Early Diagnosis of Pancreatic Cancer via Machine Learning Analysis of a National Electronic Medical Record Database.

PURPOSE: Pancreatic cancer (PaC) is often diagnosed at advanced stages, resulting in one of the lowest survival rates among patients with cancer. The purpose of this study was to investigate whether machine learning (ML) models can predict with high sensitivity and specificity an increased risk for PaC ahead of clinical diagnosis. METHODS: Optum deidentified electronic health record (EHR) data set was used to extract 1-year data for each patient and to sample for PaC diagnosis, the number of interactions with the health care system, and unique demographic and clinical features. Data for patients with PaC diagnosis were collected between 1 and 2 years before the diagnosis. Standard binary classification ML models were used on training and testing data sets. Data analyses were performed using the scikit-learn package version 1.0.1. RESULTS: The data set consisted of 18,987 patient EHRs collected between December 31, 2007, and December 31, 2017. EHRs with 10 unique features and at least three health care interactions were used for model training (N = 15,189; n = 8,438 [56%] with PaC) and testing (N = 3,798; n = 2,127 [56%] with PaC). The ensemble model achieved an AUC of 0.89, a sensitivity of 85.61%, and a specificity of 76.18% on the testing data set and produced superior results compared with other binary classifiers. Increasing unique health care interactions to nine failed to improve the AUC score. When the testing data set was enlarged to 5,696 patients, the ensemble model achieved an AUC of 0.92 and a specificity of 93.21%, but the sensitivity was compromised. CONCLUSION: The ensemble model exceeded the state-of-the-art level of performance for prediction of PaC ahead of clinical diagnosis with a minimal clinically guided input, providing a potential strategy for selection of high-risk patients for further screening.

Clinical Outcomes With Dabrafenib Plus Trametinib in a Clinical Trial Versus Real-World Standard of Care in Patients With BRAF-Mutated Advanced NSCLC.

Introduction: BRAF mutations are rare in patients with NSCLC, and treatment options are limited. Dabrafenib plus trametinib (dab-tram) was approved for BRAFV600-mutated advanced NSCLC (aNSCLC), based on results from a phase 2 study (NCT01336634). This retrospective analysis compared the effectiveness of dab-tram, based on previously reported clinical trial data, versus real-world standard of care in patients with BRAF-mutated aNSCLC. Methods: Real-world cohorts were derived from a deidentified real-world database (2011-2020) and included patients with BRAF-mutated aNSCLC receiving first-line platinum-based chemotherapy (PBC), first-line immune checkpoint inhibitors (ICIs) plus PBC, or second-line ICIs. Weighting by odds was used to estimate the average treatment effect of the treated. Results: For first-line dab-tram versus PBC, the hazard ratio (HR; 95% confidence interval) for death in unweighted and weighted analyses was 0.65 (0.39-1.1) and 0.51 (0.29-0.92; p = 0.03), respectively; unweighted and weighted median overall survival was 17.3 (12.3-40.2) versus 14.5 (9.2-19.6) months and 17.3 (14.6-not reached) versus 9.7 (6.4-19.6) months, respectively. Hazard ratio of death in unweighted and weighted analyses was 0.56 (0.29-1.1) and 0.57 (0.28-1.17), respectively, with first-line dab-tram versus PBC plus ICI, and 0.65 (0.39-1.07) and not reported (Cox proportional-hazards assumption violated), respectively, with second-line dab-tram versus ICI. Conclusions: In this indirect comparison in patients with BRAF-mutated aNSCLC, the risk of death was lower and median overall survival was longer with first-line dab-tram versus PBC. In analyses of dab-tram versus first-line PBC plus ICI or second-line ICI, sample sizes were small and findings were inconclusive with overlapping confidence intervals. Despite some limitations, the study provides useful data for this rare patient population.

COVID-19 pandemic: The impact on vulnerable children and young people in Australia.

