Versatile Coordination of Cyclopentadienyl-Arene Ligands and Its Role in Titanium-Catalyzed Ethylene Trimerization

Cationic titanium(IV) complexes with ansa-(η5-cyclopentadienyl,η6-arene) ligands were synthesized and characterized by X-ray crystallography. The strength of the metal-arene interaction in these systems was studied by variable-temperature NMR spectroscopy. Complexes with a C1 bridge between the cyclopentadienyl and arene moieties feature hemilabile coordination behavior of the ligand and consequently are active ethylene trimerization catalysts. Reaction of the titanium(IV) dimethyl cations with CO results in conversion to the analogous cationic titanium(II) dicarbonyl species. Metal-to-ligand backdonation in these formally low-valent complexes gives rise to a strongly bonded, partially reduced arene moiety. In contrast to the η6-arene coordination mode observed for titanium, the more electron-rich vanadium(V) cations [cyclopentadienyl-arene]V(NiPr2)(NC6H4-4-Me)+ feature η1-arene binding, as determined by a crystallographic study. The three different metal-arene coordination modes that we experimentally observed model intermediates in the cycle for titanium-catalyzed ethylene trimerization. The nature of the metal-arene interaction in these systems was studied by DFT calculations.

Corticosteroid suppression of antiviral immunity increases bacterial loads and mucus production in COPD exacerbations

Inhaled corticosteroids (ICS) have limited efficacy in reducing chronic obstructive pulmonary disease (COPD) exacerbations and increase pneumonia risk, through unknown mechanisms. Rhinoviruses precipitate most exacerbations and increase susceptibility to secondary bacterial infections. Here, we show that the ICS fluticasone propionate (FP) impairs innate and acquired antiviral immune responses leading to delayed virus clearance and previously unrecognised adverse effects of enhanced mucus, impaired antimicrobial peptide secretion and increased pulmonary bacterial load during virus-induced exacerbations. Exogenous interferon-β reverses these effects. FP suppression of interferon may occur through inhibition of TLR3- and RIG-I virus-sensing pathways. Mice deficient in the type I interferon-α/β receptor (IFNAR1−/−) have suppressed antimicrobial peptide and enhanced mucin responses to rhinovirus infection. This study identifies type I interferon as a central regulator of antibacterial immunity and mucus production. Suppression of interferon by ICS during virus-induced COPD exacerbations likely mediates pneumonia risk and raises suggestion that inhaled interferon-β therapy may protect

Lewis Base Mediated β-Elimination and Lewis Acid Mediated Insertion Reactions of Disilazido Zirconium Compounds

The reactivity of a series of disilazido zirconocene complexes is dominated by the migration of anionic groups (hydrogen, alkyl, halide, OTf) between the zirconium and silicon centers. The direction of these migrations is controlled by the addition of two-electron donors (Lewis bases) or two-electron acceptors (Lewis acids). The cationic nonclassical [Cp2ZrN(SiHMe2)2]+ ([2]+) is prepared from Cp2Zr{N(SiHMe2)2}H (1) and B(C6F5)3 or [Ph3C][B(C6F5)4], while reactions of B(C6F5)3 and Cp2Zr{N(SiHMe2)2}R (R = Me (3), Et (5), n-C3H7 (7), CH═CHSiMe3 (9)) provide a mixture of [2]+ and [Cp2ZrN(SiHMe2)(SiRMe2)]+. The latter products are formed through B(C6F5)3 abstraction of a β-H and R group migration from Zr to the β-Si center. Related β-hydrogen abstraction and X group migration reactions are observed for Cp2Zr{N(SiHMe2)2}X (X = OTf (11), Cl (13), OMe (15), O-i-C3H7 (16)). Alternatively, addition of DMAP (DMAP = 4-(dimethylamino)pyridine) to [2]+ results in coordination to a Si center and hydrogen migration to zirconium, giving the cationic complex [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}H]+ ([19]+). Related hydrogen migration occurs from [Cp2ZrN(SiHMe2)(SiMe2OCHMe2)]+ ([18]+) to give [Cp2Zr{N(SiMe2DMAP)(SiMe2OCHMe2)}H]+ ([22]+), whereas X group migration is observed upon addition of DMAP to [Cp2ZrN(SiHMe2)(SiMe2X)]+ (X = OTf ([12]+), Cl ([14]+)) to give [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}X]+ (X = OTf ([26]+), Cl ([20]+)). The species involved in these transformations are described by resonance structures that suggest β-elimination. Notably, such pathways are previously unknown in early metal amide chemistry. Finally, these migrations facilitate direct Si–H addition to carbonyls, which is proposed to occur through a pathway that previously had been reserved for later transition metal compounds

"Delirium Day": A nationwide point prevalence study of delirium in older hospitalized patients using an easy standardized diagnostic tool

