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Background: The occurrence and sequelae of acute myocardial infarction (AMI) in major trauma patients is underexplored across both trauma and cardiology specialties. Coronary reperfusion greatly reduces the risk of significant morbidity and mortality in AMI. However, in patients presenting with significant injuries, concurrent AMI presents a competing management priority given the increase in risk of bleeding with standard anticoagulation and antiplatelet therapy, which may be contraindicated. This study aimed to evaluate the epidemiology and clinical outcomes associated with AMI in a contemporary major trauma cohort., Methods: This study used data from the Victorian State Trauma Registry (VSTR). All adult patients with major trauma from 1 January 2013 to 31 December 2022 were included. Patients that died prior to hospital arrival were excluded. AMI was identified by ICD-10-AM diagnosis codes recorded against the first hospital admission. Clinical outcomes included in-hospital mortality, length of stay, and discharge destination., Results: 28,928 patients were identified over the 10-year study period. AMI occurred in 401 patients (1.4 %). AMI patients were older, had more comorbidities and were more frequently on anticoagulation or antiplatelet therapy. Low impact fall was the most common trauma mechanism in AMI patients. Patients with AMI experienced longer hospital stays (12 [7-20] versus 7 [4-12] days, p < 0.001) and higher rates of in-hospital mortality (adjusted RR 1.45, 95 % CI 1.25-1.65)., Conclusion: AMI in the setting of major trauma occurs in an older, more comorbid, and vulnerable group of patients. AMI is associated with an increased risk of in-hospital mortality and prolonged hospital stay in the setting of major trauma, underscoring the importance of identifying and treating major trauma associated AMI in a timely and effective manner., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

Patients with acute coronary syndrome (ACS)-related cardiogenic shock (CS) with or without concomitant CA may have disparate prognoses. We compared clinical characteristics and outcomes of patients with CS secondary to ACS with and without cardiac arrest (CA). Between 2014 and 2020, 1,573 patients with ACS-related CS with or without CA who underwent percutaneous coronary intervention enrolled in a multicenter Australian registry were analyzed. Primary outcome was 30-day major adverse cardiovascular and cerebrovascular events (MACCE) (composite of mortality, myocardial infarction, stent thrombosis, target vessel revascularization and stroke). Long-term mortality was obtained through linkage to the National Death Index. Compared with the no-CA group (n = 769, 49%), the CA group (n = 804, 51%) was younger (62 vs 69 years, p <0.001) and had fewer comorbidities. Patients with CA more frequently had ST-elevation myocardial infarction (92% vs 86%), occluded left anterior descending artery (43% vs 33%), and severe preprocedural renal impairment (49% vs 42%) (all p <0.001). CA increased risk of 30-day MACCE by 45% (odds ratio 1.45, 95% confidence interval 1.05 to 2.00, p = 0.024) after adjustment. CA group had higher 30-day MACCE (55% vs 42%, p <0.001) and mortality (52% vs 37%, p <0.001). Three-year survival was lower for CA compared with no-CA patients (43% vs 52%, p <0.001). In Cox regression, CS with CA was associated with a trend toward greater long-term mortality hazard (hazard ratio 1.19, 95% confidence interval 1.00 to 1.41, p = 0.055). In conclusion, concomitant CA among patients with ACS-related CS conferred a particularly heightened short-term risk with a diminishing legacy effect over time for mortality. CS survivors continue to exhibit high sustained long-term mortality hazard regardless of CA status., Competing Interests: Declaration of Competing Interest The authors have no competing interests to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Clinical features among patients with refractory out-of-hospital cardiac arrest (OHCA) and initial shockable rhythms of ventricular fibrillation/pulseless ventricular tachycardia are not well-characterized., Methods: We compared clinical characteristics and coronary angiographic findings between patients with refractory OHCA (incessant ventricular fibrillation/pulseless ventricular tachycardia after ≥3 direct-current shocks) and those without refractory OHCA., Results: Between 2014 and 2018, a total of 204 patients with ventricular fibrillation/pulseless ventricular tachycardia OHCA (median age 62; males 78%) were divided into groups with (36%, 74/204) and without refractory arrest (64%, 130/204). Refractory OHCA patients had longer cardiopulmonary resuscitation (23 versus 15 minutes), more frequently required ≥450 mg amiodarone (34% versus 3.8%), and had cardiogenic shock (80% versus 55%) necessitating higher adrenaline dose (4.0 versus 1.0 mg) and higher rates of mechanical ventilation (92% versus 74%; all P <0.01). Of 167 patients (82%) selected for coronary angiography, 33% (n=55) had refractory OHCA ( P =0.035). Significant coronary artery disease (≥1 major vessel with >70% stenosis) was present in >70% of patients. Refractory OHCA patients frequently had acute coronary occlusion (64% versus 47%), especially left circumflex (20% versus 6.4%) and graft vessel (7.3% versus 0.9%; all P <0.05) compared with those without refractory OHCA. Refractory OHCA group had higher in-hospital mortality (45% versus 30%, P =0.036) and greater new requirement for dialysis (18% versus 6.3%, P =0.011). After adjustment, refractory OHCA was associated with over 2-fold higher odds of in-hospital mortality (odds ratio, 2.28 [95% CI, 1.06-4.89]; P =0.034)., Conclusions: Refractory ventricular fibrillation/pulseless ventricular tachycardia OHCA was associated with more intensive resuscitation, higher rates of acute coronary occlusion, and poorer in-hospital outcomes, underscoring the need for future studies in this extreme-risk subgroup., Competing Interests: Disclosures None.

Objective: Sex differences in patients presenting with out-of-hospital cardiac arrest (OHCA) and shockable rhythm might be associated with disparities in clinical outcomes., Methods: We conducted a retrospective cohort study and compared characteristics and short-term outcomes between male and female adult patients who presented with OHCA and shockable rhythm at two large metropolitan health services in Melbourne, Australia between the period of 2014-2018. Logistic regression was used to assess the effect of sex on clinical outcomes., Results: Of 212 patients, 166 (78%) were males and 46 (22%) were females. Both males and females presented with similar rates of ST-elevation myocardial infarction (44% vs 36%, P = 0.29), although males were more likely to have a history of coronary artery disease (32% vs 13%) and a final diagnosis of a cardiac cause for their OHCA (89% vs 72%), both P = 0.01. Rates of coronary angiography (81% vs 71%, P = 0.23) and percutaneous coronary intervention (51% vs 42%, P = 0.37) were comparable among males and females. No differences in rates of in-hospital mortality (38% vs 37%, P = 0.90) and 30-day major adverse cardiac and cerebrovascular events (composite of all-cause mortality, myocardial infarction, coronary revascularization and nonfatal stroke) (39% vs 41%, P = 0.79) were observed between males and females, respectively. Female sex was not associated with worse in-hospital mortality when adjusted for other variables (odds ratio 0.66, 95% confidence interval 0.28-1.60, P = 0.36)., Conclusion: Among patients presenting with OHCA and a shockable rhythm, baseline sex and sex differences were not associated with disparities in short-term outcomes in contemporary systems of care., (© 2022 The Authors. Emergency Medicine Australasia published by John Wiley & Sons Australia, Ltd on behalf of Australasian College for Emergency Medicine.)

