Issue 10 Volume 41 May 16, 2003

20030032996 Air Force Research Lab., Edwards AFB, CA, USA
Are 19F NMR Shifts a Measure for the Nakedness of Fluoride Ions?
Gerken, M.; Boatz, J. A.; Kornath, A.; Haiges, R.; Christe, K. O.; March 13, 2002; 32 pp.; In English
Contract(s)/Grant(s): Proj-2303
Report No.(s): AD-A410513; AFRL-PR-ED-TP-2002-055; No Copyright; Avail: CASI; A03, Hardcopy
The solvent dependency of the 19F NMR shifts of the fluoride anion in CH3OH, H2O, CH3OCH3 CHCl3, CHCl2, CHF3
CH3CN, CH3NO2, (CH3)2SO and CH3COCH3 solutions was studied by theoretical calculations at the MP2/6-31++G(d,p)
and B3LYP/6-31++G(d,p) levels of theory and compared to the experimental values. It is shown that the free gaseous fluoride
anion is most shielded. The stepwise build-up of a solvation sphere was modeled for the F/nH2O system and results in a
progressive deshielding of the F nucleus with an increasing number of water ligands in the first solvation sphere. Theoretical
calculations predict the first solvation sphere of F to be comprised of six or seven monodentate water molecules. The F-H bond
distances increase from 1.42 A in the monohydrate to 1. 69 - 1.87 A and 1.82 A in the penta- and hexa-hydrates, respectively,
and the transfer of negative charge from F to the water ligands reaches its maximum for the tetrahydrate.
DTIC
Nuclear Magnetic Resonance; Chemical Reactions
20030033020 Engineering Research and Consulting, Inc., Edwards AFB, CA, USA
Polynitrogen Chemistry and the Pursuit of New High Energy Density Materials
Christe, Karl O.; Wilson, William W.; Vij, Ashwani; Vij, Vandana; Sheehy, Jeffrey A.; April 13, 2001; 3 pp.; In English
Contract(s)/Grant(s): AF Proj. 2303
Report No.(s): AD-A410568; AFRL-PR-ED-TP-2001-084; No Copyright; Avail: CASI; A01, Hardcopy
The goal of this AFOSR program is the synthesis of novel polynitrogen-derived HEDM compounds, exploiting the
synergism between theory and synthesis. Under combined DARPA, AFOSR and NSF sponsorship, we have discovered in
1999 the novel polynitrogen compound, N5(+)AsF6(-). The N5(+) cation is only the third known, homoleptic polynitrogen
species that can be prepared and isolated in bulk, the other two being N2 and the azide anion. N5(+)AsF6(-) was found to be
only marginally stable. During the past year, the N5(+) cation has successfully been tamed by preparing the stable
fluoroantimonate salts. N5(+)SbF6(-) and N5(+)Sb2F11(-). The former is surprisingly stable (up to 70 deg C) and, according
to drop weight tests, is essentially insensitive. The crystal structure of N5(-)Sb2F11(-) was determined, and the geometry of
N5(+) was found to be in excellent agreement with that predicted by our theoretical calculations. A considerable amount of
effort was spent on improving the syntheses of the precursors for the N5(+) salts. This work resulted in the discovery of a new
cis-trans isomerization process for N2F2, a disproportionation reaction of N2F2 to give NF4(+)Sb3F16(-) under mild
conditions, and several new crystal structures for salts that contain nitrogen fluoride cations. Also, a safer method for
producing N5(+) salts was developed to overcome a series of explosions, encountered in the N5SbF6 synthesis. Metathetical
reactions were carried out in SO2 and anhydrous HF solutions between N5(+)SbF6(-) and alkali metal azides, perchlorates,
and nitrates, in pursuit of N5N3, N5ClO4, and N5N02, respectively. It was also found that the N3(-) anion reacts with S02
under formation of the novel SO2N3(-) anion that was characterized by its crystal structure, vibrational spectroscopy, and
theoretical calculations.
DTIC
Nitrogen Compounds; Crystal Structure
20030033058 Air Force Research Lab., Edwards AFB, CA, USA
Partial Wetting of Non-Smooth Surfaces and Shaped Microchannels
Wapner, Phillip G.; Hoffman, Wesley P.; April 13, 2001; 19 pp.; In English
Contract(s)/Grant(s): AF Proj. 2306
Report No.(s): AD-A410545; AFRL/PRS-ED-TP-2001-086; No Copyright; Avail: CASI; A03, Hardcopy
Increasing attention is being given to partial wetting of micro-channels in MEMS micro-fluidic devices, such as pressure
sensors and accelerometers. The behavior of liquids that have contact angles with a solid surface greater than zero but less
then 180 degrees is also relevant to many other technologies. Moreover, when the solid surface is not perfectly smooth, liquid
contact with that surface is poorly understood and the subject of considerable misconception. When the contact angle is
between zero and 90 degrees, the liquid is traditionally said to ‘wet’ the capillary wall and it will enter the capillary on its own
accord. Pressure is then needed to expel it from the capillary. If the contact angle is between 90 degrees and 180 degrees, the
fluid is termed ‘non-wetting’ and pressure is needed to force it into the capillary. When capillary geometry is allowed to vary,
the traditional concepts of wetting and nonwetting must be carefully examined. The authors conducted an experiment to clarify
this point. A drop of mercury was placed directly over the juncture of two horizontal glass plates. The plates were mounted
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