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Transition-metal complexes containing (C–C)→M σ-interactions have potential applications in both catalysis and the activation and cleavage of C–C bonds. Fully characterising the bonding and interactions in complexes containing such (C–C)→M σ-interactions is vital to understand their chemical behaviour. As a result a high-resolution experimental X-ray charge density study has been undertaken on [Rh(Binor-S)(PCy3)][HCB11Me11] (Binor-S = 1,2,4,5,6,8-dimetheno-s-indacene) which contains a (C–C)→Rh interaction. The data are analysed using Bader's “Atoms in Molecules” (AIM) approach with particular attention paid to the interactions around the rhodium centre. The results provide clear evidence for the σ(C–C)→Rh interaction in the solid-state which is classified as a weak covalent interaction. These results are supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

Hydrogen bonding interactions with the π-system of thiocarbonyls are evident in the X-ray crystal structures of a range of thiourea derivatives and from an analysis of the CSD. [ABSTRACT FROM AUTHOR]

The structures of various natural amino acid hydrogen peroxide solvates are presented. All “active” hydrogen atoms (amino, hydroxy, peroxy, and water) in the studied amino acid perhydrates are involved in hydrogen bonding. Peroxide molecules form at least two donor hydrogen bonds. In the most common case, the H2O2molecule is engaged in four hydrogen bonds (two donors with –CO2−groups and two acceptors with –NH3+groups). In peroxosolvates of amino acids bearing hydrocarbon side-chains, double layers were observed. These bilayers are hydrophilic inside, while their outer surfaces are hydrophobic. It was found that donor hydrogen bonds formed by hydrogen peroxide in amino acid perhydrates are significantly stronger than those formed by water molecules in amino acid hydrates. [ABSTRACT FROM AUTHOR]

Syntheses, characterization and crystal structures of heterotetranuclear [2 × 1 + 1 × 2] co-crystals [{CuIILZnII(H2O)2}{CuIIL}2](ClO4)2(1) and [{CuIILCdII(H2O)2(CH3CN)}{CuIIL}2](ClO4)2(2), dinuclear compound [CuIILHgII(CH2COCH3)](ClO4) (3) and heterotrinuclear [2 × 1 + 1 × 1] co-crystal [{CuIILAgI(H2O)}{CuIIL}](ClO4) (4) derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) are reported herein. Compounds 3and 4crystallize in the orthorhombic Pbcaand monoclinic P21/csystems, respectively, while the space group of compounds 1and 2is monoclinic C2/c. The structure of 3consists of a monophenoxo-bridged CuIIHgIIdinuclear core in which the mercury(ii) centre is dicoordinated by the bridging phenoxo oxygen atom and the CH2carbon atom of the mono-deprotonated acetone anion. The coordination environment of HgIIin this compound is almost linear. In the CuII2AgIcompound 4, one diphenoxo-bridged [CuIILAgI(H2O)]+cation is co-crystallized with one mononuclear [CuIIL] moieties. On the other hand, the structures of the CuII3MIIcompounds 1(M = Zn) and 2(M = Cd) consist of one diphenoxo-bridged dinuclear CuIIMIIunit and two mononuclear [CuIIL] moiety; the composition of the dinuclear unit being [CuIILZnII(H2O)2]2+and [CuIILCdII(H2O)2(CH3CN)]2+for 1and 2, respectively. The AgI(in 4), ZnII(in 1) and CdII(in 2) ions in the diphenoxo-bridged dinuclear cores are tri-, tetra- and heptacoordinated, respectively. The metal ions are coordinated to two bridging phenoxo oxygen atoms, with the silver(i) and zinc(ii) centres being additionally coordinated to one and two water molecules, respectively. While in the case of cadmium(ii), the additional five coordination positions are occupied by two ethoxy oxygen atoms, two water oxygen atoms and one acetonitrile nitrogen atom. The coordination environment of silver(i) in 4is pyramidal with a scalene O3triangle as the base, whereas those of zinc(ii) and cadmium(ii) in 1and 2are distorted tetrahedral and distorted pentagonal bipyramidal, respectively. The coordinated water molecule in 4and each of the two coordinated water molecules in 1and 2are encapsulated into the O4compartment of a [CuIIL] moiety resulting in the [2 × 1 + 1 × 1] (for 4) or [2 × 1 + 1 × 2] (for 1and 2) cocrystallization and self-assemblies. Clearly, the encapsulation of the coordinated water molecule(s) is the governing force for the formation of dinuclear-mononuclear co-crystals in 1, 2and 4. In addition all four compounds 1–4have π–π stacking interactions which form dimers between pairs of adjacent molecules in the structure of 3consisting of CuIIHgIIdimers, while one-dimensional stacks are formed in the CuII3ZnII(1), CuII3CdII(2) and CuII2AgI(4) complexes. The compositions of the title compounds are compared with the related systems derived from the same ligand. The [2 × 1 + 1 × 1] co-crystal, 4, is a new type of system in terms of the number of components. Again, in spite of the tri-, tetra- and hepta-coordinated nature of the second metal ion in the dinuclear cores, co-crystallization in 1, 2and 4, respectively, are new observations. The accommodation/coordination of varieties of metal ions by the O4compartment of H2L has also been highlighted in the present investigation. [ABSTRACT FROM AUTHOR]

