(II)). Quantitative analysis of the interaction energies shows the essential role of weak intermolecular interactions, such as C-H⋯O, C-H⋯π and M⋯π, in the formation of basic structural motifs and their organization …
Selective Metal–Ligand Bond-Breaking Driven by Weak Intermolecular Interactions: From Metamagnetic Mn(III)-Monomer to Hexacyanoferrate(II)-Bridged Me…
2020
Metal–ligand coordination interactions are usually much stronger than weak intermolecular interactions. Nevertheless, here, we show experimental evidence and theoretical confirmation of a very rare...
Synthesis, crystal structure, DFT and biological activity of E-pyrene-1-carbaldehyde oxime and E-2-naphthaldehyde oxime
2020
Abstract The aldoximes E-pyrene-1-carbaldehyde oxime 1 and E-2-naphthaldehyde oxime 2 were synthesized, in ca. 90% yield, by treatment of pyrene-1-carbaldehyde or 2-naphthaldehyde, respectively, with hydroxylamine hydrochloride and sodium carbonate in MeOH. Compounds 1 and 2 were characterized by IR, 1H and 13C{1H} NMR spectroscopies, elemental analyses and single crystal X-ray diffraction (in the case of 1). The studied system (compound 1) showed significant amounts of H⋯H (44.4%), C⋯H (25.4%) and C⋯C (13.3%) intermolecular interactions in addition to the short N⋯H (5.9%) and O⋯H (6.2%) intermolecular interactions. These interactions affect the molecular packing of the studied system in th…
Supramolecular assemblies and photophysical properties of ionic homo- and heteronuclear metallophilic complexes
2019
Abstract The synthesis of two dinuclear ionic complexes with chemical formula [Au(PR 3 ) 2 ][Au(C ≡ CC 5 H 4 N-4) 2 ] that contain the water soluble phosphines, PR 3 , PTA (1, 3,5-triaza-7-phosphaadamantane, 1 ) and DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane, 2 ) is herein described. The differences on their intermolecular reorganization have been analyzed and compared with the previously reported for the neutral complexes [Au(PR 3 )(C ≡ CC 5 H 4 N-4)]. It has been evidenced that the reorganization of the ligands giving rise to the dinuclear ionic complexes produces a complete change in the properties giving rise to Au⋯Au intermolecular assemblies. These aurophilic conta…
The hetero-cubane structures of the heavy alkali metal tert-amyloxides [MOCMe2Et]4 (M = K, Rb, Cs)
2018
A series of alkali metal (Li–Cs) alkoxides of tert-pentanol (1,1-dimethylpropan-1-ol) have been prepared by reaction of the corresponding metal with the alcohol in n-hexane or n-heptane. The compounds were purified by vacuum sublimation and crystallised in n-hexane to produce crystals suitable for single-crystal X-ray diffraction studies. The structures of the potassium, rubidium, and caesium compounds revealed tetrameric units with additional intra- and intermolecular interactions between the metal atom and alkoxide methyl groups, increasing with the size of the metal involved.
Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer?
2017
The chromium(III) sensitizer [Cr(ddpd)2]3+ - based on an earth-abundant metal center - possesses a unique excited state potential energy landscape (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine). The very large energy gap between the redox active and substitutionally labile 4T2 state and the long-lived low-energy 2E spin-flip state enables a selective, efficient sensitization of triplet dioxygen to give singlet dioxygen. Ultrafast intersystem crossing after the Franck Condon point from the 4T2 to the 2E excited state within 3.5 ps precludes intermolecular electron transfer pathways from the ultrashort-lived excited 4T2 state. This specific excited state reactivity enables a …
Synthesis and characterization of new 1,4 and 1,5-disubstituted glucopyranosyl 1,2,3-triazole by 1,3-dipolar cycloaddition
2009
Abstract A series of 1,4 and 1,5-disubstituted 1-(β- d -glucopyranosyl)-1,2,3-triazoles has been prepared in an efficient manner with excellent yields using the intermolecular 1,3-dipolar cycloaddition of 1-azido-2,3,4,6-tetra-O-acetyl-β- d -glucopyranose 2 to a variety of substituted alkynes phenylacethylene 3, propargyl alcohol 4, 2-butyn-1,4-diol, 5, 3-propargylbenzimidazole 6 and propargylpyrazole 7 in toluene. The reaction takes place with the formation of both 4- and 5-regioisomers.
Surface charges at the CaF2/water interface allow very fast intermolecular vibrational-energy transfer
2020
Abstract We investigate the dynamics of water in contact with solid calcium fluoride, where at low pH, localized charges can develop upon fluorite dissolution. We use 2D surface‐specific vibrational spectroscopy to quantify the heterogeneity of the interfacial water (D2O) molecules and provide information about the sub‐picosecond vibrational‐energy‐relaxation dynamics at the buried solid/liquid interface. We find that strongly H‐bonded OD groups, with a vibrational frequency below 2500 cm−1, display very rapid spectral diffusion and vibrational relaxation; for weakly H‐bonded OD groups, above 2500 cm−1, the dynamics slows down substantially. Atomistic simulations based on electronic‐structu…