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Spin-vibronic coupling leads to spin relaxation in paramagnetic molecules, and an understanding of factors that contribute to this phenomenon is essential for designing next-generation spintronics technology, including single-molecule magnets and spin-based qubits, wherein long-lifetime magnetic ground states are desired. We report spectroscopic and magnetic characterization of the isoelectronic and isostructural series of homoleptic zerovalent transition metal triad M(CNDipp)6 (M = V, Nb, Ta; CNDipp = 2,6-diisopropylphenyl isocyanide) and show experimentally the significant increase in spin relaxation rate upon going from V to Nb to Ta. Correlated electronic calculations and first principle spin-phonon computations support the role of spin-orbit coupling in modulating spin-phonon relaxation. Our results provide experimental evidence that increasing magnetic anisotropy through spin-orbit coupling interactions leads to increased spin-vibronic relaxation, which is detrimental to long spin lifetime in paramagnetic molecules.

Reduction of bis(naphthalene)vanadium(0) by potassium naphthalene (KNp) in tetrahydrofuran (THF) provides a highly reactive, thermolabile, and so far unisolable brown substance, which affords the first reported derivatives of bis(naphthalene)vanadates. From these solutions, thermally stable (298 K) and structurally characterized compounds have been obtained, including dark-red rods of catena-poly[bis(μ

Treatment of bis(mesitylene)niobium(0) with 6–7 equivalents of 2,6-dimethylphenyl isocyanide (CNXyl) affords two products with the empirical formula Nb(CNXyl) n (n = 7 or 6), which have been shown to be the diamagnetic dimers bis[μ-N,N′,N′′,N′′′-tetrakis(2,6-dimethylphenyl)squaramidinato(2−)]bis[pentakis(2,6-dimethylphenyl isocyanide)niobium(I)], [Nb2(C9H9N)10(C36H36N4)] or [Nb(CNXyl)5]2[μ-C4(NXyl)4]·xSolvent, 1, and bis[μ-N,N′,N′′,N′′′-tetrakis(2,6-dimethylphenyl)squaramidinato(2−)]bis[tetrakis(2,6-dimethylphenyl isocyanide)niobium(I)] tetrahydrofuran trisolvate, [Nb2(C9H9N)8(C36H36N4)]·3C4H8O or [Nb(CNXyl)4]2[μ-C4(NXyl)4]·3THF (THF = tetrahydrofuran), 2. Each contains NbI bound to either five or four terminal isocyanides, respectively, and to an unprecedented bridging tetraarylsquaramidinate(2−) unit, coordinated as a bidentate ligand to each niobium center, symmetrically due to the crystallographic inversion center that coincides with the centroid of the central C4 unit. Thus, in the presence of CNXyl, the bis(mesitylene)niobium(0) is oxidized to niobium(I), resulting in the facile loss of both mesitylene groups and the reductive coupling of two CNXyl groups per niobium to provide the first examples of tetraarylsquaramidinate(2−) ligands, [cyclo-C4N4Ar4]2−, coordinated to metals. In contrast, bis(mesitylene)niobium(0) reacts with the more crowded 2,6-diisopropylphenyl isocyanide (CNDipp) to afford the paramagnetic monomer hexakis(2,6-diisopropylphenyl isocyanide)niobium(0), [Nb(C13H17N)6] or Nb(CNDipp)6, 3, the first zero-valent niobium isocyanide analog of the highly unstable Nb(CO)6, which is presently only known to exist in an argon matrix at 4.2 K.

