Iridium complexes of the conformationally rigid IBioxMe4Ligand : hydride complexes and dehydrogenation of cyclooctene

A method for accessing the formally 14 VE iridium(III) hydride fragment {Ir(IBioxMe4)2(H)2}+ (2), containing the conformationally rigid NHC ligand IBioxMe4, is reported. Hydrogenation of trans-[Ir(IBioxMe4)2(COE)Cl] (1) in the presence of excess Na[BArF4] leads to the formation of dimeric [{Ir(IBioxMe4)2(H)2}2Cl][BArF4] (3), which is structurally fluxional in solution and acts as a reservoir of monomeric 2 in the presence of excess halogen ion abstractor. Stable dihydride complexes trans-[Ir(IBioxMe4)2(2,2′-bipyridine)(H)2][BArF4] (4) and [Ir(IBioxMe4)3(H)2][BArF4] (5) were subsequently isolated through in situ trapping of 2 using 2,2′-bipyridine and IBioxMe4, respectively, and fully characterized. Using mixtures of 3 and Na[BArF4] as a latent source of 2, the reactive monomeric fragment’s reactivity was explored with excess ethylene and cyclooctene, and trans-[Ir(IBioxMe4)2(C2H4)2][BArF4] (6) and cis-[Ir(IBioxMe4)2(COD)][BArF4] (7) were isolated, respectively, through sacrificial hydrogenation of the alkenes. Complex 6 is notable for the adoption of a very unusual orthogonal arrangement of the trans-ethylene ligands in the solid state, which has been analyzed computationally using energy and charge decomposition (EDA-NOCV). The formation of 7 via transfer dehydrogenation of COE highlights the ability to partner IBioxMe4 with reactive metal centers capable of C–H bond activation, without intramolecular activation. Reaction of 7 with CO slowly formed trans-[Ir(IBioxMe4)2(CO)2][BArF4] (8), but the equivalent reaction with bis-ethylene 6 was an order of magnitude faster, quantifying the strong coordination of COD in 7

Primary and secondary care collaboration in clinical research

This is the final version. Available from the Royal College of Physicians via the DOI in this recordMore patients are seen in primary care than in any other part of the health system in the UK. Our NHS datasets are the envy of the world and provide us with huge opportunities to support our patients and populations. In this paper, we demonstrate the breadth of primary care research, recruitment and delivery options. We show how research can affect many different aspects of patient care and demonstrate, through the delivery and publication of game-changing research, the ability of recruitment in primary care to answer questions that are relevant to secondary care activity. Indeed, these complex and innovative study designs and their collaborative delivery across the multitude of diseases (acute and chronic) show the strength of primary care. Collaboration across boundaries, specialties and healthcare settings will provide increased opportunities for clinical research development and, most importantly, deliver the highest quality research to support our patients.National Institute for Health and Care Research (NIHR

Rhodium(I) and Iridium(I) complexes of the conformationally rigid IBioxMe4Ligand : computational and experimental studies of unusually tilted NHC coordination geometries

Computational methods have been used to analyze distorted coordination geometries in a coherent range of known and new rhodium(I) and iridium(I) complexes containing bioxazoline-based NHC ligands (IBiox). Such distortions are readily placed in context of the literature through measurement of the Cnt(NHC)–CNCN–M angle (ΘNHC; Cnt = ring centroid). On the basis of restricted potential energy calculations using cis-[M(IBioxMe4)(CO)2Cl] (M1; M = Rh, Ir), in-plane (yawing) tilting of the NHC was found to incur significantly steeper energetic penalties than orthogonal out-of-plane (pitching) movement, which is characterized by noticeably flat potential energy surfaces. Energy decomposition analysis (EDA) of the ground-state and pitched structures of M1 indicated only minor differences in bonding characteristics. In contrast, yawing of the NHC ligand is associated with a significant increase in Pauli repulsion (i.e., sterics) and reduction in M→NHC π back donation, but is counteracted by supplemental stabilizing bonding interactions only possible due to the closer proximity of the methyl substituents with the metal and ancillary ligands. Aided by this analysis, comparison with a range of carefully selected model systems and EDA, distorted coordination modes in trans-[M(IBioxMe4)2(COE)Cl] (M2; M = Rh, Ir) and [M(IBioxMe4)3]+ (M3; M = Rh, Ir) have been rationalized. Steric interactions were identified as the major contributing factor and are associated with a high degree of NHC pitching. In the case of Rh3, weak agostic interactions also contribute to the distortions, particularly with respect to NHC yawing, and are notable for increasing the bond dissociation energy of the distorted ligands. Supplementing the computational analysis, an analogue of the formally 14 VE Rh(I) species Rh3 bearing the cyclohexyl-functionalized IBiox6 ligand ([Rh(IBiox6)3]+, Rh3-Cy) was prepared and found to exhibit an exceptionally distorted NHC ligand (ΘNHC = 155.7(2)°) in the solid state

Feasibility tests of transmission x-ray photoelectron emission microscopy of wet samples

