Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at √s=7 TeV

Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decreas

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Observation of the decay Λb0 → pK−μ+μ− and a search for CP violation

A search for CP violation in the decay Λb 0 → pK−μ+μ− is presented. This decay is mediated by flavour-changing neutral-current transitions in the Standard Model and is potentially sensitive to new sources of CP violation. The study is based on a data sample of proton-proton collisions recorded with the LHCb experiment, corresponding to an integrated luminosity of 3 fb−1. The Λb 0 → pK−μ+μ− decay is observed for the first time, and two observables that are sensitive to different manifestations of CP violation are measured, (Formula Presented.)where the latter is based on asymmetries in the angle between the μ+μ− and pK− decay planes. These are measured to be(Formula Presented.)and no evidence for CP violation is found.[Figure not available: see fulltext.].</p

Gold(I) and Related Heterometallic Derivatives of Dimolybdenum Complexes with Asymmetric Phosphinidene Bridges

The phosphinidene-bridged complexes [Mo₂Cp₂(μ-κ¹:κ¹,η⁶-PR*)­(CO)₂] (<b>1</b>), [Mo₂Cp₂(μ-κ¹:κ¹,η⁴-PR*)­(CO)₃] (<b>2</b>), [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(η⁶-HR*)­(CO)₂] (<b>3</b>), and [Mo₂Cp₂(μ-κ¹:κ¹-PH)­(η⁶-HR*)­(CO)₂] (<b>4</b>) were examined as precursors of heterometallic gold­(I) and related derivatives (Cp = η⁵-C₅H₅, R* = 2,4,6-C₆H₂^<i>t</i>Bu₃). These complexes reacted with [AuCl­(THT)] to give the corresponding derivatives [AuMo₂ClCp₂(μ-κ¹:κ¹:κ¹,η⁶-PR*)­(CO)₂], [AuMo₂ClCp₂(μ-κ¹:κ¹:κ¹,η⁴-PR*)­(CO)₃] (Au–Mo <b>=</b> 2.8493(6) Å), [AuMo₂ClCp­(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HR*)], and [AuMo₂ClCp₂(μ₃-PH)­(CO)₂(η⁶-HR*)] formally resulting from the addition of an acceptor AuCl moiety to the short Mo–P bond of the parent substrates almost perpendicular to the corresponding Mo₂P plane. The chloride ligand was easily displaced upon reaction of the PC₅H₄-bridged gold complex with K­[MoCp­(CO)₃] to give the tetranuclear derivative [AuMo₃Cp₂(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₅(η⁶-HR*)] (Au–Mo = 2.711(2) and 2.807(2) Å). Compound <b>1</b> also reacted with HgI₂ to give a hexanuclear complex [HgMo₂Cp₂(μ-I)­I­(μ-κ¹:κ¹,η⁶-PR*)­(CO)₂]₂ containing dative Mo→Hg bonds (2.820(1) and 2.827(1) Å), whereas complex <b>3</b> gave the μ₃-PR bridged complex [HgMo₂CpI₂(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HR*)]. Complexes <b>1</b> to <b>4</b> also reacted easily with [AuL­(THT)]­PF₆ (L = THT, P­(<i>p</i>-tol)₃, PMe₃, P^<i>i</i>Pr₃) to give the corresponding cationic trinuclear derivatives [AuMo₂Cp₂(μ-κ¹:κ¹:κ¹,η⁶-PR*)­(CO)₂L]­(PF₆) (Au–Mo = 2.8080(3) Å for L = P­(<i>p</i>-tol)₃), [AuMo₂Cp₂(μ-κ¹:κ¹:κ¹,η⁴-PR*)­(CO)₃L]­(PF₆), and [AuMo₂Cp­(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HR*)­{P­(<i>p</i>-tol)₃}]­(PF₆). The blue, analogous PH-bridged complexes were more conveniently isolated as tetra-arylborate salts [AuMo₂Cp₂(μ₃-PH)­(CO)₂(η⁶-HR*)­L]­(BAr′₄) (Au–Mo = 2.8038(6) Å for L = P^<i>i</i>Pr₃; Ar′= 3,5-C₆H₃(CF₃)₂]. Compounds <b>1</b>, <b>3</b>, and <b>4</b> reacted readily with the cation [Au­(THT)₂]⁺ (as PF₆^– or BAr′₄^– salts) in a 2:1 ratio to give respectively the corresponding pentanuclear derivatives [Au­{Mo₂Cp₂(μ-κ¹:κ¹:κ¹,η⁶-PR*)­(CO)₂}₂]­(PF₆), [Au­{Mo₂Cp­(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HR*)}₂]­(PF₆) (Au–Mo = 2.7975(7) and 2.8006(7) Å), and [Au­{Mo₂Cp₂(μ₃-PH)­(CO)₂(η⁶-HR*)}₂]­(BAr′₄) (Au–Mo = 2.8233(8) and 2.8691(7) Å). Related silver complexes were obtained from the reaction of <b>3</b> and <b>4</b> with [AgCl­(PPh₃)]₄ after spontaneous symmetrization, while reaction of <b>1</b> with [Cu­(NCMe)₄]­PF₆ in a 2:1 ratio yielded the analogous copper complex [Cu­{Mo₂Cp₂(μ-κ¹:κ¹:κ¹,η⁶-PR*)­(CO)₂}₂]­(PF₆). All the above cationic gold complexes having (μ-κ¹:κ¹:κ¹,η⁶-PR*) ligands (but not the copper complex) rearranged into [Au­{Mo₂Cp­(μ-κ¹:κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HR*)}₂]­(PF₆) in refluxing 1,2-dichloroethane solution