Heart failure with reduced ejection fraction (HFrEF) is associated with significant morbidity and mortality, particularly in patients with New York Heart Association (NYHA) functional class IV symptoms. Decades of discovery have heralded significant advancements in the pharmacologic management of HFrEF. However, patients with NYHA IV symptoms remain an under-represented population in almost every clinical trial to date, leaving clinicians with limited evidence with which to guide drug treatment decisions in this patient group with severe heart failure. Randomized controlled trials of adult patients with NYHA IV symptoms of HFrEF randomized to current guideline-recommended medical therapy were included in this systematic review and meta-analysis. The outcomes of interest included the rate of all-cause mortality, cardiovascular mortality, and heart failure hospitalization. A total of 39 randomized controlled trials were included. A total of 6 studies examined angiotensin converting enzyme inhibitors, with meta-analyses of 2 demonstrating a reduced risk of all-cause mortality (relative risk (RR) 0.76, 95% confidence interval 0.59 to 0.97, p = 0.03). A total of 11 studies examined β blockers, with meta-analysis of 6 demonstrating a reduced risk of all-cause mortality (risk ratio 0.74, 95% confidence interval 0.60 to 0.92, p = 0.008). A study examined the mineralocorticoid antagonist spironolactone, reporting a reduced risk of all-cause mortality in the NYHA IV subgroup. A total of 6 studies examined device therapy, demonstrating the benefit of cardiac resynchronization therapy with or without an implantable cardiac defibrillator in reducing hospitalization in the NYHA IV subgroup. Although trial evidence exists for angiotensin converting enzyme inhibitors, β-blockers, and mineralocorticoid antagonist therapy in the NYHA IV population, the role of angiotensin receptor blockers is unclear. Ivabradine, angiotensin receptor neprilysin inhibitors, and sodium-glucose transport protein 2 inhibitors remain underinvestigated and have not been proved to provide any benefit above standard heart failure therapy in patients with HFrEF and NYHA IV symptoms., Competing Interests: Disclosures The authors have no conflicts of interest to declare., (Crown Copyright © 2022. Published by Elsevier Inc. All rights reserved.)

Background: Clinical factors favouring coronary angiography (CA) selection and variables associated with in-hospital mortality among patients presenting with out-of-hospital cardiac arrest (OHCA) without ST-segment elevation (STE) remain unclear., Methods: We evaluated clinical characteristics associated with CA selection and in-hospital mortality in patients with OHCA, shockable rhythm and no STE., Results: Between 2014 and 2018, 118 patients with OHCA and shockable rhythm without STE (mean age 59; males 75%) were stratified by whether CA was performed. Of 86 (73%) patients undergoing CA, 30 (35%) received percutaneous coronary intervention (PCI). CA patients had shorter return of spontaneous circulation (ROSC) time (17 vs. 25 min) and were more frequently between 50 and 60 years (29% vs. 6.5%), with initial Glasgow Coma Scale (GCS) score >8 (24% vs. 6%) (all p < 0.05). In-hospital mortality was 33% (n = 39) for overall cohort (CA 27% vs. no-CA 50%, p = 0.02). Compared to late CA, early CA ( ≤ 2 h) was not associated with lower in-hospital mortality (32% vs. 34%, p = 0.82). Predictors of in-hospital mortality included longer defibrillation time (odds ratio 3.07, 95% confidence interval 1.44-6.53 per 5-min increase), lower pH (2.02, 1.33-3.09 per 0.1 decrease), hypoalbuminemia (2.02, 1.03-3.95 per 5 g/L decrease), and baseline renal dysfunction (1.33, 1.02-1.72 per 10 ml/min/1.73 m 2 decrease), while PCI to lesion (0.11, 0.01-0.79) and bystander defibrillation (0.06, 0.004-0.80) were protective factors (all p < 0.05)., Conclusions: Among patients with OHCA and shockable rhythm without STE, younger age, shorter time to ROSC and GCS >8 were associated with CA selection, while less effective resuscitation, greater burden of comorbidities and absence of treatable coronary lesion were key adverse prognostic predictors., (© 2022 The Authors. Catheterization and Cardiovascular Interventions published by Wiley Periodicals LLC.)

Objectives: Despite an increase in the use of mechanical circulatory support (MCS) devices for acute myocardial infarction cardiogenic shock (AMI-CS), there is currently no randomised data directly comparing the use of Impella and veno-arterial extra-corporeal membrane oxygenation (VA-ECMO)., Methods: Electronic databases of MEDLINE, EMBASE and CENTRAL were systematically searched in November 2021. Studies directly comparing the use of Impella (CP, 2.5 or 5.0) with VA-ECMO for AMI-CS were included. Studies examining other modalities of MCS, or other causes of cardiogenic shock, were excluded. The primary outcome was in-hospital mortality., Results: No randomised trials comparing VA-ECMO to Impella in patients with AMI-CS were identified. Six cohort studies (five retrospective and one prospective) were included for systematic review. All studies, including 7093 patients, were included in meta-analysis. Five studies reported in-hospital mortality, which, when pooled, was 42.4% in the Impella group versus 50.1% in the VA-ECMO group. Impella support for AMI-CS was associated with an 11% relative risk reduction in in-hospital mortality compared to VA-ECMO (risk ratio 0.89; 95% CI 0.83-0.96, I 2 0%). Of the six studies, three studies also adjusted outcome measures via propensity-score matching with reported reductions in in-hospital mortality with Impella compared to VA-ECMO (risk ratio 0.72; 95% CI 0.59-0.86, I 2 35%). Pooled analysis of five studies with 6- or 12-month mortality data reported a 14% risk reduction with Impella over the medium-to-long-term (risk ratio 0.86; 95% CI 0.76-0.97, I 2 0%)., Conclusions: There is no high-level evidence comparing VA-ECMO and Impella in AMI-CS. In available observation studies, MCS with Impella was associated with a reduced risk of in-hospital and medium-term mortality as compared to VA-ECMO.

Characteristics of patients presenting with out-of-hospital cardiac arrest (OHCA) selected for coronary angiography (CA) and factors predicting in-hospital mortality remain unclear. We assessed clinical characteristics associated with undertaking CA in patients presenting with OHCA and shockable rhythm (CA group). Predictors of in-hospital mortality were evaluated with multivariable analysis. Of 1,552 patients presenting with cardiac arrest between 2014 and 2018 to 2 health services in Victoria, Australia, 213 patients with OHCA and shockable rhythm were stratified according to CA status. The CA group had shorter cardiopulmonary resuscitation duration (17 vs 25 minutes) and time to return of spontaneous circulation (17 vs 26 minutes) but higher proportion of ST-elevation on electrocardiogram (48% vs 24%) (all p <0.01). In-hospital mortality was 38% (n = 81) for the overall cohort, 32% (n = 54) in the CA group, and 61% (n = 27) in the no-CA group. Predictors of in-hospital mortality included non-selection for CA (odds ratio 4.5, 95% confidence interval 1.5 to 14), adrenaline support (3.9, 1.3 to 12), arrest at home (2.7, 1.1 to 6.6), longer time to defibrillation (2.5, 1.5 to 4.2 per 5-minute increase), lower blood pH (2.1, 1.4 to 3.2 per 0.1 decrease), lower albumin (2.0, 1.2 to 3.3 per 5 g/L decrease), higher Acute Physiology and Chronic Health Evaluation II score (1.7, 1.0 to 3.0 per 5-point increase), and advanced age (1.4, 1.0 to 2.0 per 10-year increase) (all p ≤0.05). In conclusion, non-selection for CA, concomitant cardiogenic shock requiring inotropic support, poor initial resuscitation (arrest at home, longer time to defibrillation and lower pH), greater burden of co-morbidities (higher Acute Physiology and Chronic Health Evaluation II score and lower albumin), and advanced age were key adverse prognostic indicators among patients with OHCA and shockable rhythm., Competing Interests: Disclosures The authors have no conflicts of interest to declare., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objectives: Approximately 5-10% of patients presenting for percutaneous coronary intervention (PCI) have concurrent atrial fibrillation (AF). To what extent AF portends adverse long-term outcomes in these patients remains to be defined., Methods: We analysed data from the multicentre Melbourne Interventional Group Registry from 2014-2018. Patients were identified as being in AF or sinus rhythm (SR) at the commencement of PCI. The primary endpoint was long-term mortality, obtained via linkage with the National Death Index., Results: 13,286 procedures were included, with 800 (6.0%) patients in AF and 12,486 (94.0%) in SR. Compared to SR, patients with AF were older (72.9±10.9 vs 64.1±12.0 p<0.001) and more likely to have comorbidities including diabetes mellitus (31.3% vs 25.0% p<0.001), hypertension (74.4% vs 65.1% p<0.001) and moderate to severe left ventricular systolic dysfunction (36.6% vs 19.5% p<0.001). Atrial fibrillation was associated with an increased risk of in-hospital mortality (11.0% vs 2.5% p<0.001) and MACE (composite of all-cause mortality, myocardial infarction, or target vessel revascularisation) (11.9% vs 4.2% p<0.001). In-hospital major bleeding was more common in the AF group (3.1% vs 1.0% p<0.001). On Cox proportional hazards modelling, AF was an independent predictor of long-term mortality (adjusted HR 1.38 95% CI 1.11-1.72 p<0.004) at a mean follow-up of 2.3±1.5 years., Conclusions: Preprocedural AF is common among patients presenting for PCI. Preprocedural AF is associated with high-rates of comorbid illnesses and portends higher risk of short- and long-term outcomes including mortality underscoring the need for careful evaluation of its risks prior to PCI., (Crown Copyright © 2022. Published by Elsevier B.V. All rights reserved.)

