Hydroboration of Terminal Alkynes Catalyzed by a Mn(I) Alkyl PCP Pincer Complex Following Two Diverging Pathways.

A stereo- and regioselective Mn(I)-catalyzed hydroboration of terminal alkynes with pinacolborane (HBPin) is described. The hydroboration reaction is highly -selective in the case of aryl alkynes and -selective in the case of aliphatic alkynes. The reaction requires no additives or solvents and proceeds with a catalyst loading of 1 mol % at 50-70 °C.

Structural Chemistry of Titanium (IV) Oxo Clusters, Part 2: Clusters without Carboxylate or Phosphonate Ligands.

Homometallic titanium oxo clusters (TOC) are one of the most important groups of metal oxo clusters. In a previous article, TOC structures with carboxylato and phosphonato ligands were reviewed and categorized. This work is now extended to clusters with other ligands.

Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes.

Unlabelled: The synthesis, characterization, and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH linkers to two phosphine donors is described. Treatment of [P(NH)P-Pr] with [MCl(THF)] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNP)(μ-Cl)(Cl)] featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMeI to give the mononuclear complexes [M(PNP)(η-Cp)(Cl)] and [M(PNP)(I)], respectively.

Characterization of PPS Piston and Packing Ring Materials for High-Pressure Hydrogen Applications.

The widespread adoption of renewable energy hinges on the efficient transportation of hydrogen. Reciprocating piston compressor technology in non-lubricated operation will play a key role, ensuring high flow rates and compression ratios. These systems rely on advanced high-strength sealing solutions for piston and rod packing rings utilizing advanced fiber-reinforced polymers.

Cage compound ScPtB: a Pt-stuffed variant of filled skutterudite structure. Electronic and structural properties.

The title compound was obtained from elements arc melting and its crystal structure was determined from single-crystal X-ray diffraction data (space group 3̄, = 10.2042(6) Å). The refinement indicated the occupancy of icosahedral 2 and cubooctahedral 8 sites solely by Sc atoms which leads to the composition ScPtB in contrast to the previously reported ternary stannides of GdNiSn type (REMSn compounds).

Electronic and Structural Properties of MPtB (M = Y, Yb): Structural Disorder in an Octahedral Boron Framework.

Two new ternary platinum borides, YPtB and YbPtB, were obtained by argon-arc melting of the elements followed by annealing at 780 °C (750 °C). The structures of these compounds combine the fragments of CaB- and AuCu-type structures [space group 3̅; = 1.15, = 4.

Selective Transfer Semihydrogenation of Alkynes Catalyzed by an Iron PCP Pincer Alkyl Complex.

Two bench-stable Fe(II) alkyl complexes [Fe(κPCP-PCP-Pr)(CO)(R)] (R = CHCHCH, CH) were obtained by the treatment of [Fe(κPCP-PCP-Pr)(CO)(H)] with NaNH and subsequent addition of CHCHCHBr and CHI, respectively. The reaction proceeds via the anionic Fe(0) intermediate Na[Fe(κPCP-PCP-Pr)(CO)]. The catalytic performance of both alkyl complexes was investigated for the transfer hydrogenation of terminal and internal alkynes utilizing PhSiH and PrOH as a hydrogen source.

Cr(II) and Cr(III) NCN pincer complexes: synthesis, structure, and catalytic reactivity.

Unlabelled: The synthesis, characterization, and reactivity of several new Cr(II) and Cr(III) complexes featuring an NCN pincer ligand with an arene backbone connected to amine donors NEt and NPr via CH-linkers is described. Reacting the in situ lithiated ligand precursor N(C-Br)N-Et with [CrCl(THF)] resulted in the formation of the Cr(III) complex -[Cr(κ-NCN-Et)(Cl)(THF)]. Upon reaction of lithiated N(C-Br)N-Pr with a suspension of anhydrous CrCl, the Cr(II) complex [Cr(κ-NCN-Pr)] is formed featuring two NCN ligands bound in κ-fashion.