Dimolybdenum Cyclopentadienyl Complexes with Bridging Chalcogenophosphinidene Ligands

The reactions of the phosphinidene-bridged complex [Mo₂Cp₂(μ-PH)­(η⁶-HMes*)­(CO)₂] (<b>1</b>), the arylphosphinidene complexes [Mo₂Cp₂(μ-κ¹:κ¹,η⁶-PMes*)­(CO)₂] (<b>2</b>), [Mo₂Cp₂(μ-κ¹:κ¹,η⁴-PMes*)­(CO)₃] (<b>3</b>), [Mo₂Cp₂(μ-κ¹:κ¹,η⁴-PMes*)­(CO)₂(CN^<i>t</i>Bu)] (<b>4</b>), and the cyclopentadienylidene-phosphinidene complex [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(η⁶-HMes*)­(CO)₂] (<b>5</b>) toward different sources of chalcogen atoms were investigated (Mes* = 2,4,6-C₆H₂^<i>t</i>Bu₃; Cp = η⁵-C₅H₅). The bare elements were appropriate sources in all cases except for oxygen, in which case dimethyldioxirane gave the best results. Complex <b>1</b> reacted with the mentioned chalcogen sources at low temperature, to give the corresponding chalcogenophosphinidene derivatives [Mo₂Cp₂{μ-κ²_P,Z:κ¹_P-ZPH}­(η⁶-HMes*)­(CO)₂] (Z = O, S, Se, Te; P–Se = 2.199(2) Å). The arylphosphinidene complex <b>2</b> was the least reactive substrate and gave only chalcogenophosphinidene derivatives [Mo₂Cp₂(μ-κ²_P,Z:κ¹_P,η⁶-ZPMes*)­(CO)₂] for Z = O and S (P–O = 1.565(2) Å), along with small amounts of the dithiophosphorane complex [Mo₂Cp₂(μ-κ²_P,S:κ¹_S′,η⁶-S₂PMes*)­(CO)₂], in the reaction with sulfur. The η⁴-complexes <b>3</b> and <b>4</b> reacted with sulfur and gray selenium to give the corresponding derivatives [Mo₂Cp₂(μ-κ²_P,Z:κ¹_P,η⁴-ZPMes*)­(CO)₂L] (L = CO, CN^<i>t</i>Bu), obtained respectively as syn (Z = Se; P–Se = 2.190(1) Å for L = CO) or a mixture of syn and anti isomers (Z = S; P–S = 2.034(1)–2.043(1) Å), with these diastereoisomers differing in the relative positioning of the chalcogen atom and the terminal ligand at the metallocene fragment, relative to the Mo₂P plane. The cyclopentadienylidene compound <b>5</b> reacted with all chalcogens, and gave with good yields the chalcogenophosphinidene derivatives [Mo₂Cp­(μ-κ²_P,Z:κ¹_P,η⁵-ZPC₅H₄)­(η⁶-HMes*)­(CO)₂] (Z = S, Se, Te), these displaying in solution equilibrium mixtures of the corresponding cis and trans isomers differing in the relative positioning of the cyclopentadienylic rings with respect to the MoPZ plane in each case. The sulfur derivative reacted with excess sulfur to give the dithiophosphorane complex [Mo₂Cp­(μ-κ²_P,S:κ¹_S′,η⁵-S₂PC₅H₄)­(η⁶-HMes*)­(CO)₂] (P–S = 2.023(4) and 2.027(4) Å). The structural and spectroscopic data for all chalcogenophosphinidene complexes suggested the presence of a significant π­(P–Z) bonding interaction within the corresponding MoPZ rings, also supported by Density Functional Theory calculations on the thiophosphinidene complex <i>syn</i>-[Mo₂Cp₂(μ-κ²_P,S:κ¹_P,η⁴-SPMes*)­(CO)₃]

