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A HIGH-LEVEL CALCULATION OF THE PROTON AFFINITY OF DIBORANE
Citation:
Betowski, L D. AND M. Enlow. A HIGH-LEVEL CALCULATION OF THE PROTON AFFINITY OF DIBORANE. JOURNAL OF MOLECULAR STRUCTURE: THEOCHEM 638(1-3):189-195, (2003).
Impact/Purpose:
The overall goals of the task are to apply NERL's core capability in advanced chemical science and technology for maximum benefit in estimating exposures of ecosystems and humans to chemical stressors and to identify emerging pollution concerns, in particular long-range airborne transport of contaminants. This task comprises several subtasks, each with individual objectives:
Subtask 1: screen exposures of National Park PRIMENet ecosystems to chemical stressors, identifying indications of exposure requiring further evaluation, and use these samples evaluate new analytical methods as replacements for standard methods in future assessments of ecosystem contaminant exposures.
Subtask 2: evaluate a new mercury analytical approach with superior performance on complex solid matrices such as biological tissues, and apply the approach to estimating exposure of ecosystems and humans to mercury.
Subtask 3: determine distribution patterns of chemical contaminants in the southern Sierra Nevada Range of California, investigate topographic and weather factors that may influence the distributions, and determine if a correlation exists between contaminant distributions and extirpation patterns of the mountain yellow-legged frog.
Subtask 4: provide analytical methods to measure a number of inorganic and organic arsenic species in a variety of environmental matrices, elucidate the environmental transformations undergone by organoarsenic animal-feed additives, and determine if the potential exists for substantially increased exposure of humans and aquatic organisms to arsenic.
Description:
The experimental proton affinity of diborane (B2H6) is based on an unstable species, B2H,+, 4 which has been observed only at low temperatures. The present work calculates the proton 5 affinity of diborane using the Gaussian-3 method and other high-level compound ab initio 6 methods as a check of the experimental value. The present value of the proton affinity of
7 diborane is thus reported at 147.7 kcal/mol, compared with the experimental value of 147 + or - 4 kcal/mol. However, the experimental value was found to be based on two values, each of which 9 are presently held in error by 12 kca1/mol, but in opposite directions.