Structures and spectroscopic characterization of the divalent complexes cis-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II) dichloromethane 0.771-solvate, [FeBr2(C9H9N)4]·0.771CH2Cl2 or cis-FeBr2(CNXyl)4·0.771CH2Cl2 (Xyl = 2,6-dimethylphenyl), trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II), [FeBr2(C9H9N)4] or trans-FeBr2(CNXyl)4, trans-dibromidotetrakis(2,6-dimethylphenyl isocyanide)cobalt(II), [CoBr2(C9H9N)4] or trans-CoBr2(CNXyl)4, and trans-dibromidobis(2,6-dimethylphenyl isocyanide)nickel(II), [NiBr2(C9H9N)2] or trans-NiBr2(CNXyl)2, are presented. Additionally, crystals grown from a cold diethyl ether solution of zero-valent Fe(CNXyl)5 produced a structure containing a cocrystallization of mononuclear Fe(CNXyl)5 and the previously unknown dinuclear [Fe(CNXyl)3]2(μ2-CNXyl)3, namely pentakis(2,6-dimethylphenyl isocyanide)iron(0) tris(μ2-2,6-dimethylphenyl isocyanide)bis[tris(2,6-dimethylphenyl isocyanide)iron(0)], [Fe(C9H9N)5][Fe2(C9H9N)9]. The (M)C—N—C(Xyl) angles of the isocyanide ligand are nearly linear for the metals in the +2 oxidation state, for which the ligands function essentially as pure donors. The νCN stretching frequencies for these divalent metal isocyanides are at or above that of the free ligand. Relative to FeII, in the structure containing iron in the formally zero-valent oxidation state, the Fe—C bond lengths have shortened, the C[triple-bond]N bond lengths have elongated, the (M)C—N—C(Xyl) angles of the terminal CNXyl ligands are more bent, and the νCN stretching frequencies have shifted to lower energies, all indicative of substantial M(dπ)→π* backbonding.

Treatment of tetraethylammonium hexacarbonyltantalate, [Et4N][Ta(CO)6], with 1.1 equivalents of molecular iodine (I2) in tetrahydrofuran (THF) at 200 K, followed by the addition of 6.0 equivalents of 2,6-diisopropylphenyl isocyanide (CNDipp) and slow warming to 293 K over a 24 h period gave the tantalum(I) iodide derivative hexakis(2,6-diisopropylphenyl isocyanide-κC)iodidotantalum(I), [TaI(C13H17N)6] or TaI(CNDipp)6, 1. Recrystallization of this substance from pentane provided deep-red nearly black parallelepipeds of the product, which was characterized by single-crystal X-ray diffraction. Addition of 1 in THF at 200 K to a suspension of an excess (5.8 equivalents) of caesium graphite (CsC8), followed by warming, filtration, and solvent removal, afforded a dark-green oily solid of unknown composition, from which several red–brown rhombohedral plates of the ditantalum salt heptakis(2,6-diisopropylphenyl isocyanide-κC)tantalum hexakis(2,6-diisopropylphenyl isocyanide-κC)tantalate, [Ta(C13H17N)7][Ta(C13H17N)6] or [Ta(CNDipp)7][Ta(CNDipp)6], 2, were harvested. Salt 2 is a unique substance, as it is the only known example of a salt containing a homoleptic cation, [MLx ]+, and a homoleptic anion, [MLy ]−, with the same transition metal and π-acceptor ligand L. In solution, 2 undergoes full comproportionation to afford the recently reported 17-electron paramagnetic zerovalent tantalum complex Ta(CNDipp)6, the only known isolable TaL 6 complex of Ta0.

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare-earth metal–carbon bonding. The crystal structures of (18-crown-6)bis(tetrahydrofuran-κO)sodium bis(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C4H8O)2(C12H24O6)][Sc(C26H20)2]·2C4H8O or [Na(18-crown-6)(THF)2][Sc(η6-C2Ph4)2]·2(THF), (1b), (η5-1,3-diphenylcyclopentadienyl)(tetrahydrofuran-κO)(η6-1,1,2,2-tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C17H13)(C26H20)(C4H8O)]·0.5C7H8or [(η5-1,3-Ph2C5H3)Sc(η6-C2Ph4)(THF)]·0.5(toluene), (5b), poly[[(μ2-η3:η3-anthracenediyl)bis(η6-anthracenediyl)bis(η5-1,3-diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K2Sc2(C14H10)3(C17H13)2(C4H8O)4]·C4H8O}nor [K(THF)2]2[(1,3-Ph2C5H3)2Sc2(C14H10)3]·THF, (6), and 1,4-diphenylcyclopenta-1,3-diene, C17H14, (3a), have been established. The [Sc(η6-C2Ph4)2]−complex anion in (1b) contains the tetraphenylethylene dianion in a symmetrical bis-η3-allyl coordination mode. The complex homoleptic [Sc(η6-C2Ph4)2]−anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D1H and13C{1H}, and 2D COSY1H–1H and13C–1H NMR data are presented forM[Sc(Ph4C2)2]·xTHF [M= Na andx= 4 for (1a);M= K andx= 3.5 for (2a)] in THF-d8media. Complex (5b) exhibits an unsymmetrical bis-η3-allyl coordination mode of the dianion, but this changes to a η4coordination mode for (1,3-Ph2C5H3)Sc(Ph4C2)(THF)2, (5a), in THF-d8solution. A45Sc NMR study of (2a) and UV–Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc—Ph4C2bond character. The unique Sc ate complex, (6), contains three anthracenide dianions demonstrating both a η6-coordination mode for two bent ligands and a μ2-η3:η3-bridging mode of a flat ligand. Each [(1,3-Ph2C5H3)2Sc2(C14H10)3]2−dianionic unit is connected to four neighbouring unitsviashort contacts with [K(THF)2]+cations, forming a two-dimensional coordination polymer framework parallel to (001).

