Reactions of POxCly-ions with H and H 2 from 298 to 500 K

Article abstract of DOI:10.1021/jp045203e

Rate constants and product branching ratios for PO_xCl _y^-ions reacting with H and H₂ were measured in a selected ion flow tube (SIFT) from 298 to 500 K. PO₂Cl^-, PO₂Cl₂^-, POCl₂^-, and POCl₃^- were all unreactive with H₂, having a rate constant with an upper limit of <5 × 10^-12 cm ³ s^-1. PC₂Cl₂^- did not react with H atoms either, having a similar rate constant limit of <5 × 10^-12 cm³ s^-1. The rate constants for PO ₂Cl^-, POCl₂^-, and POCl ₃^- reacting with H showed no temperature dependence over the limited range of 298-500 K and were approximately 10-20% of the collision rate constant Cl abstraction by H to form HCl was the predominant product channel for PO₂Cl^-, POCl₂^-, and POCl₃^-, with a small amount of Cl^- observed from POCl₂^- + H. Reactions of O₂ and O ₃ with the POCl^- products ions from the reaction of POCl₂^- + H were observed to yield predominantly PO ₃^- and PO₂^-, respectively. POCl ^- reacted with C₂ and O₃ with rate constants of 8.9 ± 1.1 × 10^-11 and 5.2 ± 3.3 × 10 ^-10 cm³ s^-1, respectively. No associative electron detachment in the reactions with H atoms was observed with any of the reactant ions; however, detachment was observed with a PO^- secondary product ion at high H atom concentrations. Results of new G3 theoretical calculations of optimized geometries and energies for the products observed are discussed.

Full text of DOI:10.1021/jp045203e

J. Phys. Chem. A 2005, 109, 2559-2563
2559
-
Reactions of POxCly Ions with H and H2 from 298 to 500 K
Anthony J. Midey,* Thomas M. Miller, Robert A. Morris, and A. A. Viggiano
Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road,
Hanscom AFB, Massachusetts 01731-3010
ReceiVed: October 20, 2004; In Final Form: December 23, 2004
Rate constants and product branching ratios for POxCly- ions reacting with H and H2 were measured in a
-
-
selected ion flow tube (SIFT) from 298 to 500 K. PO2Cl-, PO2Cl2 , POCl2 , and POCl3- were all unreactive
-
with H2, having a rate constant with an upper limit of <5 × 10-12 cm3 s-1. PO2Cl2 did not react with H
atoms either, having a similar rate constant limit of <5 × 10-12 cm3 s-1. The rate constants for PO2Cl-,
POCl2 , and POCl3- reacting with H showed no temperature dependence over the limited range of 298-500
-
K and were approximately 10-20% of the collision rate constant. Cl abstraction by H to form HCl was the
-
-
predominant product channel for PO2Cl-, POCl2 , and POCl3 , with a small amount of Cl- observed from
-
-
POCl2 + H. Reactions of O2 and O3 with the POCl- products ions from the reaction of POCl2 + H were
observed to yield predominantly PO3- and PO2 , respectively. POCl- reacted with O2 and O3 with rate constants
-
of 8.9 ( 1.1 × 10-11 and 5.2 ( 3.3 × 10-10 cm3 s-1, respectively. No associative electron detachment in the
reactions with H atoms was observed with any of the reactant ions; however, detachment was observed with
a PO- secondary product ion at high H atom concentrations. Results of new G3 theoretical calculations of
optimized geometries and energies for the products observed are discussed.
