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In 1958 Professor Alan Davison started his research career at an exciting time for the field of organometallic chemistry. New developments in spectroscopy, instrumentation and techniques to manipulate materials in controlled environments to avoid reaction with water or oxygen were becoming widely available. Controlling exposure of an element with highly reactive oxygen facilitated the isolation, characterization and discovery of an abundance of unknown compounds. Alan was an insightful and talented synthetic chemist and made many new and interesting organometallic compounds. He used the earliest commercial nuclear magnetic resonance instruments to characterize the then poorly understood transition metal hydrides and also to identify the earliest fluxional organometallic molecules. In 1970 he entered a collaboration with Professor Alun G. Jones, a nuclear chemist at Harvard Medical School, to characterize and develop the chemistry of technetium. They made a major discovery of technetium molecules which had the ability to selectively locate in human heart muscle, thereby vastly expanding the practice of nuclear medicine to a global community. Professor Alan Davison was also widely known for his outstanding qualities as a teacher and mentor.

Reaction between lithium indenyl and a chlorine substituted alpha diimine of the form [{Cl(NPh)2}C)]2 unexpectedly yielded the corresponding NH rearranged derivative [PhN(H)C(C9H6)]2 (1) rather than the predicted symmetrical α-diimine. This compound 1 was characterised by 1H NMR, 13C{1H} NMR and mass spectrometry, and additionally by X-ray diffraction. It was found that 1 was the first indene-substituted and symmetric secondary amine which was also highly fluorescent in DMSO. The reactivity of 1 towards simple inorganic and organometallic transition metals precursors based on the MX2 fragments, where M = Group 10 metals and X = halides or methyl groups, has been investigated. Surprisingly, the reaction with [PtMe2(COD)] led to the coupling reaction between the indenyl groups incorporated at the C-C ligand backbone and a new ligand (2) was discovered, in an attempt to synthesise the metal-linked diamine. Single crystal X-ray diffraction studies confirm this compound 2 to feature coupled indenyl residues and delocalised C-C bonds in the solid state. Structural authentication by X-ray crystallography showed compound 2 to be a very rare example of flat and extended aromatic organic molecule and mass spectrometry, IR and NMR spectroscopy were carried out to gain further insight into the solid state and solution phase structures. Further experiments to synthesise analogues of [PhN(H)C(Ind)]2 aiming to shift a likely equilibrium in favour the imine tautomer, by introducing bulky ortho substituents onto the benzene ring (R = Me, iPr) showed the presence of the imine tautomer to be increasingly favoured in 1H NMR spectra, with an increase in the steric bulk of the ortho substituents. However, the enamine tautomer is still observed to a minor extent even with isopropyl substituents and yields of these desired compounds were low on steric grounds.

Professor Geoff Cloke FRS celebrates his 65th birthday in 2018. In a career spanning four decades, his research endeavours have accounted for some of the most innovative synthetic chemistry of the modern era, with his many publications describing truly exceptional compounds and experimental methods that portray a unique chemical imagination. In addition to his scientific accomplishments, Cloke can be particularly proud of his successful mentoring, a level of dedication that propelled many students and post-docs on to become research leaders in their own right. In compiling this collection of some of his research articles, a small cross-section of his friends, colleagues and collaborators, wish to pay tribute to his modesty, compassion and generous personality.

Application of the covalent bond classification to the compounds [M2(η5-C5H5)2(μ-H)(μ-PCy2)(CO)2] (M = Mo, W) identifies the compounds as having two M-M bonds and a 2 electron 3 centre (2e-3c) bond incorporating the bridging hydrogen, in accord with density functional calculations, and assigns their class as ML4X4.

The Covalent Bond Classification (CBC) method provides a means to classify covalent molecules according to the number and types of bonds that surround an atom of interest. This approach is based on an elementary molecular orbital analysis of the bonding involving the central atom (M), with the various interactions being classified according to the number of electrons that each neutral ligand contributes to the bonding orbital. Thus, with respect to the atom of interest (M), the ligand can contribute either two (L), one (X), or zero (Z) electrons to a bonding orbital. A normal covalent bond is represented as M–X, whereas dative covalent bonds are represented as either M←L or M→Z, according to whether the ligand is the donor (L) or acceptor (Z). A molecule is classified as [MLlXxZz] according to the number of L, X, and Z ligand functions that surround M. Not only does the [MLlXxZz] designation provide a formal classification of a molecule, but it also indicates the electron configuration, the valence, and t...

