Multinuclear (1H, 31P, and 195Pt) NMR study and dynamical analysis of binuclear \ub5-hydrido \ub5-carbonyl Pt(I) cations with chelating diphosphines

The dynamic behaviour of the binuclear \u3bc-hydrido \u3bc-carbonyl cations with chelating diphosphines, [Pt2(P\u2013P)2-(\u3bc-H)(\u3bc-CO)]+ [P\u2013P = dppe, 1, dppp, 2, and dppb, 3] have been investigated by multinuclear (1H, 31P and 195Pt)variable temperature NMR spectroscopy. The 195Pt and 1H results are consistent with intramolecular mutual exchange of the P atoms with respect to the bridging ligands in all of the complexes 1\u20133. A detailed dynamical analysis carried out on complexes 2 and 3 shows that the dynamical process exchanges the P atoms within a single diphosphino ligand, and excludes the simultaneous P atom exchange in both ligands. The bite of the diphosphino ligands affects the rate of this process in the order 3 > 2 > 1. The process follows an activation law with \u394H\u2021 = 67 and 60 kJ mol^(-1) for 2 and 3, respectively, so that P\u2013Pt bond breaking should not be involved. The positive activation entropy (17\u201319 J K^(-1) mol^(-1) hints at a mechanism where the intermediate(s) have a less ordered structure than that of the stable complex. In accordance with the NMR results, two reactivity experiments provided further evidence of the intramolecular nature of the observed dynamics and exclude any equilibration path via Pt\u2013P and/or Pt\u2013Pt bond breaking. On these grounds, a mechanism involving rotation about a Pt\u2013Pt bond could be proposed

Recent advances in structure and function of cytosolic IMP-GMP specific 5′nucleotidase II (cN-II)

Cytosolic 5′nucleotidase II (cN-II) catalyses both the hydrolysis of a number of nucleoside monophosphates (e.g., IMP + H2O→inosine + Pi), and the phosphate transfer from a nucleoside monophosphate donor to the 5′position of a nucleoside acceptor (e.g., IMP + guanosine →inosine + GMP). The enzyme protein functions through the formation of a covalent phosphoenzyme intermediate, followed by the phosphate transfer either to water (phosphatase activity) or to a nucleoside (phosphotransferase activity). It has been proposed that cN-II regulates the intracellular concentration of IMP and GMP and the production of uric acid. The enzyme might also have a potential therapeutic importance, since it can phosphorylate some anti-tumoral and antiviral nucleoside analogues that are not substrates of known kinases. In this review we summarise our recent studies on the structure, regulation and function of cN-II. Via a site-directed mutagenesis approach, we have identified the amino acids involved in the catalytic mechanism and proposed a structural model of the active site. A series of in vitro studies suggests that cN-II might contribute to the regulation of 5-phosphoribosyl-1-pyrophosphate (PRPP) level, through the so-called oxypurine cycle, and in the production of intracellular adenosine, formed by ATP degradation

En studie om risken vid köp av lägenhet –Bostadsrättsföreningarna i Göteborgs innerstad

Backgrund och problem: Inom bostadsrätter är det säljaren som har övertag eftersom efterfrågan är större än utbudet av lägenheter samtidigt som köpare är i underläge mot säljaren, mäklaren och banken. Då är årsredovisningen ett viktigt verktyg för att tyda riskerna vid köp av en lägenhet. Syfte: Jämföra och använda årsredovisningar som ett verktyg för att beskriva och avgöra vilka risker som finns förknippade med lägenhetsköp i Göteborgs innerstad. Avgränsningar: Jag förhåller mig till riskerna som kan kopplas till årsredovisningen och avseende år. Det finns även geografisk avgräsnings som är göteborgs innerstaden. Jag tar inte upp de så kallade K- projekten på grund av att årsredovisningar baserar sig på 2013 och äldre rekommendationer och normgivning. Metod: Det är en blandning av kvantitativ och kvalitativ studie. Det är en deskriptiv studie som blandar både kvantitativa metoden och kvalitativa metoden. Resultat och slutsatser: Det bästa sättet att identifiera riskerna i sambandet med att man ska köpa en lägenhet är att jämföra resultaträkning och balansräkning med förvaltningsberättelse för att skapa en bild över riskerna. Förslag till forsatt forskning: En studie om K3 projekt och hur den kommer att påverka bostadsrättsföreningarnas resultat. Ett annat förslag är en studie om hur bostadsrättsköpare agerar innan köpet och hur de beaktar föreningens ekonomiska läge

