Probing CH-π(alkyne) interactions in a series of ethynylferrocenes

McAdam, C. John; Cameron, Scott A.; Hanton, Lyall R.; Manning, A. R.; Moratti, Stephen C.

doi:10.1039/c2ce25267h

Cited by 14 publications

(17 citation statements)

References 104 publications

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“…The cylindrical π-systems of polyynes can become involved in CH/π sp interactions. Traditionally, CH/π arene interactions have received more attention due to their abundance in biology, 50 whereas CH/π sp interactions are rarely discussed, 51 and the few existing reports focus on terminal alkynes rather than polyynes. We have analyzed the intermolecular CH/π sp and π arene /π sp interactions in polyynes having four or more triple bonds from the Cambridge Structural Database (CSD), 52 and herein we compare these data with results for polyyne rotaxanes.…”

Section: Resultsmentioning

confidence: 99%

Polyyne Rotaxanes: Stabilization by Encapsulation

et al. 2016

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Active metal template Glaser coupling has been used to synthesize a series of rotaxanes consisting of a polyyne, with up to 24 contiguous sp-hybridized carbon atoms, threaded through a variety of macrocycles. Cadiot–Chodkiewicz cross-coupling affords higher yields of rotaxanes than homocoupling. This methodology has been used to prepare [3]rotaxanes with two polyyne chains locked through the same macrocycle. The crystal structure of one of these [3]rotaxanes shows that there is extremely close contact between the central carbon atoms of the threaded hexayne chains (C···C distance 3.29 Å vs 3.4 Å for the sum of van der Waals radii) and that the bond-length-alternation is perturbed in the vicinity of this contact. However, despite the close interaction between the hexayne chains, the [3]rotaxane is remarkably stable under ambient conditions, probably because the two polyynes adopt a crossed geometry. In the solid state, the angle between the two polyyne chains is 74°, and this crossed geometry appears to be dictated by the bulk of the “supertrityl” end groups. Several rotaxanes have been synthesized to explore gem-dibromoethene moieties as “masked” polyynes. However, the reductive Fritsch–Buttenberg–Wiechell rearrangement to form the desired polyyne rotaxanes has not yet been achieved. X-ray crystallographic analysis on six [2]rotaxanes and two [3]rotaxanes provides insight into the noncovalent interactions in these systems. Differential scanning calorimetry (DSC) reveals that the longer polyyne rotaxanes (C16, C18, and C24) decompose at higher temperatures than the corresponding unthreaded polyyne axles. The stability enhancement increases as the polyyne becomes longer, reaching 60 °C in the C24 rotaxane.

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Section: Resultsmentioning

confidence: 99%

Polyyne Rotaxanes: Stabilization by Encapsulation

et al. 2016

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“…Several previous studies have reported alkyne-bridged mixed valence bis-ferrocene complexes 16,[41][42][43][44][45][46][47][48][49][50] as well as structural studies of ferrocene groups linked by alkynes and/or oligothiophenes, fluorenes or similar heterocycles. 31,[51][52][53] We have synthesized a new series of bis(ferrocenylethynyl) complexes 3-7 and a mono(ferrocenylethynyl) complex 8 incorporating novel heterocyclic spacer groups.…”

Section: Introductionmentioning

confidence: 99%

Long-Range Intramolecular Electronic Communication in Bis(ferrocenylethynyl) Complexes Incorporating Conjugated Heterocyclic Spacers: Synthesis, Crystallography, and Electrochemistry

et al. 2013

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A new series of bis(ferrocenylethynyl) complexes, 3-7, and a mono(ferrocenylethynyl) complex, 8, have been synthesized incorporating conjugated heterocyclic spacer groups, with the ethynyl group facilitating an effective long-range intramolecular interaction. The complexes were characterized by NMR, IR, and UV-vis spectroscopy as well as X-ray crystallography. The redox properties of these complexes were investigated using cyclic voltammetry and spectroelectrochemistry. Although there is a large separation of ∼14 Å between the two redox centers, ΔE(1/2) values in this series of complexes ranged from 50 to 110 mV. The appearance of intervalance charge-transfer bands in the UV-vis-near-IR region for the monocationic complexes further confirmed effective intramolecular electronic communication. Computational studies are presented that show the degree of delocalization across the Fc-C≡C-C≡C-Fc (Fc = C5H5FeC5H4) highest occupied molecular orbital.

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“…3). Such contacts are often overlooked, but they have been reported previously for both terminal and nonterminal alkyne systems (Banerjee et al, 2006;Thakur et al, 2010;McAdam et al, 2012). Overall, these contacts generate a three-dimensional network with molecules stacked in interconnected columns along the b axis ( Fig.…”

Section: Supramolecular Featuresmentioning

confidence: 80%