The major challenge for deep hydrotreating of diesel fuels is the removal of refractory sulfur-containing compounds and reducing aromatics to meet the stringent environmental regulations. In the present study, the hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDA) reactions of various real feedstocks over alumina-supported NiMoW catalyst synthesized by impregnation solution-based combustion method have been examined in order to gain insight into the capability of this preparation method to produce deep hydrotreating catalysts. The results show that a single exothermic peak with an ignition temperature of 272 °C decomposes the NiMo-urea redox solution deposited on tungsten oxide-modified alumina surface, a subsequent impregnation with NiMo-urea solution produces an increase of the decomposition period of the metal oxide precursor and urea. Furthermore, the addition of Ni and Mo to WOx-modified alumina facilities the NiO–Mo (or W) Ox interaction and promotes MeOx reducibility. On the other hand, feed with lower density and higher end-boiling point (T95) shows lower HDS reactivity and hence more demanding operating conditions (i.e., high hydrogen pressure, high reaction temperature and low liquid contact time) are required to obtain diesel fuel with low aromatics, high cetane index and ultra low-S and -N concentrations. The strong inhibiting effect of N-containing compounds and weak effect of aromatics over the HDS reactivity of real feedstock is reflected on smaller HDS rate constant than HDN rate constant for γ-alumina-supported NiMo, NiMoW and even CoMo sulfide catalysts. The presence of tungsten in the NiMo catalyst selectively enhances the rates of the HDS reactions compared to the HDN reactions, particularly of refractory S compounds.

This article provides a means to classify and represent compounds that feature 3-center 4-electron (3c–4e) interactions in terms of the number of electrons that each atom contributes to the interaction. Specifically, Class I 3c–4e interactions are classified as those in which two atoms provide one electron each and the third atom provides a pair of electrons (i.e. LX2), while Class II 3c–4e interactions are classified as those in which two atoms each provide a pair of electrons and the third atom contributes none (i.e. L2Z). These classes can be subcategorized according to the nature of the central atom. Thus, Class I interactions can be categorized according to whether the central atom provides one (i.e. μ–X) or two (i.e. μ–L) electrons, while Class II interactions can be categorized according to whether the central atom provides none (i.e. μ–Z) or two (i.e. μ–L) electrons. The use of appropriate structure-bonding representations for these various interactions provides a means to determine the covalent bond classification of the element of interest.

A new class of combustion catalyst containing copper and chlorine is described which has high activity for the total oxidation of chlorinated hydrocarbons such as CH2Cl2, CH2ClCH 2Cl, CCl4 and 1,2-dichlorobenzene (1% of gas stream) into carbon oxides, HCl and Cl2, in the presence of excess air at 300-500 °C; no catalyst deactivation or loss of copper or chlorine is observed.

W(IV) and Nb(IV) derivatives: [W(L1)MeH] (1), [W(L1)MeH] (2) and [W(L1)O] (3), [W(L2)Cl-2](4), [W(L2)H-2](5), [W(L2)H-3][BF4] (6), [Nb(L2)Cl-2](7) and [Nb(L2)(eta(2)-BH4)](8), where L1 = [(eta-C5H4)(2)SiMe2](2-) and L2 = [(eta-C5H3TMS)(2)SiMe2](2-), have been prepared and characterised. The crystal structures of compounds 5 and 8 have been determined. Thermodynamic parameters for the elimination of methane from compound 2 have been evaluated based on H-1 NMR studies in C6D6. Trimethylsilyl substituents on the cyclopentadienyl rings appear to moderate the structural and dynamic properties of the silicon-bridged ansa-tungstenocenes. (c) 2005 Elsevier Ltd. All rights reserved.

The reversible interconversions of oxo and arylimido ligands and a metathesis reaction between arylimido ligands and arylisocyanates are described. The compound [Mo(η-C 5 H 4 Me)(NPh)(μ-NPh)] 2 contains linear terminal MoNPh ligands and a planar Mo 2 (μ-N) 2 fragment.