Hexakis(2,6-diisopropylphenylisocyanide)tantalum, (1), is the first isocyanide analog of the highly unstable hexacarbonyltantalum(0), and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta(0) complexes are known, bis(benzene)tantalum and tris(1,2-bis(dimethylphosphano)ethane)tantalum, but these have only been accessed via ligand condensation with tantalum vapor in a sophisticated metal atom reactor. Consistent with its 17-electron nature, compound (1) undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, (1) qualitatively resembles hexacarbonylvanadium(0), the only paramagnetic metal carbonyl isolable under ambient conditions.

Structures and spectroscopic characterization of the divalent complexes cis-dibromidotetrakis(2,6-dimethylphenyl isocyanide)iron(II) dichloromethane 0.771-solvate, [FeBr

Treatment of bis(mesitylene)niobium(0) with 6-7 equivalents of 2,6-dimethylphenyl isocyanide (CNXyl) affords two products with the empirical formula Nb(CNXyl)

Joseph Chatt was the first to discover in the early 1960s that previously unknown transition metal compounds were accessible and isolable via the reactions of alkali metal arene radical anions with transition metal precursors containing good leaving groups, such as weakly basic neutral or anionic ligands, especially halides. Later Peter Timms confirmed the importance of these early studies with the synthesis of several new bis(arene)metal(0) sandwich compounds by a variant of Chatt's route. Following a brief historical survey of alkali metal arene compounds, first examined in some detail by Wilhelm Schlenk, use of these reagents in the conventional syntheses of anionic homoleptic arene metal complexes of the d-block elements will be described. In several cases these species are quite useful because they function as storable “naked” atomic metal anion reagents, especially in their reactions with carbon monoxide and isocyanides. In view of Chatt's seminal contributions to an often unique route to organometallic and inorganic compounds, it is proposed that this valuable synthetic method be named the “Chatt reaction” in honor of a giant of chemistry.

Treatment of tetraethylammonium hexacarbonyltantalate, [Et

The authors previously identified plasma plasminogen activator inhibitor-1 (PAI-1) level as a quantitative lung injury biomarker in primary graft dysfunction (PGD). They hypothesized that plasma levels of PAI-1 used as a quantitative trait could facilitate discovery of genetic loci important in PGD pathogenesis. A two-stage cohort study was performed. In stage 1, they tested associations of loci with PAI-1 plasma level using linear modeling. Genotyping was performed using the Illumina CVD Bead Chip v2. Loci meeting a p < 5 × 10(-4) cutoff were carried forward and tested in stage 2 for association with PGD. Two hundred ninety-seven enrollees were evaluated in stage 1. Six loci, associated with PAI-1, were carried forward to stage 2 and evaluated in 728 patients. rs3168046 (Toll interacting protein [TOLLIP]) was significantly associated with PGD (p = 0.006). The increased risk of PGD for carrying at least one copy of this variant was 11.7% (95% confidence interval 4.9-18.5%). The false-positive rate for individuals with this genotype who did not have PGD was 6.1%. Variants in the TOLLIP gene are associated with higher circulating PAI-1 plasma levels and validate for association with clinical PGD. A protein quantitative trait analysis for PGD risk prioritizes genetic variations in TOLLIP and supports a role for Toll-like receptors in PGD pathogenesis.

