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A new tris(pyrazolyl)borate ligand bearing phosphine donor groups appended to the 3-position of the pyrazolyl rings is reported, and the hemilabile behaviour of this tris-N,P ligand in coordination with K+, Tl+ and Cu+ ions is investigated.

1,1'-Difunctionalised ferrocene derivatives have been studied, which contain groups suitable for chemisorption on gold substrates, namely -NC, -PR(2) as well as a range of sulfur-containing units like -NCS, -SR, and thienyl. Thin films on gold have been fabricated from solution with most of these adsorbate species. Film thickness, composition and structure were investigated primarily by X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy. The quality of self-assembled monolayers fabricated from 1,1'-diisocyanoferrocene (1) and 1,1'-diisothiocyanatoferrocene (2) turned out to be superior to that of films based on the other adsorbate species investigated. In addition to the surface coordination behaviour of 1 towards gold substrates, relevant aspects of the molecular coordination chemistry of 1 have also been addressed, including the synthesis and characterisation of [(mu-1){Cr(CO)(5)}(2)], [Ag(2)(mu-1)(2)](NO(3))(2) x H(2)O and [(mu-1)(AuCl)(2)]. The crystal structure of the gold complex is governed by aurophilic interactions and can be taken as a model for the arrangement of 1 in self-assembled monolayers on gold.

The complexes cis-[M(CO)4(LL)], fac-[ReX(CO)3(LL)] and fac-[PtXMe3(LL)], (M = Cr, Mo, W; LL = [(C5H4SCH3)2Ru]; X = Cl, Br, I) have been synthesised. A 1H NMR study of their solution properties has shown that pyramidal inversion of the coordinated sulphur atoms is rapid on the NMR timescale at ambient temperature. At low temperatures (ca. −90° C) the motion is arrested and the tungsten complex exists as a mixture of meso and dl species in approximately equal proportions, whereas the rhenium complexes are predominantly (> 94%) in the meso form. Insolubility precluded low-temperature studies on the platinum complexes. Variable temperature bandshape analyses of the tungsten complex yielded a sulphur inversion (meso → dl) value of ΔG≠ (298 K) 32.0 ± 1.0 kJ mol−1. The massive predominance of one invertomer in the case of the rhenium complexes prevented a study of the sulphur inversion by bandshape analysis. The crystal structure of 1,1′-bis(methylthio)ruthenocene tetracarbonyltungsten has been determined. The WS bond lengths are 2.571(5) and 2.565(4) A, with a SWS bond angle of 81.1(1)°. The cyclopentadienyl rings are eclipsed and the SCH3 groups adopt a meso relationship.

Amorphous C‐Ge multilayers have been produced with periods varying from 2.6 to 12.5 nm. We have studied the multilayers using Raman spectroscopy and dc conductivity measurements and found that their properties change significantly when the carbon sublayer thickness is smaller than 2.5 nm. This value corresponds to the proposed dimension of sp2 bonded carbon islands within a‐C and we find that our results can be understood in terms of the carbon forming these islands, but the islands becoming disconnected as the nominal carbon layer thickness decreases. The conductivity shows a percolation behavior for the thinnest layers.

The complexes fac-[ReX(CO)3{(C5H4ECH3)2Fe}] (X  Cl, Br, I; E  S, Se) have been synthesised. A 1H NMR study of their solution properties showed that pyramidal inversion of the coordinated chalcogen atoms was rapid on the NMR timescale at ambient temperatures, but at low temperatures (ca. −70°C) the complexes existed as mixtures of meso and dl species, with the former predominating, particularly in the sulphur ligand complexes. Low temperature 2D-EXSY studies and variable temperature 1D bandshape analyses yielded accurate chalcogen inversion energies for both meso-1 → dl -1 and dl -1 → dl -1 exchanges. Values of ΔG‡(298 K) for these interconversions were, respectively, in the regions of 43 and 46 kJ mol−1 (S inversion) and 63 and 66 kJ mol−1 (Se inversion). The crystal structure of chloro-1,1′-bis(methylthio)ferrocenetricarbonylrhenium has been determined. The crystals have space group P 1 , with a 9.030(1), b 14.252(2), c 7.554(1) A, α 76.58(1)°, β 104.73(1)°, γ 107.08(1)° and Z = 2. Least-squares refinement gave R = 0.030 for 2930 reflections. The ReS bond lengths are 2.504(4) and 2.512(4) A and the SMe groups adopt a meso relationship analogous to the preferred solution structure. The SReS bond angle is 80.0(2)° and the non-bonded SS separation