The COVID-19 pandemic and associated system disruptions are impacting all children and young people (CYP) in Australia. For vulnerable groups of CYP, who already experience poorer health and well-being, these impacts are amplified. Challenges include reduced access to usual services, reduced community supports, financial instability, unemployment and other life circumstances that threaten to widen pre-existing inequities. This article aims to present the reasons for vulnerability of CYP during the pandemic, and to focus on actions by health professionals that mitigate additional challenges to their health and well-being. Using a rapid review of the literature and team-based discussions, eight vulnerable groups were identified: CYP with disabilities, mental health conditions and chronic diseases; CYP facing financial hardship; within the child protection system; Aboriginal; migrant and refugee; in residential care; rural; and isolated CYP. Recommendations for action are required at the level of governments, health professionals and researchers and include enhancing access to health and social supports, prioritising vulnerable CYP in resuming health activity and elevating the voice of CYP in designing the response. The pandemic can be conceptualised as an opportunity to create a more equitable society as we document the inequities that have been exacerbated. Vulnerable groups of CYP must be recognised and heard, and targeted actions must focus on improving their health outcomes during the pandemic and beyond.

FUNCTIONALIZED ELECTROSPUN POLYMER NANOFIBERS FOR TREATMENT OF WATER CONTAMINATED WITH URANIUM.

Uranium (U) contamination of drinking water often affects communities with limited resources, presenting unique technology challenges for U6+ treatment. Here, we develop a suite of chemically functionalized polymer (polyacrylonitrile; PAN) nanofibers for low pressure reactive filtration applications for U6+ removal. Binding agents with either nitrogen-containing or phosphorous-based (e.g., phosphonic acid) functionalities were blended (at 1-3 wt.%) into PAN sol gels used for electrospinning, yielding functionalized nanofiber mats. For comparison, we also functionalized PAN nanofibers with amidoxime (AO) moieties, a group well-recognized for its specificity in U6+ uptake. For optimal N-based (Aliquat® 336 or Aq) and P-containing [hexadecylphosphonic acid (HPDA) and bis(2-ethylhexyl)phosphate (HDEHP)] binding agents, we then explored their use for U6+ removal across a range of pH values (pH 2-7), U6+ concentrations (up to 10 µM), and in flow through systems simulating point of use (POU) water treatment. As expected from the use of quaternary ammonium groups in ion exchange, Aq-containing materials appear to sequester U6+ by electrostatic interactions; while uptake by these materials is limited, it is greatest at circumneutral pH where positively charged N groups bind negatively charged U6+ complexes. In contrast, HDPA and HDEHP perform best at acidic pH representative of mine drainage, where surface complexation of the uranyl cation likely drives uptake. Complexation by AO exhibited the best performance across all pH values, although U6+ uptake via surface precipitation may also occur near circumneutral pH value and at high (10 µM) dissolved U6+ concentrations. In simulated POU treatment studies using a dead-end filtration system, we observed U removal in AO-PAN systems that is insensitive to common co-solutes in groundwater (e.g., hardness and alkalinity). While more research is needed, our results suggest that only 80 g (about 0.2 lbs.) of AO-PAN filter material would be needed to treat an individual's water supply (contaminated at ten-times the U.S. EPA Maximum Contaminant Level for U) for one year.

Matrix-Independent Surface-Enhanced Raman Scattering Detection of Uranyl Using Electrospun Amidoximated Polyacrylonitrile Mats and Gold Nanostars.

Reproducible detection of uranyl, an important biological and environmental contaminant, from complex matrixes by surface-enhanced Raman scattering (SERS) is successfully achieved using amidoximated-polyacrylonitrile (AO-PAN) mats and carboxylated gold (Au) nanostars. SERS detection of small molecules from a sample mixture is traditionally limited by nonspecific adsorption of nontarget species to the metal nanostructures and subsequent variations in both the vibrational frequencies and intensities. Herein, this challenge is overcome using AO-PAN mats to extract uranyl from matrixes ranging in complexity including HEPES buffer, Ca(NO3)2 and NaHCO3 solutions, and synthetic urine. Subsequently, Au nanostars functionalized with carboxyl-terminated alkanethiols are used to enhance the uranyl signal. The detected SERS signals scale with uranyl uptake as confirmed using liquid scintillation counting. SERS vibrational frequencies of uranyl on both hydrated and lyophilized polymer mats are largely independent of sample matrix, indicating less complexity in the uranyl species bound to the surface of the mats vs in solution. These results suggest that matrix effects, which commonly limit the use of SERS for complex sample analysis, are minimized for uranyl detection. The presented synergistic approach for isolating uranyl from complex sample matrixes and enhancing the signal using SERS is promising for real-world sample detection and eliminates the need of radioactive tracers and extensive sample pretreatment steps.