Hexakis(2,6-diisopropylphenylisocyanide)tantalum is the first isocyanide analogue of the highly unstable Ta(CO)

The first reported structure of a cobalt complex containing an η6-anthracene ligand is presented. The anthracene ligand is nearly flat and coordinates the metal asymmetrically, such that the ring junction carbon atoms are slightly further from the cobalt center than are the other four., The asymmetric unit of the title structure, [Co(η6-C14H10){Sn(CH3)3}3], contains two independent mol­ecules. Each anthracene ligand is η6-coordinating to a CoIII cation and is nearly planar [fold angles of 5.4 (3) and 9.7 (3)°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co—C bond lengths to the ring junction carbon atoms than to the other four. Each CoIII cation is further coordinated by three Sn(CH3)3 ligands, giving each mol­ecule a three-legged piano-stool geometry. In each of the two independent mol­ecules, the trio of SnMe3 ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one mol­ecule, the disorder ratio refined to 0.9365 (8):0.0635 (8), while that for the other refined to 0.9686 (8):0.0314 (8). The mol­ecules are well separated, and thus no significant inter­molecular inter­actions are observed. The compound is of inter­est as the first structure report of an η6-anthracene cobalt(III) complex.

Homoleptic 2,2′-bipyridine (bipy) metalates of iron and cobalt have been synthesized directly from the corresponding homoleptic anthracene metalates. In the iron structure, bis[([2.2.2]cryptand)potassium(I)] tris(2,2′-bipyridine)ferrate(–I) anthracene(–I), [K(C18H36N2O6)]2[Fe(C10H8N2)3](C14H10), the asymmetric unit contains one potassium complex cation in a general position, the Fe center and one and a half bipy ligands of the ferrate complex on a crystallographic twofold axis that includes the Fe atom, and one half of an anthracene radical anion whose other half is generated by a crystallographic inversion center. The cations and anions are well separated and the geometry about the Fe center is essentially octahedral. In the cobalt structure, ([2.2.2]cryptand)potassium(I) bis(2,2′-bipyridine)cobaltate(–I) anthracene hemisolvate tetrahydrofuran (THF) disolvate, [K(C18H36N2O6)][Co(C10H8N2)2]·0.5C14H10·2C4H8O, the asymmetric unit contains the cation, anion, and both cocrystallized THF solvent molecules in general positions, and one half of a cocrystallized anthracene molecule whose other half is generated by a crystallographic inversion center. The cation and anion are well separated and the ligand planes in the cobaltate anion are periplanar. Each anthracene molecule is midway between and is oriented perpendicular to a pair of symmetry-related bipy ligands such that aromatic donor–acceptor interactions may play a role in the packing arrangement. The lengths of the bonds that connect the bipy rings support the assertion that the ligands are bipy radical anions in the iron structure. However, in the case of cobalt, these lengths are between the known ranges for a bipy radical anion and a bipy dianion, and therefore no conclusion can be made from the crystallography alone. One cocrystallized THF solvent molecule in the cobalt structure was modeled as disordered over three positions with appropriate geometric and thermal restraints, which resulted in a refined component mass ratio of 0.412 (4):0.387 (3):0.201 (3).

Correction for ‘The Chatt reaction: conventional routes to homoleptic arenemetalates of d-block elements’ by John E. Ellis et al., Dalton Trans., 2019, 48, 9538–9563.

Summary. The cardiology literature has suggested for decades that b-blockade protects patients with ischaemic heart disease. Extending this concept to perioperative patients initially produced promising results, with reductions in perioperative myocardial ischaemia and longer-term cardiovascular complications observed in several small randomized trials. However, subsequent larger trials have either shown no benefit or greater morbidity (especially stroke), despite reductions in cardiovascular events. Retrospective database analyses have confirmed or disputed these findings. Speciality societies, most importantly, the American Heart Association/American College of Cardiology Foundation, have promulgated guidelines for perioperative b-blockade, which have been revised, as the evidence has changed. While the European guidelines continue to emphasize perioperative b-blockade in high-risk patients, the American guidelines have reduced the strength and breadth of recommendations, focusing on haemodynamic titration. Future work will need to focus on identifying populations most likely to benefit or to be harmed, including pharmacogenetic analyses and distinctions between individual b-blockers.

