Recent Advances in the Structure and Properties of Metal–Dithiolene Complexes

Abstract

This chapter describes novel or revisited aspects discussed in Chapter 16 of The Chemistry of Metal Enolates published in 2009. In particular, the properties of square‐planar homo‐ and heteroleptic metal–dithiolene complexes, such as the uncertainty of the valence state of the central metal and the ligands, and a variety of their applications as photocatalysts and electrocatalysts for hydrogen production from water, redox‐active second‐order nonlinear chromophores, single‐component molecular conductors (SCMCs) and suitable materials for field‐effect transistors (FET), solar cells, and photodetectors, are discussed and more recent literature data reviewed. The chapter summarizes how new or optimized applications of this class of complexes, spanning from bio‐medicinal to material chemistry, are relatable to the versatility of the organic synthesis in tailoring the ligand which can bear a variety of functionalities to favor film formation, luminescent properties, donor/acceptor interactions, proton transfer reaction, chirality, to combine with the suitable metal for obtaining the complex exhibiting the desired properties.

Insight into the Properties of Heteroleptic Metal Dithiolenes: Multistimuli Responsive Luminescence, Chromism, and Nonlinear Optics

“…An analysis of the frontier MOs shows that, in all complexes, the HOMO and LUMO are both formed from the out-of-plane antibonding interactions between the metal orbital and a ligand-based C 2 S 2 orbital (Figure and Figures S9–S13). More specifically, the HOMO is mainly localized on the dithiolate system, whereas the LUMO is mainly localized on the dithiooxamidate fragment, in agreement with previous findings for similar systems. ,,,,, …”

“…More specifically, the HOMO is mainly localized on the dithiolate system, whereas the LUMO is mainly localized on the dithio-oxamidate fragment, in agreement with previous findings for similar systems. 10,11,12,19,23,26 there is a good agreement between the calculated and experimental visible spectra for all of the compounds (Figure S11). The low energy absorption band can be associated almost exclusively to an HOMO→LUMO transition (Tables S2-S6).…”

“…Indeed, the substituents affect the energy of the frontier molecular orbitals (MOs) and thus the formal oxidation state of the ligand, which spans from 2– (electron-withdrawing substituents, such as CN) to 0 (electron donating substituents, such as NR 2 ) (Figure ). Accordingly, heteroleptic d 8 metal dithiolenes with proper substituents at the C 2 S 2 moieties behave as D–M–A molecules with a non-null dipolar moment. In these D–M–A compounds, the CT process produces a decrease in the dipole moment from the ground to the excited state, giving rise to negative solvatochromism and first hyperpolarizability (β) (see Figure ).…”