Complexes of the ligand 2,3-dioxo-1,4,8,11-tetraaza-cyclotetradecane (exoO(2)-cyclam) have been prepared of formula [M(1){M(2)(exoO(2)-cyclam)}(2)][BPh(4)](2) where M(1)M(2) = CoCo (3), ZnZn (4), MnCu (5), FeCu (6), CoCu (7), NiCu (8), ZnCu (9), and [(bipy)(2)Ru{Cu(exoO(2)-cyclam)}][NO(3)](2) (10). Complex 10 crystallised in the space group C2/c and shows Jahn-Teller distorted Cu(II) with axial nitrate ligands. The {Cu(exoO(2)-cyclam)} moiety chelates to the Ru with Ru-O distances of 2.082(5) A. Complexes 5-10 show a Cu(II)/Cu(III) redox process and additional metal-centred (6, 8, 10) processes and ligand-centred (10) processes. The electrochemical and UV-Vis spectroelectrochemical study of suggested two closely-spaced oxidations based on the Cu and Ru centres which suggests that substituted derivatives of will be of interest for enhanced charge separation in dye-sensitised solar cells. Magnetic susceptibility measurements revealed dominant antiferromagnetic coupling within the trinuclear species 3, 5-8. Complex 10 showed Curie-Weiss behaviour with weak intermolecular interactions.

Three bidentate, mixed-donor ligands based on a triphenylphosphine unit bearing a pyrazole group in the ortho-position of one phenyl ring have been synthesised; the N,P ligand [2-(3-pyrazolyl)phenyl]diphenylphosphine pzphos has been synthesised and transformed into new N,P(O) and N,P(S) derivatives, [2-(3-pyrazolyl)phenyl]diphenylphosphine oxide pzphos(O) and [2-(3-pyrazolyl)phenyl]diphenylphosphine sulfide pzphos(S), respectively. The coordination chemistry of pzphos and pzphos(O) towards palladium(II) has been investigated. Depending on the ligand to metal molar ratio employed in the reactions of palladium(II) with pzphos, either the 1 : 1 chelate [Pd(pzphos)Cl2] 1a or the 2 : 1 N,P chelate [Pd(pzphos)2]Cl2 1b was obtained. 1b contains two six-membered chelate rings in which the chlorides have been displaced from the inner coordination sphere of palladium. Exchange of the chloride anions in 1b for perchlorate anions was achieved using AgClO4 to give [Pd(pzphos)2][ClO4]2 1c. Reaction of pzphos(O) under the same conditions forms the 2 : 1 adduct [Pd(pzphos(O))2Cl2] 2b regardless of the metal to ligand ratio or the order of addition of reactants. Unlike the N,P chelate 1b, the N,P(O) ligands in complex 2b bind in a monodentate fashion through the N-donor atoms of the pyrazole rings. Abstraction of the chloro ligands in compound 2b using AgClO4 gave the 2 : 1 N,P(O) chelate [Pd{pzphos(O)}2][ClO4]2 2c, in which entropically unfavourable 7-membered chelate rings are formed. X-Ray diffraction has been used to confirm the solid-state structures of the pzphos(O) ligand and the complexes 1b, 1c, 2b and 2c.

A comparative DNA scission activity study of azaferrocene, N-methyl-azaferrocene iodide and 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene (featuring iron in a +2 oxidation state), along with ferrocene (iron +2) and ferrocenium (iron +3) cation is described. Experiments indicate a high cleavage activity of azaferrocene and its N-methyl derivative in DMSO. DNA cleavage activity can be slowed down by addition of a free radical scavenger (thiourea) or triggered by addition of a reductive agent (dithiothreitol, DTT). The X-ray crystal structure of the N-methyl-2,5-dimethylazaferrocene cation (iron +2) with hexafluorophosphate as counter anion is also reported.

