Differential Reactivity of [TpRu(κ2P,N-iPr2PXPy)Cl] (X = NH, S) Bearing Hemilabile Coligands Towards NaBArF 4, Lithium Acetylide, and Acetylenes

In contrast with [TpRu(κ2P,N-iPr2PNHPy)Cl] (1a, Tp = trispyrazolylborate), [TpRu(κ2P,N-iPr2PSPy)Cl] (1b) reacts with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF 4) in fluorobenzene under nitrogen to afford the dinuclear complex [{TpRu(κ2P,N-iPr2PSPy)}2(μ-Cl)][BArF4] (1b ). Through diverse synthetic strategies, a series of neutral acetylides [TpRu(C CR)(κ2P,N-iPr2PXHPy)] [X = NH; R = Ph (2a), SiMe3 (2b); X = S; R = Ph (2c), p-C6H4Br (2d), COOMe (2e)], cationic vinylidene complexes [TpRu(=C=CHR)(κ2P,NiPr2PNHPy)]+ [X = NH; R = Ph (3a), SiMe3 (3b); X = S; R = Ph (3c), p-C6H4Br (3d)] and [TpRu(=C=CH2)(κ2P,N-iPr2PNHPy)]+ (3e), and a cationic η2-alkyne complex [TpRu(η2- HC CCOOMe)(κ2P,N-iPr2PSPy)][BArF 4] have been efficiently synthesized from 1a and 1b. The methoxy(methyl)- carbene complexes [TpRu{=C(OMe)CH3}(κ2P,N-iPr2PXPy)]- [BPh4] [X = NH (5a), S (5b)] were isolated from the reactions of 1a and 1b with acetylene gas in the presence of NaBArF4 in methanol. The deprotonation of the cationic vinylidenes derived from 1b with KtBuO affords the corresponding neutral acetylide complexes, which undergo facile protonation with CF3SO3H to reproduce the cationic vinylidenes quantitatively

Counteranion and Solvent Assistance in Ruthenium-Mediated Alkyne to Vinylidene Isomerizations

The complex [Cp*RuCl(iPr2PNHPy)] (1) reacts with 1-alkynes HC≡CR (R = COOMe, C6H4CF3) in dichloromethane furnishing the corresponding vinylidene complexes [Cp*Ru≡C≡CHR(iPr2PNHPy)]Cl (R = COOMe (2a- Cl), C6H4CF3 (2b-Cl)), whereas reaction of 1 with NaBPh4 in MeOH followed by addition of HC≡CR (R = COOMe, C6H4CF3) yields the metastable π-alkyne complexes [Cp*Ru(η2-HC≡CR)(iPr2PNHPy)][BPh4] (R = COOMe (3a-BPh4), C6H4CF3 (3b-BPh4)). The transformation of 3a-BPh4/3b-BPh4 into their respective vinylidene isomers in dichloromethane is very slow and requires hours to its completion. However, this process is accelerated by addition of LiCl in methanol solution. Reaction of 1 with HC≡CR (R = COOMe, C6H4CF3) in MeOH goes through the intermediacy of the π-alkyne complexes [Cp*Ru(η2-HC≡CR)(iPr2PNHPy)]Cl (R = COOMe (3a-Cl), C6H4CF3 (3b-Cl)), which rearrange to vinylidenes in minutes, i.e., much faster than their counterparts containing the [BPh4]− anion. The kinetics of these isomerizations has been studied in solution by NMR. With the help of DFT studies, these observations have been interpreted in terms of chloride- and methanolassisted hydrogen migrations. Calculations suggest participation of a hydrido−alkynyl intermediate in the process, in which the hydrogen atom can be transferred from the metal to the β-carbon by means of species with weak basic character acting as proton shuttles

Reactions of (polypyrazolylborato)(benzonitrile)rutheniums with terminal alkynes: Reactivity changeover by triethylamine toward arylalkyne polymerization or formation of (arylmethyl)(carbonyl) complexes

Reactions of (κ 3-polypyrazolylborato)(benzonitrile) rutheniums [RuCl{B(4-Ypz) 4}(PhCN) 2] {4-Ypz; 4-bromo-1-pyrazolyl (Y = Br) and 1-pyrazolyl (Y = H) groups} with terminal alkynes were studied. For the reactions with arylalkynes HC≡C(aryl) in the presence of NEt 3, (arylmethyl)(carbonyl)rutheniums [Ru{CH 2(aryl)}{B(4-Ypz) 4}(CO)(PhCN)] were yielded, indicating alkyne C≡C bond cleavage, whereas in the absence of NEt 3, arylalkyne polymerization proceeded instead of the (arylmethyl)ruthenium formation. Reasonably attributed reaction mechanism shows significant role of the vinylidene intermediates "Ru=C=CH(aryl)"

Critical Elements of an Information Security Management Strategy

94 p. This paper was completed as part of the final research component in the University of Oregon Applied Information Management Master's Degree Program [see htpp://aim.uoregon.edu].Not only is Information Security Strategy crucial to protect information systems, but it is central to organization survival. Harris (2006) believes security strategy should be customized because each organization is unique. Literature published from 2000 to 2008 examines information systems in the context of information security. Conclusions provide discussion of six key security policy components selected from ISO-27002 (2005), spanning definitions, objectives, management goals, controls, risk assessment, policies and standards, compliance requirements, and supporting references

Degradation of Uric Acid by Certain Aerobic Bacteria

We have isolated and identified nine cultures of aerobic bacteria capable of growing on an elective medium containing uric acid as the only source of carbon, nitrogen, and energy. Four of these cultures were identified as Aerobacter aerogenes , two as Klebsiella pneumoniae , and the remainder as Serratia killiensis, Pseudomonas aeruginosa , and Bacillus species. Another culture identified as P. fluorescens required both glucose and uric acid for growth. When 23 laboratory stock cultures were inoculated into the uric acid medium, A. aerogenes, B. subtilis, Mycobacterium phlei, P. aeruginosa , and S. marcescens were able to grow. These five cultures also grew when the uric acid was replaced with adenine, guanine, hypoxanthine, xanthine, or allantoin, but growth was poor. In all of these media, including the uric acid medium, addition of glucose along with the nitrogenous compounds yielded good growth. Induction experiments demonstrated that the ability of A. aerogenes, K. pneumoniae, P. aeruginosa, P. fluorescens, S. kiliensis, S. marcescens, B. subtilis , and Bacillus sp. to degrade uric acid is an induced property. Of these organisms, only Bacillus sp. accumulated a small amount of intracellular uric acid. </jats:p

Uso y actitudes hacia las TIC en docentes de matemáticas y su relación con el logro académico de sus estudiantes

Esta investigación buscó conocer la correlación entre el uso y la actitud del docente de matemáticas hacia las TIC y el rendimiento académico de sus estudiantes.&#x0D; El estudio se llevó a cabo con 203 estudiantes y 10 docentes de todas las escuelas del tercer año de secundaria del municipio de Montemorelos, Nuevo León, México. El diseño metodológico de este estudio es (a) cuantitativo, (b) ex post facto, (c) transversal y (d) correlacional.&#x0D; Los resultados estadísticos de esta investigación confirmaron la existencia de una correlación (r = .610) positiva media entre la variable independiente uso de las TIC por parte del docente y la variable dependiente logro académico de los estudiantes. Basándose en los resultados de esta investigación, se deduce que los estudiantes pueden tener un mejor logro académico si los docentes hacen un mejor uso de las TIC. Por otro lado, las variables actitud del docente y uso de las TIC por parte del estudiante no incidieron en el logro académico en matemáticas del estudiante.</jats:p