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International audience; Incorporating pendant silicon functionalities into phosphine ligands enables to profit from the strong σ‐electron donor and trans influence properties of Si while enhancing the coordination ability of the ligand. Herein, we show that the introduction of bulky sigma donor substituents on the Si atoms and modulation of the number of Si–H functional groups in a series of phosphinobenzylsilanes allow either the stabilization of rare highly unsaturated 14‐electron rhodium(III) and iridium(III) species devoid of agostic interactions or the access to mixed‐valence MI–MIII complexes. Our findings using isopropyl‐substituted silicon are markedly different from those obtained when employing the methyl‐substituted Si series.

International audience; Understanding and controlling the aggregation state is germane to alkyllithium chemistry. Lewis base-free alkyllithium compounds normally form tetrahedral tetramers or octahedral hexamers in the solid state with the lithium cations being three-coordinate. We report that the unsupported cyclopropyl derivative 1-(trimethylsilyl)cyclopropyllithium [μ-c-C(SiMe3)C2H4Li]4 (1), synthesized by the reduction of 1-(phenylthio)-1-(trimethylsilyl)cyclopropane, crystallizes as a tetramer in the space group I-4 with the two-coordinate lithium atoms forming a square. CC agostic interactions complete the coordination sphere around each lithium. The aggregate is preserved in hydrocarbon solution. Furthermore, CC agostic interactions compete intra- and intermolecularly with Lewis base donation as in the unsaturated dimer of 1-(phenylthio)cyclopropyllithium [Li(thf)2μ-c-C(SPh)C2H42Li (thf)] (3) which is also fully characterized.

bibtex: ISI:000414633200027 bibtex\location:'POSTFACH 101161, 69451 WEINHEIM, GERMANY',publisher:'WILEY-V C H VERLAG GMBH',type:'Article',affiliation:'Etienne, M (Reprint Author), CNRS, LCC, 205 Route Narbonne,BP44099, F-31077 Toulouse, France. Etienne, M (Reprint Author), Univ Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France. Romero, Nuria; Dufrois, Quentin; Vendier, Laure; Dinoi, Chiara; Etienne, Michel, CNRS, LCC, 205 Route Narbonne,BP44099, F-31077 Toulouse, France. Romero, Nuria; Dufrois, Quentin; Vendier, Laure; Dinoi, Chiara; Etienne, Michel, Univ Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France. Romero, Nuria, Univ Autonoma Barcelona, Dept Quim, Cerdanyola Del Valles Ba 08193, Spain. Dinoi, Chiara, LPCNO INSA, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'michel.etienne@lcc-toulouse.fr',da:'2018-12-05','doc-delivery-number':'FM0EI',eissn:'1521-3765','funding-acknowledgement':'MENESR [ANR-11-BS07-0009]; COST Action CHAOS [CA15106]','funding-text':'We thank the MENESR for a PhD grant to QD, the ANR (Green-LAkE project; ANR-11-BS07-0009) and COST Action CHAOS (CA15106) for support.','journal-iso':'Chem.-Eur. J.','keywords-plus':'AROMATIC N-HETEROCYCLES; CH BOND ACTIVATION; CRYSTAL-STRUCTURES; ALKYL COMPLEXES; H BONDS; METAL; CHEMISTRY; ETA(2)-CYCLOPROPENE; ORGANOZIRCONIUM; NIOBIUM','number-of-cited-references':'42','orcid-numbers':'Romero, Nuria/0000-0002-2704-7779 Vendier, Laure/0000-0002-7111-9258 Etienne, Michel/0000-0002-1099-3232','research-areas':'Chemistry','researcherid-numbers':'Romero, Nuria/A-9756-2016','times-cited':'0','unique-id':'ISI:000414633200027','usage-count-last-180-days':'4','usage-count-since-2013':'12','web-of-science-categories':'Chemistry, Multidisciplinary'\; International audience; This paper reports on stereospecific coupling reactions between an (2)-cyclopropene ligand and pyridine derivatives, which are preferred to alternative C-H bond activation reactions. The dicyclopropylzirconocene complex [Cp2Zr(c-C3H5)(2)](1) eliminates cyclopropane to generate the (2)-cyclopropene/bicyclobutane intermediate [Cp2Zr((2)-c-C3H4)](A). A does not activate any pyridine C-H bonds, but rather pyridine inserts into a Zr-C bond of A, yielding an azazirconacycle with a dearomatized pyridyl group [Cp2Zr\(2)-N,C-8-(2-c-C3H4)-C5H5N\](2). Kinetic data, isotopelabelling experiments, and DFT calculations indicate that the rate-determining step of this stereospecific reaction is cyclopropane elimination, and that the stability of the intermediate [Cp2Zr((2)-c-C3H4)(NC5H5)](A-py) governs the selectivity of the reaction. Complex2 tautomerizes to [Cp2Zr\(2)-N,C-8-(2-C3H5)-C5H4N\](6) through a base-catalyzed proton migration accompanied by cyclopropyl opening and restoration of conjugation within the zirconacycle.

