Enthalpies of intramolecular interactions in ferrocenyl alcohols

Baker, A. W.; Bublitz, Donald E.

doi:10.1016/0371-1951(66)80223-0

Cited by 39 publications

(25 citation statements)

References 16 publications

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“…Similar to protonation, intermolecular OH phenol ···Cp hydrogen bonds are formed exclusively for FeCp 2 , while OH phenol ···M hydrogen bonds are detected additionally in the case of RuCp 2 and OsCp 2 by treating these metallocenes with phenols . For IHBs of metallocenyl alcohols and phenols analogous observations have been made and the strength of the OH···M IHBs follows the trend Fe < Ru < Os. − Further, six-membered-ring conformations allow stronger intramolecular OH···Fe hydrogen bonds in ferrocenyl alcohols than five- or seven-membered rings. , …”

Section: Introductionmentioning

confidence: 65%

Competitive NH···Ru/Fe Hydrogen Bonding in Ferrocenyl Ruthenocenyl Tosyl Hydrazone

et al. 2016

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A strong nonclassical NH•••Fe intramolecular hydrogen bond (IHB) is present in the literature-known diferrocenyl tosyl hydrazone (1). Here, we confirm by NMR and IR spectroscopy as well as by XRD methods that an analogous NH•••Ru IHB is present in the heavier homologue diruthenocenyl tosyl hydrazone (2). The NH•••Ru IHB in 2 is stronger than the NH•••Fe IHB in 1 by 6 kJ mol −1 , as determined by IR spectroscopy. Further, we probed the E/Z isomer directing abilities of NH•••M IHBs in the synthesis of the mixed metallocenyl compound ferrocenyl ruthenocenyl tosyl hydrazone (3). 3 is obtained as a mixture of the Z and E isomers (3a,b) with NH•••Ru and NH•••Fe IHBs, respectively. At 111 °C, 3a is preferred with an isomeric ratio of 10:1 (91% 3a). The formation of the isomeric mixture allows a direct comparison of the competitive NH•••Ru/Fe hydrogen bonding. The underlying reason for the 3a:3b ratio is of thermodynamic nature, rooted in the differences in strengths of the NH•••M IHBs of Fe and Ru. Thermal and photochemical approaches and protonation to the corresponding iminium/carbenium ions [H-3a] + /[H-3b] + were employed to overcome the barrier for the E → Z isomerization 3b → 3a, with concomitant switching of the NH•••M IHB.

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Section: Introductionmentioning

confidence: 65%

Competitive NH···Ru/Fe Hydrogen Bonding in Ferrocenyl Ruthenocenyl Tosyl Hydrazone

et al. 2016

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“…This interaction results in a slightly elongated N--H bond, as determined by low-temperature neutron diffraction, and a distortion of the geometry at the metal centre away from the idealized Td symmetry of the isolated anion. Furthermore, studies of the experimentally and theoretically determined charge-density distribution for this salt show features consistent with the formulation of the N--H...Co interaction as a hydrogen bond (Brammer & Sherwood, 1995). Subsequent work has shown that the reaction of a number of different amines with HCo(CO) n leads to hydrogen-bonded salts, such as (7)-(11) (Scheme 1).…”

Section: Introductionmentioning

confidence: 66%

Hydrogen bonds involving transition metal centres – a brief review

Brammer¹,

Zhao²,

Ladipo³

et al. 1995

Acta Crystallogr Sect B

143

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Hydrogen bonding is a topic which has received much attention over the years and continues to do so as the importance of such interactions is established in all areas of chemistry. The class of hydrogen bonds that directly involves electron-rich transition metal centres in the three-centre interaction has received little attention until quite recently. Such interactions are of importance in understanding intermolecular interactions between organometallic molecules and are particularly relevant to understanding proton transfer reactions that directly involve transition metal centres.

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“…Our group and others have shown, that the electron‐rich, sterically demanding and redox‐active ferrocenyl moiety is able to form strong XH ··· Fe hydrogen bonds (X = O, N) . We suppose that ferrocene could act both as a Lewis base beyond this Brønstedt‐type basicity.…”

Section: Introductionmentioning

confidence: 79%