56 research outputs found
Mononuclear and Mixed-Metal Dimethyltin Pacman Complexes of a Schiff-Base Pyrrole Macrocycle
The synthesis of the dialkyltin complex [SnMe2-(H2L)] of an octadentate Schiff-base pyrrol macrocycle is described in which the gross Pacman geometry enforces structural discrimination between the two methyl groups. The presence of the metal-free compertment engenders the formation of mixed-metal Sn-Fe and Sn-Zn complexes in which the macrocyclic cleft has distorted considerably upon the introduction of the transition metal cation.</p
Synthesis of Bimetallic Uranium and Neptunium Complexes of a Binucleating Macrocycle and Determination of the Solid-State Structure by Magnetic Analysis
Syntheses of the bimetallic uranium(III) and neptunium(III) complexes [(UI)2(L)], [(NpI)2(L)], and [{U(BH4)}2(L)] of the Schiff-base
pyrrole macrocycles L are described. In the absence of single-crystal structural data, fitting of the variable-temperature solid-state magnetic data allows the prediction of polymeric structures for these compounds in the solid state.JRC.E.6-Actinides researc
Control of Oxo-Group Functionalization and Reduction of the Uranyl Ion
yesUranyl complexes of a large, compartmental
N8-macrocycle adopt a rigid, âPacmanâ geometry that stabilizes
the UV oxidation state and promotes chemistry at a single
uranyl oxo-group. We present here new and straightforward
routes to singly reduced and oxo-silylated uranyl Pacman
complexes and propose mechanisms that account for the
product formation, and the byproduct distributions that are
formed using alternative reagents. Uranyl(VI) Pacman
complexes in which one oxo-group is functionalized by a
single metal cation are activated toward single-electron
reduction. As such, the addition of a second equivalent of a
Lewis acidic metal complex such as MgNâł2 (Nâł = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg
functionalized as a result of MgâN bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(Nâł)Cl] favor
the formation of weaker UâOâZn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to
metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated
by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxogroup
Cation-Dependent Intrinsic Electrical Conductivity in Isostructural Tetrathiafulvalene-Based Microporous Metal-Organic Frameworks
Isostructural metalâorganic frameworks (MOFs) M[subscript 2](TTFTB) (M = Mn, Co, Zn, and Cd; H[subscript 4]TTFTB = tetrathiafulvalene tetrabenzoate) exhibit a striking correlation between their single-crystal conductivities and the shortest S···S interaction defined by neighboring TTF cores, which inversely correlates with the ionic radius of the metal ions. The larger cations cause a pinching of the S···S contact, which is responsible for better orbital overlap between pz orbitals on neighboring S and C atoms. Density functional theory calculations show that these orbitals are critically involved in the valence band of these materials, such that modulation of the S···S distance has an important effect on band dispersion and, implicitly, on the conductivity. The Cd analogue, with the largest cation and shortest S···S contact, shows the largest electrical conductivity, Ï = 2.86 (±0.53) Ă 10[subscript â4] S/cm, which is also among the highest in microporous MOFs. These results describe the first demonstration of tunable intrinsic electrical conductivity in this class of materials and serve as a blueprint for controlling charge transport in MOFs with Ï-stacked motifs.United States. Department of Energy. Office of Basic Energy Sciences (Award DE-SC0006937)National Science Foundation (U.S.). Graduate Research Fellowship Program (Award 1122374)David & Lucile Packard Foundation (Fellowship
CCDC 274152: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the worldâs repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
CCDC 274153: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the worldâs repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
Metal-directed ring-expansion in Schiff-base polypyrrolic macrocycles
The reaction between a [2 + 2] Schiff-base porphyrin analogue and zinc acetate results in the unusual formation of an enlarged [3 + 3] macrocycle that is stabilised by metal coordination and intramolecular hydrogen-bonding interactions
CCDC 617114: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the worldâs repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
CCDC 617113: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the worldâs repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
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