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Under the large ziggurat of Aššur, Iraq, two Baltic amber beads were found in a foundation deposit dating to c.1800–1750 BC. Thereby, they represent one of the earliest and remotest evidence of this material. Its extreme rarity in the Mediterranean and the Middle East before c.1550 BC and its restriction there to high-ranking sites could be explained by the fact that the Únětice culture and the Wessex culture controlled the exchange of this raw material. Probably, the amber finds in the south result from a directional exchange with at most only a few intermediaries, as other finds in Europe and the Middle East from the early 2nd millennium BC also indicate. The amber finds may thus represent gifts from well-travelled persons from central or western Europe to the elites in the south. However, after c.1550 BC the picture changes, and it is perhaps possible to speak of trade through which amber became available in larger quantities in the Mediterranean and the Middle East.

Remarkable features are reported in the diffraction pattern produced by a crystal of the second extracellular domain of tetraspanin CD9 (deemed CD9EC2), the structure of which has been described previously [Oosterheert et al. (2020[Oosterheert, W., Xenaki, K. T., Neviani, V., Pos, W., Doulkeridou, S., Manshande, J., Pearce, N. M., Kroon-Batenburg, L. M. J., Lutz, M., van Bergen en Henegouwen, P. M. P. & Gros, P. (2020). Life Sci. Alliance, 3, e202000883.]), Life Sci. Alliance, 3, e202000883]. CD9EC2 crystallized in space group P1 and was twinned. Two types of diffuse streaks are observed. The stronger diffuse streaks are related to the twinning and occur in the direction perpendicular to the twinning interface. It is concluded that the twin domains scatter coherently as both Bragg reflections and diffuse streaks are seen. The weaker streaks along c* are unrelated to the twinning but are caused by intermittent layers of non-crystallographic symmetry related molecules. It is envisaged that the raw diffraction images could be very useful for methods developers trying to remove the diffuse scattering to extract accurate Bragg intensities or using it to model the effect of packing disorder on the molecular structure.

The optical properties of two sets of donor-acceptor-donor molecules with terminal bithiophene donor units and a central diketopyrrolopyrrole (DPP) acceptor unit are studied. The two sets differ in the alkyl chains on the DPP, which are either branched at the α-carbon (3-pentyl) (1-4) or linear (n-hexyl) (5-8). Within each set, the molecules differ by the absence or presence of n-hexyl chains on the terminal thiophene rings in the 3′, 4′, or 5′ positions. While in solution, the optical spectra differ only subtly; they differ dramatically in the solid state. In contrast to 5-8, 1-4 are nonplanar as a consequence of the sterically demanding 3-pentyl groups, which inhibit π-stacking of the DPP units. Using the crystal structures of 2 (brick layer stacking) and 6 (slipped stacking), we quantitatively explain the solid state absorption spectra. By computing the molecular transition charge density and solving the dispersion relation, the optical absorption of the molecules in the crystal is predicted and in agreement with experiments. For 2, a single resonance frequency is obtained, while for 6 two transitions are seen, with the lower-energy transition being less intense. The results demonstrate how subtle changes in substitution exert large effects in optical properties.

Activation of a Si–H bond is commonly a critical step in catalytic hydrosilylation reactions. Herein, we investigate the cooperative reactivity of Ni(0) centers bearing a side-bound imine ligand toward silanes. Such complexes activate a Si–H bond of diphenylsilane, resulting in formal hydrosilylation of the imine backbone, which acts as a hydride acceptor. The resulting hydrosilazane motif engages either in coordination to nickel via the Si–H bond, forming an 18-electron η2-Si–H complex, or oxidative addition to Ni to form 16-electron Ni(II) silyl/hydride complexes. DFT calculations suggest a cooperative activation of the silane via ligand-to-ligand hydride transfer. In addition, the silicon fragment readily exchanges with external hydrosilanes, showing that the Si–N bond can be reversibly cleaved under mild conditions.

