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A comparative study of the coordination behavior of cyclo-P₅ and cyclo-As₅ ligand complexes towards the trinuclear Lewis acid complex (perfluoro-ortho-phenylene)mercury.

ABSTRACT: Reactions of the cyclo-E₅ sandwich complexes [Cp*Fe(?⁵-P₅)] (1) and [Cp*Fe(?⁵-As₅)] (2) with the planar Lewis acid trimeric (perfluoro-ortho-phenylene)mercury [(o-C₆F₄Hg)₃] (3) afford compounds that show distinctly different assemblies in the solid state. The phosphorus containing ligand 1 forms dimeric coordination units with two molecules of 3, with one P atom of each cyclo-P₅ ligand positioned in close proximity to the center of a molecule of 3. In contrast to the coordination behavior of 1, the arsenic analog 2 shows simultaneous interaction of three As atoms with the Hg atoms of 3. A DFT study and subsequent AIM analyses of the products suggest that electrostatic forces are prevalent over donor-acceptor interactions in these adducts, and may play a role in the differences in the observed coordination behavior. Subsequently, a series of [Cp^RFe(?⁵-P₅)] (Cp^R = C₅H_5-ntBu _n , n = 1-3, 6a-c) sandwich complexes was prepared and also reacted with [(o-C₆F₄Hg)₃]. In the solid state the obtained products 7a-c with increasing steric demand of the Cp^R ligands show no significant change in their assembly compared to the Cp* analog 4. All of the products were characterized by single crystal X-ray structure analysis, mass spectrometry and elemental analysis as well as NMR spectroscopy and IR spectrometry.

SUBMITTER: Fleischmann M

PROVIDER: S-EPMC5424469 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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A comparative study of the coordination behavior of cyclo-P5 and cyclo-As5 ligand complexes towards the trinuclear Lewis acid complex (perfluoro-ortho-phenylene)mercury.

Fleischmann Martin M Jones James S JS Gabbaï François P FP Scheer Manfred M

Chemical science 20141001 1

Reactions of the cyclo-E5 sandwich complexes [Cp*Fe(η5-P5)] (1) and [Cp*Fe(η5-As5)] (2) with the planar Lewis acid trimeric (perfluoro-ortho-phenylene)mercury [(o-C6F4Hg)3] (3) afford compounds that show distinctly different assemblies in the solid state. The phosphorus containing ligand 1 forms dimeric coordination units with two molecules of 3, with on ...[more]

PMID: 28553461

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Project description:The self-assembly of foldamers into macrocycles is a simple approach to non-biological higher-order structure. Previous work on the co-assembly of ortho-phenylene foldamers with rod-shaped linkers has shown that folding and self-assembly affect each other; that is, the combination leads to new emergent behavior, such as access to otherwise unfavorable folding states. To this point this relationship has been passive. Here, we demonstrate control of self-assembly by manipulating the foldamers' conformational energy surfaces. A series of o-phenylene decamers and octamers have been assembled into macrocycles using imine condensation. Product distributions were analyzed by gel-permeation chromatography and molecular geometries extracted from a combination of NMR spectroscopy and computational chemistry. The assembly of o-phenylene decamers functionalized with alkoxy groups or hydrogens gives both [2 + 2] and [3 + 3] macrocycles. The mixture results from a subtle balance of entropic and enthalpic effects in these systems: the smaller [2 + 2] macrocycles are entropically favored but require the oligomer to misfold, whereas a perfectly folded decamer fits well within the larger [3 + 3] macrocycle that is entropically disfavored. Changing the substituents to fluoro groups, however, shifts assembly quantitatively to the [3 + 3] macrocycle products, even though the structural changes are well-removed from the functional groups directly participating in bond formation. The electron-withdrawing groups favor folding in these systems by strengthening arene-arene stacking interactions, increasing the enthalpic penalty to misfolding. The architectural changes are substantial even though the chemical perturbation is small: analogous o-phenylene octamers do not fit within macrocycles when perfectly folded, and quantitatively misfold to give small macrocycles regardless of substitution. Taken together, these results represent both a high level of structural control in structurally complex foldamer systems and the demonstration of large-amplitude structural changes as a consequence of a small structural effects.

Project description:A trinuclear nickel complex of phenanthrene-9,10-dione dioxime (H2pqd), namely bis-[μ2-9,10-bis-(oxido-imino)-phenanthrene]-bis-[μ2-10-(oxido-imino)phenanthrene-9-one oxime](phenanthrene-9,10-dione dioxime)trinickel(II) toluene disolvate, [Ni3(C14H8N2O2)2(C14H9N2O2)2(C14H10N2O2)]·2C7H8, has been isolated and its crystal structure determined. This complex features three independent Ni(II) atoms that are arranged in a triangular fashion along with five supporting ligands. There are two square-planar Ni(II) atoms and a third pseudo-octa-hedral Ni(II) atom. While the square-planar Ni(II) atoms are stacked, there are no ligand bridges between them. Each square-planar Ni(II) atom, however, bridges with the pseudo-octa--hedral Ni(II) atom through Ni-N-O-Ni and Ni-O-Ni bonds. A fluorido-bor-ation reaction of the proton-bridged species gave the analogous complex bis-(μ2-bis-{[10-(oxido-imino)-9,10-di-hydro-phenanthren-9-yl-idene]amino}di-fluorido-borato)(phenanthrene-9,10-dione dioxime)trinickel(II) dichloromethane trisolvate, [Ni3(C28H16BF2N4O2)4(C14H10N2O2)]·3CH2Cl2, which shows the same binding structure, but features a widened Ni-Ni inter-action between the square-planar Ni(II) atoms. The proton-bridged complex completes the macrocyclic coordination around the square-planar Ni(II) atoms by means of an O-H⋯O hydrogen bond. Both compounds feature O-H⋯N hydrogen bonds between the oxime and the N atoms attached to square-planar nickel atom. The nickel units show no direct inter-action with their nearest neighbors in the extended lattice. Two π-stacking inter-actions between adjacent mol-ecules are found: one with a centroid-centroid distance of 3.886 (2) Å and the other with a centroid-centroid distance of 4.256 (3) Å. In the latter case, although not aromatic, the distance to the centroid of the central phenanthrene ring is shorter, with a distance of 3.528 (3) Å. Toluene mol-ecules occupy the solvent channels that are oriented along the c axis. In the fluorido-boronate structure, the solvent (DCM) was too badly disordered to be modelled, so its contribution was removed using SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18].

Dataset Information

A comparative study of the coordination behavior of cyclo-P₅ and cyclo-As₅ ligand complexes towards the trinuclear Lewis acid complex (perfluoro-ortho-phenylene)mercury.

Publications

A comparative study of the coordination behavior of <i>cyclo</i>-P<sub>5</sub> and <i>cyclo</i>-As<sub>5</sub> ligand complexes towards the trinuclear Lewis acid complex (perfluoro-<i>ortho</i>-phenylene)mercury.

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