International audience; Vanadium complexes are attractive potential alternatives to platinum-based anticancer drugs. Two vanadium(V) complexes, based on a common chelating tetradentate diaminobis(phenolato) ligand featuring a branched connectivity but differing in their labile ligands, were synthesized and characterized. Whereas the isopropoxido complex was obtained as a mixture of cis and trans isomers with regard to the orientation of the labile group vs. the amine sidearm, the salicylato-containing complex was obtained as a single trans isomer. X-ray structures of the complexes featured octahedral geometry for both. The two complexes exhibited high cytotoxic activity toward different cancer cells, often higher than that of cisplatin, including toward cisplatin-resistant ovarian cancer cells. These complexes demonstrated rapid hydrolysis, releasing the labile ligand within several minutes, with no indications of release of free chelating ligand after water exposure, suggesting that polynuclear hydrolysis products are involved in the cellular activity.

International audience; Heteroleptic silylamido complexes of the heavier alkaline earth elements calcium and strontium containing the highly fluorinated 3-phenyl hydrotris(indazolyl)borate {F12-Tp(4Bo, 3Ph)}(-) ligand have been synthesized by using salt metathesis reactions. The homoleptic precursors [Ae{N(SiMe3)2}2] (Ae = Ca, Sr) were treated with [Tl(F12-Tp(4Bo, 3Ph))] in pentane to form the corresponding heteroleptic complexes [(F12-Tp(4Bo, 3Ph))Ae{N(SiMe3)2}] (Ae = Ca (1); Sr (3)). Compounds 1 and 3 are inert towards intermolecular redistribution. The molecular structures of 1 and 3 have been determined by using X-ray diffraction. Compound 3 exhibits a Sr⋅⋅⋅MeSi agostic distortion. The synthesis of the homoleptic THF-free compound [Ca{N(SiMe2H)2}2] (4) by transamination reaction between [Ca{N(SiMe3)2}2] and HN(SiMe2H)2 is also reported. This precursor constitutes a convenient starting material for the subsequent preparation of the THF-free complex [(F12-Tp(4Bo, 3Ph))Ca{N(SiMe2H)2}] (5). Compound 5 is stabilized in the solid state by a Ca⋅⋅⋅β-Si-H agostic interaction. Complexes 1 and 3 have been used as precatalysts for the intramolecular hydroamination of 2,2-dimethylpent-4-en-1-amine. Compound 1 is highly active, converting completely 200 equivalents of aminoalkene in 16 min with 0.50 mol % catalyst loading at 25 °C.

International audience; Tuning the nature of the linker in a L∼BHR phosphinoborane compound led to the isolation of a ruthenium complex stabilized by two adjacent, δ-CH and ε-Bsp2H, agostic interactions. Such a unique coordination mode stabilizes a 14-electron "RuH2P2" fragment through connected σ-bonds of different polarity, and affords selective BH, CH, and BC bond activation as illustrated by reactivity studies with H2 and boranes.

International audience; The non-controlled redox-active metal ions, especially copper, in the brain of patients with Alzheimer disease (AD) should be considered at the origin of the intense oxidative damage in the AD brain. Several bis(8-aminoquinoline) ligands, such as 1 and PA1637, are able to chelate Cu2+ with high affinity, and are specific chelators of copper with respect to iron and zinc. They are able to efficiently extract Cu2+ from a metal-loaded amyloid. In addition, these tetradentate ligands are specific for the chelation of Cu2+ compared with Cu+. Consequently, the copper ion is easily released from the bis(8-aminoquinoline) ligand under reductive conditions, and can be trapped again by a protein having some affinity for copper such as human serum albumin (HSA) proteins. In addition, the copper is not efficiently released from [Cu(CQ)2] in reductive conditions. The catalytic production of H2O2 by [Cu2+-Aβ1−28]/ascorbate is inhibited in vitro by the bis(8-aminoquinoline) 1, suggesting that 1 should be able to play a protective role against oxidative damages induced by copper-loaded amyloids.