We report the synthesis and characterization of a series of cationic, neutral and anionic dicopper(I) complexes featuring a µ-mesityl ligand and a naphthyridine-derived PNNP expanded pincer ligand. Structural characterization showed that the protonation state of the dinucleating ligand has a pronounced effect on the bending and tilting of the µ-mesityl ligand. DFT calculations indicate that the varying orientations of the µ-mesityl ligand are inherent due to changes in electronic structure rather than crystal packing effects. NBO analysis reveals how the interactions that contribute to the 3-center 2-electron bond between the µ-mesityl ligand and the dicopper core change for the various degrees of observed bending and tilting.

Introducing charges into ligand systems fine-tunes their electronic properties and influences the solubility of their metal complexes. Herein, we present a synthesis of a dianionic, C3-symmetric ligand combining three anionic N-donors tethered to a positively charged phosphonium center. The tris-skatylmethylphosphonium (TSMP) ligand, isolated in the form of its dipotassium salt TSMPK2, is the first dianionic homoscorpionate capable of metal exchange. The potassium cations in TSMPK2 are exchangeable for other metals, which results in rich coordination chemistry. Thus, the ligand displays a bridging μ2:κ2:κ1 coordination mode with trigonal planar Cu(i) centers in the tetrameric complex [(TSMP)Cu]44-. The κ3 mode is accessed upon addition of 1 equiv. of P(OEt)3 per Cu(i) to yield the tetrahedral monomeric complex [(TSMP)CuP(OEt)3]-. Both Fe(ii) and Ni(ii) in pyridine give octahedral high-spin κ3 complexes with composition (TSMP)M(Py)3 (M = Fe, Ni). Displacement of three pyridine ligands in (TSMP)Fe(Py)3 for a second equivalent of TSMP gives a high-spin pseudotetrahedral 2 : 1 complex [(TSMP)2Fe]2- with the ligands in κ2 coordination mode. The reduction in coordination number is likely due to electrostatic repulsion of the negatively-charged indolides as well as their weaker π-accepting character as compared to pyridine. This journal is

Adaptive ligands, which can adapt their coordination mode to the electronic structure of various catalytic intermediates, offer the potential to develop improved homogeneous catalysts in terms of activity and selectivity. 2,2′-Diphosphinobenzophenones have previously been shown to act as adaptive ligands, the central ketone moiety preferentially coordinating reduced metal centers. Herein, the utility of this scaffold in nickel-catalyzed alkyne cyclotrimerization is investigated. The complex [(p-tolL1)Ni(BPI)] (p-tolL1 = 2,2′-bis(di(para-tolyl)phosphino)-benzophenone; BPI = benzophenone imine) is an active catalyst in the [2 + 2 + 2] cyclotrimerization of terminal alkynes, selectively affording 1,2,4-substituted benzenes from terminal alkynes. In particular, this catalyst outperforms closely related bi- and tridentate phosphine-based Ni catalysts. This suggests a reaction pathway involving a hemilabile interaction of the C=O unit with the nickel center. This is further borne out by a comparative study of the observed resting states and DFT calculations.

Accuracy is crucial in Deep Brain Stimulation (DBS). Electrophysiological and image-based techniques are used to avoid suboptimal positioning. Macrostimulation is the gold standard to delineate the therapeutic window intraoperatively. Despite this, electrode revision rates due to malpositioning are as high as 17%. The goal was to compare motor evoked potentials (MEPs) with the gold standard of Macrostimulation. We assessed accuracy and precision as well as the correlation in predicting motor side effects at the initial mapping 4 weeks postoperatively.In this prospective study intraoperative MEPs from 94 contacts in 16 patients undergoing STN DBS under local anesthesia were correlated to the postoperative threshold for stimulation-induced motor side effects and compared to intraoperative Macrostimulation. Analysis of accuracy, precision and correlation (Pearson) was performed.MEPs of the upper extremity had a mean percentage error of 25% (SD 38.8%) and correlated significantly with the motor threshold at postoperative mapping (R=0.235). Macrostimulation was less accurate and precise with a mean percentage error of - 68% (SD 78.8%) but had a higher correlation (R=0.388). MEPs rarely (3%) overestimated the threshold by maximally 1 mA. In contrast, Macrostimulation overestimated the threshold by over 1 mA in 69% leading to a false sense of security.MEPs are feasible in an awake setting during Deep Brain Stimulation in the STN for PD patients. MEPs of the upper extremity are more accurate and precise predicting the motor threshold and avoid a false sense of security in comparison to the gold standard of Macrostimulation.

