The role of neutral Rh(PONOP)H, free NMe2H, boronium and ammonium salts in the dehydrocoupling of dimethylamine-borane using the cationic pincer [Rh(PONOP)(η2-H2)]+ catalyst

The σ-amine-borane pincer complex [Rh(PONOP)(η1-H3B·NMe3)][BArF4] [2, PONOP = κ3-NC5H3-2,6-(OPtBu2)2] is prepared by addition of H3B·NMe3 to the dihydrogen precursor [Rh(PONOP)(η2-H2)][BArF4], 1. In a similar way the related H3B·NMe2H complex [Rh(PONOP)(η1-H3B·NMe2H)][BArF4], 3, can be made in situ, but this undergoes dehydrocoupling to reform 1 and give the aminoborane dimer [H2BNMe2]2. NMR studies on this system reveal an intermediate neutral hydride forms, Rh(PONOP)H, 4, that has been prepared independently. 1 is a competent catalyst (2 mol%, ∼30 min) for the dehydrocoupling of H3B·Me2H. Kinetic, mechanistic and computational studies point to the role of NMe2H in both forming the neutral hydride, via deprotonation of a σ-amine-borane complex and formation of aminoborane, and closing the catalytic cycle by reprotonation of the hydride by the thus-formed dimethyl ammonium [NMe2H2]+. Competitive processes involving the generation of boronium [H2B(NMe2H)2]+ are also discussed, but shown to be higher in energy. Off-cycle adducts between [NMe2H2]+ or [H2B(NMe2H)2]+ and amine-boranes are also discussed that act to modify the kinetics of dehydrocoupling

Clinical features and outcomes of elderly hospitalised patients with chronic obstructive pulmonary disease, heart failure or both

Background and objective: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) mutually increase the risk of being present in the same patient, especially if older. Whether or not this coexistence may be associated with a worse prognosis is debated. Therefore, employing data derived from the REPOSI register, we evaluated the clinical features and outcomes in a population of elderly patients admitted to internal medicine wards and having COPD, HF or COPD + HF. Methods: We measured socio-demographic and anthropometric characteristics, severity and prevalence of comorbidities, clinical and laboratory features during hospitalization, mood disorders, functional independence, drug prescriptions and discharge destination. The primary study outcome was the risk of death. Results: We considered 2,343 elderly hospitalized patients (median age 81 years), of whom 1,154 (49%) had COPD, 813 (35%) HF, and 376 (16%) COPD + HF. Patients with COPD + HF had different characteristics than those with COPD or HF, such as a higher prevalence of previous hospitalizations, comorbidities (especially chronic kidney disease), higher respiratory rate at admission and number of prescribed drugs. Patients with COPD + HF (hazard ratio HR 1.74, 95% confidence intervals CI 1.16-2.61) and patients with dementia (HR 1.75, 95% CI 1.06-2.90) had a higher risk of death at one year. The Kaplan-Meier curves showed a higher mortality risk in the group of patients with COPD + HF for all causes (p = 0.010), respiratory causes (p = 0.006), cardiovascular causes (p = 0.046) and respiratory plus cardiovascular causes (p = 0.009). Conclusion: In this real-life cohort of hospitalized elderly patients, the coexistence of COPD and HF significantly worsened prognosis at one year. This finding may help to better define the care needs of this population

Oxidative Addition of Carbon-Carbon Bonds with a Redox-Active Bis(imino)pyridine Iron Complex

Addition of biphenylene to the bis(imino)pyridine iron dinitrogen complexes, ((PDI)-P-iPr)Fe(N-2)(2) and [((PDI)-P-Me)Fe(N-2))(2)(mu(2)-N-2) ((PDI)-P-R = 2,6-(2,6-R-2-C6H3- N=CMe)(2)C5H3N; R = Me, Pr-i), resulted in oxidative addition of a C C bond at ambient temperature to yield the corresponding iron biphenyl compounds, ((PDI)-P-R)Fe(biphenyl). The molecular structures of the resulting bis(imino)pyridine iron metallacycles were established by X-ray diffraction and revealed idealized square pyramidal geometries. The electronic structures of the compounds were studied by Mossbauer spectroscopy, NMR spectroscopy, magnetochemistry, and X-ray absorption and X-ray emission spectroscopies. The experimental data, in combination with broken-symmetry density functional theory calculations, established spin crossover (low to intermediate spin) ferric compounds antiferromagnetically coupled to bis(imino)pyridine radical anions. Thus, the overall oxidation reaction involves cooperative electron loss from both the iron center and the redox-active bis(imino)pyridine ligand