Introduction
subjected to several freeze-pump-thaw cycles to remove
dissolved gases. Electron impact on POCl3 (Aldrich, 99%) in
Recently, reactions of various positive and negative ions with
H and H2 have been studied to ascertain their relevance to the
space environment.1-4 H2 and H are important species in com-
bustion processes as well. Ion-molecule chemistry from air
plasmas has been shown to be a viable method for enhancing
combustion.5,6 However, the role of negative ion chemistry in
combustion is not as well understood. In addition, oxyphos-
phorus compounds have been shown to be reasonable alterna-
tives to phosphine additives for hydrogen-fueled scramjet com-
bustors, yielding a measurable increase of the flameholding sta-
bility and output thrust in the supersonic expansion because of
enhanced H, O, and OH recombination kinetics.7 Flames doped
with oxyphosphorus compounds have also been observed to pro-
duce anions of these compounds whose profile along the flame
axis is strongly influenced by reactions with H as well as H2.8
The chemistry of anions generated from phosphorus oxy-
chloride, POCl3, has recently been studied in our laboratory
using a selected ion flow tube (SIFT).9 POCl3 is known to
an effusive source using a thoriated iridium filament produced
ions which were mass selected by a quadrupole mass filter and
injected into a fast flow of helium buffer gas (AGA, 99.997%).
The buffer gas was introduced into the flow tube through a
Venturi inlet and entrained the injected ions. The He used for
the buffer flow and discharge source was passed through a
liquid-nitrogen-cooled sieve trap to remove water vapor and
other trace impurities before entering both the flow tube and
atom source. H atoms were generated by a microwave discharge
on a mixture of He and H2 (Matheson, 99.9999%) in a Pyrex
tube. Typical H2 dissociation fractions were 5-10%. The
reaction with H2 alone was studied first because H and H2 were
added simultaneously to the reaction region. The remaining
parent ions and any product ions were sampled through a blunt
nose cone aperture and mass analyzed with a second quadrupole
mass filter and detected.
Product branching ratios were obtained by extrapolating the
measured branching ratios to zero neutral concentration to
minimize the effects of secondary chemistry. The product
branching ratios for the major species have uncertainties of
(10%.14 The H atom concentration was calibrated by the known
generate Cl-, POCl2-, and POCl3 by dissociative electron
-
attachment.10,11 Therefore, the rate constants and product
-
branching ratios of POxCly ion reactions with H2 and H,
-
including PO2Cl2 and PO2Cl- ions produced by source
rate constant for Cl- reacting with H of 9.6 × 10-10 cm3 s-1
,
chemistry from POCl3,12 have been measured in the SIFT from
298 to 500 K. The current experiments address the issues
outlined above and further our recent studies of O2 and O3
reactions with these ions.9
which does not vary over our temperature range.15,16 The rate
constants for the H atom reactions have relative uncertainties
of (20% and absolute uncertainties of (30%, slightly higher
than for stable gases such as H2, which have relative and
absolute uncertainties of (15% and (25%, respectively.13 In
addition, the ion current at the nose cone can be monitored as
a function of both the H atom concentration and total ion counts
to determine if associative detachment occurred, because product
electrons diffuse rapidly to the walls resulting in a decrease in
nose cone current.17,18
Experimental Section
(a) Kinetics Measurements. The SIFT instrument at the Air
Force Research Laboratory has been described in detail else-
where13 and will only briefly be described with regard to the
current experiments. All of the reagents have been used as
obtained from the manufacturer except for POCl3, which was
-
-
To probe for reaction pathways to PO3 and PO2 ions
previously observed in POCl3 doped flames,19 the chemistry of
* Corresponding author. E-mail: anthony.midey@hanscom.af.mil.
10.1021/jp045203e CCC: $30.25 © 2005 American Chemical Society
Published on Web 02/24/2005

2560 J. Phys. Chem. A, Vol. 109, No. 11, 2005
Midey et al.