Compounds of main‐group elements such as silicon are attractive candidates for green and inexpensive catalysts. For them to compete with state‐of‐the‐art transition‐metal complexes, new reactivity modes must be unlocked and controlled, which can be achieved through strain. Using a tris(2‐skatyl)methylphosphonium ([TSMPH3]+) scaffold, we prepared the strained cationic silane [TSMPSiH]+. In stark contrast with the generally hydridic Si−H bond character, it is acidic with an experimental pK a DMSO within 4.7–8.1, lower than in phenol, benzoic acid, and the few hydrosilanes with reported pK a values. We show that ring strain significantly contributes to this unusual acidity along with inductive and electrostatic effects. The conjugate base, TSMPSi, activates a THF molecule in the presence of CH‐acids to generate a highly fluxional alkoxysilane via trace amounts of [TSMPSiH]+ functioning as a strain‐release Lewis acid. This reaction involves a formal oxidation‐state change from SiII to SiIV, presenting intriguing similarities with transition‐metal‐mediated processes., The reactivity of a ≡SiH group can be greatly altered by enclosing it into a strained bicyclic scaffold. The resulting silane is acidic with an experimental pK a DMSO of 4.7–8.1, lower than phenol, benzoic acid, and most hydrosilanes. It also shows strain‐release Lewis acidity in the form of coordination of a THF molecule with its subsequent activation towards weak nucleophiles. The resulting ring‐opening product shows high geometric fluxionality.

Oxidative addition of aryl halides to Ni(0) is a ubiquitous elementary step in cross-coupling and related reactions, usually producing a square-planar Ni(II)-aryl intermediate. Here we show that a triphosphine ligand supports oxidative addition at a tris-ligated Ni(0) center to cleanly form stable five-coordinate Ni(II)-aryl compounds. Kinetic and computational studies support a concerted, two-electron mechanism rather than radical halogen abstraction. These results support the idea that oxidative addition to triphosphine Ni(0) species may be more generally involved in Ni/phosphine catalytic systems. ispartof: ORGANOMETALLICS vol:39 issue:8 pages:1139-1144 ispartof: location:United States status: published

The X-ray crystal structure of tris[N-(2-hydroxyethyl)-2,2′-iminodiethanolato]tris(2,2′,2′′-nitrilotriethanolato)tetrairon(II)triiron(III) bis(perchlorate), [Fe7(C6H12NO3)3(C6H13NO3)3](ClO4)2 or [Fe7(tea)3(tea-H)3](ClO4)2 (tea-H3 is triethanolamine), is known from the literature [Liu et al. (2008). Z. Anorg. Allg. Chem. 634, 778–783] as a heptanuclear coordination cluster. The space group was given as I213 and is reinvestigated in the present study. We find a new space-group symmetry of Pa\overline{3} and could detect O—H hydrogens, which were missing in the original publication. Consequences on the Fe oxidation states are investigated with the bond-valence method, resulting in a mixed-valence core of four FeII and three FeIII centres. Symmetry relationships between the two space groups and the average supergroup Ia\overline{3} are discussed in detail.

The phosphinidene complex iPr2N–P═Fe(CO)4 was prepared as a storable phosphirane solution from Collman’s reagent and iPr2NPCl2 in the olefins 1-pentene and 1-hexene. The carbene-like reagent is able to hop under very mild conditions (>−25 °C) from one olefin to another and to alkynes to give the more stable phosphirenes that likewise display dynamic covalent behavior. The olefinic solutions are effective reservoirs for the highly reactive phosphinidene complex, as is illustrated in its N–H and O–H insertion reactions with amines, alcohols, and carboxylic acids and in its P–C bond formation with Grignard reagents.