The new compounds [Nb(η-C6H5Me)(PMe3)3R](R = H or SiMe3), [Nb(η-C6H5Me)(tmps)], [Nb(η-C6H5Me)(tmps)H][tmps = MeSi(CH2PMe2)3], [Nb(η-C6H5Me)(η-C5H5)(PMe3)], [Nb(η-C6H5Me)(η-C9H7)(PMe3)], [Nb(η5-C9H7)(CO)3(PMe3)], [Nb(η-C6H5Me)(η5-C7H9)(PMe3)], [Nb(η-C7H7)(η4-C7H8)(PMe3)], [Nb(CO)3(PMe3)4][Nb(CO)5(PMe3)], [Nb(η-C7H7)(CO)2(PMe3)], [Nb(η-C6H5Me)2X](X = Br, I, Me, Ph or CH2Ph), [{Nb(η-C6H5Me)(µ-SR)2}2](R = CH2Ph, Me or Bu) and [{Mo(η-C6H5Me)(µ-SePh)2}2][PF6]2 have been prepared (indicates the crystal structure has been determined). Evidence for the anions [Nb(η-C6H5Me)(PMe3)3]– and [Nb(η-C6H5Me)(tmps)]– is presented.

A new iminophosphine ligand, [Ph2PCH2C(Ph)=N(2,6-Me2C6H 3)] (HL), and the complexes [PdX2(HL)], where X = Cl (1) and Br (2), [PdMeX(HL)], X = Cl (3) and Br (4), and [PdMe2(HL)] (5) have been prepared and characterised. Reaction of 2 with MeLi or KH leads to deprotonation of the neutral ligand to give [Pd2(μ-Br)2(L-)2], (6), where L- is [Ph2PCH=C(Ph)N(2,6-Me2C6H3)] -. Similarly, reaction of 3 with KH and triphenylphosphine affords the neutral complex [PdMe(PPh3(L-)] (7). Insertion of CO into the Pd-Me bond has been investigated, as well as the catalytic properties of [PdClMe(HL)] towards CO/ethylene copolymerisation. The crystal structures of HL, 1-3 and 5-7 have been determined.

Nanotubes are non‐destructively oxidized along their sidewalls and covalently functionalized with metal nanoparticles via carboxylate chemistry. Proteins adsorb individually, strongly and non‐covalently along nanotube lengths. Individual nanotube reaction products are characterized by atomic force microscopy.

The filling of carbon nanotubes with palladium metal crystallites is described and it is shown that when the carbon nanotube samples are opened using nitric acid, surface acid groups (CO2H and OH) are present on both the nanotubes and nanoparticles and these interact strongly with palladium ions: ultrasound pre-treatment of the carbon nanotube samples prior to the oxidation with nitric acid increases the number of these groups.

The ansa-rhenocene compound [Re{(η-C5H4)CMe2(η-C5H4)}Cl] 1 has been prepared by reaction of ReCl5 with [K2(C5H4)CMe2(C5H4)]. X-Ray crystallography shows the molecular structure to be unsymmetrical, with the angle defined by the Re-bridgehead carbon vector and the chlorine atom found to be 170.4°. A density functional study compares the electronic structure of [Re{(η-C5H4)CH2(η-C5H4)}Cl] with [Re{(η-C5H5)2Cl] and shows that for the ansa-bridged species, the chlorine binds less effectively in the central position. The calculated structure of [Re{(η-C5H4)CH2(η-C5H4)}Cl] is also found to be unsymmetrical.

High yield synthesis of propanal from methane and air can be obtained in a single pass at atmospheric pressure. Three catalytic processes are combined to give 13% yield of propanal based on total methane input. Ethene is made from the oxidative coupling reaction and carbon monoxide and hydrogen is generated from partial oxygenation of methane. These gases are combined and passed to a hydroformylation catalyst to give liquid propanal. The unreacted methane is inert in the hydroformylation stage, while oxygen deactivates the catalyst readily. The results imply that propanal can be obtained, in good yield, from methane and air provided that total oxygen conversion is achieved. The yield of propanal from the three combined processes can be substantially higher than that of ethene from the oxidative coupling reaction. Thus, higher yields of a condensible and oxygenated product are obtained. © 1992 J.C. Baltzer A.G. Scientific Publishing Company.

[W(PMe 3 ) 4 (η 2 -CH 2 PMe 2 )H] reacts with a mixture of CO 2 and H 2 (1/1, 3 atm) at room temperature to give [W(PMe 3 ) 4 H 2 (η 2 -O 2 CO)] and [{W(PMe 3 ) 3 (η 1 -PMe 2 CH 2 )} 2 (C 3 H 2 O 6 )]. [{W(PMe 3 ) 3 (η 1 -PMe 2 CH 2 )} 2 (C 3 H 2 O 6 )] has been characterised using two-dimensional homo- and hetero-nuclear correlation NMR techniques.

