Ruthenium complexes of 1,4-diazabutadiene ligands with a -RuCl moiety for catalytic acceptorless dehydrogenation of alcohols: DFT evidence of chemically non-innocent ligand participation.

The acceptorless dehydrogenative coupling (ADC) of primary alcohols to esters by diazabutadiene-coordinated ruthenium compounds is reported. Treatment of -Ru(dmso)Cl in acetone at 56 °C with different 1,4-diazabutadienes [-XCHN[double bond, length as m-dash]C(H)(H)C[double bond, length as m-dash]NCHX-; X = H, CH, OCH, and Cl; abbreviated as DAB-X], gives -Ru[κ-,-DAB-X]Cl as the kinetic product of substitution. Heating these products in -xylene at 144 °C gives the thermodynamically favored -Ru[κ-,-DAB-X]Cl isomers.

Reactions of diphosphine-stabilized Os clusters with triphenylantimony: syntheses and structures of new antimony-containing Os clusters Sb-Ph bond cleavage.

The reactivity of the trimetallic clusters [Os(CO)(μ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs(CO){μ-PhPCHPPh(CH-μ,σ)}] with triphenylantimony (SbPh) has been examined. [Os(CO)(μ-dppm)] reacts with SbPh in refluxing toluene to yield three new triosmium clusters [Os(CO)(SbPh)(μ-dppm)] (1), [HOs(CO)(SbPh){μ-PhPCHPPh(CH-μ,σ)}] (2), and [HOs(CO)(SbPh)(μ-CH)(μ-SbPh)(μ-dppm)] (3). [HOs(CO){μ-PhPCHPPh(CH-μ,σ)}] reacts with SbPh (excess) at room temperature to afford [Os(CO)(SbPh)(η-Ph)(μ-SbPh)(μ-dppm)] (4) as the sole product.

An investigation of steric influence on the reactivity of Fe(O)(OH) tautomers in stereospecific C-H hydroxylation.

Two new tetradentate N4 ligands (LN4), LN4 = Me2,Me2PyzTACN (1-(2-(3,5-dimethyl-1-pyrazol-1-yl)ethyl)-4,7-dimethyl-1,4,7-triazacyclononane) and Me2,MeImTACN (1-((1-methyl-1-imidazol-1-yl)methyl)-4,7-dimethyl-1,4,7-triazacyclononane) have been synthesized and their corresponding Fe(II) complexes [Fe(Me2,Me2PyzTACN)(CFSO)], 1Pz, and [Fe(Me2,MeImTACN)(CFSO)], 1Im, have been prepared and characterized. Complexes 1Pz and 1Im catalyse the hydroxylation of C-H bonds of alkanes with excellent efficiencies, using hydrogen peroxide as oxidant. The high H/D kinetic isotope effect values for C-H hydroxylation, large normalized tertiary/secondary C-H (C3/C2) bond selectivities in adamantane oxidation, and high degrees of stereoretention in the oxidation of -1,2-dimethylcyclohexane are indicative of metal-based oxidation processes.

Syntheses of Group 5 Amide Amidinates and Their Reactions with Water: Different Reactivities of Nb(V) and Ta(V) Complexes.

Chemistries of Nb(V) and Ta(V) compounds are essentially identical as a result of lanthanide contraction. Hydrolysis of M(NMe) (M = Nb, Ta), for example, yields [M(μ-O)(NMe)] (M = Nb, ; Ta, ) reported earlier. The similar reactivities of Nb(V) and Ta(V) compounds make it challenging, for example, to separate the two metals from their minerals.

Automatic Hemorrhage Detection From Color Doppler Ultrasound Using a Generative Adversarial Network (GAN)-Based Anomaly Detection Method.

Hemorrhage control has been identified as a priority focus area both for civilian and military populations in the United States because exsanguination is the most common cause of preventable death in hemorrhagic injury. Non-compressible torso hemorrhage (NCTH) has high mortality rate and there are currently no broadly available therapies for NCTH outside of a surgical room environment. Novel therapies, which include High Intensity Focused Ultrasound (HIFU) have emerged as promising methods for hemorrhage control as they can non-invasively cauterize bleeding tissue deep within the body without injuring uninvolved regions.

Whole Blood Selective Aortic Arch Perfusion for Exsanguination Cardiac Arrest: Assessing Myocardial Tolerance to the Duration of Cardiac Arrest.

Introduction: Selective aortic arch perfusion (SAAP) is an endovascular technique that consists of aortic occlusion with perfusion of the coronary and cerebral circulation. It been shown to facilitate return of spontaneous circulation (ROSC) after exanguination cardiac arrest (ECA), but it is not known how long arrest may last before the myocardium can no longer be durably recovered. The aim of this study is to assess the myocardial tolerance to exsanguination cardiac arrest before successful ROSC with SAAP.

Biomimics of [FeFe]-hydrogenases incorporating redox-active ligands: synthesis, redox properties and spectroelectrochemistry of diiron-dithiolate complexes with ferrocenyl-diphosphines as FeS surrogates.