Solvothermal synthesis of cobalt PCP pincer complexes from [Co(CO)].

Unlabelled: Treatment of [Co(CO)] with the -substituted P(C-X)P ligands (X = Br, Cl; R = Pr, Bu) bearing Y = NH and CH linkers under solvothermal conditions affords the five-coordinate Co(I) and Co(III) complexes [Co(PCP-R)(CO)] and [Co(PCP-R)X]. The later are paramagnetic exhibiting a solution magnetic moment in the range of 3.0-3.

Pyrrole-Based Ti(III) and Ti(IV) PNP Pincer Complexes: Insertion of Ketones into the Ti(IV)-Phosphorus Bond.

The synthesis, characterization, and reactivity of pyrrole-based Ti(III) and Ti(IV) PNP pincer complexes are described. [P(NH)P-Pr] () reacts with [TiCl(THF)] at room temperature in the presence of NEt to afford the Ti(IV) complex [Ti(PNP)(Cl)]. This complex reacts with acetone and cyclopentanone to give complexes [Ti(PNO-Pr)(Cl)] and [Ti(PNO-Pr)(Cl)], respectively.

Hydrogenation of Terminal Alkenes Catalyzed by Air-Stable Mn(I) Complexes Bearing an N-Heterocyclic Carbene-Based PCP Pincer Ligand.

Efficient hydrogenations of terminal alkenes with molecular hydrogen catalyzed by well-defined bench stable Mn(I) complexes containing an N-heterocyclic carbene-based PCP pincer ligand are described. These reactions are environmentally benign and atom economic, implementing an inexpensive, earth abundant non-precious metal catalyst. A range of aromatic and aliphatic alkenes were efficiently converted into alkanes in good to excellent yields.

Base metal complexes featuring a new pyrazole-derived PCP pincer ligand.

A new pyrazole-derived PCP pincer ligand featuring a 1-methylpyrazole backbone tethered to two di(isopropyl)phosphine moieties phenylene spacers (P(CH)P-iPr) was prepared. When reacting the ligand with group six carbonyl complexes [M(CO)] (M = Cr, Mo, W) at 130 °C, complexes of the type [M(κ-PCP-iPr)(CO)] were obtained featuring a κ,-bound ligand with a pendant phosphine arm. Upon an increase of the reaction temperature to 150 °C, in the case of molybdenum, the formation of the complex [Mo(κ-PCP-iPr)(CO)] was observed featuring a weak Mo-C bond.

Crystal-Orientation-Dependent Oxygen Exchange Kinetics on Mixed Conducting Thin-Film Surfaces Investigated by Studies.

The oxygen exchange kinetics and the surface chemistry of epitaxially grown, dense LaSrCoO (LSC) thin films in three different orientations, (001), (110), and (111), were investigated by means of impedance spectroscopy during pulsed laser deposition (i-PLD) and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). i-PLD measurements showed that pristine LSC surfaces exhibit very fast surface exchange kinetics but revealed no significant differences between the specific orientations. However, as soon as the surfaces were in contact with acidic, gaseous impurities, such as S-containing compounds in nominally pure measurement atmospheres, NAP-XPS measurements revealed that the (001) orientation is substantially more susceptible to the formation of sulfate adsorbates and a concomitant performance decrease.

Improving and degrading the oxygen exchange kinetics of LaSrCoO by Sr decoration.

Minimizing the overpotential at the air electrode of solid oxide fuel cells (SOFC) is one of the key challenges regarding a broad applicability of this technology. Next to novel materials and geometry optimization, surface modification is a promising and flexible method to alter the oxygen exchange kinetics at SOFC cathode surfaces. Despite extensive research, the mechanism behind the effect of surface decorations is still under debate.

Oxidative Desymmetrization Enables the Concise Synthesis of a trans-Cyclooctene Linker for Bioorthogonal Bond Cleavage.