Background: Patients undergoing heart transplant are at high risk for postoperative vasoplegia. Despite its frequency and association with poor clinical outcomes, there remains no consensus definition for vasoplegia, and the predisposing risk factors for vasoplegia remain unclear. Accordingly, the aim of this study was to evaluate the prevalence, predictors, and clinical outcomes associated with vasoplegia in a contemporary cohort of patients undergoing heart transplantation., Methods: This was a retrospective cohort study of patients undergoing heart transplantation from January 2015 to December 2019. A binary definition of vasoplegia of a cardiac index of 2.5 L/min/m 2 or greater and requirement for norepinephrine (≥5 µg/min), epinephrine (≥4 µg/min), or vasopressin (≥1 unit/h) to maintain a mean arterial blood pressure of 65 mm Hg, for 6 consecutive hours during the first 48 hours postoperatively, was used in determining prevalence. Given the relatively low threshold for the binary definition of vasoplegia, patients were divided into tertiles based on their cumulative vasopressor requirement in the 48 hours following transplant. Outcomes included all-cause mortality, intubation time, intensive care unit length of stay, and length of total hospitalization., Results: After exclusion of patients with primary cardiogenic shock, major bleeding, or overt sepsis, data were collected on 95 eligible patients. By binary definition, vasoplegia incidence was 66.3%. We separately stratified by actual vasopressor requirement tertile (high, intermediate, low). Stratified by tertile, patients with vasoplegia were older (52.7 ± 10.2 vs 46.8 ± 12.7 vs 44.4 ± 11.3 years, P = .02), with higher rates of chronic kidney disease (18.8% vs 32.3% vs 3.1%, P = .01) and were more likely to have been transplanted from left ventricular assist device support (n = 42) (62.5% vs 32.3% vs 37.5%, P = .03). Cardiopulmonary bypass time was prolonged in those that developed vasoplegia (155 min [interquartile range 135-193] vs 131 min [interquartile range 117-152] vs 116 min [interquartile range 102-155], P = .003). Intubation time and length of intensive care unit and hospital stay were significantly increased in those that developed vasoplegia; however, this difference did not translate to a significant increase in all-cause mortality at 30 days or 1 year., Conclusions: Vasoplegia occurs at a high rate after heart transplantation. Older age, chronic kidney disease, mechanical circulatory support, and prolonged bypass time are all associated with vasoplegia; however, this study did not demonstrate an associated increase in all-cause mortality LAY SUMMARY: Patients undergoing heart transplantation are at high risk of vasoplegia, a condition defined by low blood pressure despite normal heart function. We found that vasoplegia was common after heart transplant, occurring in 60%-70% of patients after heart transplant after excluding those with other causes for low blood pressure. Factors implicated included age, poor kidney function, prolonged cardiopulmonary bypass time and preoperative left ventricular assist device support. We found no increased risk of death in patients with vasoplegia despite longer lengths of stay in intensive care and in hospital., Competing Interests: Conflicts of Interest No conflicts of interest., (Crown Copyright © 2021. Published by Elsevier Inc. All rights reserved.)

International guidelines suggest revascularization within 24 hours in non-ST segment elevation myocardial infarction (NSTEMI). Within a large population cohort study, we aimed to explore clinical practice regarding timing targets for percutaneous coronary intervention (PCI) in NSTEMI. The Victorian Cardiac Outcomes Registry was established in 2013 as a state-wide clinical quality registry, pooling data from public and private PCI capable centers. Data were collected on 11,852 PCIs performed for NSTEMI from 2014 to 2018. Patients were divided into 3 groups by time of symptom onset to PCI (<24 hours; 24 to 72 hours; >72 hours). We performed multivariable logistic regression analysis conditional on several baseline covariates in investigating the impact of timing of PCI in NSTEMI on clinical outcomes. Patients who underwent PCI within 24 hours represented 18.4% (n = 2,178); 24 to 72 hours 45.8% (n = 5,434); >72 hours 35.8% (n = 4,240). Patients waiting longer for PCI were older (62.6 ± 12.2 vs 64.8 ± 12.6 vs 67.0 ± 12.7, p <0.001), more likely to be female (23.1% vs 24.2% vs 26.4%, p = 0.007), and have diabetes (18.6% vs 21.1% vs 27.1%, p <0.001). Multivariate logistic regression found that as compared with PCI <24 hours, PCI 24 to 72 hours and PCI >72 hours of symptom onset were associated with a decreased risk of 30-day mortality (odds ratio 0.55; 95% confidence interval 0.35 to 0.86, p = 0.008 and odds ratio 0.64; 95% confidence interval 0.35 to 1.01, p = 0.053, respectively). There was no significant difference in 30-day mortality between groups following exclusion of patients presenting with cardiogenic shock or out of hospital cardiac arrest requiring intubation. In conclusion, many registry patients undergo PCI outside the 24-hour window following NSTEMI. This delay is at odds with current guideline recommendations but does not appear to be associated with an increased mortality risk., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

Background: Narrowband ultraviolet (UV) B phototherapy (nbUVB) is a widely used modality in the treatment of psoriasis and is generally accepted to be safe in pregnancy. Previous studies have described photodegradation of serum folate after exposure to UVA radiation but the effect of UVB is not known. Insufficient folate levels predispose to neural tube defects in pregnancy. In addition, folate deficiency may increase the risk of colorectal carcinoma and influence serum homocysteine levels, which are thought to be a risk factor for cardiovascular disease., Objective: We sought to determine whether exposure to nbUVB reduces folate levels., Methods: This single-center, open observational study was conducted in a teaching hospital setting. Serum and red cell folate levels were measured in patients with psoriasis attending for nbUVB at baseline and after a minimum of 18 exposures., Results: A total of 35 patients completed the study. Mean serum and red cell folate levels at baseline were 6.34 and 410 ng/ml, respectively. After nbUVB, mean serum and red cell folate levels were 6.35 and 423 ng/ml, respectively. This was not significantly different from baseline measurements (P = .99 serum folate and P = .57 red cell folate)., Limitations: This study examined the effect of a standard course of 18 exposures of nbUVB on folate levels, rather than prolonged treatment. Adult patients with psoriasis only were investigated., Conclusion: A standard course of nbUVB does not have an effect on serum and red cell folate levels in patients with psoriasis.

