The role of surfactant organic matter in marine aerosol production has been studied under conditions in which there is a large coverage of whitecaps on the sea surface. To improve the knowledge of matter exchange and pollutant recycling from Ž .

Addition of alcohols (HOR') to the coordinated nitriles (NCR) in the platinum complexes [PtCT/NCR)]-and errand trans-[PtChlNCR^] (R = Me, Et, Ph, Bu') takes place readily under basic conditions. The Z isomer, corresponding to a trans addition of the alcohol to the C=N triple bond, is the first reaction product, subsequently undergoing isomerization to the E form. An increase of the steric bulk of the R group stabilizes the Z isomer with respect to the E isomer; in contrast, an increase of the steric bulk of the R' group stabilizes the E over the Z isomer. The structures of trans-and dr-[PtCl2{E-HN=C(OMe)Me}2] (SEE and 9EE, respectively) have been solved by single-crystal X-ray diffraction. SEE crystallizes in the space group PI (No. 2) with a = 8.491(6) Á, b = 8.603(2) Á, c = 8.973(2) Á, a = 75.56(1)°, ß = 67.52(2)°, = 85.62(2)°, V = 586.4(2) Á3, and Z = 2. 9EE crystallizes in the space group C2Jc (No. 15) with a = 15.854(3) k, b = 8.123(2) k, c = 9.471(2) k, ß -93.72(3)°, V = 1217.1(4) Á3, and Z = 4. In each complex, the Pt atom is linked to two Cl" anions and two imino ether N atoms, the coordination geometry is strictly planar, and the Pt-Cl and Pt-N bond distances have normal values. An unexpected feature resulting from the crystallographic data was the "quasi-planarity" of the imino ether moiety and electron charge delocalization over theN'XX) moiety. As a consequence, all the groups attached to the Nr*Cr*0 skeleton share the same plane, causing considerable steric strain, as indicated by deviations (5°o r even more) of some bond angles from canonical values.

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The reaction of the ruthenium(II) complex fac-[Ru(CO)(3)Cl(2)(N(1)-thz)] (I hereafter; thz = 1,3-thiazole) with human beta-amyloid peptide 1-28 (Abeta(28)) and the resulting {Ru(CO)(3)}(2+) peptide adduct was investigated by a variety of biophysical methods. (1)H NMR titrations highlighted a selective interaction of {Ru(CO)(3)}(2+) with Abeta(28) histidine residues; circular dichroism revealed the occurrence of a substantial conformational rearrangement of Abeta(28); electrospray ionization mass spectrometry (ESI-MS) suggested a prevalent 1:1 metal/peptide stoichiometry and disclosed the nature of peptide-bound metallic fragments. Notably, very similar ESI-MS results were obtained when I was reacted with Abeta(42). The implications of the above findings for a possible use of ruthenium compounds in Alzheimer's disease are discussed.

Radiopharmaceuticals containing the "fac-[M(CO)3]+ " core (M=99mTc, 186Re, or 188Re) have potential as diagnostic or therapeutic agents. Complexes with this core with sp3 amine donors have received little attention. We have studied adducts formed by ENDACH2 (HO2CCH2NHCH2CH2NHCH2CO2H) and ENACH (NH2CH2CH2NHCH2CO2H). Re(CO)3(ENDACH)-A (1A) and Re(CO)3(ENDACH)-B (1B) isomers were obtained by the reaction of ENDACH2 with Re(CO)5Cl. Re(CO)3(ENAC) (2) was obtained by the reaction of ENACH with aqueous [Re(CO)3(H2O)3]+. From single-crystal X-ray data, the three new neutral complexes, 1A, 1B, and 2, have a six-coordinate, pseudo-octahedral Re center with facially coordinated carbonyl ligands. ENDACH- and ENAC- bind facially to Re through both amine nitrogens and one carboxyl oxygen, forming two five-membered chelate rings. The Re(CO)3(ENDACH) isomers have an uncoordinated, dangling -CH2CO2H group, which is an ideal coupling site for attachment to biomolecules. The isomers differ by the configuration of the NH center bearing this dangling group. The H atom of the amine (N2) is endo (near the carbonyl ligands in the basal plane) in 1A and exo (away from carbonyl ligands) in isomer 1B. Isomers reach equilibrium (1A:1B, 70:30) after 3 days at high pH. Density functional structure optimizations were performed for isolated molecules of the type Tc(I)/Re(I)(CO)3(N2O): [Re(CO)3(NH3)2(H2O)]+, [Tc(CO)3(NH3)2(H2O)]+, [Re(CO)3(EN)(H2O)]+ (EN, ethylenediamine), [Tc(CO)3(EN)(H2O)]+, and various models for 1A, 1B, and 2. The computed structures are in good agreement with the X-ray structures. The theoretical and experimental Re-N bond distances usually agree within 0.045 A. The total electronic energy values for the computed 1A and 1B models differ by 0.815 kcal mol(-1), giving an isomer ratio of 80:20, in good agreement with the 1A/1B ratio (70:30) found.

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