TABLE 1: Rate Constants and Branching Ratios for the
Reaction of POxCly- + H and Secondary Product Ion
Chemistrya
completion before examining the secondary chemistry of the
products. However, the reaction conditions could not be adjusted
to achieve this condition given the H atom concentrations
achievable with the current source. Consequently, a large
rate constant,
[kc] (x10-9 cm3 s-1
branching ratios
)
POCl2 signal remained along with a large Cl- signal arising
-
∆H0298K
kJ mol-1
,
from the POCl2- + O3 reaction, where Cl- accounted for >75%
reactants
products
300 K
500 K
of the reactivity.9 The POCl- signal was much smaller than
-
both the remaining POCl2 and the Cl- signal just described,
0.36 [1.9]
-222 1.00
0.37 [1.9]
1.00
PO2Cl- + H f PO2- + HCl
HOPOCl + e-
meaning that any increase in Cl- would have been a small
addition to a large peak that could not be measured. It should
also be noted that the operating conditions of the mass
spectrometer needed to resolve m/z ) 79 (PO3-) vs m/z ) 82
(POCl-) severely discriminated against m/z ) 35. Thus, these
conditions precluded determining the branching ratio of Cl- that
might be generated by the POCl- reaction. Nevertheless, the
mass discrimination against m/z ) 63 (PO2-) is much less
severe, and a correction to the branching ratios for the O2 and
O3 reactions was subsequently applied. Thus, the branching
ratios for this secondary chemistry with O2 and O3 neglect any
contribution from Cl- products from these reactions. All of the
experimental results are given in Table 1.
7
<0.005 [1.9] <0.005 [1.9]
PO2C.2- H f PO2Cl- + HCl
-27
No Rxn.
No Rxn.
0.16 [1.9]
0.94
0.06
0.16 [1.9]
0.96
0.04
POCl2- + H f POCl- + HCl
Cl- + HPOCl
-45
-6
-10
-3
HOPCl2 + e-
OdPHCl2 + e-
0.38 [1.9]
-275 1.00
0.37 [1.9]
1.00
POCl3- + H f POCl2- + HCl
HOPCl3 + e-
44
secondary
chemistry
0.089 [0.62]
-4.08 >0.99
-116 <0.01
POCl- O2 f
PO3- + Cl
(b) Structure Calculations. The total energy at 0 K and the
enthalpy at 298 K for optimized geometries of the relevant
molecular species have been calculated with G3 theory21,22 using
Gaussian 03W23 with the results shown in Table 2. The structural
parameters given in Tables 3 and 4 were determined from the
MP2(Full)/6-31G(d) optimization step of G3. Electron affinities
(EA) were also determined for PO, PO2Cl, and POCl and are
compared with literature values.9,10,24-26
The wave function stability of the molecules shown in Tables
2-4 was verified for the Hartree-Fock (HF) level optimization
step of G3. However, two exceptions required additional
calculations to obtain geometries with a corresponding stable
wave function. A stable wave function at the HF level could
not easily be obtained for the isomers P-O-H and OdPHOCl,
molecules that could be produced via associative detachment
of H to PO- and PO2Cl-, respectively. Consequently, G3(B3LYP)
calculations27 were performed for two sets of related species:
the POH and HPO isomers and the HPO2Cl, OdPOHCl, PO2Cl,
PO2Cl-, and H reactants and products. Performing the additional
calculations at the same level for all of the related molecules
allowed for comparisons of the relative energies and enthalpies
PO2- + ClO
0.52 [0.92]
∼0.80
POCl- + O3 f PO2- + ClO2
PO2- + Cl + O2 -32
PO2Cl- + O2
-240 ∼0.20
-45
a The measured rate constant is given with the Su-Chesnavich
collision rate constant value in brackets,28,29 both in units of 10-9 cm3
s-1. The heat of reaction at 298 K, ∆H2098K, has been calculated with
G3 theory using the values of Fernandez et al.9 and those given in
Table 2. All of the ions below are unreactive with H2, having an upper
limit to the rate constant of <5 × 10-12 cm3 s-1. See text for details.
