Ibrahim Baba

Inventory of heavy metals and organic micropollutants in an urban water catchment drainage basin

The Linggi River drainage basin in Negeri Sembilan Malaysia is the major source of potable water for the townships of Seremban and Port Dickson. Water quality is threatened by industrial and commercial development taking place in the basin. This study investigated the concentrations and distribution of organic micro-pollutants and heavy metals within the catchment. Arsenic, copper, cadmium, lead, mercury and zinc were determined in water and sediment samples. All heavy metal concentrations were increased down the basin; arsenic and copper concentration in particular were elevated probably due respectively to flow in of arsenical herbicides in rubber and oil palm plantations and copper sulphate and an additive in pig food.Total phenol concentration also increased considerably within the catchment as a result of urbanisation. Five priority phenolic pollutants (2,4-dimethylphenol; 4-chloro-3-methylphenol; 2,4,6-trichlorophenol; 4-introphenol; pentachlorophenol) were found.

Structural systematics of RSn(S 2CN R′ R″) 2Cl compounds

Abstract Three new organotin(IV) structures of general formula RSn(S 2CN R′ R″) 2Cl, where R′ ≠ R″, namely MeSn · [S 2CN(Me)(Cy)] 2Cl ( 1), MeSn[S 2CN( i-Pr)(CH 2Ph)] 2Cl ( 2) and PhSn[S 2CN(Et)( i-Pr)] 2Cl ( 3) are described. Each structure features tin in a distorted octahedral geometry defined by a C ClS 4donor set as a result of two chelating dithiocarbamate ligands. In all cases the tin-bound carbon and chloride atoms are cis. The shorter Sn–S bond lengths in 3are correlated with the presence of the relatively more electronegative Sn-bound phenyl substituent. The new structures conform to the structural motif adopted by all other compounds with the formula RSn(S 2CN R′ R″) 2Cl, where R′ = R″, suggesting the unsymmetrical substitution pattern of the dithiocarbamate ligands in the present study does not influence the adoption of this structural motif. The homogeneity in the structural motif notwithstanding, non-systematic variations in geometric parameters are found in these structures indicating an overall influence of crystal packing upon molecular geometry.

(E)-3,4-Dihydroxy-benzaldehyde 4-ethyl-thio-semicarbazone.

The title compound, C10H13N3O2S, was prepared by condensation of 3,4-dihydroxybenzaldehyde with 4-ethyl-3-thiosemicarbazide. The molecule adopts an E configuration with respect to the C=N bond. One of the OH substituents on the dihydroxybenzene ring is disordered over the two possible 3-positions on either side of the ordered 4-hydroxy group. The occupancy of the major disorder component refined to 0.633 (7). The molecule is essentially planar, with an r.m.s. deviation through all non-H atoms of 0.0862 Å. An intramolecular N—H⋯N hydrogen bond forms between the outer amine residue and the imine N atom, generating an S(5) ring motif and contributing to the planarity of the molecule. In the crystal structure, an extensive network of classical O—H⋯O, O—H⋯S and N—H⋯S hydrogen bonds and weak C—H⋯O and S⋯O [3.301 (3) Å] interactions link molecules into sheets running approximately parallel to the ab plane.

Bis(N-isobutyl-N-propyl­dithio­carbamato-κ2S,S′)zinc(II)

In the title compound, [Zn(C8H16NS2)2], the ZnII atom is chelated by two S,S′-bidentate dithiocarbamate ions in a very distorted tetrahedral geometry. The alkyl chains of the ligands are equally disordered over two sets of sites.

CRYSTAL STRUCTURE OF DIBUTYLTIN BIS(N,N-DIISOPROPYL)DITHOCARBAMATE

hydrogen a toms are shown as spheres of arbitrary radii. Selected bond dis tances and angles : S n l — C I = 2.13(1), S n l — C I / = 2.13(1), S n l — S I = 2.530(2), S n l — S I ; = 2.530(2), S n l — S 2 = 2 .944(2) , S n l — S 2 ; = 2.944(2) Ä; C I — S n l — C I ; = 131.5(6), C I — S n l — S I = 108.1(2), C I — S n l — S I ; = 108.1(2), C I — S n l — S 2 = 83.8(1), C I — S n l — S2; = 83.8(1), C I ; — S n l — SI = 108.1(2), C I / — S n l — S I ; = 108.1(2), C I / — S n l — S 2 = 83.8(1), C I / — S n l — S 2 ; = 83.8(1), S I — S n l — S l ; = 81.7(1), S I — S n l — S 2 = 64.5(1) , S I — S n l — S2; = 146.2(1), S I / — S n l — S 2 = 146.2(1), S I / — S n l — S 2 / = 64.5(1), S 2 — S n l — S 2 ; = 149.3(1)°. S y m m e t r y t ransformation: / = 0.5 — χ , 1.5 — y , z.

3-[(E)-(4-Chloro-benzyl-idene)amino]-1-phenyl-thio-urea.

In the title compound, C14H12ClN3S, the dihedral angle between the terminal benzene rings is 56.6 (2)°; the benzene rings lie to the same side of the molecule. The major twist in the molecule occurs around the Car—N bond (ar is aromatic) [C—N—C—C = 49.9 (5)°]. The configuration about the N=C bond [1.271 (4) Å] is E. The amine H atoms lie on opposite sides of the molecule with one forming an intramolecular N—H⋯N(imine) hydrogen bond and an S(5) ring. In the crystal, centrosymmetric dimers are formed via {⋯HNC=S}2 synthons.

(Thiocyanato-N)tris(triphenylphosphine)-silver(I) chloroform solvate

Crystals of [Ag(NCS)(C18H15P)3].CHCl3 consist of discrete [Ag(PPh3)3(NCS)] molecules, in which the Ag atom is tetrahedrally surrounded by three P atoms of the PPh3 groups and the N atom of the isothiocyanate ligand, and chloroform molecules. The coordination polyhedron around the Ag atom is distorted with angles at Ag ranging from 102.58 (10) to 114.73 (3)°. The Ag—N—C angle is 159.6 (3)°.

(N-Benzyl-N-isopropyl­dithio­carbamato)chloridodiphenyl­tin(IV)

The SnIV atom in the title organotin dithiocarbamate, [Sn(C6H5)2(C11H14NS2)Cl], is penta-coordinated by an asymmetrically coordinating dithiocarbamate ligand, a Cl and two ispo-C atoms of the Sn-bound phenyl groups. The resulting C2ClS2 donor set defines a coordination geometry intermediate between square-pyramidal and trigonal-bipyramidal with a slight tendency towards the latter. The formation of close intramolecular C–H⋯Cl and C–H⋯S contacts precludes the Cl and S atoms from forming significant intermolecular contacts. The presence of C–H⋯π contacts leads to the formation of supramolecular arrays that stack along the b axis.

Di-n-butyl­bis­(N-cyclo­hexyl-N-ethyl­dithio­carbamato-κ2S,S′)tin(IV)

The SnIV atom in the title compound, [Sn(C4H9)2(C9H16NS2)2], is chelated by the two dithiocarbamate ions in a six-coordinate skew-trapezoidal-bipyramidal geometry. The two butyl groups are disordered over two positions in a 1:1 ratio.

Bis­[N-(2-hydroxy­ethyl)-N-methyl­di­thiocarbamato-S,S′]­di­phenyl­tin

The Sn atom in the title compound, [Sn(C6H5)2(C4H8NOS2)2], is six-coordinate in a cis–C2SnS4 octahedral environment.