The reaction of Pb(ClO4)2 x xH2O, an ancillary ligand L, and two equivalents of Au(CN)2(-) gave a series of crystalline coordination polymers, which were structurally characterized. The ligands were chosen to represent a range of increasing basicity, to influence the stereochemical activity (i.e., p-orbital character) of the Pb(II) lone pair. The Pb(II) center in [Pb(1,10-phenanthroline)2][Au(CN)2]2 (1) is 8-coordinate, with a stereochemically inactive lone pair; all 8 Pb-N bonds are similar. The Au(CN)2(-) units propagate a 2-D brick-wall structure. In [Pb(2,2'-bipyridine)2][Au(CN)2]2 (2), the 8-coordinate Pb(II) center has asymmetric Pb-N bond lengths, indicating moderate lone pair stereochemical activity; the supramolecular structure forms a 1-D chain/ribbon motif. For [Pb(ethylenediamine)][Au(CN)2]2 (3), the Pb(II) is only 5-coordinate and extremely asymmetric, with Pb-N bond lengths from 2.123(7) to 3.035(9) A; a rare Pb-Au contact of 3.5494(5) A is also observed. The Au(CN)2(-) units connect the Pb(ethylenediamine) centers to form 1-D zigzag chains which stack via Au-Au interactions of 3.3221(5) A to yield a 2-D sheet. (207)Pb MAS NMR of the polymers indicates an increase in both the chemical shielding span and isotropic chemical shift with increasing Pb(II) coordination sphere anisotropy (from delta iso = -2970 and Omega = 740 for 1 to delta iso = -448 and Omega = 3980 for 3). The shielding anisotropy is positively correlated with Pb(II) p-character, and reflects a direct connection between the NMR parameters and lone-pair activity. Solid-state variable-temperature luminescence measurements indicate that the emission bands at 520 and 494 nm, for 1 and 2, respectively, can be attributed to Pb --> L transitions, by comparison with simple [Pb(L)2](ClO4)2 salts. In contrast, two emission bands for 3 at 408 and 440 nm are assignable to Au-Au and Pb-Au-based transitions, respectively, as supported by single-point density-functional theory calculations on models of 3.

In a series of iron(III) halide complexes of the form {FeX[MesN(SiMe(2))]2O}2 (Mes = mesityl; X = Cl, Br, I), the ancillary diamidosilylether ligand can either chelate to one metal or instead bridge two metal centers, as a function of the halide coligand. The complexes are prepared from diamidosilyletheriron(II) precursors, which are oxidized with iodine, benzyl bromide, or PhICl2 to yield the appropriate iron(III) halide. The bromide analogue can also be synthesized by reacting the iron(II) precursor with a bromonium transfer agent (stabilized by adamantylideneadamantane). The latter reaction may proceed via an iron(IV) intermediate, which can oxidize the normally noncoordinating, inert [B(ArF)4]- counteranion [ArF = 3,5-(CF3)2Ph].

The coordination polymer Pb(H2O)[Au(CN)2]2 (1) was synthesized by the reaction of KAu(CN)2 and Pb(NO3)2. The structure contains 1-D chains of lead(II)-OH2 linked via Au(CN)2(-) moieties, generating a 2-D slab; weak aurophilic interactions of 3.506(2) and 3.4885(5) A occur within and between slabs. The geometry about each lead(II) is bicapped trigonal prismatic, having six N-bound cyanides at the prism vertices and waters at two of the faces. Dehydration at 175 degrees C yields microcrystalline Pb[Au(CN)2]2 (2), which, along with 1, was examined by 13C, 15N, 1H, and 207Pb solid-state NMR methods. Two 15N resonances are assigned to the mu2-bridging and hydrogen-bonding cyanides in 1. Upon dehydration, the 207Pb NMR spectrum becomes axially symmetric and yields a reduced shielding span, indicating higher site symmetry, while the 13C and 15N spectra reveal a single cyanide. Although no single-crystal X-ray structure of 2 could be obtained, a structure is proposed on the basis of the NMR and X-ray powder data, consisting of a lead(II) center in a distorted square-prismatic environment, with cyanides present at each corner. The birefringence of single crystals of 1 is found to be 7.0 x 10(-2) at room temperature. This value is large compared to that of most optical materials and can be attributed to the anisotropy of the 2-D slabs of 1, with all CN bonds aligned in the same direction by the polarizable lead(II) center.

A Cu(I)/Cu(II)/Zn(II) mixed-valent [Cu(en)2][Zn(NC)4(CuCN)2] polymer, which has a 2-D layer structure with six structurally inequivalent cyanides in four distinct bonding modes, has been prepared; structurally informative 13C and 15N MAS NMR spectra of this paramagnetic system are readily observable.

Two polymorphic products, [[Cu(tmeda)(mu-OH)}2Au(CN)4][Au(CN)4] (1) and [Cu(tmeda)(mu-OH)Au(CN)4]2 (2), were synthesized from {Cu(tmeda)(mu-OH)}(2)X(2) (tmeda = N,N,N',N'-tetramethylethylenediamine, X = ClO4-, BF4-) and 2 equiv of K[Au(CN)4], and their X-ray structures were determined. Both compounds have [Cu(tmeda)(mu-OH)}2(2+) dimers with [Au(CN)4]- units bound in the axial positions. However, in 1, two trans N-donor cyanides of each [Au(CN)4]- unit bind to adjacent copper(II) dimers, forming a 1-D chain, whereas complex 2 is molecular, with two mono-coordinated [Au(CN)4]- units. The 1-D polymorph 1 is formed from aqueous solution, while the molecular polymorph 2 is obtained with X = BF4- in methanol. The polymorphs have slightly different Cu-O-Cu angles, a key magnetostructural parameter, such that the 1-D chain 1, with an angle of 96.6(2) degrees, shows ferromagnetic interactions with 2J = +57.5 cm(-1) and g = 2.097, whereas the molecular complex 2, with an angle of 98.92(17) degrees, shows antiferromagnetic interactions with 2J = -143.6 cm(-1) and g = 2.047. A similar Cu(II) complex, [[Cu(tmeda)(mu-OH)]2Au(CN)4][ClO4].MeOH (3), was synthesized in methanol when X = ClO4-, in which the [Au(CN)4]- unit bridges the two Cu(II) centers within the dimer in an intramolecular fashion via cis N-donor cyanides. The average Cu-O-Cu angle of 98.4(2) degrees in 3 generates antiferromagnetic interactions with 2J = -64.8 cm(-1) and g = 2.214. Complexes 1-3 represent the first examples of [Cu(tmeda)(mu-OH)]2(2+) dimers with Cu-O-Cu angles under 100 degrees, thereby extending the range of 2J coupling constants for this moiety from 149 to 566 cm(-1). The switch to ferromagnetic interactions in 1 as a result of the coordinating, bridging [Au(CN)4]- anion suggests that cationic, dinuclear moieties that are typically antiferromagnetically coupled may, with an appropriate coordinating counterion, become ferromagnetic units.

Photopatch testing is indicated in the investigation of patients with eczematous eruptions, affecting mainly light-exposed sites and in those who give a history of worsening of their condition with sun exposure. 3 different protocols are described by the British Photodermatology Group (Br J Dermatol 1997:136:371-376), 1 of which includes irradiation of allergens 1 day after application and 2 using irradiation of allergens 2 days after application. There is no evidence for superiority of any of these protocols. We reviewed the records of all patients who underwent photopatch testing in Leeds over a 50-month period, who had had the allergens applied in triplicate with 1 set irradiated after 1 day occlusion and another after 2 days. The control was occluded for 2 days. Readings were performed at 2 days and 4 days. 15 of 74 patients photopatch tested during this period had 49 positive results between them. 43 of these were felt to be of current relevance to their clinical problem. 34 of the positive results were indicative of photoallergy. Additional photoallergic reactions were detected following 2 days occlusion and irradiation compared with 1 day occlusion (16 versus 5). In conclusion, our case series suggests that 2 days occlusion before irradiation of allergens is more sensitive at detecting photoallergy.