HTS flux pumps enable superconducting currents to be directly injected into a magnet coil without the requirement for thermally inefficient current leads. Here, we present results from an experimental mechanically rotating HTS flux pump employing a coated-conductor stator and operated at 77 K. We show the effect of varying the size of the flux gap between the rotor magnets and coated conductor stator from 1 to 7.5 mm. This leads to a corresponding change in the peak applied perpendicular magnetic field at the stator from approximately 350 to 50 mT. We observe that our experimental device ceases to maintain a measurable output at flux gaps above 7.5 mm, which we attribute to the presence of screening currents in the stator wire. We show that our mechanically rotating flux pump is well described by a simple circuit model which enables the output performance to be described using two simple parameters, the open-circuit voltage V oc and the internal resistance, R d. Both of these parameters are found to be directly proportional to magnet-crossing frequency and decrease with increasing flux gap. We show that the trend in R d can be understood by considering the dynamic resistance experienced at the stator due to the oscillating amplitude of the applied rotor field. We adopt a literature model for the dynamic resistance within our coated-conductor stator and show that this gives good agreement with the experimentally measured internal resistance of our flux pump.

A Roebel cable, one twist pitch long, was modified from its as-received state by soldering copper strips between the strands to provide inter-strand connections enabling current sharing. Various DC transport currents (representing different percentages of its critical current) were applied to a single strand of such a modified cable at 77 K in a liquid nitrogen bath. Simultaneous monitoring of I–V curves in different parts of the strand as well as in its interconnections with other strands was made using a number of sensitive Keithley nanovoltmeters in combination with a multi-channel high-speed data acquisition card, all controlled via LabView software. Current sharing onset was observed at about 1.02 of strand Ic. At a strand current of 1.3Ic about 5% of the current was shared through the copper strip interconnections. A finite element method modeling was performed to estimate the inter-strand resistivities required to enable different levels of current sharing. The relative contributions of coupling and hysteretic magnetization (and loss) were compared, and for our cable and tape geometry, and at dB/dt = 1 T s−1, and our inter-strand resistance of 0.77 mΩ, (enabling a current sharing of 5% at 1.3Ic ) the coupling component was 0.32% of the hysteretic component. However, inter-strand contact resistance values of 100–1000 times smaller (close to those of NbTi and Nb3Sn based accelerator cables) would make the coupling components comparable in size to the hysteretic components.

In May 2014, a discussion meeting entitled ‘The new chemistry of the elements’ took place—the first ever linking the Royal Society and the German Academy of Sciences, Leopoldina. The meeting confirmed and highlighted that the periodic table not only still represents the best way of understanding and mastering the fascinating and diverse science and technological applications of the known 114 chemical elements, but also underpins diverse multi-disciplinary research, inspiring and catalysing new advances and new avenues of research across the physical, biological and medical sciences.

We wish to dedicate this Discussion Meeting Issue to our friend and mentor, the late Prof. Jack Lewis, Baron Lewis of Newnham ([figure 1][1]), who is widely recognized as one of the father figures of modern inorganic chemistry and who died on 17 July 2014. It is particularly fitting since the

The reaction of lithiated 2,5-dimethylazaferrocene 1 with diethyl chlorophosphate proceeds to give lateral and ring phosphonate products. The products 2 and 3 were characterized by spectroscopic (1H, 31P{1H} NMR, MS, IR) methods and 3 was treated with W(CO)5(thf) to form a crystalline W(CO)5-complex 4 which was characterized by single-crystal X-ray analysis. The new 2,5-dimethylazaferrocenyl phosphonates were transformed into the corresponding N-methyl iodide salts 5 and 6 in quantitative yields. Both salts are water soluble and stable compounds and an analysis of their cytotoxic and anti-proliferative activity was carried out. Compound 6 possesses anti-metabolic activity which exhibited some preference towards the cancerous HeLa cell line over the non-cancerous NIH 3T3 cell line. These new compounds are the first examples of azaferrrocene (i.e. non-ferrocene) derivatives featuring biologically important phosphonate groups. The preliminary studies into cytotoxic activity indicates that as with ferrocene, azaferrocene can also be regarded as a potential source for organometallic anticancer agents, featuring the iron centre in the +2 oxidation state rather than the often utilized ferrocenium +3 species.