1099-0682; A strictly heterodinuclear MnIII-Gd complex was prepared from a tripodal ligand and characterized by positive fast-atom bombardment mass spectrometry, which evidenced replacement of a nitrato counterion by a monoethylcarbonato anion. Variable-temperature direct current and alternating current studies confirm that the MnIII-Gd magnetic interaction is antiferromagnetic. Fitting of the magnetic susceptibility data yields an extremely weak interaction parameter JMnGd equal to -0.04 cm-1, along with a weak axial zero-field splitting parameter DMn = 0.1 cm-1. This result confirms that a change in the manganese oxidation state, from MnII to MnIII, corresponds to a radical transformation of the magnetic behavior of Mn-Gd, from a ferromagnetic to an antiferromagnetic interaction. In accordance with the magnetic behavior of CoII-Gd complexes previously studied (high-spin and low-spin CoII ions), the observed magnetic behavior change may be explained by the difference in the electronic occupancy of the Mn 3d x 2-y 2 orbital, which is singly occupied for MnII and vacant for MnIII.

Diamine-monoboranes and one amine-borane alcohol precursor are utilized for cyclization reactions affording the corresponding NB(H)N- and NB(H)O-containing cyclic diaminoboranes and oxazaborolidine, resp.

International audience; The structural distortions in a bis(cyclopropyl) heterobimetallic lithium yttrium complex can be interpreted as two types of CC agostic interactions (see structure), one with a more covalent character with Y, the other with a more electrostatic character with Li. The CC agostic interaction with Y is reinforced by a CH agostic interaction.

A trianionic ligand H3L [2-hydroxy-N-(2-{[(2-hydroxyphenyl)methylene]amino}-2-methylpropyl)benzamide] with an inner N2O2 coordination site and an oxygen atom coming from an amide function not involved in this site yields a monoanionic LCo-pipH+ complex, in which the CoII ion is in a square-planar environment and a low-spin state S = 1/2. Further reaction with GdCl3·6H2O and tetramethylheptanedione (Hthd) yields a dinuclear Co–Gd complex that self-assembles into a tetranuclear species, as demonstrated by the structural determination of the [LCoGd(thd)2(MeOH)]2 complex. This genuine entity is the first example in which a CoII ion in a low-spin state is associated with a gadolinium ion. The magnetic studies confirm that two antiferromagnetic interactions are active through the double phenoxo bridge (J = –1.0 cm–1) and through the single amide bridge (j = –0.1 cm–1). Contrary to the large majority of 3d–Gd complexes that present ferromagnetic interactions, the involvement of a dxy or dyz cobalt orbital is responsible for the presence of an antiferromagnetic interaction.

The synthesis, structure determination and magnetic studies of dinuclear Ni II -Ln III complexes (Ln = Y, La, Pr, Gd) involving ortho-vanillin as the main ligand are described. Structural studies demonstrate that two types of complexes can be obtained with hexacoordinate Ni ions in slightly deformed octahedral environments and nine- or ten-coordinate lanthanide ions. The Ni and Gd ions are linked by two phenoxo bridges in one complex and two phenoxo bridges and one nitrato bridge in the other. A ferromagnetic interaction operates in the Ni-Gd complex, with a D zero field splitting term for the nickel ion, as in the Ni-La and Ni-Y complexes where these D terms are the only active magnetic terms. Among the factors responsible for the different structures are ionic radii of the Ln ions, solvent and configuration change of the starting nickel complex; the role of solvent seems to be preponderant. The weak value of the ferromagnetic Ni-Gd interaction can be explained by the flexibility and the departure from planarity of the two independent ortho-vanillin ligands.