The high-yield synthesis, spectroscopic and structural determination of three new uranium(IV) and thorium(IV)ate complexes supported by three different diamido ether ligands are reported. The reaction of Li2[2,6-iPr2PhN(CH2CH2)]2O (Li2[DIPPNCOCN]) with 1 equiv. of UCl4 in THF generates [DIPPNCOCN]UCl3Li(THF)2(1), while reaction in toluene/ether gives salt-free [DIPPNCOCN]UCl2.1/2C7H8(2), which was identified by paramagnetically shifted 1H NMR. Reaction of 0.5 equiv. of {[tBuNON]UCl2}2([tBuNON]=[(CH3)3CN(Si(CH3)2)]2O2-) with 3.5 equiv. LiI in toluene and a minimal amount of THF results in [tBuNON]UI3Li(THF)2(3) and is very similar in structure to 1. {[MesNON]ThCl3Li(THF)}2(4), a dimeric complex with a Th2Li2Cl6 core, is prepared by reaction of Li2[2,4,6-Me3PhN(Si(CH3)2)]2O (Li2[MesNON]) with ThCl4 in THF. The analogous reaction in toluene did not yield the salt-free complex but rather a sterically crowded diligated compound, [MesNON]2Th (5), which was also structurally characterized. Complex 5 was prepared rationally by reacting 2 equiv. Li2[MesNON] with ThCl4 in toluene. The reaction of 1 and 3 with 2 equiv. of LiCH2Si(CH3)3 generates the stable, salt-free organoactinides [DIPPNCOCN]U(CH2Si(CH3)3)2(6) and [tBuNON]U(CH2Si(CH3)3)2(7). Complex 6 was structurally characterized. These reactions illustrate the viability of ate complexes as useful synthetic precursors.

The dilithio salts of two chelating diamidosilylether ligands undergo a retro-Brook rearrangement from oxygen to the amido-nitrogen, thereby directly yielding a new mixed-donor amido/amino/siloxo ligand. When reacted with chromium(II), siloxo-bridged dimers and a very strong eta(2)-(N,C(ipso)) arylamido interaction are featured.

Two polymorphs of an [Au(CN)2]-based coordination polymer, Cu[Au(CN)2]2(DMSO)2, one green (1) and one blue (2), have been identified. In polymorph 1, alternation of five-coordinate Cu(II) and [Au(CN)2]- units generates 1-D chains, while 2-D corrugated sheets are obtained in polymorph 2, which contains six-coordinate Cu(II) centers. Both polymorphs form 3-D networks by virtue of aurophilic interactions of 3.22007(5) A and 3.419(3) A, respectively, and show similar weak antiferromagnetic coupling, but have different thermal decomposition temperatures. They both show vapochromic properties and, importantly, despite their significantly different solid-state structures, the vapochromic behavior of the two polymorphs is essentially identical. Upon solvent exchange, both polymorphs convert to the same Cu[Au(CN)2]2(solvent)x complex (solvent = H2O, CH3CN, dioxane, N,N-dimethylformamide, pyridine, NH3). The Cu[Au(CN)2]2(DMF) and Cu[Au(CN)2]2(pyridine)2 complexes have very similar 2-D square grid structures, comparable to that of 2. The solvent molecules adsorbed by Cu[Au(CN)2]2 bind to the Cu(II) centers, thereby altering the visible spectrum associated with the Cu(II) chromophores and the number and frequency of the nu(CN) as well. The network-stabilizing gold-gold interactions and the flexible coordination sphere of Cu(II) probably facilitate reversible solvent exchange at room temperature.

In the reaction of organic monocationic chlorides or coordinatively saturated metal-ligand complex chlorides with linear, neutral Hg(CN)(2) building blocks, the Lewis-acidic Hg(CN)(2) moieties accept the chloride ligands to form mercury cyanide/chloride double salt anions that in several cases form infinite 1-D and 2-D arrays. Thus, [PPN][Hg(CN)(2)Cl].H(2)O (1), [(n)Bu(4)N][Hg(CN)(2)Cl].0.5 H(2)O (2), and [Ni(terpy)(2)][Hg(CN)(2)Cl](2) (4) contain [Hg(CN)(2)Cl](2)(2-) anionic dimers ([PPN]Cl = bis(triphenylphosphoranylidene)ammonium chloride, [(n)Bu(4)N]Cl = tetrabutylammonium chloride, terpy = 2,2':6',6' '-terpyridine). [Cu(en)(2)][Hg(CN)(2)Cl](2) (5) is composed of alternating 1-D chloride-bridged [Hg(CN)(2)Cl](n)(n-) ladders and cationic columns of [Cu(en)(2)](2+) (en = ethylenediamine). When [Co(en)(3)]Cl(3) is reacted with 3 equiv of Hg(CN)(2), 1-D [[Hg(CN)(2)](2)Cl](n)(n-) ribbons and [Hg(CN)(2)Cl(2)](2-) moieties are formed; both form hydrogen bonds to [Co(en)(3)](3+) cations, yielding [Co(en)(3)][Hg(CN)(2)Cl(2)][[Hg(CN)(2)](2)Cl] (6). In [Co(NH(3))(6)](2)[Hg(CN)(2)](5)Cl(6).2H(2)O (7), [Co(NH(3))(6)](3+) cations and water molecules are sandwiched between chloride-bridged 2-D anionic [[Hg(CN)(2)](5)Cl(6)](n)(6n-) layers, which contain square cavities. The presence (or absence), number, and profile of hydrogen bond donor sites of the transition metal amine ligands were observed to strongly influence the structural motif and dimensionality adopted by the anionic double salt complex anions, while cation shape and cation charge had little effect. (199)Hg chemical shift tensors and (1)J((13)C,(199)Hg) values measured in selected compounds reveal that the NMR properties are dominated by the Hg(CN)(2) moiety, with little influence from the chloride bonding characteristics. delta(iso)((13)CN) values in the isolated dimers are remarkably sensitive to the local geometry.

Several iron(III) complexes incorporating diamidoether ligands are described. The reaction between [Li(2)[RN(SiMe(2))](2)O] and FeX(3) (X=Cl or Br; R=2,4,6-Me(3)Ph or 2,6-iPr(2)Ph) form unusual ate complexes, [FeX(2)Li[RN(SiMe(2))](2)O](2) (2, X=Cl, R=2,4,6-Me(3)Ph; 3, X=Br, R=2,4,6-Me(3)Ph; 4, X=Cl, R=2,6-iPr(2)Ph) which are stabilized by Li-pi interactions. These dimeric iron(III)-diamido complexes exhibit magnetic behaviour characteristic of uncoupled high spin (S= 5/2 ) iron(III) centres. They also undergo halide metathesis resulting in reduced iron(II) species. Thus, reaction of 2 with alkyllithium reagents leads to the formation of iron(II) dimer [Fe[Me(3)PhN(SiMe(2))](2)O](2) (6). Similarly, the previously reported iron(III)-diamido complex [FeCl[tBuN(SiMe(2))](2)O](2) (1) reacts with LiPPh(2) to yield the iron(II) dimer [Fe[tBuN(SiMe(2))](2)O](2) but reaction with LiNPh(2) gives the iron(II) product [Fe(2)(NPh(2))(2)[tBuN(SiMe(2))](2)O] (5). Some redox chemistry is also observed as side reactions in the syntheses of 2-4, yielding THF adducts of FeX(2): the one-dimensional chain [FeBr(2)(THF)(2)](n) (7) and the cluster [Fe(4)Cl(8)(THF)(6)]. The X-ray crystal structures of 3, 5 and 7 are described.

