Kinetics of electron attachment to SF3CN, SF3C6F5, and SF3 and mutual neutralization of Ar+ with CN- and C6F5(-).

The additions of two sulfur fluoride derivatives (SF(3)C(6)F(5) and SF(3)CN) to a flowing afterglow were studied by variable electron and neutral density mass spectrometry. Data collection and analysis were complicated by the high reactivity of the neutral species. Both species readily dissociatively attach thermal electrons at 300 K to yield SF(3) + X(-) (X = C(6)F(5), CN). Attachment to SF(3)C(6)F(5) also results in SF(3)(-) + C(6)F(5) as a minor product channel. The determined electron attachment rate constants were 1(-0.6) (+1) × 10(-7) cm(3) s(-1) for SF(3)C(6)F(5), a lower limit of 1 × 10(-8) cm(3) s(-1) for SF(3)CN, and 4 ± 3 × 10(-9) cm(3) s(-1) for SF(3). Mutual neutralization rate constants of C(6)F(5)(-) and CN(-) with Ar(+) at 300 K were determined to be 5.5(-1.6) (+1.0) × 10(-8) and 3.0 ± 1 × 10(-8) cm(3) s(-1), respectively.

Kinetics following addition of sulfur fluorides to a weakly ionized plasma from 300 to 500 K: rate constants and product determinations for ion-ion mutual neutralization and thermal electron attachment to SF5, SF3, and SF2.

Rate constants for several processes including electron attachment to SF(2), SF(3), and SF(5) and individual product channels of ion-ion mutual neutralization between SF(6)(-), SF(5)(-), and SF(4)(-) with Ar(+) were determined by variable electron and neutral density attachment mass spectrometry. The experiments were conducted with a series of related neutral precursors (SF(6), SF(4), SF(5)Cl, SF(5)C(6)H(5), and SF(3)C(6)F(5)) over a temperature range of 300-500 K. Mutual neutralization rate constants for SF(6)(-), SF(5)(-), and SF(4)(-) with Ar(+) are reported with uncertainties of 10-25% and show temperature dependencies in agreement with the theoretical value of T(-0.5). Product branching in the mutual neutralizations is temperature independent and dependent on the electron binding energy of the anion. A larger fraction of product neutrals from the SF(6)(-) mutual neutralization (0.9 ± 0.1) are dissociated than in the SF(5)(-) mutual neutralization (0.65 ± 0.2), with the SF(4)(-) (0.7 ± 0.3) likely lying in between. Electron attachment to SF(5) (k = 2.0 × 10(-8) ±(1)(2) cm(3) s(-1) at 300 K) and SF(3) (4 ± 3 × 10(-9) cm(3) s(-1) at 300 K) show little temperature dependence. Rate constants of electron attachment to closed-shell SF(n) species decrease as the complexity of the neutral decreases.

Synthesis of twist-twist pi-conjugated di-sec-alkylstilbenes and stilbene polymers.

Twist-twist pi-conjugated (TTPC) pi systems promise unique properties with their 90 degrees twist angles. Di-sec-alkyl substituted stilbenes, 5, were prepared by low-valent titanium coupling of phenyl ketones, 4. Long alkyl chains stopped the coupling reaction. Stilbenes 5 were shown to be approximately 90% TTPC. Inserting TTPC units into poly(p-phenylene) polymers created highly fluorescent, soluble, TTPC pi systems with weak electronic segmentation for organic light emitting diode (OLED) studies.