POCl- ions that were observed as product ions in the current
H atom experiments has been studied as follows. H atoms were
added at an upstream inlet to produce POCl- from POCl2
+
-
H. First, O2 separately and then a 3% O3 in O2 mixture20 were
introduced at a downstream inlet to react with the POCl- ions,
and the rate constants and relative branching ratios were
measured for O2 and then O3. It is optimal if a sufficient amount
-
of H atoms can be added to drive the POCl2 + H reaction to
TABLE 2: G3 Total Energies, Enthalpies, and Electron Affinities (EA)g
total energy (0 K)
enthalpy (298 K)
EA (calc.)
1.103
EA (lit.)
1.092,a1.00b
PO (C∞V, 2Πr)
-416.372258
-416.412774
-566.653441
-566.775100
-876.499870
-876.549106
-951.716178e
-951.793661e
-416.976138
-877.064143
-877.050838
-1337.185569
-1337.182583
-1797.214934
-952.283854
-952.288108e
-952.243667e
-0.501003
-416.368940
-416.409438
-566.648080
-566.769614
-876.495344
-876.544227
-951.711027e
-951.788053e
-416.972310
-877.059023
-877.046188
-1337.179430
-1337.176990
-1797.206856
-952.278005
-952.282096e
-952.238088e
-0.498632
PO- (C∞V, 3Σ-)
OdPOO (Cs, 2A′′)
OdPOO- (Cs, 1A′)
POCl (Cs, 1A′)
3.311
1.342
2.109e
1.06,c1.25d
2.145f
POCl- (Cs, 2A′′)
PO2Cl (C2V, 1A1)
PO2Cl- (Cs, 2A′)
HPdO (Cs, 1A′)
HO-PCl (C1, 2A)
OdPH-Cl (C1, 2A)
HO-PCl2 (Cs, 1A′)
OdPH-Cl2 (Cs, 1A′)
HOPCl3 (C1, 2A)
HO-POCl (C1, 2A)
OdPHOCl (Cs, 2A′′)
H (2S1/2
)
-0.501087e
-460.654664
-0.498726e
-460.651360
HCl (C∞V, 1Σ+)
a Zittel and Linerberger.24 b Wu and Tiernan.25 c Miller et al., MP4 theory.10 d Miller et al., G2 theory.26 e Calculated using G3(B3LYP) method.
See text for details. f Fernandez et al., G3 theory.9 g All units except EA are in hartrees. EA values are in eV.

-
Reactions of POxCly Ions
J. Phys. Chem. A, Vol. 109, No. 11, 2005 2561
TABLE 3: Bond Lengths (Å) and Angles (degrees) for
Geometries from G3 Theory
parameter
OdPCl OdPCl- HOPCl OdPHCl HPdO
r (P-O)
1.493
2.078
1.533
2.390
1.647
2.072
1.488
2.038
1.418
1.517
r (P-Cl)
r (P-H)
r (O-H)
(Cl-P-O)
(H-P-O)
(H-P-Cl)
(P-O-H)
dihedral
1.453
0.976
102.1
110.5
110.6
118.9
116.7
99.4
105.6
114.7
46.2
(Cl-P-O-H)
parameter
HOPCl3
1.618
HOPCl2 OdPHCl2 HOPdOCl
r (P-O1)
1.628
1.480
1.489a
1.629
2.041
r (P-O2)
Figure 1. Mass spectra for the reaction of POCl2- with H at 298 K as
measured in the selected ion flow tube (SIFT). The dashed line is
without any H atoms in the flow tube and the solid line is with H
atoms added to the flow tube.
r (P-Cl1)
2.194
2.098
2.033
2.073
2.073
2.016
2.016
r (P-Cl2)
r (P-Cl3)
r (P-H)
1.399
115.7
115.7
103.2
r (O-H)
0.979
95.6
0.979
101.4
0.979
117.7
100.3
H and H2 measured from 298 to 500 K are shown in Table 1.
