Alain Igau

Theoretical investigation on the photophysical properties of model ruthenium complexes with diazabutadiene ligands [Ru(bpy)(3-x)(dab)(x)](2+) (x = 1-3).

In this study we report a theoretical comparative study of some photophysical properties in the [Ru(bpy)(3-x)(dab)(x)](2+) (x = 0-3) series. Density functional theory calculations, validated by highly correlated ab initio benchmark calculations, were used to investigate the absorption and emission properties of the complexes with x = 1-3. The presence of a 1,4-diaza-1,3-butadiene (dab) ligand dramatically changes these properties because of the strong π-acceptor character of this ligand. As a result, comparing to the reference [Ru(bpy)(3)](2+) complex previously studied, we observed (i) a strong red-shift of the maximum of the absorption band, (ii) a strong decrease of the emission energy of the lowest triplet metal-to-ligand charge transfer state, with all the [Ru(bpy)(3-x)(dab)(x)](2+) (x = 1-3) complexes luminescent in the near-infrared region, while [Ru(bpy)(3)](2+) emits in the visible region, and (iii) the triplet metal-centered states become inaccessible in all the [Ru(bpy)(3-x)(dab)(x)](2+) (x = 1-3) complexes. Consequently, these complexes could be potential candidates for infrared light-emitting diodes and probes.

Can a functionalized phosphine ligand promote room temperature luminescence of the [Ru(bpy)(tpy)]2+ core?

Unexpected room temperature luminescence is observed and rationalized by highly challenging excited state calculations for a functionalized phosphine ligand coordinated on the [Ru(bpy)(tpy)](2+) core.

Unexpected Formal [1+3] Cycloadditions between Azides andα-Zirconated Phosphanes: A Route to Unprecedented Phosphazide and Iminophosphorane Complexes

Polycyclic zwitterionic complexes that incorporate one or two phosphonium unit(s) as cationic center(s) and zirconocene-ate moiety(ies) as the anionic counterpart(s) can be easily prepared by either [1+3] or [1+3] and [2+3] cycloadditions which involve bi- or tricyclic alpha-zirconated phosphanes 3 or 4 and various azides. Some of these species exhibit unprecedented phosphazide chelation with bonding between the zirconium and a nitrogen atom in the alpha position relative to phosphorus. When heated, the phosphazide complexes lose dinitrogen to form stable polycyclic zwitterionic phosphonium mono- or dinuclear complexes. The solid-state structure of the two zwitterionic complexes 5 and 8 was determined by X-ray crystallography.

[Cp2ZrHCl]n a useful reducing agent in phosphorus chemistry

Selective reductions of PO, PS, >CC<, CO bonds with [Cp2ZrHCl]n are described, as well as halogen-hydride exchanges.

Phosphoryl Group as a Strong σ-Donor Anionic Phosphine-Type Ligand: A Combined Experimental and Theoretical Study on Long-Lived Room Temperature Luminescence of the [Ru(tpy)(bpy)(Ph2PO)]+ Complex

A phosphoryl Ru(II) polypyridyl complex was prepared in a one-pot process. Theoretical analysis suggests that the phosphoryl ligand may be viewed as a strong σ-donor anionic phosphine L-type ligand. State-of-the-art free-energy profile calculations on the excited states demonstrate that both favorable thermodynamic and kinetic factors are responsible for the remarkable room temperature luminescence properties of the phosphoryl complex.

X−H (X=C, N, O, P, S) Bond Activations Induced byβ-Heterosubstituted Zirconaindenes

The azazirconacyclopentene-substituted phosphines 3 and 4 have been found to activate the C-H bonds of acetylenic systems, such as methylpropiolate, diphenylphosphinoacetylene and phenylacetylene, or of methylene compounds, such as malonitrile and diethylmalonate, to give complexes 5a-c, 6a and 6b. C-H bond activation also takes place with vinylacetate. Similar reactions with amines, alcohols, enolisable ketones, phenols, phosphonates, thiols and a second-generation SH-terminated dendrimer lead through X-H bond activation (X = N, O, P, S) to new complexes 8a-c, 9, 12 a,b, 13, 14a-c, 15, 16a and 16b. The azazirconacyclopentene-substituted amine 20 reacts to form analogous complexes. Zr-X bonds of these complexes (X = C, N, O, S) can be cleaved with diphenylchlorophosphine to give P-X phosphorus derivatives in high yield.

Zirconocene [Cp2Zr] synthon and benzynezirconocene complexes as tools in main group element chemistry

Abstract Interactions between zirconocene or benzyne zirconocene and unsaturated species incorporating main group elements lead to a variety of new metallaheterocycles. Efficient new methodologies of regiospecific syntheses of mono-, bi-, or tricyclic systems incorporating phosphorus, nitrogen, selenium, antimony, germanium or tin are reported.

Photophysical and electrochemical properties of polypyridine imine ruthenium(II) complexes: a comparative experimental and theoretical study

The photophysical and electrochemical properties of two ruthenium complexes formulated as [Ru(bpy)2LL′]2+ (bpy = 2,2′-bipyridine, LL′ = pyrim=phenylpyridin-2-ylmethylene-amine; and LL′ = Mes-dab = 1,4-dimesityl-1,4-diazabutadiene) have been investigated by a combined theoretical and experimental study. The UV/Vis absorption spectra of both complexes are dominated by absorption bands in the 400–600 region, which are assigned, by means of TD-DFT calculations, to metal-to-ligand charge transfer (MLCT) transitions, and the bands observed at 300 nm have a dominant intraligand character. The pyrim complex shows luminescence at both low and ambient temperature, whereas for the diaza Mes-dab complex no emission was observed in the visible region at all temperatures. Calculations showed that the presence of the Mes-dab ligand results in a strong decrease in the emission energy from the lowest triplet 3MLCT. As a result, we predict that the Mes-dab complex could be luminescent in the infrared region, while the pyrim complex emits in the visible region. Furthermore, in both cases, triplet metal-centered (3MC) states are inaccessible from the lowest triplet states, which is a requirement for efficient emission. Electrochemical data are typical of Ru(II) bipyridine complexes. DFT calculations, in the gas and the solvated phase, on the different oxidized and reduced species are consistent with metal-based oxidations and ligand-based reductions. The first reduction is always localized on the LL′ ligand. For the first time, the second reduction process was investigated for these kinds of complexes. It occurs at the same potential for the two complexes, as it corresponds to the reduction of the bipyridine ligands. The calculations match the experimental trend in electrochemical shifts.

Benzyne-Zirconocene Reagents as Tools in Phosphorus Chemistry

The use of η 2-benzyne and η 2-phosphabenzyne zirconocene in phosphorus chemistry is reviewed. The regiospecific reactions of these complexes with small unsaturated organic molecules incorporating phosphorus or not led to a variety of cyclic neutral or zwitterionic complexes showing a versatile behavior. New methodologies of synthesis of phosphorus heterocycles and of phosphorus ligands are described, as well as strategies of C-H and M-H (M=N, O, P, S) bond activations.

Zircona-phosphazine complexes: synthesis and X-ray determination

Addition of diazoalkane derivatives RCH(N2) [R = CO2Et (a), SiMe3 (b)] on α-phosphino zirconocene complexes 1, 4 and 6 affords stable N-metal phosphazine compounds 3a,b, 5a,b and 7a,b, respectively. The single crystal X-ray structure of 3a is reported and shows an s-transoid (E) geometry for the phosphazine substructure P1–N1–N2–C9 with a zirconium-to-nitrogen distance in the range of that of Cp2Zr–N σ-bonds in zirconate complexes, which reveals a zwitterionic canonical form for 3a.