The synthesis and characterization of copper(II), manganese(III), and iron(III) complexes [Cu 2 (L 1 )(OAc)Cs 2 -(MeOH) 2 ] n (1), [Mn 2 (H 3 L 1 ) 2 (OMe) 2 ]·2MeOH (2), [Fe 2 (H 3 L 1 ) 2 -(Hpz) 4 ](ClO 4 ) 2 ·2CH 3 CN (3), and [Fe 2 (H 3 L 3 ) 2 (OMe) 2 ]· 8MeOH (4) of potentially pentaanionic heptadentate ligands, 2-hydroxy-N-{2-hydroxy-3-[(2-hydroxybenzoyl)amino]propyl)benzamide (H 5 L 1 ) and 2-hydroxy-N-{3-hydroxy-5-[(2-hydroxybenzoyl)amino]pentyl}benzamide (H 5 L 3 ), are reported. The crystal structure and magnetic properties of these complexes have been determined. In complex 1, the ligand H 5 L 1 acts as a heptadentate, fully deprotonated ligand, [L 1 ] 5- . In complexes 2, 3, and 4, H 5 L 1 (2, 3) and H 5 L 3 (4) act as tetradentate, partially deprotonated ligands, [H 3 L 1 ] 2- and [H 3 L 3 ] 2- . In complex 1, anionic [Cu 2 (L 1 )(OAc)] 2- and cationic [Cs(MeOH)] + units are linked through a quadruply bridging acetate ion and through the phenoxido-oxygen and amido-oxygen donor atoms of [L 1 ] 5- to yield a 2D polymeric network. Complexes 2-4 form extended supramolecular networks. Magnetic susceptibility data evidence antiferromagnetic interactions for 1, 2, and 4. The Fe···Fe distance is too long to allow measurable magnetic interactions in complex 3.

The reaction of the bis(pentamethylcyclopentadienyl)pentaoxidodimetal complexes Cp*2M2O5 with four equivalents of Na2M′O4 (M, M′ = Mo, W) in acidic aqueous medium constitutes a soft and selective entry into neutral Lindqvist-type organometallic mixed-metal oxides Cp*2MoxW6–xO17 [x = 6 (1), 4 (2), 2 (3), 0 (4)]. The identity of the complexes is demonstrated by elemental analyses, thermogravimetric analyses and infrared spectroscopy. Thermal degradation of 1–4 up to above 500 °C leads to Mox/6W1–x/6O3. The molecular identity and geometry of compound 2 is further confirmed by a fit of the powder X-ray diffraction pattern with a model obtained from previously reported single-crystal X-ray structures of 1 and 4, with which 2 is isomorphous. DFT calculations on models obtained by replacing Cp* with Cp (I–IV) validate the structural assignments and assist in the assignment of the M,M′–O vibrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The synthesis, structural determination and magnetic study of a trinuclear MnII–GdIII–MnII complex involving a Schiff base ligand are described. The structural study demonstrates that the complex presents a linear arrangement of the Mn and Gd ions, with hexacoordinate Mn ions in slightly distorted or distorted trigonal prism environments and nine-coordinate gadolinium ions. The Mn and Gd ions are linked by two phenoxido bridges for one Mn–Gd subunit and two phenoxido plus one nitrato bridges for the other Mn–Gd subunit. Ferromagnetic interactions operate in the complex. The best fit takes into account two different J constants and D and E zero-field splitting terms. A strict 3d-5d(Gd) orthogonality is not possible in the present complex because all 3d orbitals of the Mn ions are occupied, which does agree with the weak value of the JMn,Gd parameter. Oxidation of this complex does not yield the corresponding MnIII–GdIII–MnIII entity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A question of coordination mode: Two new borane compounds are prepared. They act as bifunctional ligands as illustrated by their reaction with ruthenium polyhydrides which leads to the formation of two complexes (see scheme) displaying either a delta-agostic interaction of a eta(2)-B-H bond involving a trivalent boron atom or a dihydroborate ligation.

New bis(8-aminoquinoline) ligands linked on the C2 carbon atom of both quinolines have been prepared. When the linker includes a one-atom amino group, the corresponding compound is an excellent chelator of CuII ions and forms a mononuclear species with high metal ion selectivity relative to ZnII chelation. This selectivity for CuII ions was not observed for a bis(8-hydroxyquinoline) analogue. The chelating properties of these ligands are compared to those of the bis(8-aminoquinoline) ligands with different linkers between their N8 nitrogen atoms. The N8-linked bis(8-aminoquinoline) ligands have a higher affinity for CuII when the linker includes a three-atom unit or when the linker is linked directly through the N8 atom. Other ligands, including that with a dimethylamino linker on C2, are less efficient and seem to chelate CuII and ZnII with an affinity that is similar to that for dipicolylamine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