Reactivity of the Phosphinidene-Bridged Complexes [Mo₂Cp(μ-κ¹:κ¹,η⁵-PC₅H₄)(η⁶-1,3,5-C₆H₃^<i>t</i>Bu₃)(CO)₂] and [Mo₂Cp₂(μ-PH)(η⁶-1,3,5-C₆H₃^<i>t</i>Bu₃)(CO)₂] toward Alkynes: Multicomponent Reactions in the Presence of Ligands

The cyclopentadienylidene-phosphinidene complex [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(η⁶-HMes*)­(CO)₂] (<b>1</b>) (Cp = η⁵-C₅H₅; Mes* = 2,4,6-C₆H₂^<i>t</i>Bu₃) reacted with RCCR′ in refluxing toluene solutions to give the corresponding phosphide derivatives [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′}­(η⁶-HMes*)­(CO)₂] (R = R′ = CO₂Me; R = H, R′ = CO₂Me, <i>p</i>-tol), displaying a phosphametallacyclobutene ring. In contrast, the phosphinidene complex [Mo₂Cp₂(μ-PH)­(η⁶-HMes*)­(CO)₂] (<b>2</b>) reacted with MeO₂CCCCO₂Me at room temperature to give first the monocarbonyl phosphide-acyl complex [Mo₂Cp₂{μ-κ¹:κ¹,η³-PHC­(CO₂Me)C­(CO₂Me)­C­(O)}­(η⁶-HMes*)­(CO)], the latter evolving progressively to the isomeric dicarbonyl [Mo₂Cp₂(μ-κ¹:κ¹,η¹-PHC­(CO₂Me)C­(CO₂Me)}­(η⁶-HMes*)­(CO)₂] (Mo–P ca. 2.57 Å). When different ligands such as CO, PMe₃, P­(OMe)₃, or CNXyl were added at room temperature to toluene solutions containing compound <b>1</b> and different alkynes, relatively fast multicomponent reactions took place to give with good yields the corresponding phosphide-acyl complexes [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′C­(O)}­(η⁶-HMes*)­(CO)₂] (R = R′ = CO₂Me; R = H, R′ = CO₂Me, <i>p</i>-tol), and [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)­C­(O)}­(η⁶-HMes*)­(CO)­(L)] (L = PMe₃, P­(OMe)₃) or the related phosphide-iminoacyl derivatives [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′C­(NXyl)}­(η⁶-HMes*)­(CO)₂] (Xyl = 2,6-C₆H₃Me₂; R = R′ = CO₂Me; R = H, R′ = CO₂Me, C­(O)­Me), respectively, all of them displaying five-membered phosphametallacyclopentenone or phosphametallacyclopentenimine rings. Separate experiments revealed that the latter complexes (R = R′ = CO₂Me) could be decarbonylated photochemically to yield the corresponding monocarbonyls [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η³-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)­C­(X)}­(η⁶-HMes*)­(CO)] (X = O, NXyl), the latter rearranging at room temperature to give the corresponding phosphametallacyclobutene isomers [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)}­(η⁶-HMes*)­(CO)­(CX)]. A side product was also formed during the photochemical treatment of the dicarbonyl substrate, it being finally isolated after chromatographic workup as the alkenylphosphide-chloride complex [Mo₂CpCl­{μ-κ¹,η⁵:κ¹,η²-(C₅H₄)­PC­(CO₂Me)CH­(CO₂Me)}­(η⁶-HMes*)­(CO)] (Mo–P = 2.553(2) and 2.436(2) Ǻ)

Symmetrization in a Phosphinidene-Bridged Complex To Give a Diphosphanediyl Derivative with Metal-Centered Reactivity

The phosphinidene complex [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HMes*)] reacts with CO to give the diphosphanediyl derivative [Mo₂{μ-κ¹,η⁵:κ¹,η⁵-(C₅H₄)­PP­(C₅H₄)}­(η⁶-HMes*)₂]. The latter compound features unreactive lone electron pairs at phosphorus, which instead contribute to the electronic communication between metal centers via a weak π­(PP)-bonding interaction. As a result, this complex displays metal-centered acid–base and redox behavior