The polypeptides poly-L-(Trp,Lys·HBr) (Trp/Lys·HBr = n/m) and poly-L-(Tyr,Lys·HBr) (Tyr/Lys·HBr = n/m) were tested as dispersing agents for single-wall carbon nanotubes (SWCNTs) for n/(n+m) values of 0, 0.2, and 1. Best results were obtained for the two copolymers, illustrating the importance of using amphiphilic dispersing agents. The dispersion effect is 3.5 times higher for the copolymer containing tryptophan, indicating a stronger interaction of the tryptophan residue with the SWCNTs compared to tyrosine. The degrees of debundling of the SWCNTs and the apparent binding of the polypeptides with the SWCNTs are analyzed by atomic force microscopy for the different dispersions. The interactions of the aromatic amino acid residues with the SWCNTs are further probed by using optical absorbance and fluorescence spectroscopy. © 2007 American Chemical Society.

The electrochemical opening of closed-ended, pristine single-walled carbon nanotubes (SWCNTs) upon the application of either a sufficiently oxidizing or reducing electrode potential is reported. Hitherto, it has been unclear whether the side walls of SWCNTs are electrochemically active, or whether, like their multiwalled counterparts (MWCNTs), the electroactive sites on SWCNTs also reside at the edge-plane-like defects at the open ends of the tubes. Evidence is presented herein that suggests the latter case is true, i.e., that SWCNTs require edge-plane sites to be electroactive. Comparisons of the voltammetric response of end-closed SWCNTs (EC-SWCNTs), end-open (EO-SWCNTs), and SWCNTs encapsulating a metal halide filling (MX@SWCNTs, where MX represents either NaI or CuI) in aqueous electrolytes indicate that SWCNTs undergo electrochemical opening if the applied electrode potential is greater than +1.2 V vs SCE or less than -1.5 V vs SCE. This was further confirmed using ex situ X-ray photoelectron spectroscopy. The nonaqueous voltammetry of NaCl@SWCNTs, NaI@SWCNTs, CuI@SWCNTs, and ZnCl2@SWCNTs in dimethyl formamide (DMF) containing 0.1 M tetrabutyl ammonium perchlorate (TBAP) all exhibited voltammetric responses identical to that of EC-SWCNTs unless the potential was cycled beyond ca. +1.6 V vs Ag (+2.129 V vs the cobaltocene/ cobaltocenium redox couple) whereupon voltammetry corresponding to the filling material was observed, again indicating that the SWCNTs had become open-ended. Evidence for quantized charging of the EC-SWCNTs is presented in terms of the unusual "bow-tie" shape of the background charging current in DMF is also presented. © 2008 American Chemical Society.

Co-condensation of osmium atoms with benzene gives stable Os(η6-C6H6)(η4-C6H6) whereas co-condensation of osmium atoms with mesitylene forms the dimers[(η6-C6H3Me3)Os(µ-H)2(µ-CHC6H3Me2-3,5)Os(η6-C6H3Me3)] and [(η6-C6H3Me3)Os(µ-CHC6H3Me2-3,5)Os(η6-C6H3Me3)].

We report the synthesis of continuous and crystallographically aligned single crystals of molybdenum oxide based nanowires up to micrometres in length inside carbon nanotubes: opened tubes are filled using molten MoO3 followed by controlled reduction under dilute hydrogen to MoO2 material.

Density functional calculations on [Nb(η-C5H5)2(η2-BH4)], [Nb{H2Si(η-C5H4)2}(η2-BH4)] and [Nb{H2C(η-C5H4)2}(η2-BH4)], show the barrier to terminal-bridging hydrogen exchange decrease as the inter-ring angle increases, in agreement with earlier experimental data. The calculations suggest the bonding of BH4 weakens as the metallocene unit becomes more bent, and that there is stronger bonding in the transition state as the dyz orbital becomes more accessible.

Single-walled carbon nanotubes (SWNTs) functionalized with organic molecules bearing high-scattering element tags have allowed direct visualization of modification on the atomic scale. The inclusion of these tags in protecting groups allowed their subsequent removal and reincorporation to allow visualization of corresponding protection and deprotection of organic molecules on the SWNT. This method, in conjunction with direct-Staudinger ligation of glycosyl azides to surface carboxylates allowed precise incorporation of glycans to the surface of SWNTs. Resulting glyco-SWNTs interacted successfully with carbohydrate-active enzymes for the first time, allowing elaboration of the carbohydrate structure on the surface of the SWNT and demonstrating utility of these glyco-SWNTs as potential probes. Moreover, the glycosyltransferase-catalyzed transfer of [6-3H]-d-galactosyl to the surface of the SWNT allowed site-selective radiolabeling. Copyright © 2007 American Chemical Society.