Functionalized polymer-iron oxide hybrid nanofibers: Electrospun filtration devices for metal oxyanion removal.

Via a single-pot electrospinning synthesis, we developed a functionalized polymer-metal oxide nanofiber filter for point of use (POU) water treatment of metal oxyanions (e.g., arsenate and chromate). Polyacrylonitrile (PAN) functionalization was accomplished by inclusion of surface-active, quaternary ammonium salts (QAS) [cetyltrimethylammonium bromide (CTAB) or tetrabutylammonium bromide (TBAB)] that provide strong base ion exchange sites. Embedded iron oxide [ferrihydrite (Fh)] nanoparticles were used for their established role as metal sorbents. We examined the influence of QAS and Fh loading on composite properties, including nanofiber morphology, surface area, surface chemical composition, and the accessibility of embedded nanoparticles to solution. Composite performance was then evaluated using kinetic, isotherm, and pH-edge sorption experiments with arsenate and chromate, and benchmarked to unmodified PAN nanofibers and freely dispersed Fh nanoparticles. We also assessed the long-term stability of QAS in the composite matrix. For composites containing QAS or Fh nanoparticles, increasing QAS/Fh nanoparticle loading generally yielded increasing metal oxyanion uptake. The optimized composite (PAN 7 wt%, Fh 3 wt%, TBAB 1 wt%) exhibited two distinct sites for simultaneous, non-competitive metal binding (i.e., iron oxide sites for arsenate removal via sorption and well-retained QAS sites for chromate removal via ion exchange). Moreover, surface-segregating QAS enriched Fh abundance at the nanofiber surface, allowing immobilized nanoparticles to exhibit reactivity comparable to that of unsupported (i.e., suspended or freely dispersed) nanoparticles. To simulate POU application, the optimized composite was tested in a dead-end, flow-through filtration system for arsenate and chromate removal at environmentally relevant concentrations (e.g., µg/L) in both idealized and simulated tap water matrices. Performance trends indicate that dual mechanisms for uptake are maintained in kinetically limited regimes. Although chromate removal via ion exchange is more susceptible to interfering counter-ions, arsenate removal in simulated tap water indicates that ∼130 g of the composite could produce an individual's annual supply of drinking water (assuming an influent contaminated with 100 µg As/L, which is 10 times the current MCL).

Impact of Water-Dilution on the Solvation Properties of the Ionic Liquid 1-Methyltriethoxy-3-ethylimidazolium Acetate for Model Biomass Molecules.

Many studies have suggested that the processing of lignocellulosic biomass could provide a renewable feedstock to supplant much of the current demand on petroleum sources. Currently, alkyl imidazolium-based ionic liquids (ILs) have shown considerable promise in the pretreatment, solvation, and hydrolysis of lignocellulosic materials although their high cost and unfavorable viscosity has limited their widespread use. Functionalizing these ILs with an oligo(ethoxy) tail has previously been shown through experiment to decrease the IL's viscosity resulting in enhanced mass transport characteristics, in addition to other favorable traits including decreased inhibition of some enzymes. Additionally, the use of cosolvents to mitigate the cost and unfavorable traits of ILs is an area of growing interest with particular attention on water as the presence of water in biomass processes is inevitable. Through the use of biased and unbiased molecular dynamics (MD) simulations, this study provides a molecular-level perspective of the various solvent-solvent and solvent-solute interactions in binary mixtures of water and 1-methyltriethoxy-3-ethylimidazolium acetate ([Me-(OEt)3-Et-IM+] [OAc-]) in the presence of model cellulose compounds (i.e., glucose and cellobiose). It is observed that at ∼75% w/w IL and water a transition in the nanostructure of the solvent occurs between water-like and IL-like solvation characteristics. It is shown that H-bonding interactions between the anion and water are a major driving force that significantly impacts the solvent properties of the IL as well as conformational preferences of the cellulosic model compound. In addition, it is found that the oligo(ethoxy) cation tail is responsible for the reduction in the propensity for tail aggregation as compared to alkyl tails of similar length, which, combined with increased ionic shielding, results in increased diffusion and enhanced water-like solvation characteristics.