In the present investigation, various copper(ii)–alkali/alkaline earth metal ion heteronuclear complexes derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) have been studied. The syntheses, characterization and crystal structures of three [2 × 1 + 1 × 2] cocrystals [{CuIILLiI(H2O)2}{CuIIL}2](ClO4) (1), [{CuIILNaI(H2O)2}{CuIIL}2](dicyanamide) (2) and [{CuIILMgII(H2O)3}{CuIIL}2](NO3)2·H2O (3), one [3 × 1 + 5 × 1] double-decker–triple-decker cocrystal [{(CuIIL)2KI}(ClO4)]·[{(CuIIL)3KI2(μ-ClO4)}(ClO4)] (4), one dinuclear CuIIKI-based one-dimensional polymer [CuIILKI(μ-PF6)]n(5) and one hexametallic quadruple-decker compound [{(CuIIL)2RbI(μ-H2O)}2](BPh4)2·2CH3COCH3(6) are reported. Compounds 1, 2, 3and 6crystallize in the triclinic crystal system (space group P1), while the crystal systems of 4and 5are monoclinic (space group C2/c) and orthorhombic (space group P212121), respectively. The cocrystallization in 1–3takes place through the encapsulation of coordinated water molecules into the O4compartment of two mononuclear [CuIIL] moieties; both the coordinated water molecules are involved in the case of 1and 2, while 2 of the 3 coordinated water molecules are involved for 3. In 4, the potassium(i) centre in the double-decker moiety is sandwiched in between two mononuclear [CuIIL] moieties, while each of the two potassium(i) centres in the triple-decker moiety are sandwiched in between a pair of two [CuIIL] moieties. The two potassium(i) centres in the triple-decker moiety are bridged by a perchlorate anion. In 5, two cisfluorine atoms from the hexafluorophosphate anion bridge the potassium(i) centres of the neighbouring dinuclear CuIIKIunits to build up a one-dimensional polymer. The quadruple-decker hexanuclear [{(CuIIL)2RbI(μ-H2O)}2]2+dication in 6can be considered to consist of two trinuclear double-decker [(CuIIL)2RbI]+moieties, interlinked by two bridging water molecules. Structural resemblance between the structures formed with LiI, NaIand MgIIand those with 3d metal ions, the anion dependence of the topology of the copper(ii)–potassium(i) complexes, cocrystallization in the presence of the potentially bridging dicyanamide anion, the first report of a one-dimensional polymer derived from H2L and an interesting example of a quadruple-decker complex, are the major outcomes of the present investigation. All in all, structural diversity in the H2L ligand system has been further enriched by some interesting structures in the present investigation. [ABSTRACT FROM AUTHOR]