A series of the first coordination polymers using the [Au(CN)(4)](-) anion as a building block has been prepared. The planar tetracyanoaurate anion uses one, two, or four cyano groups to bridge to Ni(II) or Cu(II) centers and exhibits weak Au(III)-N(cyano) interactions between anions. Ni(en)(2)[Au(CN)(4)](2).H(2)O (1, en = ethylenediamine) is a molecular compound with the two [Au(CN)(4)](-) anions coordinating in a trans orientation to Ni(II) without further cyanide coordination. Cu(dien)[Au(CN)(4)](2) (2, dien = diethylenetriamine) forms a similar molecular complex; however, the dimensionality is increased through weak intermolecular Au-N(cyano) interactions of 3.002(14) A to form a 1-D zigzag chain. Cu(en)(2)[Au(CN)(4)](2) (3) also forms a molecular complex similar to 1, but with elongated axial bonds. The complex further aggregates through Au-N(cyano) interactions of 3.035(8) A to form a 2-D array. In [Cu(dmeda)(2)Au(CN)(4)][Au(CN)(4)] (4, dmeda = N,N-dimethylethylenediamine) one [Au(CN)(4)](-) anion coordinates via two cis-N(cyano) donors to the axial sites of two Cu(II) centers to form a 1-D zigzag chain of alternating [Cu(dmeda)(2)](2+) and [Au(CN)(2)](-) units; the other [Au(CN)(4)](-) anion forms a 1-D chain via Au-N(cyano) interactions. In [Cu(bipy)(H(2)O)(2)(Au(CN)(4))(0.5)][Au(CN)(4)](1.5) (5, bipy = 2,2'-bipyridine) one [Au(CN)(4)](-) anion uses all four cyano moieties to bridge four different Cu(II) centers, creating a 1-D chain.

The preparations of two new phosphinothiophene ligands, 3,3'-bis(diphenylphosphino)-2,2'-bithiophene (dppbt; 1) and 3,3' "-dihexyl-3',3' '-bis(diphenylphosphino)-2,5':2',2' ':5' ',2' "-quaterthiophene (hdppqt; 2) are reported. Oxidation of 1 gives 3,3'-bis(diphenylphosphine oxide)-2,2'-bithiophene (3), and the crystal structure of this compound was determined. Pd(II) and Au(I) complexes of these ligands have been synthesized and characterized. Crystal structures of [(dppbt)PdCl(2)] (1-Pd), [(hdppqt)PdCl(2)] (2-Pd), [(dppbt)(AuCl)(2)] (1-Au), and [(hdppqt)(AuCl)(2)] (2-Au) were obtained. [(dppbt)(AuCl)(2)] crystallized in two solid-state forms; crystals grown from CH(2)Cl(2)/Et(2)O show a gold-gold interaction of 3.3221(4) A, but from CH(2)Cl(2)/toluene, the molecule crystallizes as a toluene adduct (1-Au-tol) and does not show any gold-gold interaction. All the complexes were characterized via UV-vis spectroscopy and cyclic voltammetry, and the effect of the metal on the energy of the pi-pi transition and oxidation potential was determined. These data are correlated to the interannular torsion angles in the oligothienyl groups from the crystal structure studies.

An unusual metal-ligand binding motif is found in dimeric cobalt(II) complexes coordinated by diamidoether ligands that bridge the metals in a 'serpentine' fashion through the ether donors of the ligand backbone rather than the amido groups.

A series of new heterometallic coordination polymers has been prepared from the reaction of metal-ligand cations and KAg(CN)(2) units. Many of these contain silver-silver (argentophilic) interactions, analogous to gold-gold interactions, which serve to increase supramolecular structural dimensionality. Compared to [Au(CN)(2)](-) analogues, these polymers display new trends specific to [Ag(CN)(2)](-), including the formation of [Ag(2)(CN)(3)](-) and the presence of Ag...N interactions. [Cu(en)(2)][Ag(2)(CN)(3)][Ag(CN)(2)] (1, en = ethylenediamine) forms 1-D chains of alternating [Ag(CN)(2)](-) and [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.102(1) A. These chains are connected into a 2-D array by strong cyano(N)-Ag interactions of 2.572(3) A. [Cu(dien)Ag(CN)(2)](2)[Ag(2)(CN)(3)][Ag(CN)(2)] (2, dien = diethylenetriamine) forms a 1-D chain of alternating [Cu(dien)](2+) and [Ag(CN)(2)](-) ions with the Cu(II) atoms connected in an apical/equatorial fashion. These chains are cross-linked by [Ag(2)(CN)(3)](-) units via argentophilic interactions of 3.1718(8) A and held weakly in a 3-D array by argentophilic interactions of 3.2889(5) A between the [Ag(CN)(2)](-) in the 2-D array and the remaining free [Ag(CN)(2)](-). [Ni(en)][Ni(CN)(4)].2.5H(2)O (4) was identified as a byproduct in the reaction to prepare the previously reported [Ni(en)(2)Ag(2)(CN)(3)][Ag(CN)(2)] (3). In [Ni(tren)Ag(CN)(2)][Ag(CN)(2)] (5, tren = tris(2-aminoethyl)amine), [Ni(tren)](2+) cations are linked in a cis fashion by [Ag(CN)(2)](-) anions to form a 1-D chain similar to the [Au(CN)(2)](-) analogue. [Cu(en)Cu(CN)(2)Ag(CN)(2)] (6) is a trimetallic polymer consisting of interpenetrating (6,3) nets stabilized by d(10)-d(10) interactions between Cu(I)-Ag(I) (3.1000(4) A). Weak antiferromagnetic coupling has been observed in 2, and a slightly stronger exchange has been observed in 6. The Ni(II) complexes, 4 and 5, display weak antiferromagnetic interactions as indicated by their relatively larger D values compared to that of 3. Magnetic measurements on isostructural [Ni(tren)M(CN)(2)][M(CN)(2)] (M = Ag, Au) show that Ag(I) is a more efficient mediator of magnetic exchange as compared to Au(I). The formation of [Ni(CN)(4)](2)(-), [Ag(2)(CN)(3)](-), and [Cu(CN)(2)](-) are all attributed to secondary reactions of the dissociation products of the labile KAg(CN)(2).

51V NMR and IR spectroscopic studies of the complexes formed between vanadate and the alpha-hydroxylic acid ligands, (S)-2-hydroxypropanoic acid (L-(+)-lactic acid), 2-hydroxy-2-methylpropanoic acid, and 2-ethyl-2-hydroxybutanoic acid were carried out for aqueous 1 M ionic strength (NaCl) solutions. Three major products in V to L stoichiometries of 1:1, 2:2, and 3:2 were identified from vanadate and ligand concentration studies, while a pH variation study allowed charge states to be determined. At pH 7.06, the formation constants for the predominant reactions were (26 +/- 1) M (-1), (V + L <= => VL); (6.8 +/- 0.4) x 10(3) M(-1), (2VL <= => V(2)L(2)); and (3.5 +/- 0.3) x 10(3) M(-1), (V(2)L(2) + V <= => V(3)L(2)). Dissolution studies of various crystalline products were carried out for aqueous, nonaqueous, and mixed solvent systems. These studies combined with information available from X-ray structural studies provided a basis for the assignment of solution state structures. Pentacoordinate vanadium in a trigonal-bipyramidal geometry was proposed for the both the 1:1 and 2:2 complexes when in aqueous solution. Observed changes in (51)V chemical shift patterns were consistent with a cis fusion in octahedral coordination for the central vanadium of the 3:2 complex, while the remaining vanadiums retained a pentacoordinate geometry.

