Miguel Angel Harvey

Metales pesados en organismos marinos de la zona costera de la Patagonia argentina continental

Se analizaron los contenidos de Hg, Cd, Pb, Cu y Zn en moluscos, crustaceos (tejido blando - µg/g peso seco), aves y mamiferos marinos (rinon, higado y musculo - µg/g peso humedo), procedentes de la zona costera de Patagonia argentina. Los niveles de Hg fueron no detectables o muy bajos. Se encontraron niveles de Cd mas elevados que los permitidos para consumo humano en algunos moluscos (hasta 6,75 µg/g), aunque su origen seria fundamentalmente natural. Las concentraciones de Pb en crustaceos de la Bahia San Antonio (10,00 ? 13,20 µg/g) fueron relacionadas con una antigua actividad minera. Los contenidos de Cu y Zn estuvieron en la mayoria de los casos, dentro del rango informado en la literatura.

A new simplifying approach to molecular geometry description : the vectorial bond-valence model

A method to describe, analyze and even predict the coordination geometries of metal complexes is proposed, based on previous well established concepts such as bond valence and valence-shell electron-pair repulsion (VSEPR). The idea behind the method is the generalization of the scalar bond-valence concept into a vector quantity, the bond-valence vector (BVV), with the innovation that the multidentate ligands are represented by their resultant BVVs. Complex n-ligand coordination spheres (frequently indescribable at the atomic level) reduce to much simpler ones when analyzed in BVV space, with the bonus of a better applicability of the VSEPR predictions. The geometrical implications of the BVV description are analyzed for the cases of n=2 and 3 (n=number of ligands), and the validity of its predictions, checked for a large number of metal complexes.

X-ray study of two new cadmium acetato complexes

Two new cadmium acetate compounds, Cd(tpy)(Ac)2·2H2O (1) and Cd2(bbip)2 (Ac)3·0.5S2O8·2H2O (2) (tpy = 2,2′,2′′-terpyridine; bbip = 2,6-bis(benzimidazol-2-yl)pyridine; Ac = acetate), have been synthesized and their crystal structures determined. Compound 1 is monoclinic, P2(1)/n, a = 8.4899(11), b = 23.169(3), c = 10.9224(14) Å, β = 7.493(2)°, V = 2049.1(5) Å3, Z = 4, R = 0.037 for 4552 N i independent reflections and for 1619 N o observed [I>2σ(I) ] reflections. Compound 1 is monomeric, with a heptacoordinate cadmium ion bonded to two bidentate acetate groups and a tridentate tpy; two hydration water molecules complete the formula unit. Compound 2 is triclinic, , a = 10.8412(7), b = 14.4051(9), c = 15.5354(10) Å, α = 82.889(1), β = 77.953(1), γ = 85.805(1)°, V = 2351.73(3) Å3, Z = 2, R = 0.044, N i = 9014, N o = 6837. The binuclear structure has two independent Cd atoms per asymmetric unit, two bbip tridentate ligands (one attached to each cation) and three acetate groups, displaying a range of different coordination features.

Metal content in bivalve molluscs from the San José and Nuevo Gulfs, Patagonia Argentina

Comparaison des teneurs en metaux lourds relevees dans des mollusques bivalves du Golfe Nuevo (site industrialise) et du golfe San Jose (site non pollue)

Structural Studies of Complexes Containing the Peroxodisulfate Anion. II. The Crystal and Molecular Structure of Cd(S2O8) (bpy)2.H2O and Hg2(S2O8)(terpy)2(acet)2 (bpy: 2,2′-bipyridine, terpy: 2,2′,2′′-terpyridine, acet: acetate)

The crystal structures of two transition-metal complexes with different dinitrogenated bases, and the unusual peroxodisulfate anion are presented, Cd(S2O8)(bpy)2·H2O (1) and Hg2(S2O8)(terpy)2(acet)2 (2) (where bpy represents 2,2′-bipyridine, terpy represents 2,2′,2′′-terpyridine, and acet represents acetate). In both structures, though in different ways, the peroxodisulfate group acts as a bridge, giving rise to polymeric linear chains. To our knowledge these are the first structures reported wherein the anion displays such behaviour. The cadmium compound crystallizes with one water molecule of hydration, which intervenes in medium-strength H-bonds, stabilizing the structure. The mercury complex is built up of similar, though independent, chains displaying double Hg–O–Hg bridges spanning Hg···Hg distances of 4.214(1) and 3.911(1) A. The inter-chain link is achieved through weak C–H···O contacts. Compound (1) is triclinic P1–; a 7.213(3), b 9.841(6), c16.371(5) A; α 82.94(4), β 82.31(3), γ 86.32(4)˚; V 1141.6(9) A3; Z 2; conventional R (on F) being 0.0315 for 4019 No observed reflections (I> 2σ(I)). Compound (2) is also triclinic P1–; a 10.653(2), b 12.195(3), c 14.641(3) A; α 88.295(19), β 83.553(18), γ 73.921(19)˚; V 1816.0(7) A3; Z 2; R0.0498; No 6179.