Syntheses, characterization and structures of heterodinuclear compound [CuIIL1BiIII(NO3)3] (1), sandwich type heterotrinuclear compound [(CuIIL1)2BaII(NO3)2]·0.2H2O (2), heterotetranuclear compound [{CuIIL1PbII(µ-NO3)(NO3)}2] (3) and heterohexanuclear [2 × 1 + 1 × 4] cocrystal [(UVIO2)2(µ-H2O)2(NO3)4]·4[CuIIL1⊂(H2O)] (4) are described in this investigation (H2L1= N,N′-ethylenebis(3-ethoxysalicylaldiimine)). Compounds 1and 4crystallize in orthorhombic P212121and triclinic P systems, respectively, while the space group of compounds 2and 3is monoclinic P21/c. The structure of 1consists of a diphenoxo-bridged CuIIBiIIIdinuclear core containing three chelating nitrates and a 10-coordinate bismuth(III) centre. The dinuclear cores are self-assembled to two dimensions through intermolecular nitrate oxygencopper(II) semicoordination and weak C–HO hydrogen bonds. Compound 2is a double-decker CuIIBaIICuIIsystem in which a barium(II) ion is sandwiched between two mononuclear [CuIIL1] moieties. The barium(II) centre is 11-coordinate, four phenoxo and four ethoxy oxygen atoms and one chelating and one monodentate nitrate ions. Compound 3is a tetranuclear system (dimer of two dinuclear moieties) in which one nitrate is chelating, while the second nitrate behaves as both a chelating and bridging ligand. The lead(II) centre is 9-coordinate in this compound. Compound 4is a [2 × 1 + 1 × 4] cocrystal of one diaqua-bridged diuranyl(VI) moiety, containing two chelating nitrates and 8-coordinated hexagonal bipyramidal uranium(VI) centres and four inclusion species [CuIIL1⊂(H2O)]. The governing factor for the self-assembled cocrystallization in 4are the C–H·π and C–HO hydrogen bonds. The compounds reported in this investigation and other heteronuclear systems derived from N,N′-ethylenebis(3-ethoxysalicylaldiimine) indicate that this ligand system is an important example which gives rise to structurally diverse heteronuclear compounds. In addition to the structural diversity, the structural resemblance of bismuth(III) with lanthanides(III) and utilization of noncovalent interactions to form self-assembly and cocrystals are the major outcomes of the present investigations. [ABSTRACT FROM AUTHOR]

The crystal structures of six new partially fluorinated aryl 1,2,3,5-dithiadiazolyls [ArCNSSN] are reported [Ar = 2,6-F2C6H3(4); Ar = 3,4-F2C6H3(5); Ar = 3,5-F2C6H3(6); Ar = 2,3,6-F3C6H2(9); Ar = 2,4,6-F3C6H2(11); and Ar = 3,4,5-F3C6H2(12)] and compared with three previously reported structures in this series (Ar = 2,3-F2C6H3(1); Ar = 2,5-F2C6H3(3); Ar = 2,3,4-F3C6H2(7)]. Radical 4is shown to be polymorphic. Molecular electrostatic potential maps have been used to rationalise these structures. These reveal that whilst single F atoms appear to have little structure-directing influence, combinations of an ortho-F on the phenyl ring and a heterocyclic ring N, or several F atoms located in mutually orthopositions with respect to each other, generate significant regions of negative charge which have a substantial structure-directing influence. [ABSTRACT FROM AUTHOR]

The reaction of N-methylpyridinium iodide, Mepy+I−, and tetracyanoethylene (TCNE) forms [Mepy]2[TCNE]2, which possesses [TCNE]22−with an intradimer C–C bond distance of 2.806(1) Å at 50 K from X-ray diffraction, and 2.801(4) Å at 50 K from neutron diffraction. In the IR it exhibits νC≡Nabsorptions at 2191, 2174, 2169, 2163 and a νCCabsorption at 1366 cm−1, with UV/Vis absorption bands at 26,880 and 18,520 cm−1. Analysis of the cation-hydrogen to [TCNE]22−interactions do not provide evidence that the cation stabilizes formation of the [TCNE]22−dimer, which is stabilized by the intradimer 2e−-4 center C–C bonding interaction. [ABSTRACT FROM AUTHOR]