We describe here the high yield filling (i.e. > 50%) of single walled nanotubes (SWNTs) with a variety of halides, achieved according to various modified filling procedures. Both bundles and discrete SWNTs can be filled continuously up to lengths of several hundred nm, often with filling yields approaching 60-70% or better. In addition some high yield filled SWNTs were subjected to long-term washing in either boiling or room temperature, aqueous media, which does not remove the filling from the tubules, but enables effective removal of water-soluble extraneous materials.

The 17 -electron compounds [M(η-C7H7)LX2](M = Mo, L = MeCN, X = I 1; M = Mo, L = PMe3, X = I 2; M = W, L = MeCN, X = I 3; M = W, L = PMe3, X = I 4; M = W, L = PMe3, X = Br 5) have been prepared. All exhibit antiferromagnetic interactions with temperatures at χmax ranging from 12 to 17 K. The magnetic susceptibility data have been described by one-dimensional magnetic models. The crystal and molecular structures of [Mo(η-C7H7)(MeCN)l2]1 have been determined, and confirm the one-dimensional structure.

Evidence is presented for ‘in-place’ rotation of the methyl groups of agostic η2-ethyl systems leading to hydrogen scrambling in ethylene–hydride complexes.

The first examples of mesostructured materials containing Mo- and W-oxo-sulphur species incorporated into a poorly ordered MCM-41 framework have been prepared under hydrothermal condition and alkaline medium. The incorporation of oxygen-sulphur derivates of molybdenum and tungsten not only increases significantly the pore diameter, but also improves the thermal stability of the MCM-41-related mesoporous material. © 2005 Elsevier Ltd. All rights reserved.

Co-condensation of rhenium atoms with the arenas 1,3,5-R3C6H3, R3= MeH2 or Me3, or 1,4-Me2C6H4 gives the compounds [{(η-arene)Re}2(µ-CHR′)(µ-H)2], where R′= Ph, 3,5-Me2C6H3, or 4-MeC6H4 respectively, which contain a µ-arylidene group; the structurally related compounds [{(η-arene)Re}2(µ-CR1R2)(µ-H)2], where R1,R2= Me, Ph or H, CH2Ph, are formed from rhenium atoms and ethylbenzene.

Ultrasonic irradiation of gallium metal with di-iodine and alkyl iodides, RI, rapidly gives high yields of [RGaI2] via a reactive intermediate mate

The comparative crystallisation and HRTEM imaging properties of simple binary halides formed by the alkali iodides MI (M = Li, K, Na, Rb and Cs) within single walled carbon nanotubes (SWNTs) are described. The most common structure type observed within SWNTs is the rocksalt archetype, although CsI was observed to form both bcc and rocksalt structure types. In SWNTs forming in the 1.2-1.6 nm diameter range, all of the incorporated halides showed preferred orientation, with the (100) growth direction predominating for rocksalt-type packing and (112) so far observed exclusively for bcc packing. Crystals with dimensions spanning 2-6 atomic layers thickness in projection invariably exhibited lattice expansions that were attributed predominantly to a net reduction in coordination at the crystal-carbon interface. The crystallisation behaviour of UCl4-KCl and AgI-AgCl eutectic melts was compared in carbon nanotubes of different diameters and a pronounced ordering influence over the normally glassy melts was observed in narrower capillaries. HgI2 crystallised within nanotubes with ultra-narrow (i.e., 0.8 nm) capillaries were observed to form helical 2 × 1 layer crystals. © 2003 Académie des sciences. Published by Elsevier SAS. All rights reserved.

The new compounds [Nb{(eta-C5H4)X(eta-C5H4)}Cl-2] (X = CEt2 1a, C(C5H10) 1b, C2Me4 1c), [Nb{(eta-(C5H3Bu)-Bu-t)C2Me4(eta-(C5H3Bu)-Bu-t)}Cl-2] 1d, [Nb{(eta-C5H4)X(eta-C5H4)}(eta(2)-BH4)] (X = CEt2 2a*, C(C5H10) 2b, C2Me4 2c*, SiMe2 2e*), [Nb((eta-(C5H3Bu)-Bu-t)C2Me4(eta-(C5H3Bu)-Bu-t)}(eta(2)-BH4)] (2d*), [Nb{(eta-C5H4)X(eta-C5H4)}(eta(2)-BD4)] (X = C2Me4 3c, CMe2 4), and [V{(eta-C5H4)C2Me4(eta-C5H4)}(eta(2)-BH4)} (5*) have been prepared. The asterisk indicates the crystal structure has been determined. The hydrogen scrambling processes in the tetrahydroborate complexes 2a-e, 3c, 4, 5, and [Nb{(eta-C5H4)CMe2(eta-C5H4)}(eta(2)-BH4)] have been studied. The free energy barrier Delta G(double dagger) to bridge-terminal hydrogen exchange is considerably reduced when the bridging unit imposes significant structural changes in the metallocene.

