Phosphorus-stabilized titanium carbene complexes: synthesis, reactivity and DFT studies.

The synthesis of two novel titanium carbene complexes from the bis(thiophosphinoyl)methanediide geminal dianion 1 (SCS(2-) ) is described. Dianion 1 reacts cleanly with 0.5 equivalents of [TiCl4 (thf)2 ] to afford the bis-carbene complex [(SCS)2 Ti] (2) in 86 % yield.

Electron-deficient η1-Indenyl,η3-allylpalladium(II) complexes stabilized by fluxional non-covalent interactions.

Highly fluxional, solution-persistent, and formally electron-deficient (32e(-)) binuclear Pd(II)-C(0) complexes of 2-methyl-1H-indene were synthesized and structurally characterized by X-ray diffraction analysis. DFT investigations combined with a number of theoretical analyses of the bond framework suggest that the polar intermetallic interaction possesses no major covalent character. Instead of bearing a static metal-metal bond as suggested by structural X-ray diffraction analysis, the complexes display in solution significant fluxionality through haptotropy, i.

Revisiting the molecular roots of a ubiquitously successful synthesis: nickel(0) nanoparticles by reduction of [Ni(acetylacetonate)2].

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.

Room temperature tandem hydroamination and hydrosilation/protodesilation catalysis by a tricarbonylchromium-bound iridacycle.

A chromiumtricarbonyl-bound iridacycle displays novel catalytic virtues for the conversion of terminal aromatic alkynes into racemic N-phenyl, 1-arylethylamines by tandem hydro-amination and hydrosilation/protodesilation reactions under mild "one pot" conditions.

Room temperature reversible C-H activation mediated by a Pt(0) center, and stoichiometric biphenyl formation via solvent activation.

Room temperature reversible C-H activation mediated by a designed diphosphine platinum complex is presented. These findings are demonstrated through mechanistic studies involving kinetics, isotopic effects, and corroborated by DFT calculations. The coupling between two unactivated aromatic derivatives is also demonstrated.

Synthesis of planar chiral iridacycles by cationic metal π-coordination: facial selectivity, and conformational and stereochemical consequences.

Facial selectivity during the π-coordination of pseudo-tetrahedral iridacycles by neutral (Cr(CO)(3)), monocationic (Cp*Ru(+)), and biscationic (Cp*Ir(2+)) metal centers was directly influenced by the coulombic imbalance in the coordination sphere of the chelated Ir center. We also showed by using theoretical calculations that the feasibility of the related metallacycles that displayed metallocenic planar chirality was dependent to the presence of an electron-donating group, such as NMe(2), which contributed to the overall stability of the complexes. When the π-bonded moiety was the strongly electron-withdrawing Cp*Ir(2+) group, the electron donation from NMe(2) resulted in major conformational changes, with a barrier to rotation of about 17 kcal  mol(-1) for this group that became spectroscopically diastereotopic (high-field (1)H NMR spectroscopy).

Transmetalation of a nucleophilic carbene fragment: from early to late transition metals.

Early transition metal nucleophilic carbene complexes have been used as stoichiometric carbene transfer agents in a transmetalation process.

Room-temperature palladium-catalyzed Negishi-type coupling: a combined experimental and theoretical study.

An air-stable, bulky electron-accepting phosphine ligand (phosphabarrelene) allows the easy reduction of a Pd(II) precursor to a Pd(0) complex, highly active in room-temperature Negishi-type cross-coupling. DFT calculations show that the use of the electron-accepting ligand favors both transmetalation (TM) and reductive-elimination (RE) processes (see scheme; OA = oxidative addition).

Synthesis and structure of divalent thulium borohydrides, and their application in ε-caprolactone polymerisation.

The new divalent thulium compound [Tm(BH(4))(2)(DME)(2)] could be prepared by reduction of [Tm(BH(4))(3)(THF)(3)] or from TmI(2) and KBH(4). It was used as a precursor to the divalent [(Tp(tBu,Me))Tm(BH(4))(THF)] by reaction with potassium tris(2-tBu-4-Me)pyrazolylborate (KTp(tBu,Me)). Both Tm(II) compounds were found active as ε-caprolactone polymerisation catalysts.

Straightforward four-component access to spiroindolines.

Spiroindolines could be synthesized via a very convenient one-pot procedure combining a Ugi coupling and a new copper-catalyzed oxidative process at a peptidyl position. Due to the nature of the first step, this method offers a straightforward access to complex alkaloids with four points of molecular diversity.

Charge-induced facial-selectivity in the formation of new cationic planar chiral iridacycles derived from aniline.

The reaction of chiral chlorido-iridacyclic 2-(4-N,N-dimethylaminophenyl)pyridines with solvato-type [Cp*M(S)(3)](q+) (M = Ru, S = MeCN, q = 1; M = Ir, S = MeC(O)Me, q = 2) complexes produces new cationic racemic planar chiral iridacycles in an efficient and diastereospecific way.

Synthesis of samarium(II) borohydrides and their behaviour as initiators in styrene and epsilon-caprolactone polymerisation.

The bisborohydrido samarium compound Sm(BH(4))(2)(THF)(2) (1) was prepared in high yield by comproportionation between Sm and 2 equivalents of Sm(BH(4))(3)(THF)(3). Reaction of 1 with KCp* (Cp* = C(5)Me(5)) afforded the half-sandwich Cp*Sm(BH(4))(THF)(2) (2). The (1)H NMR borohydride resonances of both complexes, observed at very high field, are typical of divalent Sm compounds.

Phosphorus stabilized carbene complexes: bisphosphonate dianion synthesis, reactivity and DFT studies of O~C~O zirconium(IV) complexes.

The reactivity of the geminal dianion of tetraisopropyl methylenediphosphonate, 3, with [ZrCl4(THF)2] affords a trinuclear structure 5 in which an unprecedented triscarbene-Zr dianionic fragment is found. The overall trinuclear arrangement is assembled by PO bridging moieties. The X-ray crystal structure of 5 is presented.

Bonding mode of a new bis-phosphine-borane alkyl ligand to a Rh(I) species.

The stoichiometric reaction of [Rh(COD)Cl](2) with the anion resulting from the deprotonation of dppm(BH(3))(2) yielded a new alkyl Rh(I) complex; the coordination modes of the BH(3) groups are discussed on the basis of X-ray data, variable temperature multinuclear NMR experiments and DFT studies.

Micro-chlorido, micro-hydroxo-bridged dicarbonyl ruthenacycles: synthesis, structure and catalytic properties in hydrogen atom transfer.

Micro-chlorido, micro-hydroxo-bridged ruthenacycles containing the Ru(CO)2 motif were synthesized by reaction of micro-dichlorido-bridged congener complexes with water in the presence of disodium carbonate. The substitution of one chlorido ligand for one hydroxo occurs with high stereoselectivity affording essentially hydroxo-bridged ruthenacycles, whereby the OH ligand occupies axial positions with respect to the mean plane defined by the chelating ligand. According to computational DFT investigations this stereoselectivity stems from a marked transphobia of the hydroxo ligand towards the carbanion of the ruthenacycle.

1-phosphabarrelene complexes of palladium and their use in Suzuki-Miyaura coupling reactions.

A bulky 1-phosphabarrelene, , was obtained from the reaction of a phosphinine with benzyne; two palladium complexes of were successfully employed in the Suzuki-Miyaura coupling of several aryl chlorides with phenylboronic acid at a relatively low catalyst loading, and activated aryl chlorides were coupled at room temperature in the absence of strong bases.

Why platinum catalysts involving ligands with large bite angle are so efficient in the allylation of amines: design of a highly active catalyst and comprehensive experimental and DFT study.

The platinum-catalyzed allylation of amines with allyl alcohols was studied experimentally and theoretically. The complexes [Pt(eta(3)-allyl)(dppe)]OTf (2) and [Pt(eta(3)-allyl)(DPP-Xantphos)]PF(6) (5) were synthesized and structurally characterized, and their reactivity toward amines was explored. The bicyclic aminopropyl complex [Pt(CH(2)CH(2)CH(2)NHBn-kappa-C,N)(dppe)]OTf (3) was obtained from the reaction of complex 2 with an excess of benzylamine, and this complex was shown to be a deactivated form of catalyst 2.