We demonstrate through structural, spectroscopic, and magnetic studies that the main factors governing the nuclearity of M–Gd (M = Cu, Ni) complexes derived from compartmental Schiff base ligands are the different affinities of the lanthanide ions for the potential ligands and anions present in the reaction medium. In the eight examples studied, there is competition between the tetradentate O2O2 coordination site of the polydentate ligand and the anionic entities brought by the gadolinium salts. The strong affinity of nitrato anions for lanthanides yields dinuclear complexes and prevents formation of trinuclear entities, whereas the use of poorly coordinating anions such as triflates may yield either dinuclear or trinuclear complexes, depending on the 3d/4f ratio.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Critical analysis of possible strategies for the synthesis of novel carbo-benzene derivatives suggests several [(18-n)+n] routes for the preparation of hexaoxy[6]pericyclyne precursors. Beyond the previously attempted [9+9] symmetrical scheme (n=9), the a priori most selective strategies are those for which n=1, 4, 7, 10, 13, and 16. They involve a cyclizing double-propargylation of a C(18-n) omega-bis-terminal-skipped oligoyne containing (19-n)/3 triple bonds with a C(n) omega-dicarbonyl-skipped oligoyne containing (n-1)/3 triple bonds. To complement the previously used [11+7] strategy, the [14+4] and [8+10] strategies were thus explored. They proved to be efficient, affording seven novel hexaoxy[6]pericyclynes corresponding to six different substitution patterns. These compounds were obtained in 7-15 steps as mixtures of stereoisomers. Thus, by using dibenzoylacetylene as the C(4) electrophile, a [14+4] strategy allowed the synthesis of two hexaphenyl representatives with two or four free carbinol vertices. This approach also afforded tetraphenyl representatives in which the two remaining carbinoxy vertices were substituted with either two alkynyl or one 4-anisyl and one 4-pyridyl groups. By using the hexacarbonyldicobalt complex of butynedial as the C(4) electrophile, a [14+4] strategy also allowed the isolation of a tetraphenylhexaoxy[6]pericyclyne with two adjacent unsubstituted carbinol vertices. A regioisomer with two opposite unsubstituted carbinol vertices was obtained through an [8+10] strategy and its oxidation afforded the corresponding pericyclynedione. Several attempts at synthesizing diphenylhexaoxy[6]pericyclynes with four unsubstituted carbinoxy vertices are described. Only an [8+10] strategy allowed the generation of a fragile diphenylhexaoxy[6]pericyclyne with four adjacent unsubstituted carbinoxy vertices, which could be partly characterized. These results show that the synthesis of the nonsubstituted hexahydroxy[6]pericyclyne, the ring carbo-mer of [6]cyclitol, is a difficult challenge.

Both aromatic and heteroaromatic arenes undergo dehydrogenative borylation with pinacolborane catalyzed by a well-defined iron bis(diphosphine) complexes under UV irradiation.

One-pot reactions of Ti(NMe2)4 with a wide range of primary alkyl, aryl, and silylamines RNH2 in the presence of excess chlorotrimethylsilane produced the corresponding imido–titanium(IV) complexes [Ti(=NR)Cl2(NHMe2)2] (1a–j), in which R = tBu, 1-adamantane, Ph3C, Ph3Si, Ph, 2,6-iPr2–C6H3, 2,6-Cl2–C6H3, 2,6-Br2–4-Me–C6H2, C6F5, and 3,5-(F3C)2–C6H3. This general synthesis, which starts from commercially available reagents, represents a simple and direct route to imido complexes. Reaction of complexes 1 with pyridine afforded the six-coordinate tris-pyridine adducts [Ti(=NR)Cl2(Py)3] (2). Another advantage of this method is its tolerance to other functional groups; complexes that contain halides, ether, dialkylamino, cyano, ethynyl, olefin, and nitro substituents on the imido moiety have been prepared. The use of enantiomerically pure primary amines affords the first group of titanium complexes that contain chiral imido groups, and the use of diamines produces diimido complexes. Alternatively, CH3I has been used as an alkylating agent to generate titanium–imido complexes of the type [Ti(NR)I2(THF)2]2. All compounds were fully characterized by spectroscopic methods (IR, 1H NMR, 13C NMR) and elemental analysis. Some of the compounds were also analyzed by single-crystal X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

