Search results for "CRYSTALLOGRAPHY"

N-Acyl-glutarimides: Effect of Glutarimide Ring on the Structures of Fully Perpendicular Twisted Amides and N–C Bond Cross-Coupling

2020

N-Acyl-glutarimides have emerged as the most reactive precursors for N-C(O) bond cross-coupling reactions to date, wherein the reactivity is driven by ground-state destabilization of the amide bond. Herein, we report a full study on the effect of a glutarimide ring on the structures, electronic properties, and reactivity of fully perpendicular N-acyl-glutarimide amides. Most notably, this report demonstrates the generality of deploying N-acyl-glutarimides to achieve full twist of the acyclic amide bond, and results in the discovery of N-acyl-glutarimide amide with an almost perfect twist value, τ = 89.1°. X-ray structures of five new N-acyl-glutarimides are reported. Reactivity studies in t…

N-Cobaltocenium Amide as Reactive Nucleophilic Reagent for Donor–Acceptor Bimetallocenes

2017

Deprotonation of the aminocobaltocenium ion [Cc-NH2]+ ([H-1]+) generates the nucleophilic imine CcNH (1). Reaction of 1 with acid chlorides R–COCl (R = Ph, Fc, and Cc+) yields the reference amide [Ph-CO-NH-Cc]+ (2+) and the amide-linked hetero- and homobimetallocenes [Fc-CO-NH-Cc]+ (3+) and [Cc-CO-NH-Cc]2+ (42+), respectively. Cation–anion interactions of charged amides 2+–42+ in the solid state and in solution are probed by single crystal X-ray diffraction and NMR and IR spectroscopy. Intramolecular metal–metal interactions in donor–acceptor heterobimetallocene 3+ and in mixed-valent homobimetallocene 4+ (prepared electrochemically) are discussed within the Marcus–Hush framework aided by s…

Size‐Selective Encapsulation of Hydrophobic Guests by Self‐Assembled M 4 L 6 Cobalt and Nickel Cages

2012

Subtle differences in metal-ligand bond lengths between a series of [M(4)L(6)](4-) tetrahedral cages, where M = Fe(II), Co(II), or Ni(II), were observed to result in substantial differences in affinity for hydrophobic guests in water. Changing the metal ion from iron(II) to cobalt(II) or nickel(II) increases the size of the interior cavity of the cage and allows encapsulation of larger guest molecules. NMR spectroscopy was used to study the recognition properties of the iron(II) and cobalt(II) cages towards small hydrophobic guests in water, and single-crystal X-ray diffraction was used to study the solid-state complexes of the iron(II) and nickel(II) cages.

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…

Iron( ii ) and cobalt( ii ) complexes based on anionic phenanthroline-imidazolate ligands: reversible single-crystal-to-single-crystal transformations

2018

A series of low-spin FeII and CoII complexes based on phenanthroline-imidazolate (PIMP) ligands are reported. The FeII complex (H9O4)[Fe(PIMP)3]·(C4H10O)2(H2O) (1a) shows reversible crystalline phase transformations to afford two new phases (H9O4)[Fe(PIMP)3]·(H2O) (1b) and (H9O4)[Fe(PIMP)3]·(C8H18O)(C4H10O)(H2O) (1c) by release of diethyl ether and absorption of diethyl/dibutyl ether, respectively. This reversible uptake/release of solvent molecules is a clear example of single-crystal-to-single-crystal transformation involving a discrete metal complex. On the other hand, the corresponding CoII complex (H9O4)[Co(PIMP)3]·(C4H10O)2(H2O)2 (2) does not exhibit similar phase transformations. In …

Electrosynthesis and X‐ray Crystallographic Structure of Zn II meso ‐Triaryltriphenylphosphonium Porphyrin and Structural Comparison with Mg II meso …

2018

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.

[Bis(phosphonio)isophosphindolide]silver complexes

1996

The outcome of reactions of bis(phosphonio)isophosphindolide salts 1[X] and 6[X] (X- Cl-, Br-, CF3SO3-) with silver salts AgY (Y- = CF3SO3-, CF3CO2-, CH3CO2-, 1/2 SO4-) depends strongly on the available anions X, Y. If X-, Y- CF3SO3-, both mononuclear and dinuclear silver complexes are formed which exhibit either μ1,μ1(P) or μ2,η1(P) coordination of the cations 1, 6 to one or to both metals. In solution, dynamic equilibria between both types of products and free 1, 6 were detected by 31P-NMR spectroscopy. Mononuclear (4a, 7) and dinuclear (5a, 8) complexes were isolated as solvates with CHCl3 or THF. If X-, Y- = CF3CO2, only equilibrium mixtures between the free ligands and silver complexes…

Substitution of the laser borane anti-B18H22 with pyridine: a structural and photophysical study of some unusually structured macropolyhedral boron h…

2018

Reaction of anti-B18H221 with pyridine in neutral solvents gives sparingly soluble B16H18-3',8'-Py23a as the major product (ca. 53%) and B18H20-6',9'-Py22 (ca. 15%) as the minor product, with small quantities of B18H20-8'-Py 4 (ca. 1%) also being formed. The three new compounds 2, 3a and 4 are characterized by single-crystal X-ray diffraction analyses and by multinuclear multiple-resonance NMR spectroscopy. Compound 2 is of ten-vertex nido:ten-vertex arachno two-atoms-in-common architecture, long postulated for a species with borons-only cluster constitution, but previously elusive. Compound 3a is of unprecedented ten-vertex nido:eight-vertex arachno two-atoms-in-common architecture. The si…

Highly Anisotropic Rhenium(IV) Complexes: New Examples of Mononuclear Single-Molecule Magnets

2013

The rhenium(IV) complex (NBu4)2[ReBr4(ox)] (1) (ox = oxalate and NBu4(+) = tetra-n-butylammonium cation) has been prepared and its crystal structure determined by X-ray diffraction. The structure is made up of discrete [ReBr4(ox)](2-) anions and bulky NBu4(+) cations. Each [ReBr4(ox)](2-) anion is surrounded by six NBu4(+) cations, which preclude any significant intermolecular contact between the anionic entities, the shortest rhenium···rhenium distance being 9.373(1) Å. Variable temperature dc and ac magnetic susceptibility measurements and field-dependent magnetization experiments on polycrystalline samples of 1 reveal the occurrence of highly anisotropic magnetically isolated Re(IV) cent…