Joanne A. Smieja

Preservation of sulfidic waters containing dissolved As(III)

Solutions containing variable concentrations of sulfide (0 to 31 ppm) and arsenite (0.35 to 10 ppm) were subjected to several different preservation treatments. As predicted by equilibrium thermodynamics, at near-neutral pH the experimental solutions were undersaturated with respect to orpiment (As2S3). However, upon acidification to pH 2 with HCl or HNO3, instantaneous precipitation of poorly crystalline As2S3 occurred in sulfidic solutions which resulted in the loss of dissolved arsenite. These results have implications concerning the practice of acidifying water samples containing hydrogen sulfide with HCl or HNO3 for the purpose of preserving total arsenic values. If a near-neutral water sample contains 1 ppm arsenite and as little as 0.4 ppm sulfide, loss of dissolved arsenic will occur upon acidification. An alternative three-step preservation method involving base addition, oxidation, and acidification is proposed and investigated as an appropriate technique for preserving sulfide-bearing aqueous samples for total arsenic.

Highly ordered thin films prepared with octabutoxy copper phthalocyanine complexes

Langmuir-Blodgett (LB) films of copper (II) 1,4,8,11,15,18,22,25-octabutoxyphthalocyanine, nCuPc(OBu)(8), (non-peripheral substitution) and copper (II) 2,3,9,10,16,17,23,24-octabutoxyphthalocyanine, pCuPc(OBu)(8), (peripheral substitution), were fabricated and characterized by optical spectroscopy and scanning probe microscopy. The LB films were transferred onto hydrophilic substrates by vertical dipping. Although they posses relatively short polar substituents both compounds form smooth, uniform, dense, and highly stable LB monolayers composed of linear arrays of cofacial oligomers. The long range discotic assemblies of LB and spun cast films of pCuPc(OBu)(8) and nCuPc(OBu)(8) posses physical and chemical properties favorable for molecular electronic device application.

Unusual Bis(imido)metalloporphyrins. The synthesis of M(4-R-TPP)(NC6H4NO2)2 (M = Ru, R = H; M = Os, R = Cl) and structural study of the osmium derivative

Reaction of [Ru(TPP)] 2 with p -nitrophenylazide yields Ru(TPP)(NC 6 H 4 NO 2 ) 2 in high yield as indicated by 1 H NMR spectroscopy. All attempts to isolate a pure crystalline sample of this new bis (arylimido)ruthenium porphyrin were unsuccessful due to its high reactivity. Os(4-Cl-TPP)(NC 6 H 4 NO 2 ) 2 was synthesized and structurally characterized. The structure of Os(4-Cl-TPP)(NC 6 H 4 NO 2 ) 2 is similar to the previously characterized Os(TTP)(NC 6 H 4 NO 2 ) 2 but quite different from other bis (imido)osmium complexes. The imido bonds in the new bis (arylimido)osmium porphyrin are bent with average OsNC bond angles of 142.5° suggesting the imido ligands act as four-electron donors. The eclipsed orientation of the imido ligands indicates the presence of one π bonding and one non-bonding molecular orbital. In solution, 1 H NMR spectroscopy indicates the structure of Os(4-Cl-TPP)(NC 6 H 4 NO 2 ) 2 is dynamic with free rotation around the imido NC and NOs bonds.

Nanomechanical properties of ordered phthalocyanine Langmuir–Blodgett layers

The mechanical properties of monolayer and multilayer structures of several symmetrically substituted alkoxy copper phthalocyanine, CuPc(OR) 8 , Langmuir-Blodgett (LB) films were evaluated. One-dimensional compliance of the monolayers was determined from the slopes of the surface pressure-area isotherms. Multilayers were examined using a SPM and a commercial nanoindentation system. The nanomechanical studies show a distinct relationship between the position and length of alkoxy substituents on the Pc macrocycle and the LB film elasticity and hardness. The phthalocyanine complexes with peripheral octabutoxy and octaoctyloxy substituents form stiff LB monolayers and multilayers. The nonperipheral alkoxy derivetized CuPc films were less stiff. For monolayer films, it appears that the extent of π-π interaction determines the strength of the film. In multilayers, significant additional stability can be imparted through interdigitation of long paraffinic chains which play a significant role in determining the interlayer structure of the LB layers.

The reduction of cluster-coordinated nitric oxide using molecular hydrogen. Synthesis and characterization of H4Os3(NH)(CO)8

Abstract The reaction of molecular hydrogen with HOs 3 (CO) 10 (NO) leading to the reduction of the nitrosyl ligand has been studied. Four products have been isolated and a reasonable mass balance of osmium has been obtained. Two of the products, H 2 Os3(NH)(CO) 9 and the unusual hydrogen-rich cluster H 4 Os 3 (NH)(CO) 8 are new, and spectroscopic data for their formulations and proposed structures are presented. The other two products, HOs 3 (NH 2 )(CO) 10 and H 4 Os 4 (CO) 12 , have been previously characterized. A new route to HOs 3 (NH 2 )(CO) 10 starting from the triazenido cluster, HOs 3 (HN 3 H)(CO) 10 , has also been studied. Interconversions between the imido and amido clusters were investigated.

Reactivity of Os(TTP)(NC6H4NO2)2 (TTP=dianion of 5,10,15,20-tetra(p-tolyl)porphyrin) including a kinetic study of imido ligand transfer to phosphines

Abstract Imido ligand transfer occurs when Os(TTP)(NC 6 H 4 NO 2 ) 2 (TTP=dianion of 5,10,15,20-tetra( p -tolyl)porphyrin) is treated with excess phosphine. The rate of transfer to PMe 3− x Ph x ( x =0, 1, 2, 3) and P(OMe) 2 Ph depends on the basicity and the steric properties of the phosphine. No imido ligand transfer is observed when Os(TTP)(NC 6 H 4 NO 2 ) 2 is treated with excess dimethyl fumarate, styrene, cis -cyclooctene, or 2,3-dimethylbutene under a variety of reaction conditions.

Synthesis and characterization of dichloro[5,10,15,20-tetrakis(p-tolyl)porphyrinato]osmium(IV), a potential precursor to organometallic porphyrinato complexes of osmium

Abstract Dichloro[5,10,20-tetrakis(p-tolyl)porphyrinato]osmium(IV), Os(TTP)Cl2, was prepared by reaction of stannous(II) chloride dihydrate with dioxo[5,10,15,20-tetrakis(p-tolyl)porphyrinato]osmium(VI), Os(TTP)O2. The compound was characterized by 1H NMR, IR, and UV-Visible spectroscopy and by X-ray crystallography. The compound has a trans-dichloro configuration with octahedral Os(IV). The short OsCl bond distances of 2.294(2) A, magnetic moment of 1.63 BM, and isotropic shifts in the 1H NMR spectrum are consistent with π-donation from the halide.