Synthesis and molecular structure of Cr(salen)(mu-N)RhCl(COD): the first example of a heterobimetallic nitride-bridged complex containing chromium

Five-coordinate Cr(N)(salen) {salen is 2,2'-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolate} reacts with [RhCl(COD)](2) (COD is 1,5-cyclooctadiene) to yield the heterobimetallic nitride-bridged title compound, namely chlorido-2kappaCl-[2(eta(4))-1,5-cyclooctadiene]{2,2'-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato-1kappa(4)O,N,N',O'}-mu-nitrido-1:2kappa(2)N:N-chromium(V)rhodium(I), [CrRh(C(16)H(14)N(2)O(2))ClN(C(8)H(12))]. The Cr-N bond of 1.5936 (14) A is elongated by only 0.035 A compared to the terminal Cr-N bond in the precursor. The nitride bridge is close to being linear [173.03 (9) degrees] and the Rh-N bond of 1.9594 (14) A is very short for a monodentate nitrogen-donor ligand, indicating significant pi-acceptor character of the Cr[triple bond]N group.

(E,E,E)-1,3,5-Tris[4-(acetylsulfanyl)styryl]benzene toluene hemisolvate

The first crystal structure of a three-terminal sulfur end-capped oligophenylenevinylene, C36H30O3S3 x 0.5C7H8, has been determined at 122 (1) K. The molecular threefold symmetry is not utilized in the crystal structure. It is confirmed that the double bonds have been fully transformed into a trans configuration by iodine treatment.

Dinuclear 1,4,7-triazacyclononane (tacn) complexes of cobalt(III) with amido and tacn bridges. Synthesis, characterization and reversible acid-accelerated bridge cleavage

Amido-bridged dinuclear cobalt(III) complexes with 1,4,7-triazacyclononane (tacn) were synthesized from [Co(tacn)(O3SCF3)3] by treatment with potassium amide in liquid ammonia at 100 degrees C. Two isomeric triply bridged complexes, [(tacn)Co(mu-NH2)3Co(tacn)]3+ and [(tacn)Co(mu-NH2)2[mu-tacn(-H)]Co(NH3)]3+, were isolated as perchlorates, and the crystal structure of the perrhenate of the latter complex was determined by X-ray diffraction. In this compound a nitrogen atom (deprotonated) from one of the tacn ligands forms a third bridge together with two amido bridges. In 1.0 M (Na,H)ClO4 ([H+] 0.1-1.0 M) the two isomers undergo acid-accelerated amido bridge cleavage, as earlier found for chromium(III) analogues, in spite of the fact that such bridges are co-ordinatively saturated. The triamido-bridged isomer is in this acid medium in equilibrium with [(H2O)(tacn)Co(mu-NH2)2Co(tacn)(NH3)]4+. An isolated perchlorate of this complex appeared to be the salt of the trans-ammineaqua isomer as determined by X-ray diffraction. Equilibration from both sides fits the first-order rate constant dependence k(obs)=6.2(3) x 10(-5)[H+] + 2.1(2) x 10(-5)(s(-1)) at 40 degrees C. Prolonged treatment of the two triply bridged isomers in 1.0 M HClO4 at elevated temperature produces primarily triply bridged dinuclear species where one or two amido bridges have been replaced by hydroxo bridges.

The trans influence in mer-trichloronitridobis(triphenylarsine)ruthenium(VI)

The title compound, mer-[RuCl(3)N(C(18)H(15)As)(2)], is the first structurally characterized example of a nitride complex in which ruthenium is six-coordinated to monodentate ligands only. The Ru[triple-bond]N bond length [1.6161 (15) A] is relatively long, and the trans influence of the nitride ligand is reflected by the difference between the Ru--Cl(trans) and Ru--Cl(cis) bond lengths [0.1234 (4) A]. The N--Ru--Cl(trans) axis is sited on a twofold axis.

Bile salt-stimulated lipase in the milk of Fulani and Kanuri women in Nigeria and native Nepalese women

Human milk provides newborns with several physiologically important proteins not found in cow's milk, including bile salt-stimulated lipase (BSSL) that compensates for the reduced lipolytic capability of the newborn intestine. We analyzed the milk of two ethnically distinct groups of women in northern Nigeria and Nepal. The milk of the Nepalese women (n = 36) contained slightly more BSSL activity (mean, 38.8 units/mL) than that of Fulani (n = 48; mean, 30.3 units/mL) and Kanuri (n = 90; mean 27.6 units/mL) women in Nigeria. There was also a weak positive correlation between the BSSL content of the milk and the body mass index (BMI) of the lactating women. The BSSL activity declined with the length of lactation for both well-nourished and undernourished women. The presence of a heat-stable inhibitor of BSSL in cow's milk was also demonstrated. This finding, along with the decrease in BSSL activity postgestation, could be of significance to populations such as the Fulani of the western Sahel who supplement the diets of their infants with unpasteurized cow's milk.

Legionnaires' disease: new clinical perspective from a prospective pneumonia study

In an attempt to ascertain the incidence of Legionnaires' disease at our hospital, a prospective case-control pneumonia study was conducted for 11 months. Specialized diagnostic tests for Legionella pneumophila, including serologic study, direct immunofluorescent examination, and selective culture, were made routinely available in our hospital. To our surprise, L. pneumophila was the most common cause of pneumonia (22.5 percent) attributable to a single pathogen, followed by Streptococcus pneumoniae (10.6 percent). In 68.8 percent of the cases, Legionnaires' pneumonia was hospital-acquired. In contrast to other investigators, we found that abdominal pain, diarrhea, neurologic signs, abnormal liver function results, hypophosphatemia, and hematuria did not occur significantly more frequently in pneumonia caused by L. pneumophila than in that caused by other microorganisms. However, hyponatremia within five days of onset of pneumonia occurred significantly more frequently in Legionnaires' disease (p less than 0.0001). Since the clinical presentation is nonspecific, specialized laboratory tests are necessary to make the diagnosis. As a result of our experience, we suggest an approach using serologic tests as a screen to determine whether more specialized tests for Legionnaires' disease should be introduced into a hospital without previously recognized cases of Legionnaires' disease.