A series of new N4 and N8 macrocycles has been prepared, that includes cis-exogenous O2, S2 and S/O atoms to allow chelation to a metal external to the macrocyclic ring. We found that thioamide units within the macrocycles were unstable to attack by secondary amines and thus alkylated precursors containing only tertiary amines could lead to exogenous-S2 macrocycles. Cyclisation of alkylated tetraamine precursors with dimethyloxalate or dithiooxamide led to both N4 and N8 macrocycles via 1 + 1 and 2 + 2 cyclisation reactions with exogenous-O2 or S2 respectively. Alkylation of preformed exogenous-O2 macrocycles was explored and led to alkyl substitution at the secondary amine nitrogens in the ring, however synthesis of these species was overall lower yielding than cyclisation using alkylated tetraamine precursors. Thionation of an exo-O2 macrocycle using an analogue of Lawesson's Reagent led to formation of the analogous exogenous-S2 and exogenous-O,S macrocycles. Related S2N2 macrocycles with exogenous-O2 were prepared by a cyclisation route but could not be isolated free of larger ring analogues.

Dramatic increases in the luminescent lifetime of the Er3+ ion in a molecular complex have been observed by chelating the rare-earth ion with a perfluorinated imidodiphosphinate sensitizing ligand, F-tpip. For solution, powder, and evaporated thin films of Er(F-tpip)3, the average lifetimes of the 1530 nm emission band range between 150 and 220 mus, corresponding to a maximum 50-fold increase relative to the nonfluorinated analogue, Er(tpip)3. These are the longest reported lifetimes for the Er3+ ion in a simple organic chelate. These remarkable improvements in luminescence efficiency and excited-state lifetime represent a significant step forward in the design and fabrication of near-infrared (NIR)-emitting molecular devices for communications, sensing, and analytical detection.

The "one-pot" synthesis and characterization of a large 28-mer macrocycle (H(4)L(2)) with oxamido units capable of complexing guest ions through oxygen or nitrogen donor atoms is reported. Single-crystal structure determination of H(8)L(2)(NO(3))(4) and (Cu(2)[H(2)L(2)](H(2)O)(2))(NO(3))(2) demonstrated that the macrocycle contains two sites capable of complexing two nitrate anions or two copper(II) ions, involving a large structural reorganization in the conformation of the macrocyclic framework on coordination of the copper(II) ions when compared to the nitrate. Electrochemical and magnetic susceptibility measurements on the dinuclear Cu(II) complex and the related mononuclear and trinuclear Cu(II) complexes derived from the related 14-mer macrocycle were carried out and illustrate the role of the oxamido groups in mediating metal-metal interaction and delocalization.

Two new unsymmetrical 1'-substituted hydroxyferrocene ligands featuring either phosphine or phosphine oxide substituents have been synthesised and the phosphine oxide derivative has been structurally characterised. A nickel complex of the hydroxyl/phosphine ligand has been formed, along with preliminary evaluation of the complex for catalysis of ethylene polymerisation.

Interest in the chemistry of ferrocene remains intense, largely due to applications within catalysis. New synthetic routes to unsymmetrical ferrocene ligands have provided another facet to this area, as substituents can be designed to be electronically- and/or sterically-distinct in order to affect the environment around the catalytically-active metal centre. This critical review provides a concise summary of the synthetic routes that have been applied to the synthesis of unsymmetrical ferrocene ligands, along with a systematic survey of the applications of these ligands in homogeneous catalysis. The aim is to help the reader select a suitable ferrocenediyl ligand for a particular synthetic application, and in the synthesis of ligands that require particular structural and/or electronic features. (186 references.)

Metal alkynyl complexes hold a fascination for synthetic chemists, structural chemists, and materials scientists alike. Harnessing the unique overlap of metal and carbon orbitals is a challenge that can be overcome in many ways and hence, there are many synthetic routes toward M-C=C-bond-forming reactions that utilize a wide variety of transition-metal and alkynyl reagents. Some methods can be widely applied, while others are specific to a particular metal or compound. The linear geometry of the alkynyl unit and its pi-unsaturated character have led to metal alkynyls becoming attractive building blocks for molecular wires and polymeric organometallic materials, which can possess interesting properties, such as optical nonlinearity, luminescence, liquid crystallinity, and electrical conductivity. A unique, multifaceted approach, often combining talents from all three of the above chemical disciplines, has served as a driving force behind the intense research into the development of metal alkynyl sigma complexes, the progress of which, particularly in the last ten years, is summarized in this review.

