Electronic structure and metal-metal communication in (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni) complexes: a DFT investigation

International audienceDFT calculations with full geometry optimization have been performed on the series (CpM)2(as-indacene) and (CpM)2(s-indacene) (M = Mn, Fe, Co, Ni), as well as on the cations of the Fe, Co and Ni complexes. The compounds where M = Fe and Ni (as-indacene series) and M = Mn, Fe and Co (s-indacene series) were found to possess closed-shell ground states. In the mixed-valent cations as well as in the other open-shell species, the degree of metal-metal communication and the participation of the ligand into the spin density were evaluated. In general, the larger the total electron number, the larger the metal-metal communication and ligand participation to the frontier orbitals

A new copper(I) coordination polymer from 2,6-bis(1<i>H</i>-benzotriazol-1-ylmethyl)pyridine: Synthesis, characterization, and use as additive in transparent submicron UV filters

<p>The use of a new copper(I) coordination polymer (CP) as additive in transparent composite films of 190 nm of thickness for ultraviolet (UV) shielding is presented. The luminescent 1-D Cu(I) CP was easily synthesized through a self-assembly process between Cu(I) iodide and 2,6-bis(1<i>H</i>-benzotriazol-1-ylmethyl)pyridine (L). The CP, [Cu₂(<i>μ</i> − I)₂(<i>μ</i> − <b>L</b>)₂]_<i>n</i>, was structurally characterized by infrared, UV–visible diffuse reflectance and photoluminescence spectroscopy, elemental and thermogravimetric analyses, single-crystal and powder X-ray diffraction, and relativistic density functional theory calculations. The CP was dispersed and immobilized into a polymeric matrix in the presence of Sudan I, yielding a composite material that exhibits a reduction of 49% of the UV transmittance at 350 nm. Thus, the use of a new Cu(I) CP in polymeric composite films appears as a novel approach toward ultrathin and transparent UV shielding films, which have potential applications as protection layers of paints and coatings that tend to degrade when exposed to UV radiation.</p

[Cp*Ru(s-indacene)RuCp*] and [Cp*Ru(s-indacene)RuCp*]+: Experimental and theoretical findings concerning the electronic structure of neutral and mixed valence organometallic systems

International audienceThe reaction of 2,6-diethyl-4,8-dimethyl-s-indacenyl-dilithium (Li2Ic′) with [Cp*RuCl]4 gives the organometallic binuclear bis-pentamethylcyclopentadienyl-ruthenium-s-indacene complex, [{Cp*Ru}2Ic′] (1, Ic′ = 2,4-diethyl-4,8-dimethyl-s-indacene), in high yields. The subsequent oxidation of 1 with a ferricinium salt ([Fc]+[BF4]−) gives the mixed valence compound [{Cp*Ru}2Ic′]+[BF4]− (1+). Compound 1 was structurally characterized by X-ray crystallography, finding that both {Cp*Ru} fragments are coordinated to opposite sites of the Ic′ ligand. The structural and electronic features of 1 and 1+ have been rationalized by Density Functional Theory (DFT) calculations, which suggest that both metallic centers get closer to the Ic′ and subtle electronic reorganizations occurs when chemical oxidation takes place. Cyclic voltammetry and ESR experiments suggest a high electronic interaction between the metallic centers mediated by the Ic′ bridging ligand. Time dependent DFT (TD-DFT) calculations were carried out to understand and assign the intervalence band present in the mixed-valent specie (1+). The main achievement of this article is to feature the relationship of the experimental data with the computational results obtained with the Amsterdam Density Functional package (ADF). Both experimental and theoretical facts demonstrate that the mixed valence system (1+) is a delocalized one, and it can be classified as a Class III system according to the Robin & Day classification