Reaction of [Pt-2(dppp)(2)(H)(3)][BF4] with styrene or phenylacetylene gives the same mu-hydrido mu-alkylidene derivative, [Pt-2(dppp)(2)(mu-H)(mu-CHCH2Ph)][BF4]

The reaction of the binuclear platinum hydride [Pt-2(dppp)(2)(H)(3)][BF4] with styrene or phenylacetylene gives the same mu-hydrido mu-alkylidene diplatinum complex, [Pt-2(dppp)(2)(mu-H)(mu-CHCH2Ph)][BF4], under the same mild experimental conditions. Experiments with deuterium-labeled reagents show that the hydrogenation of phenylacetylene does not occur through the transfer of the acetylenic proton and suggest that the hydrogenation to styrene as an intermediate step is not implied. The C-13 NMR spectra of the reaction product of an equimolecular mixture of [Pt-2(dPPP)(2)(H)(3)][BF4] and [Pt-2(dppp)(2)(D)(3)][BF4] with phenylacetylene suggest that fragmentation of the dimeric Pt2H3+ core does not occur. Possible phenylacetylene hydrogenation pathways are discussed

Ionic binuclear platinum(II) hydrides

The new hydrides [(LL)2Pt2H3][BF4] (I: LL = 1,2-bis(diphenylphosphino)ethane; II: LL = 1,2-bis(diphenylarsino)ethane) were obtained by reaction of (LL)Pt(PzH)2][BF4]2 (PzH = 3,5-dimethylpyrazole) with KBH4 in MeOH or EtOH. \ua9 1977

X-RAY CRYSTAL-STRUCTURE OF [1,2-BIS(DIPHENYLPHOSPHINO)ETHANE]BIS(3,5-DIMETHYL-PYRAZOLE-N)PLATINUM(I I) TETRAFLUOROBORATE DICHLOROMETHANE SOLVATE, [(PH2PCH2CH2PPH2)PT(3,5-ME2PZH)2][BF4]2.CH2CL2

The crystal structure of the compound [(Ph2PCH2CH2PPh2)Pt(3,5-Me2pzH)2][BF4]2\ub7CH2Cl2 has shown that the ligands around the Pt atom are approximately in a square planar coordination, whereas the pyrazole rings point roughly in the same direction, away from the coordination plane. This unusual conformation is probably due to the hydrogen bonds with fluorine atoms of the BF4- anion. Bond distances and angles are compared with those in other pyrazole complexes

SYNTHESIS AND STRUCTURE OF [PT2(MU-H)(MU-CHCH2PH)(DIPHOS)2][BF4]

The first compound in which a hydride- and an alkylidene-ligand bridge two Pt-atoms is present in the complex cation 2, which is formed on reaction of the complex 1 with styrene. 2 was characterized NMR spectroscopically and by an X-ray structure analysis. the Pt[BOND]Pt distance of 2.735(1) \uc5 indicates that there is bonding interaction between the two metal atoms

Trinuclear platinum hydrides

The isolation of trinuclear platinum cations containing hydrido ligands, viz. [HxPt3(dpe)3]+ and [HxPt3(dpae)3]+, is reported (dpe=(Ph2PCH2)2 and dpae=Ph2PCH2CH2AsPh2). \ua9 1981 Elsevier Sequoia S.A