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A series of substituted phosphinines, 1‐phosphabarrelenes and 5‐phosphasemibullvalenes were synthesized and evaluated for their potential application as ligands in homogeneous catalytic reactions. While their buried volume (%Vbur) was calculated to get insight into the steric properties, [LNi(CO)3] complexes were prepared in order to determine the corresponding Tolman electronic parameter. ETS‐NOCV (extended‐transition‐state natural orbital for chemical valence) calculations on [LAuCl] complexes further allowed an estimation of the σ‐ and π‐contributions to the L−M interaction. AuI coordination compounds of selected examples were prepared and characterized by single crystal X‐ray diffraction. Finally, the three classes of PIII compounds were successfully used in the AuI‐catalyzed cycloisomerization of N‐2‐propyn‐1‐ylbenzamide, showing very good activities and selectivities, which are comparable with the reported data of cationic phosphorus‐based gold catalysts. [ABSTRACT FROM AUTHOR]

The first AuIII carbene complex was prepared by reacting a geminal dianion with a (P,C) cyclometalated AuIII precursor. Its structure and bonding situation have been thoroughly investigated by experimental and computational means. The presence of a high-energy highest occupied molecular orbital (HOMO) centered at the carbene center suggests nucleophilic character for the AuIII carbene complex. This unprecedented feature was confirmed by reactions with two electrophiles (PhNCS and CS2), resulting in two types of C=C coupling reactions. [ABSTRACT FROM AUTHOR]

A series of tridentate aryloxy-based ligands were synthesized and characterized for their coordination behaviour towards TiIV. Coordination studies revealed that the nature of the central atom (amine vs. ether) and the type of bridging spacer (aromatic vs. aliphatic) are important aryloxy ligand parameters and influence the ligand coordination mode and the formation of stable titanium complexes. This series of titanium complexes were evaluated in ethylene oligomerization and polymerization after activation with methylaluminoxane (MAO) and showed the preferential formation of polyethylene. In some cases, the formation of a small amount of 1-hexene suggests the existence of several catalytic centres in the reaction mixture. [ABSTRACT FROM AUTHOR]

The properties of 13 monodentate P-donor ligands not previously characterized in the Ligand Knowledge Base (LKB) approach have been determined computationally, allowing their addition to the LKB-P map of ligand space.1Consideration of ligand positions and close neighbors in ligand space can help to establish a chemical context and hence guide their application to organometallic catalysis. Here we demonstrate this potential application of the LKB-P map and discuss known and likely applications of these ligands. [ABSTRACT FROM PUBLISHER]

Oxidation of the square planar Rh(I) complex [Rh(SPSMe)(PPh3)] (SPSMe = l-methyl-l-P-2,6-bis(diphenylphosphinosulfide)-3,5-(bisphenyl)-phosphinine) (1) based on mixed SPS-pincer ligand with hexachloroethane yielded the Rh(III) dichloride complex [Rh(SPSMe)(PPh3)Cl2] (2), which was structurally characterized. The homoleptic Rh(III) complex [Rh(SPSMe)2][Cl] (4) was obtained via the stoichiometric reaction of SPSMe anion (3) with [Rh(tht)3Cl3] (tht = tetrahydrothiophene). Complex 4, which was characterized by X-ray diffraction, was also studied by cyclic voltammetry. Complex 4 can be reversibly reduced at E= -1.16 V (vs SCE) to give the neutral 19-electron Rh(II) complex [Rh(SPSMe)2] (5). Accordingly, complex 5 could be synthesized via chemical reduction of 4 with zinc dust. EPR spectra of complex 5 were obtained after electrochemical or chemical reduction of 4 in THF or CH2Cl2. Hyperfine interaction with two equivalent 31P nuclei was observed in liquid solution, while an additional coupling with a spin ½ nucleus, probably 103Rh, was detected in frozen solution. The 31P couplings are consistent with DFT calculations that predict a drastic increase in the axial P-S bond lengths when reducing (SPSMeM)2Rh(III). In the reduced complex, the unpaired electron is mainly localized in a rhodium dz² orbital, consistent with the g-anisotropy measured at 100 K. [ABSTRACT FROM AUTHOR]

The stoichiometric reaction of [Rh(COD)Cl]2 with the anion resulting from the deprotonation of dppm(BH3)2 yielded a new alkyl Rh(I) complex; the coordination modes of the BH3 groups are discussed on the basis of X-ray data, variable temperature multinuclear NMR experiments and DFT studies. [ABSTRACT FROM AUTHOR]

Highlights from the article: Cover Feature: Phosphinine-Based Ligands in Gold-Catalyzed Reactions (Chem. Eur. J. 37/2019) Keywords: density functional calculations; heterocycles; homogeneous gold catalysis; phosphorus ligands; X-ray diffraction Density functional calculations, heterocycles, homogeneous gold catalysis, phosphorus ligands, X-ray diffraction.

