William L. Waltz

Bio: William L. Waltz is an academic researcher. The author has contributed to research in topics: Aqueous solution & Potassium. The author has an hindex of 5, co-authored 5 publications receiving 331 citations.

Fast reaction studies of rhenium carbonyl complexes: the pentacarbonylrhenium(0) radical

Abstract: The Re(CO)/sub 5/ radical has been generated in the pulse radiolysis of a variety of organorhenium compounds in ethanol solution as well as in the flash photolysis of Re/sub 2/(CO)/sub 10/ in isoctane solution. This radical exhibits an optical absorption band in the visible region with a maximum at 535 nm and a molar extinction coefficient, in ethanol, of epsilon/sub 535/ 1000 +- 100 M/sup -1/ cm/sup -1/. Absolute rate constants were determined for the reactions of the solvated electron, in ethanol, with Re(CO)/sub 5/Br (6.7 x 10/sup 9/), Re(CO)/sub 5/SO/sub 2/CH/sub 3/ (6.6 x 10/sup 9/), and Re/sub 2/(CO)/sub 10/ (7.8 x 10/sup 9/ M/sup -1/ s/sup -1/). Rate constants were also obtained for the reactions of Re(CO)/sub 5/ and of Mn(CO)/sub 5/ in abstracting a chlorine atom from carbon tetrachloride in ethanol solution. The values, at 22/sup 0/C, are 3.9 x 10/sup 7/ and 6.1 x 10/sup 5/ M/sup -1/ s/sup -1/, respectively, indicating a 65-fold higher reactivity for the pentacarbonylrhenium radical as compared with the pentacarbonylmanganese radical in this abstraction reaction. The rate constant for the recombination reaction of Re(CO)/sub 5/ radicals in isooctane was found to be 2k/sub 7/ = 5.4 x 10/sup 9/ M/sup -1/more » s/sup -1/.« less

Pulse radiolysis studies of decacarbonyldimanganese(0) and halopentacarbonylmanganese(I). The pentacarbonylmanganese(0) radical

Abstract: The pulse radiolysis of Mn/sub 2/(CO)/sub 10/, Mn(CO)/sub 5/Br, and Mn(CO)/sub 5/I in ethanol solution has been investigated. The Mn(CO)/sub 5/ radical, which was observed, exhibits an optical absorption band with a maximum at 830 nm and a molar absorption coefficient of epsilon/sub 830/ = 800 +- 80 M/sup -1/ cm/sup -1/. Absolute rate constants were determined for the reactions of the solvated electron with Mn/sub 2/(CO)/sub 10/(9.1 x 10/sup 9/ M/sup -1/ s/sup -1/), Mn(CO)/sub 5/Br (1.0 x 10/sup 10/ M/sup -1/ s/sup -1/), and Mn(CO)/sub 5/I(1.02 x 10/sup 10/ M/sup -1/ s/sup -1/). For the iodide system, Mn(CO)/sub 5/ is also formed by the reaction of ..cap alpha..-ethanol radical with Mn(CO)/sub 5/I(1.5 x 10/sup 8/ M/sup -1/ s/sup -1/). The recombination of Mn(CO)/sub 5/ has a rate constant of 2k = 1.2 x 10/sup 9/ M/sup -1/ s/sup -1/; Mn/sub 2/(CO)/sub 10/ is identified as a final product in the radiolysis of the halide complexes. Mn(CO)/sub 5/ reacts with O/sub 2/(1.8 x 10/sup 9/ M/sup -1/ s/sup -1/). 4 figures.

The relationship between cupric ion activity and the toxicity of copper to phytoplankton [Thalassiosira pseudonana, Nannochloris atomus, Algae]

Abstract: Culture experiments with the estuarine diatom Thalassiosira pseudonana (clone 3H) in highly chelated seawater media demonstrate that growth rate inhibition and copper content of cells are related to cupric ion activity, and not to total copper concentration. Cupric ion activity was altered independently of total copper concentration by varying the chelator concentration, and the pH. Cellular copper content (moles/ cell) of 3 to 4 day old cultures followed a hyperbolic relation with cupric ion activity: 4.8 X 10• Gou Cu/cell = acu + 10 0.2 where a ou is the cupric ion activity. Copper inhibited growth rate at activities above 3 X 10-u M and growth ceased at values above 5 X 10--0 M; however, the relation between growth rate inhibition and cupric ion activity was not a simple hyperbolic function. In experiments with the estuarine green alga Nannochloris atomus (clone GSB nanno), growth rate inhibition also was related to cupric ion activity with partial growth rate inhibition occuring in the activity range 4 X 10-u to 2 X 10--0 M. Calculated estimates of cupric ion activity in seawater indicate that natural activity levels can be inhibitory to these phytoplankton depending on pH and the degree of copper complexation by natural organic ligands.

π-Conjugated Lewis Base: Efficient Trap-Passivation and Charge-Extraction for Hybrid Perovskite Solar Cells

Abstract: A π-conjugated Lewis base is introduced into perovskite solar cells, namely, indacenodithiophene end-capped with 1.1-dicyanomethylene-3-indanone (IDIC), as a multifunctional interlayer, which combines efficient trap-passivation and electron-extraction. Perovskite solar cells with IDIC layers yield higher photovoltages and photocurrents, and 45% enhanced efficiency compared with control devices without IDIC.

Pyrophosphito-bridged diplatinum chemistry

Abstract: The most widely studied diplatinum(II) complex is Pt{sub 2}({mu}-P{sub 2}O{sub 5}H{sub 2}){sub 4}{sup 4{minus}} (abbreviated Pt{sub 2}), which contains bridging (P,P-bonded) pyrophosphito ligands. The excited-state chemistry exhibited by Pt{sub 2} is probably the richest of all d{sup 8}-d{sup 8} complexes. Photophysical studies confirm that the properties of the photoactive excited state are a manifestation of d{sup 8}-d{sup 8} metal-metal interactions. This report looks at the photochemistry of Pt{sub 2}, because the observed reactions with substrates include rare examples of atom abstractions in addition to electron transfer and other well-studied inorganic excited-state processes.

Involvement of a binuclear species with the Re-C(O)O-Re moiety in CO2 reduction catalyzed by tricarbonyl rhenium(I) complexes with diimine ligands: strikingly slow formation of the Re-Re and Re-C(O)O-Re species from Re(dmb)(CO)3S (dmb = 4,4'-dimethyl-2,2'-bipyridine, S = solvent).

Abstract: Excited-state properties of fac-[Re(dmb)(CO)3(CH3CN)]PF6, [Re(dmb)(CO)3]2 (where dmb = 4,4‘-dimethyl-2,2‘-bipyridine), and other tricarbonyl rhenium(I) complexes were investigated by transient FTIR and UV−vis spectroscopy in CH3CN or THF. The one-electron reduced monomer, Re(dmb)(CO)3S (S = CH3CN or THF), can be prepared either by reductive quenching of the excited states of fac-[Re(dmb)(CO)3(CH3CN)]PF6 or by homolysis of [Re(dmb)(CO)3]2. In the reduced monomer's ground state, the odd electron resides on the dmb ligand rather than on the metal center. Re(dmb)(CO)3S dimerizes slowly in THF, kd = 40 ± 5 M-1 s-1. This rate constant is much smaller than those of other organometallic radicals which are typically 109 M-1 s-1. The slower rate suggests that the equilibrium between the ligand-centered and metal-centered radicals is very unfavorable (K ≈ 10-4). The reaction of Re(dmb)(CO)3S with CO2 is slow and competes with the dimerization. Photolysis of [Re(dmb)(CO)3]2 in the presence of CO2 produces CO with a 2...