A computationally guided synthetic route to a free silanide derived from tris(3‐methylindol‐2‐yl)methane ([(tmim)Si]−) through nucleophilic substitution on the SiII precursor (Idipp)SiCl2 is reported (Idipp=2,3‐dihydro‐1,3‐bis(2,6‐diisopropylphenyl)‐1H‐imidazol‐2‐ylidene). This approach circumvents the need for strained tetrahedral silanes as synthetic intermediates. Computational investigations show that the electron‐donating properties of [(tmim)Si]− are close to those of PMe3. Experimentally, the [(tmim)Si]− anion is shown to undergo clean complexation to the base metal salts CuCl and FeCl2, demonstrating the potential utility as a supporting ligand.

We re-investigated the crystal structure of diaquobis(salicylato)copper(II), CuSal, which is an OD material with disordered layer stacking. The diffraction pattern consists of sharp Bragg spots and diffuse streaks. From the Bragg reflections we determined the ordered part of the structure, which can either be described by an orthorhombic or a twinned monoclinic lattice. The main motif of the structure consists of one-dimensional coordination polymers that are connected by hydrogen bonds into two-dimensional layers. The layer stacking is disordered and from simulation

Mononuclear, coordinatively unsaturated rhenium(V) dioxo species of the type XReO2 (X = Me, substituted cyclopentadienyl) have long been postulated as intermediates in rhenium-catalyzed deoxydehydration, but their characterization was precluded because of aggregation into dimeric or oligomeric structures. Using the bulky 1,2,4-tri-tert-butylcyclopentadienyl (Cpttt) ligand, the rhenium(V) dioxo species (Cpttt)ReO2 could now be observed, in equilibrium with the dimeric form [(Cpttt)Re(O)μ-O]2, and characterized by NMR, IR, and UV-vis spectroscopies, as well as electrospray ionization mass spectrometry. (Cpttt)ReO2 is shown to be the primary product of reduction of the rhenium(VII) complex (Cpttt)ReO3 with PPh3 and demonstrated to react with ethylene glycol significantly faster than its dimeric counterpart, supporting its role as an intermediate in rhenium-catalyzed deoxydehydration reactions.

Replacing nitrogen by phosphorus in otherwise similar structures changes the properties of the resulting compounds significantly due to the electronic differences that exist between these heteroatoms. While the "hard" nitrogen atom of the pyridine moiety acts as a good σ-donor, the "soft" phosphorus atom of the phosphinine core results in a rather strong π-acceptor capacity. A series of novel group 6 complexes [M(CO)4(L^L)] (M = Cr0, Mo0, W0) have been synthesized, in which L^L is either 2-(2′-pyridyl)-4,6-diphenylphosphinine (P,N) or the corresponding bipyridine derivative, 2-(2′-pyridyl)-4,6-diphenylpyridine (N,N) as a chelating, bidentate ligand. The here presented results describe a detailed investigation of the structural and spectroscopic properties of the coordination compounds [M(CO)4(P,N)] and [M(CO)4(N,N)] (M = Cr0, Mo0, W0), leading to a better understanding of such intriguing aromatic phosphorus heterocycles.

π-Coordinating ligands are commonly found in intermediate structures in homogeneous catalysis, and are gaining interest as supporting ligands for the development of cooperative catalysts. Herein, we systematically investigate the binding of the ketone group - a strongly accepting π-ligand - to mid-to-late metals of the first transition series. To this end, the coordination of 2,2'-bis(diphenylphosphino)benzophenone (Phdpbp), featuring a ketone moiety flanked by two strongly binding P-donor groups, to Fe, Co, Ni and Cu is explored. The ketone moiety does not bind to the metal in M(II) complexes, whereas M(I) complexes (Fe, Co, Ni) adopt an η2(C,O)-coordination. A structural and computational investigation of periodic trends in this series was performed. These data suggest that the coordination of the ketone to M(I) can mostly be described by the resonance extremes of the Dewar-Chatt-Duncanson model, i.e. the π-complex and the metallaoxacycle extreme, with a possible minor contribution of a ketyl radical resonance structure in the case of the iron complex.