In silico insights into the solvation characteristics of the ionic liquid 1-methyltriethoxy-3-ethylimidazolium acetate for cellulosic biomass.

Lignocellulosic biomass is a domestically grown, sustainable, and potentially carbon-neutral feedstock for the production of liquid fuels and other value added chemicals. This underutilized renewable feedstock has the potential to alleviate some of the current socio-economic dependence on foreign petroleum supplies while stimulating rural economies. Unfortunately, the potential of biomass has largely been underdeveloped due to the recalcitrant nature of lignocellulosic materials. Task-specific ionic liquids (ILs) have shown considerable promise as an alternative non-aqueous solvent for solvation and deconstruction of lignocellulose in the presence of metal chloride catalyst or enzymes. Recently it has been hypothesized that adding oxygen atoms to the tail of an imidazolium cation would alleviate some of the negative characteristics of the ILs by increasing mass transport properties, and decreasing IL deactivation of enzymes, while at the same time retaining favorable solvation characteristics for lignocellulose. Reported here are fully atomistic molecular dynamic simulations of 1-methyltriethoxy-3-ethylimidazolium acetate ([Me-(OEt)3-Et-IM(+)] [OAc(-)]) that elucidate promising molecular-level details pertaining to the solvation characteristics of model compounds of cellulose, and IL-induced side-chain and ring puckering conformations. It is found that the anion interactions with the saccharide induce alternate ring puckering conformations from those seen in aqueous environments (i.e.(1)C4), while the cation interactions are found to influence the conformation of the ω dihedral. These perturbations in saccharide structures are discussed in the context of their contribution to the disruption of hydrogen bonding in cellulosic architecture and their role in solvation.

Partitioning of naturally-occurring radionuclides (NORM) in Marcellus Shale produced fluids influenced by chemical matrix.

Naturally-occurring radioactive materials (NORM) associated with unconventional drilling produced fluids from the Marcellus Shale have raised environmental concerns. However, few investigations into the fundamental chemistry of NORM in Marcellus Shale produced fluids have been performed. Thus, we performed radiochemical experiments with Marcellus Shale produced fluids to understand the partitioning behavior of major radioelements of environmental health concern (uranium (U), thorium (Th), radium (Ra), lead (Pb), and polonium (Po)). We applied a novel radiotracer, (203)Pb, to understand the behavior of trace-levels of (210)Pb in these fluids. Ultrafiltration experiments indicated U, Th, and Po are particle reactive in Marcellus Shale produced fluids and Ra and Pb are soluble. Sediment partitioning experiments revealed that >99% of Ra does not adsorb to sediments in the presence of Marcellus Shale produced fluids. Further experiments indicated that although Ra adsorption is related to ionic strength, the concentrations of heavier alkaline earth metals (Ba, Sr) are stronger predictors of Ra solubility.

High Trans Kinetic Selectivity in Ruthenium-Based Olefin Cross-Metathesis through Stereoretention.

The first kinetically controlled, highly trans-selective (>98%) olefin cross-metathesis reaction is demonstrated using Ru-based catalysts. Reactions with either trans or cis olefins afford products with highly trans or cis stereochemistry, respectively. This E-selective olefin cross-metathesis is shown to occur between two trans olefins and between a trans olefin and a terminal olefin. Additionally, new stereoretentive catalysts have been synthesized for improved reactivity.

Structural characterization of environmentally relevant ternary uranyl citrate complexes present in aqueous solutions and solid state materials.

Organic acids are important metal chelators in environmental systems and tend to form soluble complexes in aqueous solutions, ultimately influencing the transport and bioavailability of contaminants in surface and subsurface waters. This is particularly true for the formation of uranyl citrate complexes, which have been utilized in advanced photo- and bioremediation strategies for soils contaminated with nuclear materials. Given the complexity of environmental systems, the formation of ternary or heterometallic uranyl species in aqueous solutions are also expected, particularly with Al(iii) and Fe(iii) cations. These ternary forms are reported to be more stable in aqueous solutions, potentially enhancing contaminant mobility and uptake by organisms, but the exact coordination geometries of these soluble molecular complexes have not been elucidated. To provide insight into the nature of these species, we have developed a series of geochemical model compounds ([(UO(2))(2)Al(2)(C(6)H(4)O(7))(4)](6-) (U(2)Al(2)), [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)](6-) (U(2)Fe(2)-1) and [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)(H(2)O)(2)](6-) (U(2)Fe(2)-2) and [(UO(2))(2)Fe(4)(OH)(4)(C(6)H(4)O(7))(4)](8-) (U(2)Fe(4))) that were characterized by single-crystal X-ray diffraction and vibrational spectroscopy. Mass spectroscopy was then employed to compare the model compounds to species present in aqueous solutions to provide an enhanced understanding of the ternary uranyl citrate complexes that could be relevant in natural systems.

A systematic review of economic evaluations in second and later lines of therapy for the treatment of non-small cell lung cancer.

INTRODUCTION: Non-small cell lung cancer (NSCLC) is associated with high morbidity and mortality. Surgery is generally accepted as the first-line treatment in patients with advanced/metastatic NSCLC, followed by radiotherapy and chemotherapy as second-line treatments. Docetaxel or erlotinib are generally recommended as the first-line chemotherapy option. The objective of this review was to identify previously published economic evaluations in NSCLC for second- and later-line treatments in order to (i) determine common modelling approaches and (ii) establish the relative cost effectiveness of these treatments. An overview of model critique was also produced to identify common criticisms from health technology assessment (HTA) bodies on the models submitted. METHODS: MEDLINE, Embase, EconLit, MEDLINE in Process(®) and NHS Economic Evaluation Database (NHSEED) were searched (database start-October 2011), along with proceedings from eight major conferences (2007-2011). National Institute for Health and Clinical Excellence (NICE), Scottish Medicines Consortium (SMC), Pharmaceutical Benefits Advisory Committee (PBAC) and Canadian Agency for Drugs and Technologies in Health (CADTH) websites and the International Network of Agencies for Health Technology Assessment (INAHTA) database were also searched for appraisals in second- or later-line NSCLC. All published studies and HTA appraisals that reported economic evaluations of interventions used in current clinical practice as second- or later-line treatment in patients with advanced/metastatic NSCLC were included. Only studies in English were considered for inclusion. Studies which met the eligibility criteria after the screening of full-text articles were extracted by a reviewer and checked by a second party. Where multiple publications were identified describing a single study, the extracted data were compiled into one entry. RESULTS: A total of 29 studies were included which clearly evaluated second-line or later-line regimens. Most studies were either cost-effectiveness or cost-utility evaluations. Three-state transition Markov models were frequently used in cost-effectiveness and cost-utility evaluations. The model inputs were well reported and commonly consisted of data from pivotal trials. Sensitivity analyses were conducted in the majority of studies and covered variables such as cost, effectiveness, hospitalization and treatment duration. Therapies (docetaxel, pemetrexed and erlotinib) are for the most part cost-effective/cost-saving second-line therapies compared with best supportive care (BSC). Six erlotinib HTAs, across NICE, SMC, and PBAC, and four pemetrexed HTAs, one by NICE and three by SMC, were identified. The CADTH website did not provide sufficient detail on the appraisals and was excluded. Certain aspects of the models and model assumptions, e.g. efficacy inputs, were criticized or determined unjustifiable by the NICE, SMC and PBAC appraisal committees. Erlotinib and pemetrexed were considered to be cost effective versus docetaxel by NICE and SMC in the final submissions. PBAC considered erlotinib to be cost effective versus BSC following a price reduction in 2008. CONCLUSION: Three-state Markov models are often used to conduct economic analysis in NSCLC and are regarded as appropriate to HTA agencies. Docetaxel, erlotinib and BSC are suitable comparators that should be considered for use in the model in the UK and Australia. Further, manufacturers should carefully select underlying assumptions used in the model, for both costs and clinical inputs, where the latter is derived from direct head-to-head trial data.