The enthalpies of reaction at 298 K, ∆H0298K, are included in
Table 1 and have been determined from both the previous9 and
new G3 calculations. The new G3 calculations of the total ener-
gy at 0 K and the enthalpy at 298 K are presented in Table 2,
representing optimized structures given in Tables 3 and 4 as men-
tioned above. None of the ions currently studied react with H2
to a measurable extent; therefore, the limitations of the instrument
permit only an upper bound for the rate constant of <5 × 10-12
cm3 s-1 for the H2 reaction. PO2Cl2- is unreactive with H atoms
as well. A comparable limit can be placed on the rate constant
for this reaction since no products were observed. A similar
lack of reactivity of PO2Cl2- with O2, O3, and even POCl3 has
been previously been observed in the SIFT.9,12 This ion is very
stable as evidenced by G3 calculations (EA PO2Cl2 ) 5.788
eV)9 and is a prominent terminal ionic species in the reaction
(Cl1-P-O1)
(Cl1-P-O2)
(Cl2-P-O1)
(Cl3-P-O1)
(Cl1-P-Cl2)
(Cl1-P-Cl3)
(Cl2-P-Cl3)
(H-P-O1)
(H-P-O2)
(H-P-Cl2)
(P-O-H)
(O-P-O)
dihedral
94.1
101.4
99.2
105.3
147.6
102.9
104.2
117.1
101.4
101.4
111.5
-19.3
-168.3
85.7
115.9
-51.0
51.0
109.9
116.0
-143.8
(Cl1-P-O-H)
dihedral
(Cl2-P-O-H)
dihedral
(Cl3-P-O-H)
dihedral
-15.9
of POCl2 and POCl3 with O3.9 The rate constants for the
reactive species are roughly 10-20% of the Su-Chesnavichvich
collision rate constant28,29 and show no temperature dependence
over the temperature range of 298-500 K presently studied.
By far the most prevalent channel for all three reactive ions,
PO2Cl-, POCl3-, and POCl2-, is Cl abstraction by H to form
HCl. Cl abstraction is also exothermic for the PO2Cl2- reaction
with H even though the ion proves to be unreactive. Figure 1
-
-
(O1-P-O2-H)
a P-O1 is a double bond, P-O2 is a single bond.
TABLE 4: Bond Lengths (Å) and Angles (degrees) for
Geometries from G3 Theory
parameter
PdO PdO- OdPOO OdPOO-
r (P-O1)
1.538 1.595
1.487a
1.704
1.372
105.2
115.7
180.0
1.519a
1.601
1.514
110.8
98.7
r (P-O2)
-
shows mass spectra for the POCl2 reaction taken with and
r (O2-O3)
(O1-P-O2)
without H atoms added. The mass spectrum shows almost
-
(P-O2-O3)
exclusively POCl2 before the H atoms are added. At high
concentrations of H atoms, three products are observed: Cl-,
POCl-, and PO-. However, PO- is exclusively a secondary
product formed from POCl- reacting with H as shown in eq 1.
dihedral (O-P-O-O)
180.0
a P-O1 is the terminal P-O double bond.
of reaction and for determination of stable wave functions, where
the geometries were optimized using density functional theory
(DFT) at the B3LYP/6-31G(d) level for G3(B3LYP).
POCl- + H f PO- + HCl + 46 kJ mol-1
f Cl- + HPO + 47 kJ mol-1
The wave functions of these oxyphosphorus compounds using
G3(B3LYP) were all stable using DFT, with the only exception
still being the high-lying P-O-H isomer. However, this isomer
lies ca. 1.5 eV higher in energy than HsPdO according to both
the G3 and DFT calculations. Although the energy of the opti-
mized wave function is thus somewhat uncertain, the P-O-H
isomer would still be inaccessible at the temperatures studied
here. The G3(B3LYP) energies are also given in Table 2.