The ability of the bis(imidazolyl)ketone ligand BMdiPhIK (bis(1-methyl-4,5-diphenylimidazolyl)ketone) to function as a redox active ligand has been investigated. The reduction of [M(BMdiPhIK)Cl2] (M = Fe and Zn) complexes resulted in a pinacol-type coupling to form dinuclear complexes featuring very weak and abnormally elongated C–C bonds (1.729(5) and 1.708(3) Å for Fe and Zn, respectively). Oxidation of these complexes using ferrocenium in the presence of Cl− ions regenerated the original [M(BMdiPhIK)Cl2] complexes, showing the reversibility of the coupling process. This makes it a potentially interesting approach for the storage of electrons and application of the BMdiPhIK ligand as a redox active ligand. Graphical abstract: Formation of exceptionally weak C–C bonds by metal-templated pinacol coupling

Due to their well-defined three-dimensional geometry, spiro compounds are widely utilized in drug research. From the central tetrahedral carbon atom, besides the regular structure, an inverted spiro connectivity may be envisioned. Here we disclose the synthesis of this molecule class that we have coined quasi[1]catenanes. Next to their fascinating and aesthetic shape, the higher compactness as compared to regular spiro bicycles is noteworthy. To enable synthetic access to compact entangled multimacrocyclic molecules, we have developed a new strategy. The key element is a template, which is covalently connected to the linear precursors, and spatially directs the sterically congested backfolding macrocyclizations that are required to give quasi[1]catenanes. Similarly, quasi[1]rotaxanes are made., Spiro compounds contain two or more rings linked together through one common atom. Here the authors provide a method to backfold both rings, producing spiro quasi[1]catenanes, via a strategy of temporarily linking the linear intermediates with covalent bonds.

Catalytic hydrogenation of carboxylic acid esters is essential for the green production of pharmaceuticals, fragrances, and fine chemicals. Herein, we report the efficient hydrogenation of esters with manganese catalysts based on simple bidentate aminophosphine ligands. Monoligated Mn PN complexes are particularly active for the conversion of esters into the corresponding alcohols at Mn concentrations as low as 0.2 mol % in the presence of sub‐stoichiometric amounts of KOtBu base.

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The crystal structure of para-methyl-l-phenylalanine at 230 K resembles that of the para-fluorinated analogue from the literature but is commensurately modulated with seven molecules in the asymmetric unit (Z′ = 7). At 100 K, the superstructure loses its modulation, leading to a unit cell with Z′ = 1, with clear disorder in the phenyl ring orientations. The methyl-substituent in para-methyl-l-phenylalanine has, in contrast to fluorine, no polar interactions with protons of neighboring molecules, which might allow for the well-defined modulation of the crystal structure at 230 K., The crystal structure of para-methyl-l-phenylalanine at 230 K is a commensurately modulated superstructure with seven molecules in the asymmetric unit. This structure loses its modulation at 100 K. Both structures are interpreted by comparing them with the structures of l-Phe and its para-fluorinated derivative.

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American studies journal; Vol. 63, No. 03, 2017. 2199-7268, Special Edition: The Plain People: Contemporary Perspectives and Future Prospects

Photochemical activation of [(PNNH)Rh(N3)] (PNNH=6-di-(tert- butyl)phosphinomethyl-2,2′-bipyridine) complex2 produced the paramagnetic (S=1/2), [(PNN)Rh-N.-Rh(PNN)] complex3 (PNN-=methylene- deprotonated PNNH), which could be crystallographically characterized. Spectroscopic investigation of 3 indicates a predominant nitridyl radical ( .N2-) character, which was confirmed computationally. Complex3 reacts selectively with CO, producing twoequivalents of [(PNN)Rh I(CO)] complex4, presumably by nitridyl radical N,N-coupling. The first isolated nitridyl radical (.N2-) complex was obtained by photochemical activation of the rhodium-azide complex [(PNNH)Rh(N3)] (1), producing N2, H2, and the paramagnetic complex2. Complex2 reacts selectively with CO to produce complex3, presumably by N,N-coupling of nitridyl radicals.