Capillary electrophoretic separation-based approach to determine the labeling kinetics of oligodeoxynucleotides.

With the recent advances in electron microscopy (EM), computation, and nanofabrication, the original idea of reading DNA sequence directly from an image can now be tested. One approach is to develop heavy atom labels that can provide the contrast required for EM imaging. While evaluating tentative labels for the respective nucleobases in synthetic oligodeoxynucleotides (oligos), we developed a streamlined CE protocol to assess the label stability, reactivity, and selectivity. We report our protocol using osmium tetroxide 2,2'-bipyridine (Osbipy) as a thymidine (T) specific label. The observed rates show that the labeling process is kinetically independent of both the oligo length, and the base composition. The conditions, i.e. temperature, optimal Osbipy concentration, and molar ratio of reagents, to promote 100% conversion of the starting oligo to labeled product were established. Hence, the optimized conditions developed with the oligos could be leveraged to allow osmylation of effectively all Ts in ssDNA, while achieving minimal mislabeling. In addition, the approach and methods employed here may be adapted to the evaluation of other prospective contrasting agents/labels to facilitate next-generation DNA sequencing by EM.

Implicit and explicit olfactory memory in people with and without Down syndrome.

This study examined differences in implicit and explicit memory performance between people with Down syndrome (DS), their siblings, children matched on mental age, and university undergraduates, using olfactory stimuli. The DS and mental-age matched participants were also compared on two tasks of executive function. The data revealed implicit memory for olfactory stimuli. Further, people with DS performed similarly to each control group on the implicit memory task, but performed significantly poorer than all control groups on the explicit memory task. Impairment to executive functioning was identified as a possible cause of this deficit in explicit memory as people with DS performed more poorly than the mental-age matched controls on both tasks of executive function.

Cost-effectiveness of duloxetine: the Stress Urinary Incontinence Treatment (SUIT) study.

OBJECTIVE: To assess the cost-effectiveness of duloxetine compared with conservative therapy in women with stress urinary incontinence (SUI). METHODS: Cost and outcome data were taken from the Stress Urinary Incontinence Treatment (SUIT) study, a 12-month, prospective, observational, naturalistic, multicenter, multicountry study. Costs were assessed in UK pound and outcomes in quality adjusted life years using responses to the EuroQol (EQ-5D); numbers of urine leaks were also estimated. Potential selection bias was countered using multivariate regression and propensity score analysis. RESULTS: Duloxetine alone, duloxetine in combination with conservative treatment, and conservative treatment alone were associated with roughly two fewer leaks per week compared with no treatment. Duloxetine alone and with conservative treatment for SUI were associated with incremental quality-adjusted life-years (QALYs) of about 0.03 over a year compared with no treatment or with conservative treatment alone. Conservative treatment alone did not show an effect on QALYs. None of the interventions appeared to have marked impacts on costs over a year. Depending on the form of matching, duloxetine either dominated or had an incremental cost-effectiveness ratio (ICER) below pound900 per QALY gained compared with no treatment and with conservative treatment alone. Duloxetine plus conservative therapy had an ICER below pound5500 compared with no treatment or conservative treatment alone. Duloxetine compared with duloxetine plus conservative therapy showed similar outcomes but an additional cost for the combined intervention. CONCLUSIONS: Although the limitations of the use of SUIT's observational data for this purpose need to be acknowledged, the study suggests that initiating duloxetine therapy in SUI is a cost-effective treatment alternative.

Solution interaction of potassium and calcium bis(trimethylsilyl)amides; preparation of Ca[N(SiMe3)2]2 from dibenzylcalcium.

