The widely used preparation of Ni(0) nanoparticles from [Ni(acac)(2)] (acac=acetylacetonate) and oleylamine, often considered to be a thermolysis or a radical reaction, was analyzed anew by using a combination of DFT modeling and designed mechanistic experiments. Firstly, the reaction was followed up by using TGA to evaluate the energy barrier of the limiting step. Secondly, all the byproducts were identified using NMR spectroscopy, mass spectrometry, FTIR, and X-ray crystallography. These methods allowed us to depict both main and side-reaction pathways. Lastly, DFT modeling was utilized to assess the validity of this new scheme by identifying the limiting steps and evaluating the corresponding energy barriers. The oleylamine was shown to reduce the [Ni(acac)(2)] complex not through a one-electron radical mechanism, as often stated, but as an hydride donor through a two-electron chemical reduction route. This finding has strong consequences not only for the design of further nanoparticles syntheses that use long-chain amine as a reactant, but also for advanced understanding of catalytic reactions for which these nanoparticles can be employed.

The reactions of the samarium(II) complexes Tmp 2 Sm (Tmp = 2,3,4,5-tetramethyl-1H-phosphol-1-yl) and Cp* 2 Sm(THF) 2 (Cp* = 1,2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl) with pyridine were found to be different, despite the fact that the Cp* and Tmp π-ligands are similar in size. With Tmp 2 Sm, a simple adduct, Tmp 2 Sm(pyridine) 2 is isolated, while with Cp* 2 Sm(THF) 2 pyridine is dimerized with concomitant oxidation of samarium to form [Cp* 2 Sm-(C 5 H 5 N)] 2 [μ-(NC 5 H 5 −C 5 H 5 N)]. However, reaction of Tmp 2 Sm with acridine, a better π-acceptor than pyridine, did result in acridine dimerization and the isolation of [Tmp 2 Sm] 2 [μ-(NC 13 H 9 −C 13 H 9 N)]. DFT calculations on the model structures of Tmp 2 Sm and Cp* 2 Sm, and on the single electron transfer step from Sm to pyridine and acridine in these ligand environments, confirmed that, even though the Sm−πligand bonds are mostly ionic, the different electronic properties of the Tmp ligand versus that of Cp are responsible for the difference in reactivity of Tmp 2 Sm and Cp* 2 Sm.■ EXPERIMENTAL SECTION Computational Details. Calculations were performed with the GAUSSIAN 03 suite of programs. 10 DFT was applied by means of the

Reaction mechanisms for the oxidative reactions of CO(2) and COS with [(C(5)Me(5))(2)Sm] have been investigated by means of DFT methods. The experimental formation of oxalate and dithiocarbonate complexes is explained. Their formation involve the samarium(III) bimetallic complexes [(C(5)Me(5))(2)Sm-CO(2)-Sm(C(5)Me(5))(2)] and [(C(5)Me(5))(2)Sm-COS-Sm(C(5)Me(5))(2)] as intermediates, respectively, ruling out radical coupling for the formation of the oxalate complex.

The nature of the metal–ligand interaction in divalent samarium complexes is investigated by a variety of quantum chemical tools and compared to the analogous strontium–ligand interaction. The complexes under study are the decamethylsamarocene Sm(C5Me5)2, the octamethyldiphosphasamarocene Sm(C4Me4P)2, and the decamethylstrontocene Sr(C5Me5)2. Molecular orbital descriptions, binding energy decompositions and topological analyses based on the electron density reveal the non-negligible role of covalency in the samarium–ligand interaction. The results are supported by an orbital energetic contribution in the metal–ligand interaction and a number of samarium–carbon bond critical points and electron localization function valence basins. The covalent contribution to the samarium–ligand bond contrasts with the highly ionic strontium–ligand interaction.

The catalytic activity both of cationic [(XDPP)Au][X] (XDPP = bis-2,5-diphenylphosphole xantphos X = BF(4)) and of the isolated gold hydride complex [(XDPP)(2)Au(2)H][OTf] in the dehydrogenative silylation process is presented. A parallel theoretical study using density functional theory revealed a mechanism involving the counter anion as a co-catalyst, which was experimentally confirmed by testing various counterions (X = OTf, NTf(2), PF(6)). Finally, a "Au(2)H(+)" species was determined as the intermediate during the catalytic cycle, which correlates well with the experimental findings on the first example of catalytic activity of an isolated "Au-H" complex.

A phosphorus analog of salen ligands featuring iminophosphorane functionalities in place of the imine groups was synthesised in 2 steps from o-diphenylphosphinophenol via the preparation of the corresponding bis-aminophosphonium salt. This novel tetradentate ligand (1), which we named phosphasalen, was coordinated to Pd(II) and Ni(II) metal centres affording complexes 6 and 7 respectively, which were characterised by multinuclear NMR, elemental and X-ray diffraction analyses. Both neutral complexes adopt a nearly square-planar geometry around the metal with coordination of all iminophosphorane and phenolate moieties. The electronic properties of these new complexes were investigated by cyclic voltammetry and comparison with known salens was made when possible. Moreover, the particular behaviour of the phosphasalen nickel complex 7 was further investigated through magnetic moment measurements and a DFT study.

An effective methodology to deal with the theoretical treatment on the redox chemistry of divalent organolanthanide complexes is reported and has been tested on two representative substrates, pyridine and CO(2), with two different metals (samarium and thulium). An influence of the ancillary ligands, namely, C(5)Me(5) (Cp*) or (2,3,4,5-tetramethylphospholyl) (Tmp), on the one- or two-electron oxidation processes is observed. The theoretical results are in excellent agreement with the experimental observations indicating the efficiency of the method.

Twice the fun: Dimeric FeII diphosphonium bis(alkynyl) complexes are formed by oxidation of the corresponding FeII alkynyl phosphine complexes. The structure of these organometallic diphosphonium salts and their monomeric precursors were established by X‐ray crystallography. The PP bond can be cleaved by two‐electron reduction to regenerate the monomers.