The title compound, [(C2H5)4N][FeCl4], has at room temperature a disordered structure in the high-hexagonal space group P63 mc. At 230 K, the structure is merohedrally twinned in the low-hexagonal space group P63. The volume has increased by a factor of 9 with respect to the room-temperature structure. At 170 and 110 K, the structure is identical in the orthorhombic space group Pca21 and twinned by reticular pseudomerohedry. The volume has doubled with respect to the room-temperature structure. All three space groups, viz. P63 mc, P63 and Pca21, are polar and the direction of the polar axis is not affected by the twinning. In the P63 and Pca21 structures, all cations and anions are well ordered.

Recent studies on water-splitting photoelectrochemical cells (PECs) have demonstrated the intriguing possibility of controlling the spin state in this chemical reaction to form H 2 and O 2 by exploiting the chirality of organic π-conjugated supramolecular polymers. Although this fascinating phenomenon has been disclosed, the chiral supramolecular materials reported thus far are not optimized for acting as efficient photosensitizer for dye-sensitized PECs. In this work we report on the design, synthesis, and characterization of chiral supramolecular aggregates based on C 3 -symmetric triphenylamine-based dyes that are able to both absorb visible light and control the spin state of the process. Variable temperature-dependent spectroscopic measurements reveal the assembly process of the dyes and confirm the formation of chiral aggregates, both in solution as well as on solid supports. Photoelectrochemical measurements on TiO 2 -based anodes validate the advantage of using chiral supramolecular aggregates as photosensitizer displaying higher photocurrent compared to achiral analogues. Moreover, fluorimetric tests for the quantification of the hydrogen peroxide produced, confirm the possibility of controlling the spin of the reaction exerting spin-selection with chiral supramolecular polymers. These results represent a further step towards the next-generation of organic-based water-splitting solar cells.

The synthetic scope of proton-responsive sulfonamidophosphorus (METAMORPhos) ligands is expanded and design principles for the selective formation of particular tautomers, ion pairs, or double condensation products are elucidated. These systems have been introduced in the coordination sphere of Ru for the first time, thereby enabling the exclusive coordination as a monoanionic P,O chelate. Depending on the Ru precursor, halide-bridged dinuclear species 3-5 or cymene-derived piano-stool complexes 6-9 are isolated. The METAMORPhos framework is shown to play a role in the heterolytic cleavage of H-2, with species 7 converted into neutral monohydride 10. Substitution chemistry with cymene complex 7 has also been examined, thereby giving rise to tetrakis(acetonitrile) adduct 11. Introduction of a second equivalent of METAMORPhos ligand to this species yielded the bis(ligated) derivative 13, for which variable-temperature (VT) NMR spectroscopy indicates coalescence of the phosphine donors at high temperature. Solid-state structures of 3, 6, 11, and 13 are presented to establish the precise bonding situation of the inorganic PNSO framework within METAMORPhos upon coordination as a proton-responsive monoanionic P,O chelate.

Selective functionalization of white phosphorus is achieved by addition of ArLi to unique cationic coinage metal η(2)-P4 complexes. This novel approach allows controlled P-C bond formation using the bulky DmpLi (Dmp = 2,6-Mes2C6H3) and the unencumbered MesLi, giving sterically diverse doubly complexed RP4 butterfly derivatives in a single step.

The transient bicyclo[1.1.0]tetraphosphabutane anion, generated from white phosphorus (P4 ) and Mes*Li (Mes*=2,4,6-tBu3 C6 H2 ), can be trapped by BPh3 in THF. This Lewis acid stabilized anion can be used as an [RP4 ](-) transfer agent, reacting cleanly with neutral Lewis acids (B(C6 F5 )3 , BH3 , and W(CO)5 ) to afford unique singly and doubly coordinated butterfly anions, and with the trityl cation to form a neutral, nonsymmetrical, all-carbon-substituted P4 derivative. This reaction path enables a simple, stepwise functionalization of white phosphorus.