Rationnelle Les patients qui ont une intervention de chirurgie vasculaire sont a plus haut risque de morbidite et de mortalite cardio-vasculaires peri-operatoire. L'index revise de risque cardiaque (IRRC) est un outil valide et couramment employe au chevet du patient pour estimer le risque d'evenement myocardique defavorable majeur peri-operatoire. Nous avons suppose que l'inclusion de l'indication pour la chirurgie ajouterait une information independante et pronostique a l'IRRC dans la prediction de la mortalite de toute cause a 30 jours et a un an lors les procedures vasculaires chirurgicales sous inguinales ouvertes. Methodes Il s'agit d'une etude retrospective de 603 patients qui ont eu une chirurgie vasculaire ouverte par pontage sous inguinal entre janvier 2002 et janvier 2008 dans un centre medical de soin tertiaire. L'IRRC et l'indication de la chirurgie etaient determines. Les criteres d'evaluation principaux etaient la mortalite de toute cause a 30 jours (incluant toute la mortalite hospitaliere, independamment du temps) et a un an. Resultats La mortalite globale a 30 jours etait de 32 (5,3%). Les facteurs de risque independants de deces precoce etaient le score IRRC, l'âge ≥80 ans, la classe 4 de statu physique de l'American Society of Anesthesiologists, et la chirurgie en urgence. La mortalite globale a un an, incluant les deces precoce, etait de 114 (18,9%). L'indication chirurgicale, le score IRRC, l'âge, la classe 4 de statu physique de l'American Society of Anesthesiologists, le sexe feminin, et la chirurgie en urgence etaient tous des facteurs predictifs independants de la mortalite a un an. Conclusions Les scores d'IRRC etaient associes a la mortalite a 30 jours et a un an chez les patients ayant une chirurgie de pontage du membre inferieur. L'indication pour la chirurgie etait predictive de la mortalite a un an mais pas de la mortalite a 30 jours.

Background Patients who undergo vascular surgery are at increased risk of perioperative cardiovascular morbidity and mortality. The Revised Cardiac Risk Index (RCRI) is a validated and widely used bedside tool for estimating the risk of a perioperative major adverse myocardial event. We hypothesized that inclusion of the indication for surgery would add independent and prognostic information to the RCRI in predicting all-cause 30-day and 1-year mortality in open infrainguinal vascular surgical procedures. Methods This was a retrospective study of 603 patients who underwent open infrainguinal bypass vascular surgery between January 2002 and January 2008 at a tertiary care medical center. RCRI and indication for surgery were determined. The primary outcomes of interest were all-cause 30-day mortality (which included all in-hospital mortality, regardless of time) and all-cause 1-year mortality. Results Overall 30-day mortality was 32 (5.3%). Independent risk factors for early death were RCRI score, being of age ≥80 years, American Society of Anesthesiologists Physical Status classification = 4, and emergency surgery. Overall 1-year mortality, including early deaths, was 114 (18.9%). Indication for surgery, RCRI score, age, American Society of Anesthesiologists Physical Status classification = 4, female sex, and emergency surgery were all independent predictors of 1-year mortality. Conclusions The RCRI score was associated with both 30-day and 1-year mortality in patients undergoing lower extremity bypass surgery. Indication for surgery was predictive of 1-year mortality but not of 30-day mortality.

The causal factors of the systemic inflammatory response to cardiopulmonary bypass (CPB) were correctly identified in the early 1990 s: "... activation of complement, coagulation, fibrinolytic, and kallikrein cascades, activation of neutrophils with degranulation and protease enzyme release, oxygen radical production, and the synthesis of various cytokines from mononuclear cells" [Butler 1993]. Why therefore have clinical advances to curb the systemic inflammatory response proven such a disappointment? Part of the problem is that cardiac surgery has never taken intellectual ownership of this issue, borrowing its diagnosis from critical care medicine and failing to define the minimal criteria that should be measured when reporting on the systemic inflammatory response. An evidence based review of the current literature by many of the coauthors on this paper found that the majority of studies on the systemic inflammatory response did not measure a single one of the causal factors listed above - thus hindering our ability to identify mechanisms of causation and identify drug targets [Landis 2008]. A panel of experts convened at the Outcomes XII meeting, Barbados 2008, drafted the present consensus document in order to provide a framework to guide future studies and interdictions of the systemic inflammatory response. Herein, we have recommended: 1) mandatory reporting of minimal CPB and perfusion criteria that may affect outcomes, 2) reporting of a minimal set of causal inflammatory markers linked to adverse sequelae, and 3) reporting of at least one clinical end-point of organ injury, from a list of endpoints and markers of organ injury that balance practicality with clinical meaningfulness. It is our collective belief that this document will serve as a foundation for furthering our understanding of the influence of CPB practice with the systemic inflammatory response by standardizing the reporting of research findings in the peer-reviewed literature.