Palladium-catalyzed electrophilic allylation of aldehydes with allyistannanes has been proposed in the literature as a model reaction illustrating the potential of nucleophilic η¹-alIyl palladium pincer complexes to promote new catalytic processes. This reaction was studied by a joint experimental and theoretical approach. It was shown that pincer palladium complexes featuring a S~P~S and a S~C~S tridentate ligand are efficient catalysts for this reaction. The full mechanism of this transformation was studied in detail by means of DFT calculations. Two pathways were explored: the commonly proposed mechanism involving η¹-allyl palladium intermediates and a Lewis acid promoted mechanism. Both of these mechanisms were compared to the direct transformation that was shown experimentally to occur under mild conditions. The mechanism involving an η¹-allyl palladium intermediate has been discarded on energetic grounds, the nucleophilic attack and the transmetalation step being more energetically demanding than the direct reaction between allyltin and the aldehyde. On the other hand, a mechanism where the palladium acts as a Lewis acid proved to be fully consistent with all experimental and theoretical results. This mechanism involves (L~X~L)Pd+ species which activate the aldehyde moiety toward nucleophilic attack. [ABSTRACT FROM AUTHOR]

Differentsynthetic strategies are proposed to obtain a family of scandium carbenecomplexes. Starting either from scandium trichloride, scandium trisbenzyl,or the known scandium bis(diphenylthiophosphinoyl)methanediidechloride complex 1, the homoleptic bis-carbene complex[Sc{C(PPh2S)2}2Li(THF)2] (3), the alkyl-carbene complex [Sc{C(PPh2S)2}{CH(PPh2S)2}(THF)] (5), the amido-carbene complex [Sc{C(PPh2S)2}{N(SiMe3)2}(THF)] (7), and the phosphido-carbene complex [Sc{C(PPh2S)2}{P(SiMe3)2}(Py)2](8) were obtained. The influence of the nature of theanionic ligand in transposition to the carbene ligandon the geometries at Sc was probed by DFT calculations in the caseof complexes 7and 8. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of UI3(THF)4 with [M(Et2O)][SPSMe] (M=Li, K; [SPSMe]− =1-methyl-2,6-bis(diphenylphosphine sulfide)-3,5-diphenylphosphinine anion) gave the cationic tris SPS complex [U(SPSMe)3]I (1). Similar reaction of U(BH4)3(THF)3 and [M(Et2O)][SPSMe] afforded, in addition to the [U(SPS)3]+ cation, crystals of the sulfido complex [U{(μ3-S)4U3(SPSMe)3(BH4)3}2] (2). The metal environment in 1 is a tricapped trigonal prism and the core of the heptanuclear cluster 2 is a corner-shared double-cubane. [Copyright &y& Elsevier]

Abstract: This article provides an overview of the chemistry of monoanionic S–P–S and dianionic S–C–S ligands featuring two phosphinosulfide ligands as pendant groups. These new pincer-type structures are easily assembled from phosphinines and the bis-sulfide derivative of the bis(diphenylphosphino)methane, respectively. Monoanionic S–P–S pincer ligands easily coordinate group 10 and group 9 metal fragments through displacement reactions. Palladium(II) complexes of S–P–S ligands efficiently catalyze cross-coupling processes, allowing the formation of boronic esters and biphenyl derivatives. Rh(I) complexes of S–P–S ligands react in a regioselective way with small molecules (O2, SO2, CS2, MeI) to afford the corresponding Rh(I) or Rh(III) derivatives. S–C–S dianonic ligands, which are readily obtained through a bis-metallation at the central carbon atom of Ph2P(nf 2P(nf 2, react with Pd(II) and Ru(II) precursors to afford new carbene complexes. Samarium and thulium alkylidene complexes of these S–C–S dianionic ligands were synthesized in a similar way. Reaction of the lanthanide derivatives with ketones or aldehydes yields olefinic derivatives through a ‘Wittig-like’ process. [Copyright &y& Elsevier]