Verocytotoxin-producing Escherichia coli O157 in minced beef and dairy products in Italy

A total of 3879 samples of foodstuffs were examined for the presence of Verocytotoxin-producing Escherichia coli O157 (VTEC O157). The survey was conducted by 9 of the 10 Italian Veterinary Public Health Laboratories. Samples were collected between May 2000 and September 2001 in 14 regions and comprised 931 minced beef specimens and 2948 dairy products (DP) with less than 60 days of ripening. The DP included 657 pasteurised and 811 unpasteurised bovine DP, 477 pasteurised and 502 unpasteurised ovine DP, and 501 water-buffalo’s milk mozzarella cheese. Samples were collected at retail level, from plants processing minced beef and dairy plants and from farms directly manufacturing cheeses. All the samples were tested using a sensitive procedure based on ISO/DIS 16654:1999 (later ISO 16654:2001), which includes an immunomagnetic separation step. A preliminary inter-laboratory trial was organised with artificially contaminated samples to assess the ability of all the participating laboratories to isolate E. coli O157 by the established procedure. VTEC O157 was isolated from four (0.43%) of the minced beef samples, collected in four different regions and during different months, but was not detected in any of the dairy products. E. coli O157 VT_eae+ was isolated from one raw cow’s milk cheese. This survey provided national data on the presence of VTEC O157 in foodstuffs, demonstrating a low prevalence of the organism. The survey also encouraged updating of knowledge and procedures on VTEC O157 in laboratories with official responsibility for microbiological testing of foods of animal origin

Oxidation and Reduction of Bis(imino)pyridine Iron Dinitrogen Complexes: Evidence for Formation of a Chelate Trianion.

Oxidation and reduction of the bis­(imino)­pyridine iron dinitrogen compound, (^iPrPDI)­FeN₂ (^iPrPDI = 2,6-(2,6-ⁱPr₂–C₆H₃–NCMe)₂C₅H₃N) has been examined to determine whether the redox events are metal or ligand based. Treatment of (^iPrPDI)­FeN₂ with [Cp₂Fe]­[BAr^F₄] (BAr^F₄ = B­(3,5-(CF₃)₂-C₆H₃)₄) in diethyl ether solution resulted in N₂ loss and isolation of [(^iPrPDI)­Fe­(OEt₂)]­[BAr^F₄]. The electronic structure of the compound was studied by SQUID magnetometry, X-ray diffraction, EPR and zero-field ⁵⁷Fe Mössbauer spectroscopy. These data, supported by computational studies, established that the overall quartet ground state arises from a high spin iron­(II) center (<i>S</i>_Fe = 2) antiferromagnetically coupled to a bis­(imino)­pyridine radical anion (<i>S</i>_PDI = 1/2). Thus, the oxidation event is principally ligand based. The one electron reduction product, [Na­(15-crown-5)]­[(^iPrPDI)­FeN₂], was isolated following addition of sodium naphthalenide to (^iPrPDI)­FeN₂ in THF followed by treatment with the crown ether. Magnetic, spectroscopic, and computational studies established a doublet ground state with a principally iron-centered SOMO arising from an intermediate spin iron center and a rare example of trianionic bis­(imino)­pyridine chelate. Reduction of the iron dinitrogen complex where the imine methyl groups have been replaced by phenyl substituents, (^iPrBPDI)­Fe­(N₂)₂ resulted in isolation of both the mono- and dianionic iron dinitrogen compounds, [(^iPrBPDI)­FeN₂]⁻ and [(^iPrBPDI)­FeN₂]^2‑, highlighting the ability of this class of chelate to serve as an effective electron reservoir to support neutral ligand complexes over four redox states

Electronic Structure Determination of Pyridine N‑Heterocyclic Carbene Iron Dinitrogen Complexes and Neutral Ligand Derivatives

The electronic structures of pyridine N-heterocyclic dicarbene (^iPrCNC) iron complexes have been studied by a combination of spectroscopic and computational methods. The goal of these studies was to determine if this chelate engages in radical chemistry in reduced base metal compounds. The iron dinitrogen example (^iPrCNC)­Fe­(N₂)₂ and the related pyridine derivative (^iPrCNC)­Fe­(DMAP)­(N₂) were studied by NMR, Mössbauer, and X-ray absorption spectroscopy and are best described as redox non-innocent compounds with the ^iPrCNC chelate functioning as a classical π acceptor and the iron being viewed as a hybrid between low-spin Fe(0) and Fe­(II) oxidation states. This electronic description has been supported by spectroscopic data and DFT calculations. Addition of <i>N</i>,<i>N</i>-diallyl-<i>tert</i>-butylamine to (^iPrCNC)­Fe­(N₂)₂ yielded the corresponding iron diene complex. Elucidation of the electronic structure again revealed the CNC chelate acting as a π acceptor with no evidence for ligand-centered radicals. This ground state is in contrast with the case for the analogous bis­(imino)­pyridine iron complexes and may account for the lack of catalytic [2π + 2π] cycloaddition reactivity