Oxidation of [CpTi(CO) 4 ] − by I 2 , Ph 3 SnCl, and Me 3 SnCl in the presence of four equivalents of CNXyl, Xyl = 2,6-dimethylphenyl, affords unprecedented titanium tetraisocyanide complexes, [CpTi(CNXyl) 4 E], E = I, SnPh 3 , SnMe 3 . These have been isolated and characterized by spectroscopic methods as well as single-crystal X-ray crystallography. A by-product of the iodine reaction was the Ti(III) complex, [CpTi(CNXyl) 2 I 2 ], which was also characterized by X-ray crystallography.

BACKGROUND: Strategies to limit adverse cardiac events after vascular surgery continue to evolve. Early recognition and treatment of myocardial ischemia may be a key to improving postoperative survival rates. Cardiac troponin I (cTnI) screening is an effective means of surveillance for postoperative myocardial ischemic injury and has long-term prognostic value. METHODS: We designed a Markov-based decision analysis model to determine the cost-effectiveness of routine surveillance with cTnI on postoperative Days 0, 1, 2, and 3, with an aim to institute tight heart rate control (60–65 bpm) with close monitoring and coronary care in the intensive care unit for 5 days in patients with cTnI 1.5 ng/mL. The key input variables obtained from published literature were as follows: probability of myocardial infarction, 0.049; cost of cTnI surveillance, $357; cost and efficacy of interventions, $13,145 and 0.55, respectively. The time horizon was lifetime and the target population being individuals aged 65 yr (median) undergoing elective open abdominal aortic surgery. The perspective for analysis was third-party payer. RESULTS: The incremental cost-effectiveness ratio for cTnI surveillance was $12,641 per quality-adjusted life year compared with standard care without cTnI surveillance. During one-way sensitivity analysis, probability of myocardial infarction and efficacy of interventions were found to influence the cost-effectiveness. Multivariate sensitivity analysis with second-order Monte Carlo simulation revealed that cTnI surveillance was favored in 90.75% of simulations at a commonly used threshold of $50,000 per quality-adjusted life year. CONCLUSIONS: In patients presenting for elective open abdominal aortic surgery, intensive surveillance with cTnI and early institution of aggressive -blockade is cost-effective. (Anesth Analg 2007;105:1346‐56)

Objectives: It was hypothesized that anesthesiologists’ decisions to provide perioperative β-blockade during vascular surgery would be influenced more by physician factors than by those of their patients. Design: Mail survey. Setting: Case presentation. Participants: Four hundred thirty-nine anesthesiologists in the United States who responded to a survey. Interventions: By using Microsoft Word Mail Merge (Microsoft, Redmond, WA), 6 factors in a hypothetical patient presenting for vascular surgery (sex, race, age, comorbidities, functional status, and magnitude of surgical stress) were randomly varied. Measurements and Main Results: The response rate was 22%. Self-reported propensity to use β-blockade was significantly increased among anesthesiologists who worked in New England, among those who worked in larger hospitals, or who had received fellowship training. Among healthy patients, β-blockers were more likely to be used for older than younger patients. Among sicker patients, however, the reverse was true. Heart rate triggers for β-blockade use were higher than heart rates associated with improved outcomes in pivotal β-blocker trials. Conclusions: Preferences for perioperative β-blockade use in vascular surgery patients are influenced by anesthesiologists’ demographics as well as patient comorbidities or degree of surgical stress. This finding suggests that efforts to increase perioperative β-blockade in high-risk vascular patients face significant barriers from some groups of clinicians.

