Coastal gradients of small microplastics and associated pollutants influenced by estuarine sources.

Small microplastics (SMPs) in the gulf of Cadiz was sampled at 5 m depth by pumping it through the ship's pipe system and filtered through a 45 µm mesh size net. Our study reveals that higher densities have been found (130 mg·m-3) compared to other regions worldwide and these densities decreased from the coastline to the outer stations, showing a general coastal gradient influenced by estuarine outflows. SMPs with a size range between 45 and 193 µm were predominant and most of them composed by polyethylene and polypropylene. The metals associated with the MPs were mainly Na (21.1%), K (11.3%), Fe (8.5%), Ca (2.1%), Cr (1.8%), Zr (13.3%) and Hf (0.7%). The high proportion of Zr compared to Fe, which is different from what can be found in the environment, suggests that this metal is intrinsic to the materials used in catalytic processes during plastic production.

Synthesis of Exceptionally Stable Iron and Ruthenium η1 -tetrahedro-Tetraphosphorus Complexes: Evidence for a Strong Temperature Dependence of M-P4 π Back Donation.

At variance with white phosphorus, the most reactive allotrope of the element, which is unstable and ignites spontaneously in air, the new η1 -tetrahedro-tetraphosphorus complexes [Cp*M(PR3 )2 (η1 -P4 )]Y (M=Fe, Ru; Y=Cl, PF6 , BPh4 , BAr$\rm{^{\prime }_{4}}$; Cp*=C5 Me3 the structure of the [Cp*Fe(Ph2 PCH2 CH2 PPh2 )(η1 -P4 )]+ ion is depicted) exhibit a surprising and unprecedented thermal stability and an astonishing reluctance to react with oxygen and other oxidants.

Oligomerization of styrenes mediated by cationic allyl nickel complexes containing triphenylstibine or triphenylarsine.

The cationic complexes [Ni(eta(3)-CH(2)C(R)CH(2))(SbPh(3))(3)][BAr'(4)] (R = CH(3), H ; Ar' = 3,5-C(6)H(3)(CF(3))(2)), [Ni(eta(3)-CH(2)C(R)CH(2))(AsPh(3))(2)][BAr'(4)] (R = CH(3), H ), [Ni(eta(3)-CH(2)CHCH(2))(PPh(3))(L)][BAr'(4)] (L = SbPh(3), AsPh(3)), and the neutral derivatives [Ni(eta(3)-CH(2)C(R)CH(2))Br(L)] (L = SbPh(3), R = CH(3), H ; L = AsPh(3), R = CH(3), H ) have been prepared and characterized. The X-ray crystal structures of , , , and have been determined. These complexes are very active catalyst precursors for the low-molecular weight oligomerization of RC(6)H(4)CH[double bond, length as m-dash]CH(2) to mainly dimers and trimers of styrene (R = H) or 4-methylstyrene (R = CH(3)). They also catalyse the oligomerization of alpha-methylstyrene to dimers and trimers, or to higher oligomers depending upon the reaction conditions (solvent and temperature). The oligomerization reactions were carried out at 25 degrees C in most cases, in dichloromethane, 1,2-dichloroethane or fluorobenzene, using a olefin/catalyst ratio equal to 2000. The oligomerization products were characterised by means of GPC/SEC.

Unprecedented eta(1)-P(basal) coordination of P(4)X(3) molecules (X = S, Se). An experimental and theoretical study of the apical vs basal complexation dichotomy.

Reaction of [(triphos)Re(CO)(2)(OTf)] (1) [triphos = MeC(CH(2)PPh(2))(3); OTf = OSO(2)CF(3)] with P(4)S(3) and P(4)Se(3) yields pairs of coordination isomers, namely, [(triphos)Re(CO)(2)[eta(1)-P(apical)-P(4)X(3)]](+) (X = S, 2; Se, 5) and [(triphos)Re(CO)(2)[eta(1)-P(basal)-P(4)X(3)]](+) (X = S, 3; Se, 6). The latter represent the first examples of the eta(1)-P(basal) coordination achieved by the P(4)X(3) molecular cage. Further reaction of 2/3 and 5/6 mixtures with 1 affords the dinuclear species [[(triphos)Re(CO)(2)](2)[mu,eta(1:1)-P(apical,)P(basal)-P(4)X(3)]](2+) (X = S, 4; Se, 7) in which the unprecedented M-eta(1)-P(basal)/eta(1)-P(apical)-M' bridging coordination of the P(4)X(3) molecule is accomplished. A theoretical analysis of the bonding properties of the two coordination isomers is also presented. The directionality of apical vs basal phosphorus lone pairs is also discussed in terms of MO arguments.

Synthesis, characterisation and molecular structure of Re(III) 2-oxacyclocarbenes stabilised by a benzoyldiazenido ligand.

A family of new Fischer-type rhenium(III) benzoyldiazenido-2-oxacyclocarbenes of formula [(ReCl2[eta1-N2C(O)Ph][=C(CH2)nCH(R)O](PPh3)2][n = 2, R = H (2), R = Me (3); n = 3, R = H (4), R = Me (5)] have been prepared by reaction of [ReCl2[eta2-N2C(Ph)O](PPh3)2] (1) with omega-alkynols, such as 3-butyn-1-ol, 4-pentyn-1-ol, 4-pentyn-2-ol, 5-hexyn-2-ol in refluxing THF. The correct formulation of the carbene derivatives 2-5 has been unambiguously determined in solution by NMR analysis and confirmed for compounds 2-4 by X-ray diffraction methods in the solid state. All complexes are octahedral with the benzoyldiazenido ligand, Re[N2C(O)Ph], adopting a "single bent" conformation. The coordination basal plane is completed by an oxacyclocarbene ligand and two chlorine atoms. Two triphenylphosphines in trans positions with respect to each other complete the octahedral geometry around rhenium. The reactivity of 1 towards different alkynes and alkenes including propargyl- and allylamine has been also studied. With propargyl amine, monosubstituted or bisubstituted complexes, [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2C triple bond CH]n(PPh3)(3-n)][n= 1 (6); n = 2 (7)], have been isolated depending on the reaction conditions. In contrast, the reaction with allylamine gave only the disubstituted complex [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2CH=CH2]2(PPh3)] (8). The molecular structure of the monosubstituted adduct has been confirmed by X-ray analysis in the solid state.