Photoluminescence of a triangular Hg4+3 cluster

Abstract

The chaster compound Hg,(pdppm)&30& (dppm=diphenylphosphinomethane) which contains the triangular Hgf+ moiety shows an intense low-temperature (77 K) photoluminescence at I-= 658 nm. This emission is assumed to originate from a metal-centered ss excited state which undergoes a Jahn-Teller distortion.

Mercury Phosphates with the Triangular Hg4+3 Cluster: (Hg3)3(PO4)4 and (Hg3)2(HgO2)(PO4)2

“…This is caused by space required for the additional molecular orbitals needed for two-electron, three-center bonding. Assuming D F symmetry for the Hg> triangle the overlap of the 6s orbitals of each mercury atom generates a bonding MO a and two degenerate antibonding orbitals e, which are perpendicular to the Hg plane (22). For both compounds the mean distances, dM (Hg}Hg)"2.666 A > for (Hg ) (PO ) and 2.682 A > for (Hg ) (HgO )(PO ) , inside a triangle are in the same range and are similar to those found in terlinguaite with dM (Hg}Hg)"2.666 A > and kutznetsovite with dM (Hg}Hg)"2.675 A > .…”

Casting Light on the Darkening of Colors in Historical Paintings

“…4þ cluster in D 3h symmetry can be considered as given by the overlap of the s orbital, generating a bonding a 0 1 and two degenerate weakly antibonding orbitals e 0 . Severe Jahn-Teller type distortions are known to occur in such Hg 3 4þ clusters when photoexcited electrons occupy such degenerate levels [25][26][27][28], leading to slow release of one Hg atom and formation of stable dimeric Hg 2 2þ units (see Fig. 3) [29,30].…”

Colour degradation of artworks: an ab initio approach to X-ray, electronic and optical spectroscopy analyses of vermilion photodarkening

“…Since nature avoids degeneracy, a distortion (Jahn Teller mechanism, JT) is expected when photoexcited electrons occupies such degenerate levels. Trimeric fragments of Hg 3 4+ in their excited state disproportionate under photolysis and eventually release Hg atoms [53][54][55][56] to reduce the strain energy in the lattice, although a long exposure [54][55][56] is needed to dissociate the fragment, with release of one Hg atom and stabilization of dimeric H 2 2+ units. 52,57 An ab initio approach for the JT mechanism is not yet available and will surely be a major challenge.…”