f HOPCl + e- + 48 kJ mol-1
(1)
It is not possible to completely deconvolute the secondary
chemistry because the reaction of POCl- with H appears to be
near collisional; that is, the secondary chemistry is much faster
than the primary chemistry. It is clear, however, that PO- is
formed in that reaction, whereas Cl- and e- may also be formed
-
as well as shown in eq 1. The reaction of POCl2 with H also
Results and Discussion
has a minor primary product channel giving Cl- and HPOCl
that is only slightly exothermic, but it is possible that the Cl-
product signal is primarily from the POCl- reaction in eq 1. In
(a) H and H2 Reactions. Rate constants and branching ratios
for the reactions of PO2Cl-, PO2Cl2-, POCl2-, and POCl3- with

2562 J. Phys. Chem. A, Vol. 109, No. 11, 2005
Midey et al.
addition, PO- has been observed to undergo associative
detachment with H, making it hard to distinguish if POCl- does
as well. Nevertheless, forming POHCl with the H bound to the
O via this route is 48 kJ mol-1 (0.50 eV) exothermic based on
the current G3 theoretical results in Table 2.
An interesting observation is that none of the primary POxCly-
ions studied undergo associative detachment with H atoms. The
reaction of POCl2- with H is g3 kJ mol-1 (0.03 eV) exothermic
for either HPOCl2 isomer as shown in Table 1, perhaps
indicating barriers to forming the neutral product. Previous
studies of PO- ion reactions have found that PO- was very
difficult to make in the ion source of the SIFT so that insufficient
signal was available for measuring the rate constant for the H
atom reaction, given the relatively low total concentrations of
H as well.30 The final product fractions in Table 1 have been
corrected for the secondary chemistry of the product ions.
corrections. After making this correction, as well as correcting
for the ∼1% PO3- contribution from the POCl2- reaction with
O3, the branching ratios for POCl- reacting with O3 are ca. 0.80
-
PO2 and 0.20 PO2Cl- at 298 K. The rate constant for the
POCl- + O3 reaction is 5.2 ( 3.3 × 10-10 cm3 s-1. This
measurement has a much larger error limit than typical
measurements because of the small concentration of O3 and the
small deviations in successive rate constant measurements that
accumulate when correcting for the O2 reactivity. Nevertheless,
-
these results clearly show that the reaction of POCl2 with H
-
-
is the first step in a pathway to both PO2 and PO3
.
The minimum energy structures for PO3 and PO3- have been
shown to be planar with three equal P-O double bonds in the
anion.9 New G3 calculations show that peroxide forms of PO3
-
and PO3 exist having stable planar z-shaped structures with
the parameters given in Table 4. This neutral PO3 isomer is
3.199 eV higher in energy than the ground-state PO3, whereas
As mentioned above, the G3 results in Tables 2-4 show that
a stable minimum energy structure for POHCl exists having an
H bound to the O atom with the O-H bond slightly displaced
from the Cl-P-O plane. Another stable structure of HPOCl
with H bound to the P atom lies 0.36 eV higher in energy. All
of the other neutral molecules containing H shown in Tables 2
and 3 also have the lowest energy structure with H bound to O
(using G3 theory). The only exception is H-PdO, which is
ca. 1.5 eV more stable than P-O-H as discussed above. For
HPO2Cl, the isomer having a P-H bond is 1.21 eV higher in
energy using G3(B3LYP). Therefore, this isomer will not play
a role up to 500 K. Interestingly, the O-H bond that forms is
∼0.98 Å in all of the optimized structures shown.
-
the analogous PO3 isomer is 5.044 eV higher than the planar
ground-state PO3 anion. Even though the reaction of POCl-
-
with O2 is 408 kJ mol-1 (4.23 eV) exothermic, this higher energy
form of PO3- will not be accessible in the current temperature
range. However, this species may become important at higher
temperatures.
Conclusions
The rate constants and branching ratios for the reactions of
PO2Cl-, PO2Cl2-, POCl2-, and POCl3 with H and H2 have
-
been measured in the SIFT from 298 to 500 K. None of the
-
ions react with H2, and PO2Cl2 does not react with H either,
placing a limit on the rate constant of <5 × 10-12 cm3 s-1 for
all of the systems where no reaction was observed. The rate
constants for H atom reactions are <20% of the collision rate
constant and do not vary with temperature from 298 to 500 K.