One of the central themes in cuprate superconductivity is the evolution of the electronic properties with the charge carrier concentration, p, expressed as the number of holes per Cu ion in the CuO2 planes. In YBa2Cu3O7−δ (YBCO), p is well known to vary with oxygen content (δ) and with substitution of Ca2+ for Y3+. In this Letter, we show that p also varies with the fraction of Cu–O “chain layer” stacking faults. The resulting parabolic variation in the superconducting transition temperature (Tc) is also well known; however, the effect on the critical current density (Jc) is less well explored. We show that the self-field Jc follows a common trend for all these hole doping methods, rising to a sharp peak on the slightly overdoped side of the Tc(p) parabola. In contrast, the in-field Jc anisotropy at high temperatures and low fields is determined solely by the stacking-fault fraction, not by hole doping, such that a sample free from stacking faults tends towards an isotropic Jc. These results serve to emph...

A Roebel cable is a good candidate for low-voltage windings in a high-temperature superconductor (HTS) transformer because of its high current-carrying capability and low AC loss. Transport AC loss measurements were carried out in 1.8 m long 15/5 (fifteen 5 mm wide strands) and 15/4 Roebel cables. The results were compared with those in many Roebel cables composed of 2 mm wide Roebel strands. Comparison of the AC losses hinted that the intrinsic difference in normalized transport AC losses is due to differences in the g/w (ratio of the horizontal gap between the Roebel strands over the Roebel strand width) values. The intrinsic difference was confirmed by measuring transport AC loss in a series of horizontally arranged parallel conductor pairs with various g values. A method to scale transport AC losses in Roebel cables with varying strand parameters was developed. The scaling method will be useful for a rough assessment of AC loss in one-layer solenoid winding coils, such as in a HTS transformer.

We have developed a cryogen-free critical-current (Ic) measuring system comprising a conduction-cooled 8 T HTS magnet and convection-cooled sample, both cooled by commercial cryocoolers. The sample can be rotated and transport currents of up to 800 A delivered with less than 0.5 K temperature rise during the Ic measurement. The system is automated with respect to variations in temperature (30–90 K), field (0–8 T), and field angle (0–360°). We have used this system to measure HTS wire samples, concentrating on metal-organic deposited YBCO on RABiTS substrates. Particular emphasis is given to the evolution of Ic anisotropy with temperature, and the dangers of extrapolating from 77 K to 30 K.

We provide an alternative explanation for the results of Matsui et al. [J. Appl. Phys. 114, 233911 (2013)] by considering the effects of disorder on flux pinning.

The importance of nonlinear optical phenomena has been known for some time; however, since the mid-1980s, there has been an explosion of interest in searching for and developing nonlinear optical materials that possess commercial device applications. To date, the systems have been utilized in information processing, optical switching, optical frequency conversion, and telecommunications and, with the advancing development of optotechnology, burgeoning demands for suitable materials are becoming apparent. Photons can carry information faster, more efficiently, and over longer distances (with less signal degradation and more efficiently) than electrons and, as a result, photonics will begin to take over from electronics in information and communication technologies. During this transition, the hybrid technology of optoelectronics—in which electrons interface with photons—will become increasingly important.

The smallest band gap observed so far (1.77 eV) for an organometallic polymer is exhibited by the blue, rigid-rod polymer 2, which is prepared by the reaction of trans-[PtCl

A series of compounds featuring metallic fragments around the periphery of a 1,3,5-triethynylbenzene core have been synthesized. By using several synthetic methods, metallic units such as cis-[RuCl2(dppm)2], cis-[OsCl2(dppm)2] and [RuCl(η-C5H5)(PPh3)2] have been treated with the aromatic acetylide ligand to introduce one, two or three metallic centres. Electrochemical studies showed that the bimetallic trans-[HCCC6H3{CCRuCl(dppm)2}2] and trans-[HCCC6H3{CCOsCl(dppm)2}2] species undergo two separated one-electron oxidations thus indicating that the central triethynylbenzene unit allows communication between the two peripheral metal subunits. The compounds [(HCC)2C6H3CCRu(η-C5H5)(PPh3)2], [HCCC6H3{CCRu(η-C5H5)(PPh3)2}2] and [C6H3{CCRu(η-C5H5)(PPh3)2}3] each show separated one-electron oxidations (though these are less reversible than for the previous compounds mentioned) again demonstrating the electronic communication amongst the peripheral metal centres through the organic linkage. Chemical oxidation has been carried out on the [Ru(η-C5H5)(PPh3)2]-containing species affording mixed-valence species consistent with those produced by successive electrochemical oxidation.