Rhenium supported on γ-alumina has been tested as a catalyst for the partial oxidation and dry reforming of methane at different temperatures. This is the first study to show that a non-group VIII metal catalyst can catalyse both these reactions to their thermodynamic equilibria, and give greater than 85% methane conversions at 1050 K. No carbon deposition was detected after 72 hours. The specific activities are comparable to those of other reported catalysts containing ruthenium, rhodium and iridium. However, the kinetic measurements show that the activity of the rhenium catalyst decreases dramatically at lower temperatures. Thus, at about 873 K, the rhenium catalyst gave less than 5% methane conversion, which is significantly lower than for other metals. This dramatic temperature effect on the catalytic activity can be attributed to the oxidation of the catalyst.

For the first time we report on the electrochemical characteristics of nanometer sized polyhedral graphite onions dispersed amongst arc-MWCNTs. These are formed during the electric arc discharge method of producing ultrapure MWCNTs (arc-MWCNTs). The carbon onions are randomly dispersed amongst the arc-MWCNTs which are produced with very little amorphous carbon deposits or other unwanted impurities and are formed as closed-ended tubes. By comparison with commercially available open-ended hollow-tube multiwalled carbon nanotubes made using the chemical vapor deposition method (cvd-MWCNTs), a glassy carbon electrode (GCE), an edge-plane pyrolytic graphite electrode (eppg) and basal plane pyrolytic graphite (bppg) electrode, we can speculate that it is the edge-plane-like defect sites that are the electroactive sites responsible for the apparent 'electrocatalysis' seen with a wide range of analytes including: ferrocyanide, ruthenium hexaamine(III), nicotinamide adenosine dinucleotide (NADH), epinephrine, norepinephrine, cysteine, and glutathione. The arc-MWCNTs themselves are produced as closed-ended tubes with very few, if any, edge-plane-like defect sites evident in their HRTEM characterization. Therefore we speculate that it is the carbon onions dispersed amongst the arc-MWCNTs which have incomplete graphite shells or a rolled-up 'Swiss-roll' structures that posses the edge-plane-like defect sites and are responsible for the observed voltammetric responses. Carbon onions are no more or no less 'electrocatalytic' than open-ended MWCNTs which in turn are no more electrocatalytic than an eppg electrode. As the carbon onions are ubiquitous in MWCNTs formed using the arc-discharge method the authors advise that caution should be taken before assigning any electrocatalytic behavior to the MWCNTs themselves as any observed electrocatalysis likely arises from the carbon onion impurities. © 2008 Wiley-VCH Verlag GmbH and Co. KGaA.

Using high resolution electron microscopy and first principles quantum mechanical calculations we have explored the fundamental physics and chemistry of the semiconductor, HgTe grown inside single wall carbon nanotubes. This material forms a low-dimensional structure based on a repeating Hg2Te2 motif in which both atom species adopt new coordination geometries not seen in the bulk. Density-functional theory calculations confirm the stability of this structure and demonstrate conclusively that it arises solely as a consequence of constrained low dimensionality. This change is directly correlated with a modified electronic structure in which the low-dimensional form of HgTe is transformed from a bulk semimetal to a semiconductor.

Carbon extracted from a cathodic graphite rod following arc-discharge in helium is examined using high-resolution electron microscopy. It is found that, in addition to the well known extended graphitic tubules ('buckytubes'), carbon produced in this way contains many other novel graphitic structures. Of particular interest are small hollow particles which, although essentially tubular, appear to differ in significant ways from the extended tubules. Evidence for tetrahedral bonding in some of the graphitic particles is also presented.

A carbon soot formed by arc evaporation and activated by heating under carbon dioxide is found to have a surprisingly high internal micropore volume (> 0.25 ml g-1) and an apparent BET surface area of ca. 700 m 2 g-1, a large proportion of the pores are ca. ≤5 Å; transmission electron microscopy shows a highly disordered microstructure, which electron irradiation readily transforms into quasi spherical concentric nanoparticles of diameter of ca. 60 Å, the carbon material, which is highly absorbent to methane, shows molecular sieving properties and is more inert to oxidation than other forms of high surface area carbon.