Facile acetylide transfer reactions take place between gold(i) complexes Au(CCAr)(PPh3) (Ar = C6H5or C6H4Me-4) and a variety of representative inorganic and organometallic complexes MXLn(M = metal, X = halide, Ln= supporting ligands) featuring metals from groups 8–11, to afford the corresponding metal–alkynyl complexes M(CCR)Lnin modest to good yield. Reaction products have been characterised by spectroscopic methods, and molecular structure determinations are reported for Fe(CCC6H4Me-4)(dppe)Cp, Ru(CCC6H4Me-4)(dppe)Cp*, Ru(CCC6F5)(η2-O2)(PPh3)Cp*, Ir(CCC6H4Me-4)(η2-O2)(CO)(PPh3)2, Ni(CCC6H4Me-4)(PPh3)Cp and trans-Pt(CCAr)2L2(Ar = C6H5, L = PPh3; Ar = C6H4Me-4, L = PPh3, PMe3). [ABSTRACT FROM AUTHOR]

This paper reports preparation of new silyl hydride complexes of ruthenium supported by the Cp/PR3ligand set. It is shown that the easiest and most general route to these complexes is provided by the thermal reaction of [RuCp(PR3)(H)3] with hydrosilanes. Complexes [RuCp(PR3)(H)2(SiMe2Cl)] exhibit Interligand Hypervalent Interactions (IHI) between the hydride and silyl ligands. Comparison of the X-ray structures of complexes [RuCp(PPri3)(H)2(SiMe2Cl)], [RuCp(PPhPri2)(H)2(SiMe2Cl)], and [RuCp(PPh3)(H)2(SiMe2Cl)] shows that the IHI weakens with the decreasing electron-releasing ability of the phosphine. Comparison of the X-ray structure of [RuCp(PPh3)(H)2(SiMe2Cl)] with the structure of the previously reported complex [RuCp*(PPh3)(H)2(SiMe2Cl)] reveals that the lack of IHI in the latter compound is due to unfavourable steric interactions between the bulkier Cp* ring and the SiMe2Cl group. [ABSTRACT FROM AUTHOR]

Six inclusion compounds containing a photoreactive guest molecule, 4-oxo(phenylacetyl)morpholine or 1-(phenylglyoxylyl)piperidine, with different host molecules have been crystallized. The guest molecules underwent photochemical reaction upon irradiation. Examining their structures suggests that γ-hydrogen abstraction by an oxygen, the first step in cyclization of α-oxoamides, should be possible in all cases. In four cases crystallinity was maintained during and at the end of the conversion process i.e. the process was a single-crystal to single-crystal transformation. The crystal structure of the product crystals revealed that in two of the inclusion compounds the product obtained is a result of enclosure to a four-membered ring while in the other two the product obtained results from enclosure to a five-membered ring. The morpholine molecules adopt two different conformations. The photochemical reaction may take different courses either as a result of the different conformation or as a result of the different shapes of the cavities provided by the host molecules. [ABSTRACT FROM AUTHOR]

The crystal structure of trans-4-(trifluoromethyl) cinnamic acid (1) has been determined in the triclinic space group P1̄. Differential scanning calorimetry showed that 1 undergoes a single fully reversible temperature induced phase transition at around 132/131 K (cooling/heating). Single crystal structure determinations, carried out at 200, 145 and 120 K, revealed that the volume of the unit cell quadruples as the crystal is cooled through the phase transition with Z′ increasing from 2 to 8. The structures are stabilised by the presence of O–H⋯O hydrogen bonding and C–H⋯O interactions. The results of DSC, single crystal and powder X-ray diffraction studies on 1 are reported. [ABSTRACT FROM AUTHOR]

Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by 31P NMR spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P–P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P–P bond lengths are intermediate between single and double bonds. [ABSTRACT FROM AUTHOR]

The syntheses of the cyclic N-phosphino-amidines and -guanidines Ph2PN(Pri)C(NPri2)N(Pri) (1) and Ph2PN(c-Hex)C(R)N(c-Hex) [R = piperazino (2), morpholino (3), Me (4), and Ph (5)] are reported. DFT studies have identified the preferred structures for compounds 1–5 with the E-configuration being the most stable form for the N-phosphino-amidines, while the Z-conformation is preferred for the N-phosphino-guanidines something that highlights the potential of such systems to act as κ2-P,N-chelates. The differences in donor characteristics of 2–5 have been probed through the study of their corresponding P(v) selenide derivatives (6–9) and their complexes with the cis-RhCl(CO) (10–12) and cis-PdCl2 (13–17) fragments. In line with the DFT studies both the amidines and guanidines are found to coordinate as κ2-P,N-chelates, with the latter being moderately weaker donor ligands. The molecular structures of compounds 3 and 4, together with those of the Rh and Pd complexes 10 and 15, respectively, have been determined in the solid state by X-ray crystallography, the latter confirming bidentate κ2-P,N-chelation. [ABSTRACT FROM AUTHOR]