We performed feasibility tests of photoelectron emission spectromicroscopy of wet samples in the water window (285-532 eV) soft x-ray spectral region. Water was successfully confined in an ultrahigh vacuum compatible compartment with x-ray transparent sides. This water cell was placed in the MEPHISTO spectromicroscope in a transmission geometry, and complete x-ray absorption spectra of the water window region were acquired. We also show micrographs of test samples, mounted outside of the compartment, and imaged through the water. This technique can be used to study liquid chemistry and, at least to the micron level, the microstructure of wet samples. Possibilities include cells in water or buffer, proteins in solution, oils of tribological interest, liquid crystals, and other samples not presently accessible to the powerful x-ray photoelectron emission spectromicroscopy technique

Influence of Ring Contraction on the Electronic Structure of Nickel Tetrapyrrole Complexes: Corrole vs Porphyrin

The influence of the contracted corrole macrocycle, in comparison to the larger porphyrin macrocycle, on the electronic structure of nickel was studied with X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Synthesis and in situ characterization of the Ni complexes of octaethylporphyrin (NiOEP) and hexaethyldimethylcorrole (NiHEDMC) were performed in ultra-high vacuum. XPS and NEXAFS spectra reveal a +2 oxidation state and a low-spin d8 electron configuration of Ni in both complexes, despite the formal trianionic nature of the corrole ligand. UPS, in combination with density functional theory (DFT) calculations, support the electronic structure of a Ni(II) corrole with a π-radical character of the ligand. The NEXAFS spectra also reveal differences in the valence electronic structure, which are attributed to the size mismatch between the small Ni(II) center and the larger central cavity of NiOEP. Analysis of the gas-phase structures shows that the Ni−N bonds in NiOEP are 4%–6% longer than those in NiHEDMC, even when NiOEP adopts a ruffled conformation. The individual interactions that constitute the Ni−ligand bond are altogether stronger in the corrole complex, according to bonding analysis within the energy decomposition analysis and the natural orbitals for chemical valence theory (EDA-NOCV)

Provision of preventive health care in systemic lupus erythematosus: data from a large observational cohort study

IntroductionCancer and infections are leading causes of mortality in systemic lupus erythematosus (SLE) after diseases of the circulatory system, and therefore preventing these complications is important. In this study, we examined two categories of preventive services in SLE: cancer surveillance (cervical, breast, and colon) and immunizations (influenza and pneumococcal). We compared the receipt of these services in SLE to the general population, and identified subgroups of patients who were less likely to receive these services.MethodsWe compared preventive services reported by insured women with SLE enrolled in the University of California, San Francisco Lupus Outcomes Study (n=685) to two representative samples derived from a statewide health interview survey, a general population sample (n=18,013) and a sample with non-rheumatic chronic conditions (n=4,515). In addition, using data from the cohort in both men and women (n=742), we applied multivariate regression analyses to determine whether characteristics of individuals (for example, sociodemographic and disease factors), health systems (for example, number of visits, involvement of generalists or rheumatologists in care, type of health insurance) or neighborhoods (neighborhood poverty) influenced the receipt of services.ResultsThe receipt of preventive care in SLE was similar to both comparison samples. For cancer surveillance, 70% of eligible respondents reported receipt of cervical cancer screening and mammography, and 62% reported colon cancer screening. For immunizations, 59% of eligible respondents reported influenza immunization, and 60% reported pneumococcal immunization. In multivariate regression analyses, several factors were associated with a lower likelihood of receiving preventive services, including younger age and lower educational attainment. We did not observe any effects by neighborhood poverty. A higher number of physician visits and involvement of generalist providers in care was associated with a higher likelihood of receiving most services.ConclusionsAlthough receipt of cancer screening procedures and immunizations in our cohort was comparable to the general population, we observed significant variability by sociodemographic factors such as age and educational attainment. Further research is needed to identify the physician, patient or health system factors contributing to this observed variation in order to develop effective quality improvement interventions

High resolution synchrotron radiation-based x-ray photoemission spectroscopy study of the Si-rich beta-SiC(100) 3X2 surface oxidation

We investigate the initial oxidation and interface formation of cubic silicon carbide for the silicon rich beta-SiC(100) 3x2 surface reconstruction by high resolution synchrotron radiation-based soft x-ray photoemission spectroscopy. The surface is exposed to low doses of molecular oxygen ranging from 1 up to 10 000 L, at surface temperatures from 25 to 500 degreesC. Significant formation of SiO(2) is found for the surface at room temperature, with the rate of oxidation increasing with temperature. Valence band data and Si 2p core level spectra show that even at low exposures, significant oxidation is taking place, with a surface reactivity to oxygen much larger than for silicon surfaces. The oxidation products, which are grown at very low temperatures (less than or equal to500 degreesC) include SiO(2) as a dominant feature but also substoichiometric oxides Si(+1), Si(+2), Si(+3), and significant amounts of mixed oxide products involving C atoms (Si-O-C). (C) 2003 American Vacuum Society