Theoretical investigation of thermally and photochemically induced haptotropic rearrangements of chromium ligands on naphthalene systems

Influence of Ion Pairing in Inter-Ring Haptotropic Rearrangements in Cationic Cyclopentadienyl Complexes of Ruthenium with Naphthalene: A DFT Investigation

“…9 −11 The influence of photochemical activation on such rearrangements has been poorly and not thoroughly investigated, although many thermally induced reactions have photochemical analogues 12−14 which might be quite complex and possibly involve not only the lowest triplet state. 15 This is why we have decided to investigate the aforementioned problems theoretically in order to stimulate searches for experimental support of the existence of such IRHRs in various PAL complexes of transition metals and to analyze them correctly. In this paper we investigate intramolecular η 6 :η 6 -IRHR in the cationic cyclopentadienyl naphthalene complex of ruthenium (Scheme 2).…”

“…Since the pioneering semiempirical work of Albright et al, DFT investigations have been performed mostly for chromium tricarbonyl complexes of PAL − and only to some extent for molybdenum and tungsten . On the other hand, it is quite strange and intriguing that η 6 :η 6 -IRHR in synthetically available and very stable PAL complexes of the iron triad (Fe, Ru, Os), which are important from a synthetic practical point of view, have been virtually not investigated. − The influence of photochemical activation on such rearrangements has been poorly and not thoroughly investigated, although many thermally induced reactions have photochemical analogues − which might be quite complex and possibly involve not only the lowest triplet state . This is why we have decided to investigate the aforementioned problems theoretically in order to stimulate searches for experimental support of the existence of such IRHRs in various PAL complexes of transition metals and to analyze them correctly.…”

Potential Energy Mapping of the Excited-States of (η6-Arene)Cr(CO)3 Complexes: the Evolution Toward CO-Loss or Haptotropic Shift Processes

“…It is interesting to note that vibrational relaxation into this potential well takes approximately 6 ps and this reflects its shallow nature and the lack of a steeply accelerating PE profile between the Franck–Condon region and the lowest energy vibrational level in this potential energy well . Barriers to CO-loss have been calculated recently for (η 6 -arene)Cr(CO) 3 systems (arene = polyaromatic ligand) but the likely consequence for the kinetics of CO-loss was not discussed . However barriers of this magnitude are sufficient to arrest the CO-loss process and facilitate detection of the excited state precursors on the ps time scale.…”

“…43 Barriers to COloss have been calculated recently for (η 6 -arene)Cr(CO) 3 systems (arene = polyaromatic ligand) but the likely consequence for the kinetics of CO-loss was not discussed. 63 However barriers of this magnitude are sufficient to arrest the CO-loss process and facilitate detection of the excited state precursors on the ps time scale. TDDFT calculations on a COligated iron heme system indicated the presence of a similar barrier to CO-loss.…”

Ring-whizzing in polyene-PtL2 complexes revisited

“…A more inclusive term is haptotropic rearrangement [ 3 ] wherein a metal atom changes its hapticity along the reaction path. Haptotropic rearrangements in ML 3 and MCp complexes are numerous [ 4 – 9 ] and have found use in synthetic strategies [ 10 ], switching devices [ 11 – 13 ] and energy storage [ 14 – 15 ]. Much less is known about the polyene–ML 2 analogs.…”