Reactions of half-sandwich ruthenium metal acetylide complexes with 1-cyano-4-dimethylaminopyridinium salts afford complexes containing mono- or di-cyanovinylidene ligands; the procedure can be adapted to permit the simple synthesis of a cyanoacetylide complex, via the in situ deprotonation of a primary cyanovinylidene complex. [ABSTRACT FROM AUTHOR]

Nitrogen donor tetradentate ligands 4,4′-bipyridazine (bpdz) and pyridazino[4,5-d]pyridazine (pp) were prepared by inverse electron demand Diels–Alder cycloaddition reactions of 1,2,4,5-tetrazine. Examination of their behaviour towards silver(i) ions revealed a special potential of the ligands for the design of 3D coordination frameworks involving characteristic polynuclear and polymeric silver(i)–pyridazine motifs and multiple coordination of the ligands. Ag4(pp)5(ClO4)4 and Ag4(pp)5(SiF6)(BF4)2·4H2O adopt a unique 3D trinodal 4,4,5-connected topology based upon five-fold coordination of the metal ions and tetradentate bridging function of the organic modules. Complexes Ag3(L)3(SO3CF3)3·nH2O and Ag4(L)3(X)4·nH2O (L = bpdz, pp; X = BF4−, 0.5SiF62−) illustrate formation of highly-connected frameworks incorporating trinuclear clusters as an origin of the net connectivity. In the carboxylate complexes Ag2(L)(RFCOO)2 (RF = CF3, C2F5, C3F7) the pyridazine and acido ligands act as complementary linkers for generation of 3D frameworks involving helicate motifs. Fused bicyclic pyridazine pp is a unique system combining very efficient σN-donor ability and pronounced π-acidity. The coordination frameworks commonly exhibit strong anion–π interactions, including unprecedented examples of double anion–π,π binding that occur between pyridazino[4,5-d]pyridazine as a double π,π-receptor for geometry complementary SiF62− anions. [ABSTRACT FROM AUTHOR]

A new polydentate ligand 4,4′-bipyridazine (4,4′-bpdz) was prepared by employing inverse electron demand cycloaddition of 1,2,4,5-tetrazine. A unique combination of structural simplicity, ampolydentate character and efficient donor properties towards Cu(i), Cu(ii) and Zn(ii) provide wide new possibilities for the synthesis of coordination polymers incorporating the 4,4′-bpdz module either as a bi-, tri- or tetradentate connector between the metal ions. 1D coordination polymers Cu2(4,4′-bpdz)(CH3CO2)4·4H2O and Zn(4,4′-bpdz)(NO3)2, and interpenetrated (4,4)-nets in [Cu(4,4′-bpdz)2(H2O)2]S2O6 were closely related to 4,4′-bipyridine compounds. 1D “ladder-like” polymer Cu2(4,4′-bpdz)3(CF3CO2)4 and the unprecedented 3D binodal net ({86}{63;83}) in [Cu3(4,4′-bpdz)6(H2O)4](BF4)6·6H2O were based upon a combination of linear and angular organic bridges. Complex [Cu3(OH)2(4,4′-bpdz)3(H2O)2{CF3CO2}2](CF3CO2)2·2H2O has a “NbO-like” 3D topology incorporating discrete dihydroxotricopper(ii) clusters linked by tri- and tetradentate ligands. The tetradentate function of the 4,4′-bpdz ligand was especially relevant for copper(i) complexes, which adopt layered Cu2X2(4,4′-bpdz) (X = Cl, Br) or 3D chiral framework (X = I) structures based upon infinite (CuX)n chains. The electron deficient character of the ligand was manifested by short anion–π interactions (O–π 3.02–3.20; Cl–π 3.35 Å), which may be involved as a factor for controlling the supramolecular structure. [ABSTRACT FROM AUTHOR]