Background: To date, delirium prevalence in adult acute hospital populations has been estimated generally from pooled findings of single-center studies and/or among specific patient populations. Furthermore, the number of participants in these studies has not exceeded a few hundred. To overcome these limitations, we have determined, in a multicenter study, the prevalence of delirium over a single day among a large population of patients admitted to acute and rehabilitation hospital wards in Italy. Methods: This is a point prevalence study (called "Delirium Day") including 1867 older patients (aged 65 years or more) across 108 acute and 12 rehabilitation wards in Italian hospitals. Delirium was assessed on the same day in all patients using the 4AT, a validated and briefly administered tool which does not require training. We also collected data regarding motoric subtypes of delirium, functional and nutritional status, dementia, comorbidity, medications, feeding tubes, peripheral venous and urinary catheters, and physical restraints. Results: The mean sample age was 82.0 \ub1 7.5 years (58 % female). Overall, 429 patients (22.9 %) had delirium. Hypoactive was the commonest subtype (132/344 patients, 38.5 %), followed by mixed, hyperactive, and nonmotoric delirium. The prevalence was highest in Neurology (28.5 %) and Geriatrics (24.7 %), lowest in Rehabilitation (14.0 %), and intermediate in Orthopedic (20.6 %) and Internal Medicine wards (21.4 %). In a multivariable logistic regression, age (odds ratio [OR] 1.03, 95 % confidence interval [CI] 1.01-1.05), Activities of Daily Living dependence (OR 1.19, 95 % CI 1.12-1.27), dementia (OR 3.25, 95 % CI 2.41-4.38), malnutrition (OR 2.01, 95 % CI 1.29-3.14), and use of antipsychotics (OR 2.03, 95 % CI 1.45-2.82), feeding tubes (OR 2.51, 95 % CI 1.11-5.66), peripheral venous catheters (OR 1.41, 95 % CI 1.06-1.87), urinary catheters (OR 1.73, 95 % CI 1.30-2.29), and physical restraints (OR 1.84, 95 % CI 1.40-2.40) were associated with delirium. Admission to Neurology wards was also associated with delirium (OR 2.00, 95 % CI 1.29-3.14), while admission to other settings was not. Conclusions: Delirium occurred in more than one out of five patients in acute and rehabilitation hospital wards. Prevalence was highest in Neurology and lowest in Rehabilitation divisions. The "Delirium Day" project might become a useful method to assess delirium across hospital settings and a benchmarking platform for future surveys

A new polymorph of the heterometallic cluster Ru4Pt2(CO)18

ABSTRACT By reacting Ru(CO)_5 with the stoichiometric amount of Pt(C_7H_10)_3(C_7H_10=bicyclo[2.2.1]heptene) in heptane and by removing the excess of CO, two polymorphs of Ru_4Pt_2(CO)_18, 1, were isolated and characterized by X-ray diffraction, namely the already known monoclinic (a) and a new orthorhombic (b) phase. Crystal data of the b phase: space group Pna2_1; a=17.738(3), b=15.596(2), c=10.357(1), V=2865 Å^3. IR spectra (Nujol mulls) of the two polymorphs are significantly different, while no difference was noticed in solution. The air-stable compounds quickly decompose in a carbon monoxide atmosphere giving Ru_3CO_12 and the unstable [Pt(CO)]_n, n⩽2

Competitive ligation between carbon monoxide and propiononitrile in chloro-complexes of platinum(II)

EtCN partially displaces coordinated carbon monoxide from cis-PtCl2(CO)2 giving an equilibrium mixture of the two geometrical isomers of PtCl2(CO)(NCEt), together with unreacted cis-PtCl2(CO)2, as monitored by IR and NMR measurements. The equilibrium has also been studied starting from PtCl2(NCEt)2, through displacement of coordinated EtCN by CO. The equilibrium constant of the reaction between PtCl2(CO)(NCEt) [cis + trans] and CO to produce cis-PtCl2(CO)2 (48 ± 6, corresponding to ΔG0 = -9.5 ± 0.3 kJ mol-1) has been measured at 23.4 °C, in the presence of SnCl2 as catalyst, the uncatalysed reaction being exceedingly slow. With an appropriate control of the CO partial pressure, PtCl2(CO)(NCEt) was obtained in a nearly quantitative yield either from cis-PtCl2(CO)2 + EtCN or from PtCl2(NCEt)2 + CO. The molecular and crystal structure of cis-PtCl2(CO)(NCEt) has been solved by X-ray diffractometry

The NHR2/CO2 system as a metal ion extraction reagent from aqueous solution into hydrocarbons: copper(II) and zinc(II)

ABSTRACT A substantially quantitative transfer of copper(II) or zinc(II) salts from aqueous solution into a hydrocarbon (heptane or toluene) promptly occurs under carbon dioxide in the presence of a dialkylamine (NHR2 , R= Bu, Bz). Recovery of the metal complexes from the organic phase affords copper dialkylcarbamates of formula Cu(O2CNR2)2(NHR2)2 or m-oxo tetranuclear zinc carbamato complexes, Zn4(m4-O)(O2CNR2)6, respectively, in high yield and purity. An X-ray diffraction study on a single crystal of Cu(O2CNBz2)2(NHBz2)2 1 has shown the compound to be mononuclear with tetracoordinated copper in an almost perfect square-planar geometry. The zinc derivative has the well-established oxo-centred tetranuclear structure (R = Bu, 2)