The compounds [{(η-C5H5)(µ-{η1:η5-C5H4})Mo}2] and [{(η-C5H5)(µ-[η1:η5-C5H4])WH}2] have been prepared; the systems [M(η-C5H5)X2](M = Mo or W, X2= Cl2 or O)–NaHg deoxygenate epoxides catalytically.

Cocondensation of tungsten vapour with 1,2,3,4,5-pentamethylcyclopentadiene gives bis(η-pentamethylcyclopentadienyl)tungsten dihydride, (η-C5Me5)2WH2; photolysis of the dihydride yields, sequentially, the ‘tucked-in’ compounds (η-C5Me5)W(η-C5Me4CH2)H and (η-C5Me5)W(η-C5Me3CH2CH2).

Reduction of [ZrCI4] in the presence of cycloheptatriene and PMe3 forms [Zr(η6-C7H8)(PMe3)2Cl 2](1), and reaction of iodotrimethylsilane with [Zr(η7-C7H7)(PMe3)2](2), produced from [Zr(η6-C7H8)2](4)via[Zr(η7-C7H7)(tetrahydrofuran)2l](5), forms [Zr(exo-η6-C7H7SiMe3)(PMe3)2l2](3); the crystal structures of (1),(3),and (5) have been determined.

Extended-Huckel molecular-orbital calculations for the model systems [W2(cp)2Cl4], [Mo2(cp)2(µ-Cl)2, and [Re2(cp)2Cl2(µ-Cl)2](cp =η-C5H5) were used to analyse the bonding in the three observed, distinct geometries of metal–metal bonded (η-cyclopentadienyl)transition metal dihalide dimers of the general formula [{M(η-C5R5)X2}2], and are supported by He I and He II photoelectron spectra for [W2(η-C5H4Pri)2Cl4] and by a He I photoelectron spectrum for [Mo2(η-C5H4Me)2(µ-Br)4]. The He I and He II photoelectron spectra are also reported for the related complex [Mo2(η-C5H4Pri)2(µ-SMe)4]. The calculations show that the metal d-electron count is the most important factor selecting the observed geometry of [{M(η-C5R5)X2}2](X = Cl or Br) species, but that the extent of metal–metal overlap and non-bonding interactions within the (µ-X)4 linkages of the quadruply bridged isomers must also be considered.

The hydrogen evolution from aqueous methanol solutions was found to follow two stages of zero order kinetics during photoreactions using TiO 2 as the photocatalyst. Maximal hydrogen evolution was found at the 10% (v/v) methanol solution. X-ray photoelectron spectroscopy (XPS) shows that Ti(1566) defects are formed on the surface of TiO 2 and X-ray powder diffraction (XRD) indicates that Ti(1566) defects are also formed in the bulk after photoreaction. Formation of defects is also shown by broadening of Bragg peaks and blue shifts and peak broadening in Raman spectroscopy. The defect disorder results in the increase of hydrogen evolution. UV-vis diffuse reflection spectra confirm that new absorptions in the visible light region are related to the defect content. At high methanol concentration, XPS implies that the active sites of the surface are blocked by hydroxyl groups, which results in the decrease of hydrogen evolution. TEM images showed that the photoreaction occurred on the surface of the photocatalyst as the surface of the TiO 2 became rough after the photoreaction.

The new imido compounds [M(η-C5H4R)Cl2(NR′)]*(M = Mo, R = H, R′= But, Prn or Ph; M = Mo, R = Me, R′= But or Ph; M = W, R = H, R′= But), [Mo (η-C5H4R)Cl(L)(NR′)](R = H, R′= But, L =η-C2H4, or η-C2Me2; R = Me, R′= But, L = C2H4*; R = H, R′= Ph, L =η-C2Me2), [{Mo(η-C5H4R)(η-C2H4)(NBut)}2Hg]*(R = H, Me), [Mo (NBut)Cl2(PMe3)3], [Mo(η-C5H5)Cl3(NBut)] and the π-allyl complex [Mo(η-C5H4Me)(η-C3H5)(NBut)] are synthesised; *indicates that the crystal structure has been determined.

The reduction of electrodes coated with C 60 -fullerene is examined in acetonitrile solution containing a wide variety of supporting electrolytes (MClO 4 ; M = Li, Na, Ba 0.5 , NR 4 ). Electrochemical intercalation is observed with the formation of fulleride salts. Intercalation is typically irreversible except for the case of R = n -butyl where stable coats of fullerides may be formed into which charge can be passed with near chemical reversibility. Electron-transfer reactions at electrodes modified with C 60 coatings were investigated for diverse substrates. With unreduced coats impeded diffusion to the metal surface was seen, whereas with films reduced in the presence of tetrabutylammonium perchlorate coat-mediated electron transfer to the substrate was possible.

The pseudo-trigonal bis(η-cyclopentadienyl)-molybdenum and -tungsten imido complexes [M(η-C5H4R)(η-C5H4R′)(NBut)](M = Mo or W; R = R′= Me or H, R′= Pri R = H) are reported together with the ring-slipped indenyl analogue [Mo(η-C5H4Pri)(η3-C9H7)(NBut)] and the metal-methylated salts [Mo(η-C5H4Me)2(NBut)Me]X (X = I or BF4); the X-ray structures of [Mo(η-C5H5)2(NBut)] and [Mo(η-C5H4Me)2(NBut)Me]BF4 suggest that the NBut ligand acts as a strong π-donor to the metal centre; photoelectron studies identify an unusually low ionization-energy band largely localized on the ligands.

Carbon nanotubes can be filled with different materials leading to one-dimensional crystallization of salts within the confining nanotube walls. The typical nanotube internal diameter is -1nm. Twisted chains of CdCl2, a polyhedral chain structure with unusual cation coordination, were found. A high pressure rocksalt structure in halides such as CsCl, and tetragonal distortions in halides such as KI were also observed. Image reconstruction generated phase images with aberration corrected atomic positions to better than 0.01 nm accuracy.

The new compounds [M(η-C7H8)L2Cl2](M = Zr, L = PMe31; M = Hf, L = PMe32; M = Zr, L = PMe2Ph 3; M = Hf, L = PMe2Ph 4; M = Zr, L = PMePh25) have been synthesised by reduction of MCl4 using sodium amalgam in the presence of the tertiary phosphine and cycloheptatriene. Lithium indenide reacts with the triene compounds to give [M(η-C7H7)(η5-C9H7)](M = Zr 6 or Hf 8) which react with trimethylphosphine or 1,2-bis(dimethylphosphino)ethane (dmpe) to form [M(η-C7H7)(η5-C9H7)(PMe3)](M = Zr 7 or Hf 9) and [{Hf(η-C7H7)(η5-C9H7)}2(µ-dmpe)]10 respectively. Treatment of 1 or 2 with sodium cyclopentadienide gives [M(η-C5H5)2{η2-1,2-(or -3,4-) C7H8}(PMe3)][M = Zr 11 or Hf 12). The X-ray crystal structures of 1, 10 and [Zr(η-C5H5)2(η2-3,4-C7H8)(PMe3)]11a have been determined.

Reactions between [Fe(η-C 5 H 5 )(MeCO)(CO)(L)], L = PPh 3 ( 1 ), PMe 3 ( 2 ), PPhMe 2 ( 3 ), PCy 3 ( 4 ), CO ( 5 ), and B(C 6 F 5 ) 3 give new complexes [Fe(η-C 5 H 5 ){MeCOB(C 6 F 5 ) 3 }(CO)(L)] L = PPh 3 ( 7 ), PMe 3 ( 8 ), PPhMe 2 ( 9 ), PCy 3 ( 10 ), CO ( 11 ), where B(C 6 F 5 ) 3 coordinates selectively to the O-acyl groups. Hydrolysis of 7 gives [Fe(η-C 5 H 5 ){HOB(C 6 F 5 ) 3 }(CO)(PPh 3 )] ( 6 ). The X-ray structures of 6 , 8 and 11 have been determined. Calculations, using density functional theory, demonstrate that the charge transfer to the acyl group on Lewis acid coordination is more significant in the σ than the π system. Both effects lead to a lengthening of the acyl C–O bond thus π populations cannot be inferred from the distance changes.

Co-condensation of atoms of tungsten rhenium, and chromium with a mixture of cyclohexane and trimethylphosphine causes activation of the cyclohexane giving the compounds W(η-C6H8)(PMe3)2H4, W(η-C6H8)(PMe3)3H2, W(η-C6H6)(PMe3)2H2, W(PMe3)4H4, Re(η-C6H6)(PMe3)2H, and Cr(η-C6H6)(PMe3)3 respectively; when tungsten atoms react with a 3 : 1 mixture of cyclohexane and perdeuteriocyclohexane, together with PMe3, then the absence of mixed H–D tungsten Products indicates that the C–H activation processes are intramolecular.