[FeFe]-Ase biomimics containing a redox-active ferrocenyl diphosphine have been prepared and their ability to reduce protons and oxidise H studied, including 1,1'-bis(diphenylphosphino)ferrocene (dppf) complexes Fe(CO)(μ-dppf)(μ-S(CH)S) ( = 2, edt; = 3, pdt) and Fe(CO)(μ-dppf)(μ-SAr) (Ar = Ph, -tolyl, -CHNH), together with the more electron-rich 1,1'-bis(dicyclohexylphosphino)ferrocene (dcpf) complex Fe(CO)(μ-dcpf)(μ-pdt). Crystallographic characterisation of four of these show similar overall structures, the diphosphine spanning an elongated Fe-Fe bond ( 2.6 Å), lying to one sulfur and to the second.

Characterizing Brain Perfusion in a Swine Model of Raised Intracranial Pressure.

Introduction: Perfusion of the brain is critical, but this can be compromised due to focal space occupying lesions (SOL). SOLs can raise intracranial pressure (ICP), resulting in reduced cerebral blood flow (CBF). Most gyrencephalic models of brain injury focus on parenchymal injury, with few models of acutely elevated ICP.

Open chest selective aortic arch perfusion vs open cardiac massage as a means of perfusion during in exsanguination cardiac arrest: a comparison of coronary hemodynamics in swine.

Aim: To describe and compare the aortic-right atrial pressure (AoP-RAP) gradients and mean coronary perfusion pressures (CPPs) generated during open chest selective aortic arch perfusion (OCSAAP) with those generated during open cardiac massage (OCM) in hypovolemic swine.

Methods: Ten male Hanford swine utilized in a prior poly-trauma study were included in the study. Animals were rendered hypovolemic via a 30% volume bleed.

Development of a Swine Polytrauma Model in the Absence of Fluid Resuscitation.

Background: In locations in which access to resuscitative therapy may be limited, treating polytraumatized patients present a challenge. There is a pressing need for adjuncts that can be delivered in these settings. To assess these adjuncts, a model representative of this clinical scenario is necessary.

An estrogen (17α-ethinyl estradiol-3-sulfate) reduces mortality in a swine model of multiple injuries and hemorrhagic shock.

Background: Although 17α-ethinyl estradiol-3-sulfate (EES) reduces mortality in animal models of controlled hemorrhage, its role in a clinically relevant injury model is unknown. We assessed the impact of EES in a swine model of multiple injuries and hemorrhage.

Methods: The study was performed under Good Laboratory Practice, with 30 male uncastrated swine (25-50 kg) subjected to tibial fracture, pulmonary contusion, and 30% controlled hemorrhage for an hour.

Measuring Cardiac Output in a Swine Model.

Swine are frequently used in medical research given their similar cardiac physiology to that of humans. Measuring cardiac parameters such as stroke volume and cardiac output are essential in this type of research. Contrast ventriculography, thermodilution, and pressure-volume loop (PV-loop) catheters can be used to accurately obtain cardiac performance data depending on which resources and expertise are available.

Development of an Endovascular Model of Pelvic Hemorrhage Using Volumetric Computed Tomography Validation.

Purpose: Uncontrolled pelvic hemorrhage from trauma is associated with mortality rates above 30%. The ability of an intervention to reduce blood loss from pelvic trauma is paramount to its success. The objective of this study was to determine if computed tomography volumetric analysis could be used to quantify blood loss in a porcine endovascular pelvic hemorrhage model.

Selective aortic arch perfusion versus open cardiac massage in exsanguination cardiac arrest: A comparison of coronary pressure dynamics in swine.

Aim: To evaluate the mean aortic-right atrial pressure (AoP-RAP) gradients and mean coronary perfusion pressures (CPPs) observed during open cardiac massage (OCM) versus those obtained with selective aortic arch perfusion (SAAP) in post-mortem hypovolemic swine.

Methods: Post-mortum, male swine, utilized in prior studies of hemorrhage, were included in the study. Animals were bled ∼25-50% of circulating volume prior to death.

The functional vascular anatomy of the swine for research.

Objectives: Swine () are utilized broadly in research settings, given similarities to human vessel size and function; however, there are some important differences for clinicians to understand in order to interpret and perform translational research. This review article uses angiograms acquired in the course of a translational research program to present a description of the functional anatomy of the swine.

Methods: Digital subtraction angiography and computed tomography angiography were obtained throughout the course of multiple studies utilizing power injection with iodinated contrast.

Development of a computed tomography perfusion protocol to support large animal resuscitation research.

Background: Adequate cerebral perfusion is crucial for a positive neurological outcome in trauma; however, it is difficult to characterize in the acute setting with noninvasive methods. Intra-arterial computed tomography perfusion may offer a solution. The aim of this study was to develop an intra-arterial computed tomography perfusion protocol for resuscitation research.

The Cardiac Physiology Underpinning Exsanguination Cardiac Arrest: Targets for Endovascular Resuscitation.