Modified trans-cyclooctenes (TCO) are capable of highly efficient molecular manipulations in biological environments, driven by the bioorthogonal reaction with tetrazines (Tz). The development of click-cleavable TCO has fueled the field of in vivo chemistry and enabled the design of therapeutic strategies that have already started to enter the clinic. A key element for most of these approaches is the implementation of a cleavable TCO linker.

Late-stage derivatization of a (B,O)-doped perylene.

Regioselective di- and tetrabrominations of the (B,O)-perylene 1 afford derivatives 2-4. Despite their poor solubility, 2 and 4 could be used in Stille-type coupling reactions to introduce two CCMe (5) or four CC(-CHBu) substituents (6), respectively. The alkynylated derivatives show blue-green photoluminescence with appreciable quantum efficiencies.

The Vienna Genesis: An Example of Late Antique Purple Parchment.

The investigation and conservation of the Vienna Genesis, a Late Antique manuscript on purple parchment, included the study of parchment production and purple dyeing in the sixth century. The process of parchment making and of purple dyeing was recreated and compared with the Vienna Genesis and other manuscripts from the sixth and eighth centuries. Parchment made from the hides of young lambs and dyed with orchil resembled the folios of the Vienna Genesis.

Synthesis and characterization of cobalt SCS pincer complexes.

Unlabelled: The synthesis and characterization of two Co(II) complexes stabilized by a tridentate SCS pincer ligand are described. Paramagnetic [Co(κ-SCS-Et)] and [Co(κ-SCS-Bu)(κ-SCS-Bu)] were obtained via transmetalation protocol from CoBr and S(C-Br)S-R (R = Et, Bu). Oxidation of the latter with [CpFe]PF affords the diamagnetic 18 VE complex [Co(κ-SCS-Bu)]PF.

The channel structure of trithallium penta-anti-m-on-ate(V), TlSbO.

Single crystals of TlSbO were grown by solid-state reaction in a corundum crucible under air (1273 K, 12 h). The structure was determined by single-crystal X-ray diffraction. It is isotypic to the KSbO, RbSbO and CsSbO analogues with ortho-rhom-bic symmetry and cell parameters = 24.

Insights into the Correlation between Residual Stresses, Phase Transformation, and Wettability of Femtosecond Laser-Irradiated Ductile Iron.

Despite numerous studies on the wettability behavior of ductile iron after ultrafast laser structuring, the correlation between the phase change due to the interaction with an intense pulse and wettability is not yet well understood. In the present work, phase transformations of ductile iron substrates after femtosecond laser irradiation are investigated and correlated with the wettability behavior. Laser parameters such as fluence (F), cumulative fluence (CH), number of pulses (N), and scan speed were varied to produce hierarchical structures with different morphologies and phase concentrations.

Polytypism in mcalpineite: a study of natural and synthetic CuTeO.

Synthetic and naturally occurring forms of tricopper orthotellurate, CuTeO (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, CuTeO is shown to occur in two polytypes. The higher-symmetric CuTeO-1C polytype is cubic, space group Ia3, with a = 9.

Hydroboration of Terminal Alkenes and -1,2-Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex.

A Mn-catalyzed hydroboration of terminal alkenes and a 1,2-diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti-Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans-1,2-selectivity. The most active pre-catalyst is bench-stable alkyl bisphosphine Mn complex fac-[Mn(dippe)(CO)(CHCHCH)].

Manganese-Catalyzed Dehydrogenative Silylation of Alkenes Following Two Parallel Inner-Sphere Pathways.

We report on an additive-free Mn(I)-catalyzed dehydrogenative silylation of terminal alkenes. The most active precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex [Mn(dippe)(CO)(CHCHCH)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn-alkyl bond to yield an acyl intermediate which undergoes rapid Si-H bond cleavage of the silane HSiR forming the active 16e Mn(I) silyl catalyst [Mn(dippe)(CO)(SiR)] together with liberated butanal.