Treatment of [M(CO)(6)](-), M = Nb, Ta, with Ag(+), I(2) or NO(+) in the presence of CNXyl provided [M(CNXyl)(7)](+), M(CNXyl)(6)I, or cis-[M(CNXyl)(4)(NO)(2)](+), which are isocyanide analogues of the unknown carbonyl complexes [M(CO)(7)](+), M(CO)(6)I, or cis-[M(CO)(4)(NO)(2)](+), respectively. Reduction of M(CNXyl)(6)I by cesium graphite gave the respective Cs[M(CNXyl)(6)], which have been structurally characterized and represent the first isolable homoleptic isocyanidemetalates for second or third row transition metals. Nitrosylation of [Ta(CNXyl)(6)](-) affords a rare example of a mononitrosyl tantalum complex, Ta(CNXyl)(5)NO, which is an isocyanide analogue of the unknown Ta(CO)(5)NO. This study emphasizes, inter alia, the remarkable versatility of the CNXyl ligand compared to CO in stabilizing various electronic environments at heavier group 5 metal centers.

A chronological survey of the syntheses and characterizations of homoleptic mononuclear metal carbonyl anions is presented, from the first isolated example, [Fe(CO)4]2-, to the most recently reported species, [Hf(CO)6]2-. These materials are of historical interest, since they are the first compounds to contain transition metals in formal negative oxidation states, but remain important reagents in all areas of chemical synthesis and often closely resemble electron-rich nonmetallic compounds in their ability to function as Lewis and Bronsted bases, nucleophiles, and/or reducing agents. Prospects for the syntheses of new carbonyl anions for the very early and late transition metals and the lanthanides and actinides are also discussed.

Reduction of VCl3(THF)3(THF is tetrahydrofuran) and NbCl4(THF)2by alkali metal pyrene radical anion salts in THF affords the paramagnetic sandwich complexes bis[(1,2,3,3a,10a,10b-η)-pyrene]vanadium(0), [V(C16H10)2], and bis[(1,2,3,3a,10a,10b-η)-pyrene]niobium(0), [Nb(C16H10)2]. Treatment of tris(naphthalene)titanate(2−) with pyrene provides the isoelectronic titanium species, isolated as an (18-crown-6)potassium salt, namelycatena-poly[[(18-crown-6)potassium]-μ-[(1,2-η:1,2,3,3a,10a,10b-η)-pyrene]-titanate(−I)-μ-[(1,2,3,3a,10a,10b-η:6,7-η)-pyrene]], {[K(C12H24O6)][Ti(C16H10)2]}n. The first two compounds have very similar packing, with neighboring molecules arranged orthogonally to one another, such that aromatic donor–acceptor interactions are likely responsible for the specific arrangement. The asymmetric unit contains a half-occupancy metal center η6-coordinated to one pyrene ligand, with the fullM(pyrene)2molecule generated by a crystallographic inversion center. In the titanium compound, the cations and anions are in alternating contact throughout the crystal structure, in one-dimensional chains along the [101] direction. As in the other two compounds, the asymmetric unit contains a half-occupancy Ti atom η6-coordinated to one pyrene ligand. Additionally, the asymmetric unit contains one half of an (18-crown-6)potassium cation, located on a crystallographic inversion center coincident with the K atom. The full formula units are generated by those inversion centers. In all three structures, the pyrene ligands are eclipsed and sandwich the metals in one of two inversion-related sites. These species are of interest as the first isolable homoleptic pyrene transition metal complexes to be described in the scientific literature.

Reduction of Na[Ir(CO)4] by sodium metal in (Me2N)3PO, followed by treatment with liquid ammonia, provided high yields (ca. 90%) of unsolvated Na3[Ir(CO)3], a thermally stable, pyrophoric orange solid. This substance contains iridium in its lowest known formal oxidation state of -3 and has been characterized by IR spectroscopy, elemental analyses, and derivative chemistry, i.e., by its conversion to the triphenylgermyl and triphenylstannyl complexes, trans-[Ir(CO)3(EPh3)2](-), E = Ge, Sn. Single-crystal X-ray structures of the tetraethylammonium salts of these species, as well as [Co(CO)3(SnPh3)2](-), confirm the trigonal bipyramidal nature of the anions, originally predicted on the basis of their IR spectra in the carbonyl stretching frequency region. These structural characterizations provide important additional evidence for the presence of metal tricarbonyl units in Na3[M(CO)3], M = Co, Ir.

