Carbon−Phosphorus Bond Activation of Tri(2-thienyl)phosphine at Dirhenium and Dimanganese Centers

Reaction of [Re2(CO)9(NCMe)] with tri(2-thienyl)phosphine (PTh3) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re2(CO)9(PTh3)] (1), [Re2(CO)8(NCMe)(PTh3)] (2), and [Re2(CO)8(PTh3)2] (3). Complex 2 was also obtained from the room-temperature reaction of [Re2(CO)8(NCMe)2] with PTh3 and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene affords [Re2(CO)8(μ-PTh2)(μ-η1:κ1-C4H3S)] (4) and [Re2(CO)7(PTh3)(μ-PTh2)(μ-H)] (5), respectively, both resulting from carbon−phosphorus bond cleavage of a coordinated PTh3 ligand. Reaction of [Re2(CO)10] and PTh3 in refluxing xylene gives a complex mixture of products. These products include 3−5, two further binuclear products, [Re2(CO)7(PTh3)(μ-PTh2)(μ-η1:κ1-C4H3S)] (6) and [Re2(CO)7(μ-κ1:κ2-Th2PC4H2SPTh)(μ-η1:κ1-C4H3S)] (7), and the mononuclear hydrides [ReH(CO)4(PTh3)] (8) and trans-[ReH(CO)3(PTh3)2] (9). Binuclear 6 is structurally similar to 4 and can be obtained from reaction of the latter with 1 equiv of PTh3. Formation of 7 involves a series of rearrangements resulting in the formation of a unique new diphosphine ligand, Th2PC4H2SPTh. Reaction of [Mn2(CO)10] with PTh3 in refluxing toluene affords the phosphine-substituted product [Mn2(CO)9(PTh3)] (10) and two carbon−phosphorus bond cleavage products, [Mn2(CO)6(μ-PTh2)(μ-η1:η5-C4H3S)] (11) and [Mn2(CO)5(PTh3)(μ-PTh2)(μ-η1:η5-C4H3S)] (12). Both 11 and 12 contain a bridging thienyl ligand that is bonded to one manganese atom in a η5-fashion. The molecular structures of eight of these new complexes were established by single-crystal X-ray diffraction studies, allowing a detailed analysis of the disposition of the coordinated ligands

Mechanical Mixing of Garnet Peridotite and Pyroxenite in the Orogenic Peridotite Lenses of the Tvaerdal Complex, Liverpool Land, Greenland Caledonides

The Tvaerdal Complex is an eclogite-bearing metamorphic terrane in Liverpool Land at the southern tip of the Greenland Caledonides. It is a Baltic terrane that was transferred to Laurentia during the Scandian orogeny. It exposes a few small garnet dunite and harzburgite lenses, some containing parallel layers of garnet pyroxenite and peridotite (including lherzolite). Sm–Nd mineral ages from the pyroxenites indicate recrystallization occurred at the same time (≈405 Ma) as eclogite recrystallization in the enclosing gneiss. Geothermobarometry indicates these eclogites and pyroxenites shared a similar pressure-temperature history. This congruent evolution suggests pyroxenite-bearing peridotite lenses were introduced from a mantle wedge into subducted Baltic continental crust and subsequently shared a common history with this crust and its eclogites during the Scandian orogeny. Some garnet peridotite samples contain two garnet populations: one Cr-rich (3·5–6·2 wt % Cr2O3) and the other Cr-poor (0·2–1·4 wt %). Sm–Nd analyses of two such garnet peridotites define two sets of apparent ages: one older (>800 Ma) for Cr-rich garnets and the other younger (<650 Ma) for Cr-poor garnets. We propose that the younger Cr-poor garnets were derived from fractured and disaggregated garnet pyroxenite layers (i.e. are M2) and were mixed mechanically with older (i.e. M1) garnets of the host peridotite during intense Scandian shearing. Mechanical mixing may be an important mantle process

The tmRDB and SRPDB resources

Maintained at the University of Texas Health Science Center at Tyler, Texas, the tmRNA database (tmRDB) is accessible at the URL with mirror sites located at Auburn University, Auburn, Alabama () and the Royal Veterinary and Agricultural University, Denmark (). The signal recognition particle database (SRPDB) at is mirrored at and the University of Goteborg (). The databases assist in investigations of the tmRNP (a ribonucleoprotein complex which liberates stalled bacterial ribosomes) and the SRP (a particle which recognizes signal sequences and directs secretory proteins to cell membranes). The curated tmRNA and SRP RNA alignments consider base pairs supported by comparative sequence analysis. Also shown are alignments of the tmRNA-associated proteins SmpB, ribosomal protein S1, alanyl-tRNA synthetase and Elongation Factor Tu, as well as the SRP proteins SRP9, SRP14, SRP19, SRP21, SRP54 (Ffh), SRP68, SRP72, cpSRP43, Flhf, SRP receptor (alpha) and SRP receptor (beta). All alignments can be easily examined using a new exploratory browser. The databases provide links to high-resolution structures and serve as depositories for structures obtained by molecular modeling