Analyzing critical currents from an information theoretic or statistical point of view allows one to identify distinct populations of microstates contributing to the critical current under particular conditions of temperature and applied field. We show how this knowledge can be correlated with the known microstructure of a sample to identify how different physical populations of pinning centers are contributing to these statistical populations of microstates. We will then show that by tracking the variation of critical current with temperature, field, and field angle we can construct a picture of the relative contributions of different defect populations under different conditions. We particularly focus our analysis on YBCO thin film coated conductors with potential commercial application.

The variation in transition temperature Tc with oxygen deficiency or calcium substitution in Y1-xCaxBa2Cu3O7-δ (YBCO) is a well-known manifestation of the generic hole-doping phase diagram governing the superconducting cuprates. Less well understood is the role that microstructural defects can play in determining hole doping. We have investigated the formation of Y124-type stacking faults in metal-organic deposited (MOD) YBCO coated conductors and shown that these defects also act to reduce the hole concentration in YBCO. With low stacking-fault density, Tc can be as low as 89 K when fully oxygen loaded and can increase to a maximum of 94 K when partially unloaded. The presence of stacking faults limits the degree to which fully oxygen loaded YBCO can be overdoped. The critical current density Jc is optimized by full oxygen loading but with a moderate density of stacking faults. We have demonstrated substitution of calcium for yttrium in YBCO by modification of the MOD precursor resulting in an increase in hole concentration and consequent decrease in Tc. Jc is initially depressed by calcium substitution but partially recovers upon incorporation of a moderate density of stacking faults.

We measure transport ac losses in an 8/2 (eight 2-mm-wide strands) YBCO Roebel cable at 77 and 65 K without dc parallel magnetic field, and at 77 K under dc parallel magnetic fields of 0-1.5 T. The transport ac loss in the Roebel cable scales with temperature and dc parallel magnetic field as the square of the cable's critical current.

We measured the total AC loss in a 6/2 (i.e. 6 strands of 2 mm width) Roebel cable by incorporating a transport measurement method for Roebel cable into a total AC loss measurement system. The amplitude and frequency of the external magnetic field and applied transport current, and the field angle (the angle between the field and the normal vector to the cable surface) were varied. The results for 60 scale with the perpendicular magnetic field component, and increase with increasing transport current. In the high magnetic field region, the total AC loss values for a current amplitude I Ic agree with the Brandt model for a 2 mm-wide Roebel strand, not for a thin strip with the Roebel cable width. This shows the advantage of a Roebel cable over equivalent stacks composed of wider conductors. The total AC losses in a parallel magnetic field become more independent of the field amplitude with increasing current amplitude due to the increased dominance of the transport AC losses in the total AC losses. No frequency dependence was observed in the total AC loss data. A maximum entropy model was successfully constructed for the total AC loss results in a perpendicular magnetic field. (Some figures may appear in colour only in the online journal)

We measure transport ac losses in planar one-layer four-turn parallel coated conductor arrays (1 × 4) and in two-layer (2L) four-turn parallel coated conductor arrays (2 × 4) with a frequency up to 1 kHz. The horizontal separation between the conductors, i.e., gh, and the vertical separation between the neighboring superconducting layers, i.e., gv, were varied to investigate the transport ac loss dependence on gh and gv. In 2L arrays, the tapes in the top layer sit either aligned with the tapes in the bottom layer or aligned with the gaps between the tapes in the bottom layer. We show that the losses differently scale in arrays with low turn numbers to the scaling expected with an infinite array of tapes.

AC loss measurements in five single pancake coils wound with 4 mm wide commercial high temperature superconductor wires were carried out to investigate the dependence of coil AC loss on separation between the superconductor layers in the neighbouring coil turns (g) and coil turn number (N) for a given number of ampere-turns NI. The highest frequency was set at approximately 1 kHz. The AC losses measured at different frequencies agreed well with each other. AC loss in the coils with the same N increases with decreasing g. When g is increased to 1.5 times the tape width (6 mm), the loss level is similar to that in an isolated wire. Transport AC loss per unit length in the pancake coils increases with increasing turn number. However, when g is increased to 1.5 times the tape width, the loss level in the coils with different turn number is almost the same. This indicates that, at the same NI, a coil with greater N is advantageous, even considering the conductor length difference. Therefore to achieve a given level of NI for a coil and minimize AC loss, we should favour coils with more turns. Coil AC loss can be measured using voltage taps attached to copper blocks outside a coil with reasonable accuracy. This is important for measuring AC loss in a coil with a complicated structure where voltage taps are not able to be attached inside the coil. AC loss in a nine-turn pancake coil wound with a 5 m long 9/2 Roebel cable (i.e. with 9 mm × 2 mm width strands) was measured using voltage loops arranged in each Roebel strand in the central turn of the coil. The AC loss in the coil was compared with two straight 9/2 Roebel cables with and without spacing between the strands. The combination of inter-strand spacing and turn spacing is an effective way to reduce AC loss in a single pancake coil wound with a Roebel cable.

Transport AC loss in a short length of 9/2 YBCO Roebel cable, (i.e. with 9 × 2 mm width strands), with 0.25 mm spacers between the strands is measured. The frequency varies from 59 to 354 Hz. The result is compared with the loss for a cable without spacers between the strands. Transport AC loss is decreased by the presence of the spacers. The AC loss reduction due to the extra spacing is more significant when the amplitude of the cable current is small compared to the cable Ic. The losses in the cable with spacers normalized by the square of the cable currents plotted against It/Ic approximately agree with those in a cable without spacers. Electromagnetic modelling was carried out for 9/2 and 8/2 cables, modelled as parallel stacks, to assist in understanding the above experimental results. The 8/2 configuration allows the greater use of symmetry to speed computations. Reasonable agreement between the numerical results and the measured results was obtained. This supports suggestions made in previous publications that the transport AC loss in a Roebel cable is roughly equivalent to the loss in two parallel stacks carrying the same current in each tape. The electromagnetic analysis in the 8/2 stacks shows the flux lines are more perpendicular to the strand face when the vertical space between strands is smaller, and this leads to a larger induced electrical field and larger AC loss. At small current amplitudes, the modelling shows the spacing has a strong effect on the AC loss in the surfaced part of the strands.

(R-DAB)FeI(2) complexes containing bidentate diimide ligands (R-DAB = RN=CH-CH=NR; R = (i)Pr, c-C(6)H(11)) have been investigated for their ability to react with carbon monoxide to form iron(II) dicarbonyl complexes, (R-DAB)FeI(2)(CO)(2). Solution IR spectroscopy revealed two νCO stretches between 2000 and 2040 cm(-1) corresponding to a cis-arrangement of the carbonyl ligands around the iron. Photochemical decarbonylation was achieved by UV irradiation (365 nm), which occurred within 5 min as evidenced by solution IR spectroscopy. (c-C(6)H(11)-DAB)FeI(2) has been characterised by X-ray crystallography. Reactions using (11)C-labelled carbon monoxide were investigated and revealed that both (R-DAB)FeI(2) species were not effective as trapping complexes due to the low concentrations of [(11)C]CO used in these experiments. A Fe(TPP)(THF)(x) (TPP = tetraphenylporphyrin) complex was investigated with unlabelled CO and the monocarbonyl adduct Fe(TPP)(THF)CO was formed in situ as identified by IR spectroscopy (νCO = 1966 cm(-1)) yet was stable to CO loss upon UV irradiation. Carbonylation reactions of in situ-generated Fe(TPP)(THF)(x) using [(11)C]CO revealed that 97% of the [(11)C]CO stream could be trapped in one pass of the gas at room temperature and at atmospheric pressure.

We have investigated the frequency dependent contributions to the magnetic ac loss in a 10 strand Roebel cable with 2 mm wide non-insulated strands and a transposition length of 90 mm. This cable is made from 40 mm wide YBCO coated conductor tape manufactured by AMSC and stabilized by electroplating 25 µm thick copper on either side prior to the mechanical punching of the cable strands. The measurements were carried out in both perpendicular and parallel field orientation, at frequencies in the range of 30–200 Hz. While the loss in the perpendicular orientation is predominantly hysteretic in nature, we observe some frequency dependence of the loss when the cable approaches full flux penetration at high field amplitudes. The magnitude is consistent with eddy current losses in the copper stabilization layer. This supports the fact that the inter-strand coupling loss is not significant in this frequency range. In the parallel field orientation, the hysteresis loss in the Ni–W alloy substrate dominates, but we see an unusually strong frequency dependent contribution to the loss which we attribute to intra-strand current loops.

We discuss production of lengths of up to 27 m of YBCO Roebel cable. Results for 5/2 (5 strands, 2 mm width), 9/2 and 15/5 cables produced from standard 12 mm commercial YBCO wire are presented. We discuss specifications for the input wire and suggest using a statistical correlation function, using data from magnetic field scanning, that is shown to produce high performance strands. We discuss advances in manufacturing techniques including cable insulation processes. Transport and magnetic AC loss data are presented for 5/2 cable which demonstrates the effectiveness of decreased strand width and the transposition of strands. Both losses are predominantly hysteretic in nature. Finally, the cable DC transport is presented and we discuss the possibilities for high current cables in high field applications.

Transport AC loss in a short length of 9/2 YBCO Roebel cable (nine 2 mm wide strands) is measured. The AC loss data are compared with those in a 5/2 YBCO Roebel cable (five 2 mm wide strands) as well as that in a single strand. All the strands composing the cables and the single strand are insulated and cut from the same stock material. The validity of the measurement method was reconfirmed by results at a range of frequencies. At a wide range of It/Ic, the normalized AC losses in the Roebel cable were around 6.2–6.7 times of those in the single strand. This is less than the nine times predicted for a tight bundle of nine conductors. The normalized transport AC losses in the 5/2 Roebel cable are much smaller than those in the 9/2 Roebel. This should be due to larger superposition of magnetic field in the 9/2 Roebel. The Ic of the 9/2 and 5/2 Roebel cables is determined by serial connection of the strands. This eliminates the effect where differing resistances in the current terminations cause uneven current sharing between strands when the strands are connected in parallel.

New unsymmetrical hydroxyferrocenes were synthesised from dibromoferrocene. The oxygen heteroatom was introduced via lithiation and quenching with bis-trimethylsilylperoxide followed by hydrolysis to unmask the hydroxyl functionality. The coordination chemistry of 1'-(diphenylphosphino)-1-hydroxyferrocene 2 was explored with palladium and rhodium precursors. A dinuclear palladium methyl complex with bridging ferrocenyloxo groups was obtained from the reaction between 2 and (cyclooctadiene)methylchloropalladium(II). With tetracarbonyldichlorodirhodium(I), two complexes were isolated. The major product was a bis ligand cis phosphine ligated complex with one ligand bound in a chelating mode and one with a pendant hydroxyl group. A minor product was crystallographically characterised as a dinuclear ferrocenyloxo-bridged rhodium carbonyl complex. The coordination chemistry of 2 and the corresponding phosphine oxide 3 was examined with group 4 metals and the resulting complexes examined as ethylene polymerisation catalysts. The ligands were found to bind in either a chelating fashion or with pendant phosphine donors. In all cases, low to moderately active ethylene polymerisation catalysts were found. The catalysts were very unstable and catalyst residues were observed in the isolated polymer indicating a short catalyst lifetime.

Transport AC loss in a 5/2 YBCO Roebel cable (five 2 mm wide strands) with a pitch length of 90 mm is measured over a range of frequencies from 59 to 354 Hz. Five rectangular voltage loops are arranged from pairs of voltage taps attached at one pitch length separation on each strand. There are significant differences in the apparent transport AC loss measured from the different voltage loops at low frequency due to phase shifts in the current in each strand with respect to the phase of the total cable current. The difference in transport AC losses measured from different voltage loops becomes small with increasing frequency, because current is more equally distributed in each strand due to the higher reactance at high frequency. At 354 Hz, results measured with different voltage loops agree well with each other. As theoretically expected, the transport AC losses at different frequencies calculated from the mean value of in-phase voltages measured from the five different voltage loops agree well with each other. At It/Ic = 0.85, the transport AC loss in the 5/2 Roebel cable normalized by the number of strands and square of critical current per strand is around 2.9 times that in a single strand compared to the prediction of five times for a close bundle composed of five conductors. This difference may be due to the transposition of the strands.

A new potentially hexadentate P(2)N(4) ligand has been prepared and its coordination chemistry to Pd(II) and Pt(II) investigated. The ligand bonds in a chelating fashion via the diphosphine backbone to PdCl(2) and PtCl(2) while the appended pyridyl groups remain non-bonding. Abstraction of the chloride ions from the platinum complex results in fluxional exchange of the pyridyl groups in solution at room temperature on the NMR timescale. X-ray crystallographic analysis of this platinum complex revealed a tetracoordinate complex with two bound and two free pyridyl arms.