OBJECTIVE: To determine the excess mortality associated with obesity (defined by body mass index (BMI)) in older people, with and without adjustment for other risk factors associated with mortality and for demographic factors. DESIGN: Retrospective cohort analysis of the Longitudinal Study of Aging (LSOA). SETTING: Nationally representative sample of community-dwelling older people. PARTICIPANTS: Seven thousand five hundred and twenty-seven participants age 70 and older in 1984. MEASUREMENTS: We used Cox regression to calculate proportional hazards ratios for mortality over 96 months. We tested the hypothesis that increased BMI (top 15%) increased mortality rates in older people. RESULTS: Death occurred in 38% of the cohort: 54% of the thin (lowest 10% of the population, BMI 28.5 kg/m2), and 37% of the remaining participants (normal) died. Adjustment for demographic factors, health services utilization, and functional status still demonstrated reduced mortality in obese older people (hazard ratio 0.86, 95% confidence interval (CI) = 0.77–0.97) compared with normal. After adjustment, thin older people remained more likely to die (hazard ratio 1.46, 95% CI = 1.30–1.64) than normal older people. Sensitivity analyses for income, mortality during the first two years of follow-up, and medical comorbidities did not substantively alter the conclusions. CONCLUSION: Obesity may be protective compared with thinness or normal weight in older community-dwelling Americans.

The first homoleptic paramagnetic transition metal isocyanide, V(CNXyl)6 (2, Xyl = 2,6-dimethylphenyl), can be isolated in high yield by reacting bis(naphthalene)vanadium(0) (1a) or bis(1-methylnap...

Treatment of Mn(CO)3(NO)(PPh3) in THF at 20°C with excess sodium amalgam, followed by treatment with cryptand 2.2.2, or with two equiv. of potassium tri-sec-butylborohydride afforded high isolated yields (≥80%) of air sensitive yellow solids identified as [Na(crypt.2.2.2)]2[Mn(CO)3(NO)] and K2[Mn(CO)3(NO)], respectively. These products contain the only known mixed carbonylnitrosylmetallate dianion, isoelectronic with [Fe(CO)4]2− and [Mn(CO)4]3−. Reactions of [Mn(CO)3(NO)]2− with Ph3SnCl, Mn(CO)4(NO) and Fe(CO)5, followed by metathesis, provided the new derivatives [Et4N][Mn(CO)3(NO)(SnPh3)], [PPN]2[Mn2(CO)6(NO)2], and [PPN]2[MnFe(CO)7(NO)]. On the basis of IR spectral data the latter two have been formulated to contain non-bridged structures analogous to that previously established for the isoelectronic salt [PPN]2[Fe2(CO)8].

UNLABELLED Sixty-four patients undergoing elective major surgery were randomly assigned into a double-blinded, placebo-controlled, clinical trial to test the hypothesis that premedication with clonidine would attenuate postoperative reductions in circulating lymphocytes. The treatment group (n = 28) received a clonidine skin patch (0.3 mg/d) and a 0.6-mg oral loading dose 60-90 min before surgery. The control group (n = 36) received placebo patches and pills. Absolute blood levels of the following lymphocyte subsets were measured before induction of a standardized general anesthetic (baseline) and the morning after surgery: CD2, CD3, CD4, CD8, CD20, CD56, and the CD4:CD8 ratio. Significant decreases in lymphocyte subsets CD2, CD3, and CD4 were found in both groups; CD56 was significantly decreased only in the placebo group. However, the extent of lymphocyte depletion from baseline to Postoperative Day 1 between the clonidine and placebo groups was not different. Plasma concentrations of epinephrine, norepinephrine, and cortisol were measured from blood samples drawn at 8:00 AM on Postoperative Day 1. Plasma norepinephrine levels were significantly lower among patients who received clonidine. However, no significant differences were found in plasma epinephrine or cortisol levels between the clonidine and placebo groups. With a clinical dose, clonidine did not prevent postoperative lymphocyte depletion. alpha2-Agonists may not suppress adrenocortical stress responses sufficiently to prevent postoperative immune suppression. IMPLICATIONS Lymphocyte (white blood cell) counts often decrease after major surgery. We hypothesized that clonidine would reduce hormonal stress and blunt reductions in lymphocytes after major surgery. In a randomized trial, we found no differences from placebo in cortisol levels or lymphocyte changes. Lymphocyte levels did not predict infectious complications.