Near-IR Absorbers Based on Pt(II)-Dithiolene Donor–Acceptor Charge-Transfer (CT) Systems: A Structural Analysis to Highlight DA Interactions

The packing interactions of a series of electron donor (D) and electron acceptor (A) charge transfer (CT) near-IR absorbers based on platinum-dithiolene complexes are reinvestigated here as a case study also by using the Hirshfeld surface analysis. This analysis on systems, which exhibit the 1:1, 2:1 and 2:2 columnar stacking patterns between D and A, allows to point out that several inter-actions of atoms and fragments are involved in the stacking interactions but also that only a lim-ited fraction of these interactions, limited to the 1:1 D/A columnar stacking case, can be relatable to the absorption features of this class of compounds

Structural changes in MII dithione/dithiolato complexes (M = Ni, Pd, Pt) on varying the dithione functionalization

The Ni triad [M(R2pipdt)(dmit)] based on donor/acceptor S,S′ ligands, where R2pipdt = 1,4-diisopropyl-piperazine-2,3-dithione (acceptor) and dmit = 2-thioxo-1,3-dithiole-4,5-dithiolato (donor), was completed by preparing and characterizing the Pd(2) and Pt(3) compounds in addition to the already known Ni(1) complex. The rationale behind the work was to compare the properties and structures inside the triad with those of the corresponding Ni(4), Pd(5) and Pt(6) complexes where R = Bz. Minor changes in the properties as redox active nonlinear second-order (NLO) chromophores were observed in solution for the two triads. Instead, different structural features, reflected by changes in the diffuse reflectance spectra, were observed in their crystals on changing R from Bz to Pri in the piperazine ring and also, more surprisingly, inside the triads. 2 (isostructural with 1) and 3 crystallized in monoclinic P21/n and orthorhombic Pbca space groups, respectively. The crystal packings of 2 and 3 are also markedly different. In particular 1 and 2 form head-to-tail dimers whereas 3 forms supramolecular layers characterized by a partial stack between the molecular planes. Large differences in the crystal structures, induced by the diverse number and types of interactions exchanged by the peripheral fragments of the ligands, were found in the Bz-triad. Indeed, the molecules are stacked in a head-to-head and in a head-to-tail fashion in 4 and in 5/6, respectively. Moreover, significantly different packings were observed. The Hirshfeld surface analysis was used to provide a detailed description of the main types of interactions involved in the crystal packing of the six complexes

Recent advances in the structure and properties of metal–dithiolene complexes

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

Effetti spaziali o settoriali? La crescita della dimensione media d'impresa in Italia

Using a recent version of the spatial shift-share, we decompose in this article the change of the average firm size in the Italian provinces into components of spatial (regional and neighboring level) and sectoral nature. The analysis, carried out with reference to the period 2004-2009, points out relevant differences in relation to which size class is taken into account. In particular, it emerges an evident divide North-South in the provincial distribution of the spatial and sectoral effects when we consider the micro-firms (1-10 employees), while the geography seems to be more complex for the small-firms (11-50 employees)