Exsanguination leading to cardiac arrest is the terminal phase of uncontrolled hemorrhage. Resuscitative interventions have focused on preload and afterload support. Outcomes remain poor due to several factors but poor coronary perfusion undoubtedly plays a role.

A new synthetic route for the preparation of [Os(CO)(μ-OH)(μ-H)] and its reaction with bis(diphenylphosphino)methane (dppm): syntheses and X-ray structures of two isomers of [Os(CO)(μ-OH)(μ-H)(μ-dppm)] and [Os(CO)(μ-CO)(μ-O)(μ-dppm)].

The triosmium cluster [Os(CO)(μ-OH)(μ-H)] containing bridging hydride and hydroxyl groups at a common Os-Os edge was obtained in good yield ( 75%) from the hydrolysis of the labile triosmium cluster [Os(CO)(NCMe)] in THF at 67 °C. [Os(CO)(μ-OH)(μ-H)] reacts with dppm at 68 °C to afford the isomeric clusters 1 and 2 with the general formula [Os(CO)(μ-OH)(μ-H)(μ-dppm)] that differ by the disposition of bridging dppm ligand. Cluster 1 is produced exclusively from the reaction of [Os(CO)(μ-OH)(μ-H)] with dppm in CHCl at room temperature in the presence of added MeNO.

Development of a Selective Aortic Arch Perfusion System in a Porcine Model of Exsanguination Cardiac Arrest.

Hemorrhage constitutes the majority of potentially preventable deaths from trauma. There is growing interest in endovascular resuscitation techniques such as selective aortic arch perfusion (SAAP) for patients in cardiac arrest. This involves active perfusion of the coronary circulation via a thoracic aortic balloon catheter and is approaching clinical application.

Reactions of triosmium and triruthenium clusters with 2-ethynylpyridine: new modes for alkyne C-C bond coupling and C-H bond activation.

The reaction of the trimetallic clusters [HOs(CO)] and [Ru(CO)L] (L = CO, MeCN) with 2-ethynylpyridine has been investigated. Treatment of [HOs(CO)] with excess 2-ethynylpyridine affords [HOs(CO)(μ-CHNCH=CH)] (1), [HOs(CO)(μ-CHNC[double bond, length as m-dash]CH)] (2), [HOs(CO)(μ-CHNC[double bond, length as m-dash]CCO)] (3), and [HOs(CO)(μ-CH[double bond, length as m-dash]CHCHN)] (4) formed through either the direct addition of the Os-H bond across the C[triple bond, length as m-dash]C bond or acetylenic C-H bond activation of the 2-ethynylpyridine substrate. In contrast, the dominant pathway for the reaction between [Ru(CO)] and 2-ethynylpyridine is C-C bond coupling of the alkyne moiety to furnish the triruthenium clusters [Ru(CO)(μ-CO){μ-CHNC[double bond, length as m-dash]CHC(CHN)[double bond, length as m-dash]CH}] (5) and [Ru(CO)(μ-CO){μ-CHNCCHC(CHN)CHCHC(CHN)}] (6).

Electrocatalytic proton-reduction behaviour of telluride-capped triiron clusters: tuning of overpotentials and stabilization of redox states relative to lighter chalcogenide analogues.

Reaction of [Fe3(CO)9(μ3-Te)2] (1) with the corresponding phosphine has been used to prepare the phosphine-substituted tellurium-capped triiron clusters [Fe3(CO)9(μ3-Te)2(PPh3)] (2), [Fe3(CO)8(μ3-Te)2(PPh3)] (3) and [Fe3(CO)7(μ3-Te)2(μ-R2PXPR2)] (X = CH2, R = Ph (4), Cy (5); X = NPri, R = Ph (6)). The directly related cluster [Fe3(CO)7(μ3-CO)(μ3-Te)(μ-dppm)] (7) was isolated from the reaction of [Fe3(CO)10(μ-Ph2PCH2PPh2)] with elemental tellurium. The electrochemistry of these new clusters has been probed by cyclic voltammetry, and selected complexes have been tested as proton reduction catalysts.

Improving the safety of resuscitative endovascular balloon occlusion of the aorta - Compliant versus semi-compliant balloon systems.

Objectives: Resuscitative endovascular balloon occlusion of the aorta is an alternative to resuscitative thoracotomy in non-compressible torso haemorrhage. Low-profile, compliant balloon catheter systems have been developed, which can be deployed without the need for fluoroscopy. However, concern exists for over inflation and aortic injury, especially as compliant balloon material can stretch reducing syringe feedback and limiting the effectiveness of a safety valve.

Electron Transfer Mediated by Iron Carbonyl Clusters Enhance Light-Driven Hydrogen Evolution in Water by Quantum Dots.

Photocatalytic water splitting has become a promising strategy for converting solar energy into clean and carbon-neutral solar fuels in a low-cost and environmentally benign way. Hydrogen gas is such a potential solar fuel/energy carrier. In a classical artificial photosynthetic system, a photosensitizer is generally associated with a co-catalyst to convert photogenerated charge into (a) chemical bond(s).

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters - diastereomeric control of enantioselectivity.

Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P-P*)] (P-P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters.