ILCT transition

SC (3ct values indicates that the ILCT transitions coincide with the dipole moment axes in complexes such as (52) and (53).81... 

Figure 2. A plot of aromatic reduction potential versus the energy of the ILCT transition for the (dppe)Pt S2C2(2-Het)(H) complexes ( ). The approximate energy of the d to d transition for the (dppe)Pt S2C2(2-Het)(H) complexes ( ).

There are heterocyclic-substituted platinum 1,2-enedithiolates that have ILCT emissions that are either enabled by protonation of the ground state or quenched by protonation of the excited states. Which process is operative is dependent on the heterocycle appended to the 1,2-enedithiolate, and hence the electron affinity of the accepting orbital in the ILCT transition (see Fig. 2). 

A ligand itself may consist of a reducing and oxidizing part. Accordingly, ILCT transitions can then exist [6,7,154] and an emission from ILCT states could appear. Indeed, such emissions have been observed. 

The pyridinium acceptor is covalently attached to the dithiolate donor which provides a rr-electron for the ILCT transition. 

When the R substituent is a strong electrcMi-donating group, the increase of the value of the quadratic hyperpolarizabDity fi is dominated by an intraligand CT (ILCT) transition, with the metal center, which behaves as an electron-acceptor. 

Figure 3 ILCT transitions of the ( -butylammonium)Ir (CO)2(maleonitrile) complex. Luminescence and excitation spectra at 77 K show resolved structure. The dotted line gives the solution absorption spectrum...

Generally, these TC-to-n " transitions are insensitive to the metal center and have been assigned to LLCT and ILCT transitions, respectively (see Sections V and VI) [10,20]. 

The ordering of the electronic transitions in the (phosphine)2Pt S2C2(Het) (R ) complexes depends on the appended heterocycle. For these complexes the energy of the ILCT transition tracks with the reduction potential and hence the electron affinity of the heterocycle [30]. Consistent with this observation, the energy of the transition is lowei by protonation and alkylation of the heterocycle (see Section VI) [30-35]. 

There are emissive homoleptic bis(l-2-enedithiolate) Pt, Zn, Cd, and Hg dianions. Even though these complexes are isostructural, their excited state assignments differ. The homoleptic platinum complexes, [Pt(mnt)2] " and [Pt(qdt)2] ", have a lowest lying MLCT transition whereas the corresponding group UB complexes, [M(mnt)2] " (M = Zn, Cd, and Hg), [Zn(qdt)2] ", and [Zn(tdt)2] ", have what is best described as a lowest lying ILCT transition [16,29,36]. 

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