The Sonogashira cross-coupling of two equivalents of para-substituted ethynylbenzenes with 2,5-diiodothiophene provides a simple synthetic route for the preparation of 2,5-bis(para-R-phenylethynyl)thiophenes (R = H, Me, OMe, CF3, NMe2, NO2, CN and CO2Me) (1a–h). Likewise, 2,5-bis(pentafluorophenylethynyl)thiophene (2) was prepared by the coupling of 2,5-diiodothiophene with pentafluorophenylacetylene. All compounds were characterised by NMR, IR, Raman and mass spectroscopy, elemental analysis, and their absorption and emission spectra, quantum yields and lifetimes were also measured. The spectroscopic studies of 1a–h and 2 show that both electron donating and electron withdrawing para-subsituents on the phenyl rings shift the absorption and emission maxima to lower energies, but that acceptors are more efficient in this regard. The short singlet lifetimes and modest fluorescence quantum yields (ca. 0.2–0.3) observed are characteristic of rapid intersystem crossing. The single-crystal structures of 2,5-bis(phenylethynyl)thiophene, 2,5-bis(para-carbomethoxyphenylethynyl)thiophene, 2,5-bis(para-methylphenylethynyl)thiophene and 2,5-bis(pentafluorophenylethynyl)thiophene were determined by X-ray diffraction at 120 K. DFT calculations show that the all-planar form of the compounds is the lowest in energy, although rotation of the phenyl groups about the C≡C bond is facile and TD-DFT calculations suggest that, similar to 1,4-bis(phenylethynyl)benzene analogues, the absorption spectra in solution arise from a variety of rotational conformations. Frequency calculations confirm the assignments of the compounds’ IR and Raman spectra. [ABSTRACT FROM AUTHOR]

Four new (E)-4-styrylquinoline compounds containing two methoxy substituents or an 18-crown-6-ether fragment were synthesized in order to investigate the [2 + 2]-photocycloaddition (PCA) reaction in the solid state. These compounds reveal different abilities to undergo the photoreaction depending on the packing of the quinoline molecules in thin polycrystalline films and single crystals. The only products from the irradiation of (E)-4-styrylquinolines were an rctt isomer of 1,2,3,4-tetrasubstituted cyclobutane and, rarely, a Z isomer of the styrylquinoline. The rctt cyclobutane derivative was formed as a result of the PCA of centrosymmetric syn-‘head-to-tail’ dimeric pairs of the reactant species that are preorganized in such a way as to promote this reaction. Peculiarities in the crystal packing motifs that are typical for single crystals of 4-styrylquinoline compounds are discussed. The solvate molecules can affect significantly the packing of styrylquinolines. Benzene solvate molecules create a soft, flexible, shell about the dimeric pairs that facilitates the PCA in the single crystal without causing degradation of the crystal. In crystal packing that contains CH2Cl2 and H2O solvate molecules, they are prone to form complicated systems of hydrogen bonds with crown-ether oxygen atoms and each other. This results in distorting the organic molecule geometry toward non-planarity and accomplishing a new type of crystal packing uncommon for styrylheterocycles, in which the PCA is impossible. The topochemical single-crystal-to-single-crystal PCA reaction was monitored for one of the species. Two cyclobutane derivatives obtained in single crystals were subjected to recrystallization from a solution. The new single crystals formed belong to different crystal systems, with different unit cell parameters as compared with initial single crystals; significant differences in the geometry of the cyclobutane molecules were also found. This implies that the cyclobutane derivatives obtained in the solid phase have a molecular geometry that is somewhat stressed. [ABSTRACT FROM AUTHOR]

One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, R=Me, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones. [ABSTRACT FROM AUTHOR]

New transition metal catalysts have been prepared and applied for in situ formation of acyl nitroso dienophiles. [ABSTRACT FROM AUTHOR]

The triple decker dinuclear Cr(ii) salt [(η5-C5Me5)Cr(μ2:η5-P5)Cr(η5-C5Me5)]+ (SbF6)− has been structurally characterised by multiple temperature X-ray diffraction experiments from 290 K to 12 K. This material shows changes in its structural features which correlate with its magnetic response, including a structural transition with a change of symmetry from the orthorhombic space group Fddd to the monoclinic I2/a at ∼160 K and an abrupt rearrangement of electron density at ∼23 K [ABSTRACT FROM AUTHOR]