Reactivity of phenyldi(2-thienyl)phosphine towards Group 7 Metal Carbonyls: Carbon–phosphorus Bond Activation

Addition of phenyldi(2-thienyl)phosphine (PPhTh2) to [Re2(CO)10−n(NCMe)n] (n = 1, 2) affords the substitution products [Re2(CO)10−n(PhPTh2)n] (1, 2) together with small amounts of fac-[ClRe(CO)3(PPhTh2)2] (3) (n = 2). Reaction of [Re2(CO)10] with PPhTh2in refluxing xylene affords a mixture which includes 2, [Re2(CO)7(PPhTh2)(μ-PPhTh)(μ-H)] (4), [Re2(CO)7(PPhTh2)(μ-PPhTh)(μ-η1,κ1(S)-C4H3S)] (5) and mer-[HRe(CO)3(PPhTh2)2] (6). Phosphido-bridged 4 and 5 are formed by the carbon–phosphorus bond cleavage of the coordinated PPhTh2 ligand, the cleaved thienyl group being retained in the latter. Reaction of [Mn2(CO)10] with PPhTh2 in refluxing toluene affords [Mn2(CO)9(PPhTh2)] (7) and the carbon–phosphorus bond cleavage products [Mn2(CO)6(μ-PPhTh)(μ-η1,η5-C4H3S)] (8) and [Mn2(CO)5(PPhTh2)(μ-PPhTh)(μ-η1,η5-C4H3S)] (9). Both 8 and 9 contain a bridging thienyl ligand which is bonded to one manganese atom in a η5-fashion

Therapeutic drug monitoring in inflammatory bowel disease : implementation, utilization, and barriers in clinical practice in Scandinavia

Background and aims Therapeutic drug monitoring (TDM) may optimize biologic and thiopurine therapies in inflammatory bowel disease (IBD). The study aimed to investigate implementation and utilization of TDM in Scandinavia. Methods A web-based questionnaire on the use of TDM was distributed to Scandinavian gastroenterologists via the national societies. Results In total, 297 IBD physicians prescribing biologic therapies, equally distributed between community and university hospitals, were included (response rate 42%) (Norway 118 (40%), Denmark 86 (29%), Sweden 50 (17%), Finland 33 (11%), Iceland 10 (3%)). Overall, TDM was applied during biologic therapies by 87%, and for TNF-inhibitors >90%. Among the users, reactive and proactive TDM were utilized by 90% and 63%, respectively. Danish physicians were significantly less inclined to use TDM compared to other Scandinavian countries; (58% vs 98%); OR 0.03 [0.01-0.09], p 10 IBD patients/week (p = 0.005). TDM scenarios were interpreted in accord with available evidence but with discrepancies for proactive TDM. The main barriers to TDM were lack of guidelines (51%) and time lag between sampling and results (49%). TDM of thiopurines was routinely used by 87%. Conclusion TDM of biologic and thiopurine therapies has been broadly implemented into clinical practice in Scandinavia. However, physicians call for TDM guidelines detailing indications and interpretations of test results along with improved test response times.Peer reviewe

Hydrogen bond rotations as a uniform structural tool for analyzing protein architecture

Proteins fold into three-dimensional structures, which determine their diverse functions. The conformation of the backbone of each structure is locally at each Cα effectively described by conformational angles resulting in Ramachandran plots. These, however, do not describe the conformations around hydrogen bonds, which can be non-local along the backbone and are of major importance for protein structure. Here, we introduce the spatial rotation between hydrogen bonded peptide planes as a new descriptor for protein structure locally around a hydrogen bond. Strikingly, this rotational descriptor sampled over high-quality structures from the protein data base (PDB) concentrates into 30 localized clusters, some of which correlate to the common secondary structures and others to more special motifs, yet generally providing a unifying systematic classification of local structure around protein hydrogen bonds. It further provides a uniform vocabulary for comparison of protein structure near hydrogen bonds even between bonds in different proteins without alignment