The excavations at Tall Halaf remained undisturbed for more than seven decades. Recently, however, German and Syrian archaeologists have resumed work there — and are gaining new and varied insights into the settlements of the Ancient Near East

Mehr als sieben Jahrzehnte ruhten die Grabungen am Tell Halaf. Vor kurzem haben deutsche und syrische Archaologen die Arbeit wieder aufgenommen – und gewinnen erneut vielfaltige Einblicke in die altorientalische Siedlungsgeschichte

Reaction of [PdClMe(P^N)2] with SnCl2 followed by Cl-abstraction leads to apparent Pd-C bond activation, resulting in methylstannylene species trans-[PdCl{(P^N)2SnClMe}][BF4] (P^N = diaryl phosphino-N-heterocycle). In contrast, reaction of Pt analogues with SnCl2 leads to Pt-Cl bond activation, resulting in methylplatinum species trans-[PtMe{(P^N)2SnCl2}][BF4]. Over time, they isomerise to methylstannylene species, indicating that both kinetic and thermodynamic products can be isolated for Pt, whereas for Pd only methylstannylene complexes are isolated. Oxidative addition of RSnCl3 (R = Me, Bu, Ph) to M(0) precursors (M = Pd or Pt) in the presence of P^N ligands results in diphosphinostannylene pincer complexes trans-[MCl{(P^N)2SnCl(R)}][SnCl4R], which are structurally similar to the products from SnCl2 insertion. This showed that addition of RSnCl3 to M(0) results in formal Sn-Cl bond oxidative addition. A probable pathway of activation of the tin reagents and formation of different products is proposed and the relevancy of the findings for Pd and Pt catalysed processes that use SnCl2 as a co-catalyst is discussed.

Reacting white phosphorus (P4 ) with sterically encumbered aryl lithium reagents (aryl=2,6-dimesitylphenyl or 2,4,6-tBu3 C6 H2 ) and B(C6 F5 )3 gives the unique, isolable Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutane anion. Subsequent alkylation of the nucleophilic site of the RP4 anion gives access to non-symmetrical disubstituted bicyclic tetraphosphorus compounds. This novel method enables PC bond formation in a controlled fashion using white phosphorus as starting material.

Digital technology furnishes an extensive array of options for open and closed-loop control of automotive electronic systems. A large number of parameters can be included in the process to support optimal operation of various systems. After receiving the electric signals transmitted by the sensors, the control unit processes these data in order to generate control signals for the actuators. The control program, the “software”, is stored in a special memory and implemented by a microcontroller. The control unit and its components are referred to as “hardware”. The EDC control unit contains all of the algorithms for open and closed-loop control needed to govern the engine-management processes.

The first Fe-based catalytic system for the oxidative cleavage of unsaturated fatty acids and esters to carboxylic acids is reported. The system comprises [Fe(OTf)(2)(6-Me-PyTACN)] (2) (6-Me-PyTACN = 1-[(6-methyl-2-pyridyl) methyl]-4,7-dimethyl-1,4,7-triazacyclononane, OTf = trifluoromethane sulfonate anion) as the catalyst (3 mol%) either with a combination of hydrogen peroxide and NaIO4 or exclusively with NaIO4 as the oxidant, and operates at 0 degrees C or ambient temperature. Under these standard conditions (method A), methyl oleate is converted in a one-pot procedure into 50-55% of both nonanoic and azelaic acid, together with some epoxide and aldehyde intermediates as byproducts. These yields can be further improved by addition of sulfuric acid (method B) to hydrolyze the epoxide byproducts, by including a pH neutralization step and addition of more catalyst (1 mol%). Under the optimized conditions, both methyl oleate and oleic acid are converted into high yields of the corresponding carboxylic acids (80-85%). Overall, this catalytic system provides an alternative to the industrial ozonolysis of oleic acid and to catalytic Ru-and Os-based systems for the oxidative cleavage of unsaturated fatty acids and ester B.M.W. and R.J.M.K.G. acknowledge Utrecht University for financial support through its 'Focus and Massa' program. M.C. acknowledges financial support from the European Research Council (ERC-2009-StG-239910), MINECO of Spain (CTQ2012-37420-C02-01/BQU, Consolider-Ingenio CSD2010-00065) and the Catalan DIUE of the Generalitat de Catalunya (2009SGR637 and ICREA Academia Award). The X-ray diffractometer has been financed by the Netherlands Organization for Scientific Research (NWO)