Electronic Structure Determination of Pyridine N‑Heterocyclic Carbene Iron Dinitrogen Complexes and Neutral Ligand Derivatives

The electronic structures of pyridine N-heterocyclic dicarbene (^iPrCNC) iron complexes have been studied by a combination of spectroscopic and computational methods. The goal of these studies was to determine if this chelate engages in radical chemistry in reduced base metal compounds. The iron dinitrogen example (^iPrCNC)­Fe­(N₂)₂ and the related pyridine derivative (^iPrCNC)­Fe­(DMAP)­(N₂) were studied by NMR, Mössbauer, and X-ray absorption spectroscopy and are best described as redox non-innocent compounds with the ^iPrCNC chelate functioning as a classical π acceptor and the iron being viewed as a hybrid between low-spin Fe(0) and Fe­(II) oxidation states. This electronic description has been supported by spectroscopic data and DFT calculations. Addition of <i>N</i>,<i>N</i>-diallyl-<i>tert</i>-butylamine to (^iPrCNC)­Fe­(N₂)₂ yielded the corresponding iron diene complex. Elucidation of the electronic structure again revealed the CNC chelate acting as a π acceptor with no evidence for ligand-centered radicals. This ground state is in contrast with the case for the analogous bis­(imino)­pyridine iron complexes and may account for the lack of catalytic [2π + 2π] cycloaddition reactivity

Oxidative Addition of Carbon–Carbon Bonds with a Redox-Active Bis(imino)pyridine Iron Complex

Addition of biphenylene to the bis­(imino)­pyridine iron dinitrogen complexes, (^iPrPDI)­Fe­(N₂)₂ and [(^MePDI)­Fe­(N₂)]₂(μ₂-N₂) (^RPDI = 2,6-(2,6-R₂C₆H₃NCMe)₂C₅H₃N; R = Me, ⁱPr), resulted in oxidative addition of a CC bond at ambient temperature to yield the corresponding iron biphenyl compounds, (^RPDI)­Fe­(biphenyl). The molecular structures of the resulting bis­(imino)­pyridine iron metallacycles were established by X-ray diffraction and revealed idealized square pyramidal geometries. The electronic structures of the compounds were studied by Mössbauer spectroscopy, NMR spectroscopy, magnetochemistry, and X-ray absorption and X-ray emission spectroscopies. The experimental data, in combination with broken-symmetry density functional theory calculations, established spin crossover (low to intermediate spin) ferric compounds antiferromagnetically coupled to bis­(imino)­pyridine radical anions. Thus, the overall oxidation reaction involves cooperative electron loss from both the iron center and the redox-active bis­(imino)­pyridine ligand

Oxidative Addition of Carbon–Carbon Bonds with a Redox-Active Bis(imino)pyridine Iron Complex

Addition of biphenylene to the bis­(imino)­pyridine iron dinitrogen complexes, (^iPrPDI)­Fe­(N₂)₂ and [(^MePDI)­Fe­(N₂)]₂(μ₂-N₂) (^RPDI = 2,6-(2,6-R₂C₆H₃NCMe)₂C₅H₃N; R = Me, ⁱPr), resulted in oxidative addition of a CC bond at ambient temperature to yield the corresponding iron biphenyl compounds, (^RPDI)­Fe­(biphenyl). The molecular structures of the resulting bis­(imino)­pyridine iron metallacycles were established by X-ray diffraction and revealed idealized square pyramidal geometries. The electronic structures of the compounds were studied by Mössbauer spectroscopy, NMR spectroscopy, magnetochemistry, and X-ray absorption and X-ray emission spectroscopies. The experimental data, in combination with broken-symmetry density functional theory calculations, established spin crossover (low to intermediate spin) ferric compounds antiferromagnetically coupled to bis­(imino)­pyridine radical anions. Thus, the overall oxidation reaction involves cooperative electron loss from both the iron center and the redox-active bis­(imino)­pyridine ligand