A series of coordination polymers containing Cu(II) and [Au(CN)(2)](-) units has been prepared. Most of their structures incorporate attractive gold-gold interactions, thus illustrating that such "aurophilic" interactions can be powerful tools for increasing structural dimensionality in supramolecular systems. [Cu(tren)Au(CN)(2)][Au(CN)(2)] (1, tren = tris(2-ethylamino)amine) forms a cation/anion pair, which is weakly linked by hydrogen bonds but not by aurophilic interactions. [Cu(en)(2)Au(CN)(2)][Au(CN)(2)] (2-Au, en = ethylenediamine) is a 2-D system composed of a chain of [Au(CN)(2)](-) anions and another chain of [(en)(2)Cu-NCAuCN](+) cations; short Au-Au bonds of 3.1405(2) A connect the anions. This bond is shorter than that observed in the analogous silver(I) structure, 2-Ag. The average M-C bond lengths of 1.984(8) A in 2-Au are significantly shorter than those found in 2-Ag, suggesting that Au(I) is smaller than Ag(I). Cu(dien)[Au(CN)(2)](2) (3, dien = diethylenetriamine) forms a 1-D chain of tetranuclear [Au(CN)(2)](-) units that are bound to [Cu(dien)] centers. Aurophilic interactions of ca. 3.35 A hold the tetramer together. Cu(tmeda)[Au(CN)(2)](2) (4, tmeda = N,N,N',N'-tetramethylethylenediamine) forms a 3-D network by virtue of aurophilic interactions of 3.3450(10) and 3.5378(8) A. Altering the Cu:Au stoichiometry yields Cu(tmeda)[Au(CN)(2)](1.5)(ClO(4))(0.5) (5), which has an unusual 2-D rhombohedral layer structure (space group R32). Complex 5 is composed of three mutually interpenetrating Cu[Au(CN)(2)](1.5) networks which are interconnected by aurophilic interactions of 3.4018(7) and 3.5949(8) A. Weak antiferromagnetic coupling is observed in 2 and 5.

The conformational preferences about the C-N bond in N-(4-methoxyphenyl)-2,3,4,6-tetra-O-acetyl-alpha (1) and beta-D-glucopyranosylamine (2), in the solid state and in solution, have been investigated. The crystal structure of the axially substituted alpha anomer (1) indicates a conformational preference about the C-1-N bond in which nN-->sigma*C-O exo-anomeric interactions may be expressed, although this conformational preference is not displayed in solution. The solution conformation relieves steric interactions that result from expression of the exo-anomeric effect in the solid-state conformation. The conformational preference in the equatorially substituted beta anomer (2) both in solution and in the solid state is similar and permits expression of nN-->sigma*C-O exo-anomeric interactions. The structural data for 1 and 2 indicate significant differences in O-5-C-1-N-1 bond angles but insignificant differences in each of the O-5-C-1 or C-1-N-1 bond lengths. The J(C-1-H-1 coupling constants in 1 and 2 indicate a greater coupling constant for the alpha anomer that is consistent with a dominant nO-->sigma*C-H orbital interaction in the beta anomer that weakens the C-1-H-1 bond.

The homoallylically substituted alcohols (1-OH and 3-OH) of the sterically congested alkene adamanylideneadamantane (1-H) react with acid catalysis in a solvent of 50% v/v acetic acid:50% v/v aqueous sulfuric acid at 110 degrees C to give a saturated ketone 5, the structure of which has been characterized by (1)H and (13)C NMR spectroscopy and by single-crystal X-ray diffraction. Isotopic labeling studies demonstrate that the reaction involves a stereospecific protonation of the double bond and an intramolecular 1,4-hydride transfer from the secondary alcohol C-H to the other carbon of the olefin. The rearrangement reaction exhibits a kinetic isotope effect (KIE) of 2.34 +/- 0.17 for the intramolecular hydride transfer reaction and a competitive isotope effect of 1.2 for protonation of the olefin. These results are consistent with a two-step reaction in which the protonation of the double bond, a potentially reversible process, is followed by the rate-determining, intramolecular 1,4-hydride transfer.

Reaction of CpIr(CO)(2) (3, Cp = eta(5)-C(5)Me(5)) with [N(2)Ar][BF(4)] (Ar = p-C(6)H(4)OMe) in acetone at -78 degrees C affords the nitrogen extrusion product [CpIr(CO)(2)(Ar)][BF(4)] (5), but in dichloromethane it yields a dinuclear product [Cp(CO)(2)Ir-Ir(Cl)(CO)Cp][BF(4)] (6). By carrying out this very reaction in ethanol solution, a nitrogen-retained product [CpIr(CO)(OEt)(NHNAr)][BF(4)] (7) is obtained, containing an aryldiazene ligand. Deprotonation of 7 gives quantitatively the neutral doubly-bent aryldiazenido complex CpIr(CO)(OEt)(N(2)Ar) (8). The IR nu(CO) absorptions measured for the dinuclear compound 6 indicate no bridging carbonyl, but a (13)C NMR study in solution shows that 6 is stereochemically nonrigid at ambient temperature; its three carbonyl ligands are all involved in a fast exchange process, and this process is frozen at -86 degrees C. Exchange of the CO groups via a terminal-bridging-terminal process accompanied by rotation about the Ir-Ir axis is suggested. The molecular structure of 6 in the solid state has been established by single crystal X-ray crystallographic analysis and is consistent with the solution spectra. By reaction of [N(2)Ar][BF(4)] with the dinuclear complex [CpIr(CO)](2) (4) in acetone, the complex [{CpIr(CO)}(2)(1-eta(1)-1,2-eta(2)-p-C(6)H(4)OMe)][BF(4)] (9) with a rare sigma,pi-bridging aryl group has been obtained and crystallized. The molecular structure containing an asymmetric bridging aryl group is established for 9 in the solid state by a single crystal X-ray crystallographic analysis. However, the identical (1)H NMR features observed at ambient temperature and -90 degrees C in solution (i.e., a singlet resonance for the two Cp ligands and a symmetric AA'BB' pattern for the p-C(6)H(4)OMe) indicate a static or time-averaged symmetrical molecular geometry for 9. Compound 6 crystallizes in the monoclinic space group P2(1)/c with a = 10.583(2) Å, b = 14.256(3) Å, c= 16.818(4) Å, beta = 95.91 (2) degrees, V = 2523.9 Å(3), and Z = 4. Refinement yielded R(F)() = 0.027 and R(w)(F)() = 0.033 for 3299 observed reflections (I(o) >/= 2.5sigma(I(o))) of 4427 unique reflections. Compound 9 crystallizes in the monoclinic space group P2(1)/n with a = 11.695(2) Å, b = 19.911(3) Å, c= 12.539(2) Å, beta = 96.54(1) degrees, V = 2900.8 Å(3), and Z = 4. Refinement yielded R(F)() = 0.025 and R(w)(F)() = 0.035 for 3444 observed reflections (I(o) >/= 2.5sigma(I(o))) of 4526 unique reflections.

A crystalline glycylglycine complex of monoperoxovanadate has been obtained and its X-ray structure determined. The coordination is pentagonal bipyramidal with the peroxo group and a tridentate glycylglycine occupying the equatorial positions. The axial positions of the anion are occupied by the oxo ligand and by one oxygen of the peroxo group of the adjacent anion. The latter interaction establishes the seventh bond and produces a dimeric structure in the crystalline material. NMR studies of its dissolution in water combined with previously reported results from equilibrium measurements show that the dimer dissociates in water to the monomeric precursor. It is proposed that this monomer corresponds to the complex responsible for the inhibition of the vanadium-catalyzed decomposition of hydrogen peroxide by glycylglycine. Crystal structure of [NEt(4)][VO(O(2))(GlyGly)].1.58H(2)O: monoclinic, space group P2(1); Z = 4; a = 10.618(2) Å; b = 14.803(2) Å; c = 11.809(2) Å; beta = 101.37(2) degrees; V = 1819.7 Å(3); T = 198 K; R(F)() = 0.029 for 2664 data (I(o) >/= 2.5sigma(I(o))) and 431 variables.