Reactivity of the Phosphinidene-Bridged Complexes [Mo₂Cp(μ-κ¹:κ¹,η⁵-PC₅H₄)(η⁶-1,3,5-C₆H₃^<i>t</i>Bu₃)(CO)₂] and [Mo₂Cp₂(μ-PH)(η⁶-1,3,5-C₆H₃^<i>t</i>Bu₃)(CO)₂] toward Alkynes: Multicomponent Reactions in the Presence of Ligands

The cyclopentadienylidene-phosphinidene complex [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(η⁶-HMes*)­(CO)₂] (<b>1</b>) (Cp = η⁵-C₅H₅; Mes* = 2,4,6-C₆H₂^<i>t</i>Bu₃) reacted with RCCR′ in refluxing toluene solutions to give the corresponding phosphide derivatives [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′}­(η⁶-HMes*)­(CO)₂] (R = R′ = CO₂Me; R = H, R′ = CO₂Me, <i>p</i>-tol), displaying a phosphametallacyclobutene ring. In contrast, the phosphinidene complex [Mo₂Cp₂(μ-PH)­(η⁶-HMes*)­(CO)₂] (<b>2</b>) reacted with MeO₂CCCCO₂Me at room temperature to give first the monocarbonyl phosphide-acyl complex [Mo₂Cp₂{μ-κ¹:κ¹,η³-PHC­(CO₂Me)C­(CO₂Me)­C­(O)}­(η⁶-HMes*)­(CO)], the latter evolving progressively to the isomeric dicarbonyl [Mo₂Cp₂(μ-κ¹:κ¹,η¹-PHC­(CO₂Me)C­(CO₂Me)}­(η⁶-HMes*)­(CO)₂] (Mo–P ca. 2.57 Å). When different ligands such as CO, PMe₃, P­(OMe)₃, or CNXyl were added at room temperature to toluene solutions containing compound <b>1</b> and different alkynes, relatively fast multicomponent reactions took place to give with good yields the corresponding phosphide-acyl complexes [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′C­(O)}­(η⁶-HMes*)­(CO)₂] (R = R′ = CO₂Me; R = H, R′ = CO₂Me, <i>p</i>-tol), and [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)­C­(O)}­(η⁶-HMes*)­(CO)­(L)] (L = PMe₃, P­(OMe)₃) or the related phosphide-iminoacyl derivatives [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PCRCR′C­(NXyl)}­(η⁶-HMes*)­(CO)₂] (Xyl = 2,6-C₆H₃Me₂; R = R′ = CO₂Me; R = H, R′ = CO₂Me, C­(O)­Me), respectively, all of them displaying five-membered phosphametallacyclopentenone or phosphametallacyclopentenimine rings. Separate experiments revealed that the latter complexes (R = R′ = CO₂Me) could be decarbonylated photochemically to yield the corresponding monocarbonyls [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η³-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)­C­(X)}­(η⁶-HMes*)­(CO)] (X = O, NXyl), the latter rearranging at room temperature to give the corresponding phosphametallacyclobutene isomers [Mo₂Cp­{μ-κ¹,η⁵:κ¹,η¹-(C₅H₄)­PC­(CO₂Me)C­(CO₂Me)}­(η⁶-HMes*)­(CO)­(CX)]. A side product was also formed during the photochemical treatment of the dicarbonyl substrate, it being finally isolated after chromatographic workup as the alkenylphosphide-chloride complex [Mo₂CpCl­{μ-κ¹,η⁵:κ¹,η²-(C₅H₄)­PC­(CO₂Me)CH­(CO₂Me)}­(η⁶-HMes*)­(CO)] (Mo–P = 2.553(2) and 2.436(2) Ǻ)

Symmetrization in a Phosphinidene-Bridged Complex To Give a Diphosphanediyl Derivative with Metal-Centered Reactivity

The phosphinidene complex [Mo₂Cp­(μ-κ¹:κ¹,η⁵-PC₅H₄)­(CO)₂(η⁶-HMes*)] reacts with CO to give the diphosphanediyl derivative [Mo₂{μ-κ¹,η⁵:κ¹,η⁵-(C₅H₄)­PP­(C₅H₄)}­(η⁶-HMes*)₂]. The latter compound features unreactive lone electron pairs at phosphorus, which instead contribute to the electronic communication between metal centers via a weak π­(PP)-bonding interaction. As a result, this complex displays metal-centered acid–base and redox behavior