Synthesis and reactivity studies of palladium(II) complexes containing the N-phosphorylated iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph): application to the catalytic synthesis of 2,3-dimethylfuran

Reactions of [PdCl2(COD)] with 1 equiv. of the iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph) lead to the novel Pd(II) derivatives cis-[PdCl2(kappa2-(P,N)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)] (R=Et, Ph). Pd-N bond cleavage readily takes place upon treatment of these species with a variety of two-electron donor ligands. By this way, complexes cis-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)(L)] (R=Et, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3; R=Ph, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3) have been synthesized in high yields. The addition of two equivalents of ligands to dichloromethane solutions of [PdCl2(COD)] results in the formation of complexes trans-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)2] (R=Et, Ph), which can be converted into the dicationic species [Pd(Ph2PCH2P{=NP(=O)(OR)2}Ph2)2][SbF6]2 (R=Et, Ph) by treatment with AgSbF6. Complex also reacts with CNtBu to afford trans-[Pd(kappa1(P)-Ph2PCH2P{=NP(=O)(OPh)2}Ph2)2(CNtBu)2][SbF6]2. The structures of and have been determined by single-crystal X-ray diffraction methods. In addition, the ability of these Pd(II) complexes to promote the catalytic cycloisomerization of (Z)-3-methylpent-2-en-4-yn-1-ol into 2,3-dimethylfuran has also been studied.     

Fixed lock-time relaxation dispersion in the rotating frame

The spin-lattice relaxation dispersion may be probed in the laboratory frame through field-cycling NMR relaxometry. The experiment, as usually done, has the basic weakness that the low frequency end of the measured dispersion can be blurred by the presence of local fields. An understanding of the nature of such local fields was found to be essential to the interpretation of the dispersion profile. In this work, an attempt was made to determine the extent to which specific information can be obtained from a rotating frame experiment. The technique consists in the study of the NMR signal dispersion at a fixed spin-lock time, as a function of the radio frequency field intensity. Within this scheme, a strong dispersion can be attributed to the presence of a non-zero magnetic field component along the laboratory-frame Zeeman-axis in the rotating-frame. At on-resonance condition, this component is exclusively due to the presence of local fields as projected on that axis.     

Association of probability measures on partially ordered spaces

A notion of association of probability measures on partially ordered (Polish) spaces is introduced and its basic properties are investigated. This generalizes the classical notion of association among random variables, due to Esary, Proschan, and Walkup. The relation between association and monotone stochastic kernels is investigated and a theorem of Jogdeo is generalized. The general theory is applied to stochastic processes with both discrete and continuous time parameter and partially ordered state spaces. Also, an application to mixtures of statistical experiments is included.     

Pseudoparaproteinemia Detected by CE due to Omnipaque™ Infusion: A Case Report

Serum or plasma protein electrophoresis is often performed in clinical laboratories to detect and monitor M-components. During the last decade, capillary electrophoresis (CE) has emerged as an interesting alternative to traditional analysis of serum, plasma and urine proteins by agarose gel electrophoresis. We here report a case of pseudoparaproteinemia detected by capillary electrophoresis after Omnipaque? (iohexol) infusion in a patient with normal kidney function. It is important for the laboratories to be aware of this source of erroneous results and not misclassify it as monoclonal gammopathies.     

PHOTOPHYSICS OF METHYLENE BLUE-POLYNUCLEOTIDE COMPLEXES IN THE PICOSECOND TIME RANGE: INFLUENCE OF THE LOCAL STRUCTURE OF THE POLYNUCLEOTIDE

Abstract—
The photophysics of methylene blue (MB) complexed with 2'-deoxycytidylyl-2'-deoxygua-nosine, polydeoxyguanylic-deoxycytidylic acid, polydeoxyguanylic-polydeoxycytidylic acid and poly-guanylic acid, respectively, was investigated by transient absorption spectroscopy with a time resolution of ˜1 ps. The decays of the transient difference spectra indicate that the radiationless process responsible for the strong shortening of the S, state lifetime of MB associated with a guanine in the polynucleotide chain is similar to that already observed in the case of the MB—guanosine-5'-monophosphate complex, that is, the excited state decays by return of molecules to the ground state without formation of a detectable intermediate state. The local structure of the polynucleotide apparently does not change the nature of the deactivation process but influences significantly the deactivation rate. Thus, the intercalation of MB between guanosine and cytosine increases this rate constant (as compared to that of the MB—guanosine-5'-monophosphate complex) while the interaction of MB intercalated with a supplementary guanine has an opposite effect. The results are discussed in connection with the photosensitizing effect of MB in nucleic acid damage.     

Unvollständinge Chelatisierung durch N-Acylthioharnstoffe: Die Struktur von Bis[N-(1-pyrrolidinyl-thiocarbonyl)-benzamidato]quecksilber(II)

Incomplete Chelation by N-Acylthioureas: Structure of Bis[N-(1-pyrrolidinyl-thiocarbonyl)-benzamidato] mercury(II) Bis[N-(1-pyrrolidinyl-thiocarbonyl)-benzamidato]mercury(II) crystallizes in the monoclinic space group P2₁/c with a = 10.126, b = 22.347, c = 11.384 Å, β = 109.13° and Z = 4. The structure was solved by application of direct methods to difference structure factors (DIRDIF). The final R value was R = 0.06 for 2195 observed reflections. Mercury exhibits the characteristic coordination number 2 with linear arrangement of the S ligators. Both O ligators, however, show weak bonds to Hg. For that reason the mercury complex should be better described as a labilized chelate with the effective coordination number 4. With regard to the excellent extractibility of mercury(II) with N-acylthioureas the formation and existence, respectively, of such a labilized chelate seems to be favourable.