Ca[N(SiMe(3))(2)](2) (1) is isolated in nearly quantitative yield from the room temperature reaction of Ca(CH(2)Ph)(2)(THF) and HN(SiMe(3))(2) in toluene. A commonly used preparation of 1 involving the reaction of potassium bis(trimethylsilyl)amide, K[N(SiMe(3))(2)] (2), with CaI(2) can produce material that contains substantial amounts of potassium, probably in the form of a calciate such as K[Ca{N(SiMe(3))(2)}(3)]. The favorable formation of K[Ca{N(SiMe(3))(2)}(3)] from 1 and 2 was confirmed with density functional theory calculations. Deliberate doping of solutions of 1 with 2 initially causes only an upfield shift in the single (1)H NMR resonance observed for 1; not until K/Ca ratios exceed 1:1 is the presence of the added potassium obvious by the appearance of an additional peak in the spectrum.

Copper complexes of anionic nitrogen ligands in the amidation and imidation of aryl halides.

Copper(I) imidate and amidate complexes of chelating N,N-donor ligands, which are proposed intermediates in copper-catalyzed amidations of aryl halides, have been synthesized and characterized by X-ray diffraction and detailed solution-phase methods. In some cases, the complexes adopt neutral, three-coordinate trigonal planar structures in the solid state, but in other cases they adopt an ionic form consisting of an L 2Cu (+) cation and a CuX 2 (-) anion. A tetraalkylammonium salt of the CuX 2 (-) anion in which X = phthalimidate was also isolated. Conductivity measurements and (1)H NMR spectra of mixtures of two complexes all indicate that the complexes exist predominantly in the ionic form in DMSO and DMF solutions. One complex was sufficiently soluble for conductance measurements in less polar solvents and was shown to adopt some degree of the ionic form in THF and predominantly the neutral form in benzene. The complexes containing dative nitrogen ligands reacted with iodoarenes and bromoarenes to form products from C-N coupling, but the ammonium salt of [Cu(phth) 2] (-) did not. Similar selectivities for stoichiometric and catalytic reactions with two different iodoarenes and faster rates for the stoichiometric reactions implied that the isolated amidate and imidate complexes are intermediates in the reactions of amides and imides with haloarenes catalyzed by copper complexes containing dative N,N ligands. These amidates and imidates reacted much more slowly with chloroarenes, including chloroarenes that possess more favorable reduction potentials than some bromoarenes and that are known to undergo fast dissociation of chloride from the chloroarene radical anion. The reaction of o-(allyloxy)iodobenzene with [(phen) 2Cu][Cu(pyrr) 2] results in formation of the C-N coupled product in high yield and no detectable amount of the 3-methyl-2,3-dihydrobenzofuran or 3-methylene-2,3-dihydrobenzofuran products that would be expected from a reaction that generated free radicals. These data and computed reaction barriers argue against mechanisms in which the haloarene reacts with a two-coordinate anionic copper species and mechanisms that start with electron transfer to generate a free iodoarene radical anion. Instead, these data are more consistent with mechanisms involving cleavage of the carbon-halogen bond within the coordination sphere of the metal.

Relative rates for the amination of eta3-allyl and eta3-benzyl complexes of palladium.

Reactions of nucleophiles with metal-bound hydrocarbyl pi-ligands bound in an eta3-fashion are key steps in a variety of carbon-carbon and carbon-heteroatom bond-forming reactions. To reveal factors that control the rates of reaction of nucleophiles with this type of ligand, the rates of reactions of an aromatic and an aliphatic amine with a series of eta3-allyl, eta3-benzyl, and eta3-phenethyl palladium complexes ligated by the bisphosphine (R)-BINAP to form allylic and benzylic amines were measured. These data showed that the less common addition to an eta3-benzyl complex is faster than the more common addition to an eta3-allyl complex. The relative rates of reaction followed the trend naphthylmethyl > naphthylethyl > benzyl > 1,1-dimethylallyl > allyl. Computational studies suggest that there is a correlation between the amount of positive charge at the site of nucleophilic attack and the rate of C-N bond formation.