Structural Studies on Complexes Containing the Peroxodisulfate Anion. I The Crystal and Molecular Structure of Cd(pds)(phen)2(H2O)·H2O and Cd(pds)(dmph)2 [pds = Peroxodisulfate (S2O8 2–); phen = 1,10-Phenanthroline; dmph = 2,9-Dimethyl-1,10-phenanthroline]

The crystal structures of two unreported CdII complexes with different dinitrogenated bases and the unusual peroxodisulfate anion (pds, S2O8 2–) are presented: Cd(pds)(phen)2(H2O)·H2O and Cd(pds)(dmph)2 (phen = 1,10- phenanthroline; dmph = 2,9-dimethyl-1,10-phenanthroline). Both compounds are monomeric. In the first, the anion acts as a monodentate ligand, as in all previously reported structures where it binds to a cation, while in the second it displays novel chelate behaviour. Both structures are stabilized by hydrogen-bonding networks, with mediumstrength interactions mediated by aqua and hydration water molecules in the first case and much weaker ones provided by C–H…O contacts in the second. Compound (1) is triclinic, P1–, a 8.745(3), b 9.260(5), c 17.564(3) A, α 96.80(2), β 101.581(3), γ 105.97(3)˚, V 1316.6(9) A3, Z 2, R 0.044, No 4384. Compound (2) is monoclinic, Cc, a 22.233(12), b 9.566(5), c16.017(8) A, β 123.78(3)˚, V2831(3) A3, Z 4, R 0.024, No 2363.

Tetraaqua(2,2'-bipyridyl-N,N')cadmium(II) sulfate and catena-poly[[[diaqua(2,2'-bipyridyl-N,N')cadmium(II)]-μ-(sulfato-O:O')] hydrate]

In both title compounds, [Cd(C 10 H 8 N 2 )(H 2 O) 4 ]SO 4 , (I), and [Cd(SO 4 )(C 10 H 8 N 2 )(H 2 O) 2 ].H 2 O, (II), the Cd II ion is octahedrally coordinated. In (I), the Cd 2+ ion is coordinated to a bipyridine and four water molecules, the structure being monomeric and strictly ionic in nature, and in (II), to a bipyridine, two water molecules and two O atoms from two translationally related sulfate groups, thus defining polymeric chains along the unique crystallographic b axis.

An unusual two-dimensional hydrogen-bonding network in bis(2,9-dimethyl-1,10-phenanthrolin-1-ium) peroxodisulfate dihydrate.

The title compound, 2C(14)H(13)N(2)(+).S(2)O(8)(2-).2H(2)O, is a protonated amine salt which is formed from two rather uncommon ionic species, namely a peroxodisulfate (pds(2-)) anion, which lies across a crystallographic inversion centre, and a 2,9-dimethyl-1,10-phenanthrolin-1-ium (Hdmph(+)) cation lying in a general position. Each pds(2-) anion binds to two water molecules through strong water-peroxo O-H...O interactions, giving rise to an unprecedented planar network of hydrogen-bonded macrocycles which run parallel to (100). The atoms of the large R(8)(8)(30) rings are provided by four water molecules bridging in fully extended form (...H-O-H...) and four pds(2-) anions alternately acting as long (...O-S-O-O-S-O...) and short (...O-S-O...) bridges. The Hdmph(+) cations, in turn, bind to these units through hydrogen bonds involving their protonated N atoms. In addition, the crystal structure also contains pi-pi and aromatic-peroxo C-H...O interactions.

Weak C–H…O Interactions Leading to Measurable Effects in Polymeric Sulfates [M(SO4)L(H2O)2]n (M = Cd, Zn, Cu; L = bipy, phen, dmp)

The structure of two sulfate complexes, [Zn(SO4)phen(H2O)2]n and [Cd(SO4)bipy(H2O)2]n, are presented. They are polymeric and isomorphous to an homologous series already reported, namely [Zn(SO4)bipy(H2O)2]n, [Cd(SO4)dmph(H2O)2]n, [Cu(SO4)bipy(H2O)2]n, and [Cu(SO4)phen(H2O)2]n (bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline). The compounds organize into double polymeric chains internally linked through strong (O–H)water…Osulfate bonds. The interaction between these ‘strips’ is governed by weak (C–H)ligand…Osulfate bonds, which explain a seemingly abnormal expansion/contraction of some cell parameters in the homologous series. Both compounds are monoclinic, C2/c. [Zn(SO4)phen(H2O)2]n: a 15.156(3), b 14.152(3), c 6.7010(13) A, β 103.43(3)°, V 1398.0(5) A3, Z 4, conventional R (on F) being 0.028 for No 1615 observed reflections (I >2σ(I)). [Cd(SO4)bipy(H2O)2]n: a 15.705(3), b 13.049(3), c 6.8912(14) A, β 104.59(3)°, V 1366.7(5) A3, Z 4, R 0.052, No 1516.

Bis­[2,6-bis(1H-benzimidazol-2-yl-κN3)pyridinato-κN]zinc(II)

The structure of [Zn(C(19)H(12)N(5))(2)], which is monomeric and consists of neutral Zn(bbip-H)(2) entities [bbip-H is the anionic form of bis(benzimidazolyl)pyridine, formed by the loss of one H atom], has been solved from a racemic twin. The Zn atom lies at a site with imposed 222 symmetry and the bbip-H ligand has imposed twofold symmetry. The imidazolyl H atom is disordered over two symmetry-related positions, thus raising the molecular symmetry as required by the space group. The angle between the planes of the two coordinated bbip-H ligands is 84.6 (3) degrees, so defining a distorted octahedral environment around the metal atom.