The only product observed is Cl abstraction by H, except for a
The bond lengths and angles for the POCl neutral calculated
here agree well with previous experimental31 and theoretical31-33
values. The EA for POCl of 1.34 eV calculated here agrees
better with the G2 value of Miller et al.26 of 1.26 eV than with
the lower level MP2 value of 1.06 eV.10 The G3 EA of PO of
1.10 eV is in good agreement with the experimental value of
Zittel and Lineberger of 1.092 eV from photoelectron spectro-
scopy,24 values which are both higher than the 1.00 eV value
of Wu and Tiernan.25 G3(B3LYP) calculations for PO2Cl and
PO2Cl- give an EA of 2.109 eV, in excellent agreement with
the G3 value calculated recently.9 The present bond lengths for
PO and PO- are both ca. 0.06 Å longer than the literature
values.34 The molecular parameters for HPO are in good
agreement with experimental35 and higher level theoretical
values,35,36 with the current MP2 P-O bond length being ca.
0.03 Å longer than these values.35,36
minor reaction pathway with POCl2 that produces Cl- and
-
HOPCl. Combining the present results with the O3 reactions
-
studied previously9 shows that a pathway from electrons to PO2
-
and PO3 exists for methane-oxygen flames doped with
POCl3,19 where the H atom reaction products can react with O2
and O3. In the future, we also plan to examine reactions with O
1
-
atoms and O2(a ∆g) for more robust pathways to PO3 and
-
PO2
.
Acknowledgment. We thank John Williamson and Paul
Mundis for technical support. This work was supported by the
Air Force Office of Scientific Research under Program Number
EP2303BMA1. A.J.M. and T.M.M. are under contract to
Visidyne, Inc. through Contract Number F19628-99-C-0069.
-
(b) Pathways to PO2 and PO3-. The flame results of
-
-
Goodings and co-workers show that PO3 and PO2 are the
main ions observed when POCl3 is added to an atmospheric
pressure methane-oxygen flame.19 One potential first step in
References and Notes
-
the process is electron attachment to form POCl3- and POCl2
.
(1) Scott, G. B. I.; Fairley, D. A.; Freeman, C. G.; McEwan, M. J.;
Adams, N. G.; Babcock, L. M. J. Phys. Chem. A 1997, 101, 4973-4978.
(2) Scott, G. B. I.; Fairley, D. A.; Freeman, C. G.; McEwan, M. J.;
Spanel, P.; Smith, D. J. Chem. Phys. 1997, 106, 3982-3987.
(3) McEwan, M. J.; Scott, G. B. I.; Adams, N. G.; Babcock, L. M.;
Terzieva, R.; Herbst, E. Astrophys. J. 1999, 513, 287-293.
Since the flame is at atmospheric pressure, the former may
dominate.11 Our combined work on the H, O2 and O3 reactions
shows that only a minor route exists for generating PO3- from
-
the reactions of POCl2 and POCl3-, both of which can be
produced by electron attachment to POCl3 as just discussed.10,11
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-
-
For example, POCl3 reacts with H to form POCl2 which is
also formed directly in electron attachment. However, there is
only a minor channel in the reaction of POCl2- with ozone that
(5) Williams, S.; Midey, A. J.; Arnold, S. T.; Bench, P. M.; Viggiano,
A. A.; Morris, R. A.; Maurice, L. Q.; Carter, C. D. “Progress on the
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-
forms PO3 (ca. 1%).
As seen in Table 1, POCl- reacts with O2 with a rate constant
of 8.9 ( 1.1 × 10-11 cm3 s-1 to form >99% PO3 at 298 K,
-
-
with a trace amount of PO2 also observed. Correcting the O3
branching ratios and rate constants for the O2 reaction is also
required, and the results for O3 in Table 1 reflect these

-
Reactions of POxCly Ions
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