We have developed a new strategy that uses the Krohnke synthesis for the preparation of various substituted phenylpyridines in excellent yields (up to 88 %). Starting with the appropriate commercially available acetophenone, a variety of phenylpyridines substituted by either electron-donating (i.e. methyl, methoxy) or -withdrawing groups (i.e. bromide, nitro) on the phenyl ring are obtained in a two-step synthesis. The corresponding functionalized cyclometalated ruthenium complexes can be prepared with unusually high yields by

Two new ruthenium(II) complexes of formula [Ru(bpy)2(L1)][PF6] and [Ru(bpy)2(L2)][PF6]2 are reported. HL1 is a (nitrophenyl)ethenyl-substituted phenylpyridine ligand, and L2 is the bipyridine analogue of HL1. The X-ray crystal structure of [Ru(bpy)2(L1)][PF6] has been solved, and the compound is found to crystallize in the monoclinic C2/c space group. The electronic spectrum of the cyclometalated derivative [Ru(bpy)2(L1)][PF6] exhibits a low-lying transition that is red-shifted from 454 to 546 nm relative to that of the parent bipyridine-based complex, which reveals an important charge-transfer character. To support this assumption, the nonlinear optical properties were investigated by the hyper-Rayleigh scattering technique and indicate a molecular static hyperpolarizability (β0) equal to 230 × 10–30 cm5 esu–1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The reaction of [Cp2Ti(CO)2] with borane adducts CF3C6H4CN·B(C6F5)3 and [H2O·B(C6F5)3] has afforded the titanaazirine [Cp2Ti(η2-C,N-F3CC6H4CN)·B(C6F5)3] (1) and the TiIII salt [Cp2Ti][HOB(C6F5)3] (2), respectively. In both cases, a Ti···F interaction between the titanium centre and an ortho-fluorine atom of the tris(perfluorophenyl)borane is observed in the X-ray structure determination. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Functionalization of CO2 is a challenging goal and precedents exist for the generation of HCOOH, CO, CH3OH, and CH4 in mild conditions. In this series, CH2O, a very reactive molecule, remains an elementary C1 building block to be observed. Herein we report the direct observation of free formaldehyde from the borane reduction of CO2 catalyzed by a polyhydride ruthenium complex. Guided by mechanistic studies, we disclose the selective trapping of formaldehyde by in situ condensation with a primary amine into the corresponding imine in very mild conditions. Subsequent hydrolysis into amine and a formalin solution demonstrates for the first time that CO2 can be used as a C1 feedstock to produce formaldehyde.

Key feature of the presented synthesis is the nitration of terpyridine N,N′′-dioxide (II) in fuming nitric acid and fuming sulfuric acid with concomitant reduction of the N-oxides [cf.

A single crystal of KVTeO5, potassium vanadium tellurite, has been grown. The present structure determination has been conducted together with the refinement of the NaVTeO5 homologue, sodium vanadium tellurite, for the sake of precise comparison. The network consists of [VTeO5]n ribbons built up by VO4 tetrahedra linking centrosymmetric Te2O6 groups and stacked along the [010] direction; the alkali cations are intercalated in between. The TeIV atom exhibits a typical one-sided coordination number (CN) of 4, completed by a lone pair, which forms a distorted triangular bipyramid with the four O atoms.

The cover picture shows some various examples ofterminal imido–titanium complexes of the general formula Ti(=NR)Cl2(NHMe2)2 that are accessible through the reported one-pot reaction of Ti(NMe2)4 with a primary amine RNH2 in the presence of excess chlorotrimethylsilane. This procedure appears to be general to the generation of a wide range of imido groups: alkyl-, silyl-, and arylimido groups, as well as functional organoimido, chiral imido, and diimido ligands. Ti(=NR)Cl2(NHMe2)2 complexes are of particular interest as organometallic synthons and for further applications in the field of homogeneous catalysis and materials science. The background photo of the famous palm tree vault of the Jacobins church (Toulouse, France, founded in the 13th–14th centuries) symbolizes the diversity of the compounds – arranged in arc around the palm tree vault – that can be prepared by using our promising synthetic strategy, and provides a solid foundation – the pillar – for attractive applications. Details are discussed in the article by C. Lorber et al. on p. 4503 ff. The authors acknowledge Christian Bergounhou (LCC Toulouse) for the Palm Tree photograph.