Addition of carbon monoxide (0.5-2 atm) to iridium(III) fluorosulfate, Ir(SO(3)F)(3), dissolved in HSO(3)F over 4 days and at 60 degrees C, results in the quantitative formation of tris(carbonyl)iridium(III) fluorosulfate Ir(CO)(3)(SO(3)F)(3). Slow evaporation of the solvent produces single crystals of mer-Ir(CO)(3)(SO(3)F)(3). Crystal structure data for mer-Ir(CO)(3)(SO(3)F)(3): monoclinic, space group P2(1)/c, Z = 4, a = 8.476(1) Å, b = 12.868(2) Å, c = 12.588 (1) Å, beta = 108.24(1) degrees, V = 1304.0 Å(3), T = 200 K, R(F)() = 0.022 for 2090 data (I(o) >/= 2.5sigma(I(o))) and 200 variables. Vibrational spectra of the crystalline solid are consistent with a mer-isomer with CO stretching modes at 2249 (A(1)), 2208 (B(1)), and 2198 (A(1)) cm(-)(1) in the IR spectrum. In solution of HSO(3)F, additional CO stretching bands attributed to the fac-isomer are found in the FT-Raman and IR spectra at 2233 (A(1)) and 2157 cm(-)(1) (E). Additional evidence for a mixture of fac- and mer-isomers comes from (19)F NMR spectra. The vibrational spectra suggest strongly reduced iridium to CO pi-back-bonding. The crystal structure reveals significant intra- and intermolecular contacts between the electropositive C atom of the CO groups and O or F atoms of the fluorosulfate groups. Hence mer-tris(carbonyl)iridium(III) fluorosulfate becomes the first thermally stable, structurally characterized, and predominantly sigma-bonded carbonyl derivative of a metal in the +3 oxidation state.

The synthesis of bis(carbonyl)mercury(II) undecafluorodiantimonate(V), [Hg(CO)(2)][Sb(2)F(11)](2), and that of the corresponding mercury(I) salt [Hg(2)(CO)(2)][Sb(2)F(11)](2) are accomplished by the solvolyses of Hg(SO(3)F)(2) or of Hg(2)F(2), treated with fluorosulfuric acid, HSO(3)F, in liquid antimony(V) fluoride at 80 or 60 degrees C, respectively, in an atmosphere of CO (500-800 mbar). The resulting white solids are the first examples of metal carbonyl derivatives formed by a post-transition element. Both salts are characterized by FT-IR, FT-Raman, and (13)C-MAS-NMR spectroscopy. For [Hg(CO)(2)][Sb(2)F(11)], unprecedentedly high CO stretching frequencies (nu(av) = 2279.5 cm(-)(1)) and stretching force constant (f(r) = 21.0 +/- 0.1) x 10(2) Nm(-)(1)) are obtained. Equally unprecedented is the (1)J((13)C-(199)Hg) value of 5219 +/- 5 Hz observed in the (13)C MAS-NMR spectrum of the (13)C labeled isotopomers at delta = 168.8 +/- 0.1 ppm. The corresponding values (nu(av) = 2247 cm(-)(1), f(r) = (20.4 +/- 0.1) x 10(2) Nm(-)(1), (1)J((13)C-(199)Hg) = 3350 +/- 50 Hz and (2)J((13)C-(199)Hg) 850 +/- 50 Hz) are found for [Hg(2)(CO)(2)][Sb(2)F(11)](2), which has lower thermal stability (decomposition point in a sealed tube is 140 degrees C vs 160 degrees C for the Hg(II) compound) and a decomposition pressure of 8 Torr at 20 degrees C. The mercury(I) salt is sensitive toward oxidation to [Hg(CO)(2)][Sb(2)F(11)](2) during synthesis. Both linear cations (point group D(infinity)(h)()) are excellent examples of nonclassical (sigma-only) metal-CO bonding. Crystal data for [Hg(CO)(2)][Sb(2)F(11)](2): monoclinic, space group P2(1)/n; Z = 2; a = 7.607(2) Å; b = 14.001(3) Å; c = 9.730(2) Å; beta = 111.05(2) degrees; V = 967.1 Å(3); T = 195 K; R(F) = 0.035 for 1983 data (I(o) >/= 2.5sigma(I(o))) and 143 variables. The Hg atom lies on a crystallographic inversion center. The Hg-C-O angle is 177.7(7) degrees. The length of the mercury-carbon bond is 2.083(10) Å and of the C-O bond 1.104(12) Å respectively. The structure is stabilized in the solid state by a number of significant secondary interionic Hg- - -F and C- - -F contacts.

Two models of allorecognition of MHC molecules have been proposed. One emphasizes specificity for MHC molecule-bound peptides and the other for exposed MHC polymorphisms. We predicted that the latter model would predominate in responder:stimulator combinations whose MHC molecules differed extensively in their TCR-contacting surfaces and that this would be reflected in biased TCR usage. Two panels of anti-DR11 T cell clones were generated, one from a DR17 and the other from a DR15 responder. The TCR-contacting surfaces of DR17 and DR11 have multiple differences, and those of DR15 and DR11 are very similar. TCR analysis by polymerase chain reaction amplification and mAb staining revealed that five out of nine DR17 anti-DR11 clones used the V beta 13 and two the V beta 6, family. In contrast seven different V beta families were used by the eight DR15 anti-DR11 clones. A similar bias in TCR V beta usage was observed in the polyclonal DR17 and DR11 T cell lines from which the clones were derived, and in a second DR17 anti-DR11 line from a different individual. These results support the concept that specificity for the foreign MHC structure itself may play an important role in the alloresponse between responders and stimulators with structurally dissimilar MHC molecules.

The human fibroblast cell line, M1, expressing the products of transfected DRA and DRB1*0101 genes (M1-DR1) was unable to present intact influenza antigens to a series of DR1-restricted human T cell lines and clones, but was fully able to present synthetic peptides for T cell recognition. In contrast, M1-DR1 cells infected with live influenza virus were recognized by two polyclonal hemagglutinin- or whole virus-specific T cell lines and one of four T cell clones. This difference could not be accounted for simply by the ability of infectious virus to overcome a defect in antigen uptake by the M1-DR1 cells, in that direct studies of endocytosis showed that the M1 cells were more efficient than human B cells in the internalization of exogenous protein. These data suggested that the M1 cells were unable to present exogenous antigens but were capable of loading major histocompatibility complex (MHC) class II molecules with peptides derived from endogenous antigens. To investigate this further, the M1-DR1 cells were super-transfected with a cDNA encoding the p33 and p35 forms of the human invariant chain (Ii). Expression of the Ii chain was detected by intracytoplasmic staining of transfectants, and by metabolic labeling. Equimolar amounts of the p33 and p35 forms were detected, and the high level of p35 Ii was reflected by extensive retention of Ii protein in the endoplasmic reticulum. Addition of the Ii chain led to no recovery of presentation of intact antigens with DR1, but inhibited the presentation of live virus. These data indicate that MHC class II molecules in the M1-DR1 cells can be loaded with peptides derived from endogenous proteins, possibly in the biosynthetic pathway, and that the Ii chain has a role in limiting this route of class II antigen presentation.