Limits...
Ring-whizzing in polyene-PtL 2 complexes revisited

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Ring-whizzing was investigated by hybrid DFT methods in a number of polyene–Pt(diphosphinylethane) complexes. The polyenes included cyclopropenium+, cyclobutadiene, cyclopentadienyl+, hexafluorobenzene, cycloheptatrienyl+, cyclooctatetraene, octafluorooctatetraene, 6-radialene, pentalene, phenalenium+, naphthalene and octafluoronaphthalene. The HOMO of a d10 ML2 group (with b2 symmetry) interacting with the LUMO of the polyene was used as a model to explain the occurrence of minima and maxima on the potential energy surface.

No MeSH data available.


Three other coordination geometries that did not lead to new stationary points are shown in 35–37.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4979650&req=5

Figure 11: Three other coordination geometries that did not lead to new stationary points are shown in 35–37.

Mentions: The picture for COT–Pt(dpe) is not so clear. Our calculations would have 28, 30 and 32 in rapid equilibrium with the overwhelming majority of the equilibrium shifted to the tricyclic compound. The low temperature 31P and 13C NMR of COT–Pt(R2PCH2CH2PR2), R = iPr [55], clearly shows that either 28 or 31 (the authors prefer 31) is in rapid equilibrium with 30. There is no spectroscopic evidence consistent with the existence of 32. It may well be the case that bulky iPr groups in place of hydrogens alter the relative energetics. Perhaps computations with a different functional and/or a larger basis set might bring theory and experiment into agreement. Furthermore, moving from Pt to the isoelectronic Ni also can have a significant impact. An X-ray of the COT–Ni complex [56] reveals the structure is analogous to that for 29. An X-ray of another Ni complex [60] produces a bis-η2 isomer, 35. This is also true for C8F8–Ni complexes with certain ligand sets [57–58]. We carried out a number of potential energy minimizations as shown in Fig. 11 starting from 35, as well as, η1, 36, and η3, 37. Unfortunately none of these produced new stationary points. We will return to this Ni versus Pt issue later.


Ring-whizzing in polyene-PtL 2 complexes revisited
Three other coordination geometries that did not lead to new stationary points are shown in 35–37.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4979650&req=5

Figure 11: Three other coordination geometries that did not lead to new stationary points are shown in 35–37.
Mentions: The picture for COT–Pt(dpe) is not so clear. Our calculations would have 28, 30 and 32 in rapid equilibrium with the overwhelming majority of the equilibrium shifted to the tricyclic compound. The low temperature 31P and 13C NMR of COT–Pt(R2PCH2CH2PR2), R = iPr [55], clearly shows that either 28 or 31 (the authors prefer 31) is in rapid equilibrium with 30. There is no spectroscopic evidence consistent with the existence of 32. It may well be the case that bulky iPr groups in place of hydrogens alter the relative energetics. Perhaps computations with a different functional and/or a larger basis set might bring theory and experiment into agreement. Furthermore, moving from Pt to the isoelectronic Ni also can have a significant impact. An X-ray of the COT–Ni complex [56] reveals the structure is analogous to that for 29. An X-ray of another Ni complex [60] produces a bis-η2 isomer, 35. This is also true for C8F8–Ni complexes with certain ligand sets [57–58]. We carried out a number of potential energy minimizations as shown in Fig. 11 starting from 35, as well as, η1, 36, and η3, 37. Unfortunately none of these produced new stationary points. We will return to this Ni versus Pt issue later.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Ring-whizzing was investigated by hybrid DFT methods in a number of polyene–Pt(diphosphinylethane) complexes. The polyenes included cyclopropenium+, cyclobutadiene, cyclopentadienyl+, hexafluorobenzene, cycloheptatrienyl+, cyclooctatetraene, octafluorooctatetraene, 6-radialene, pentalene, phenalenium+, naphthalene and octafluoronaphthalene. The HOMO of a d10 ML2 group (with b2 symmetry) interacting with the LUMO of the polyene was used as a model to explain the occurrence of minima and maxima on the potential energy surface.

No MeSH data available.