A study of the products of the reaction of phosphorus and dioxygen

Article abstract of DOI:10.1021/jp993623b

The products of the reaction of laser-ablated red phosphorus and dioxygen have been studied using experiment and theory. The bands at 480.3 and 1273.3 cm^-1, previously attributed to PO₃ in the matrix isolation IR experiments, are reassigned to PO₃^- Also observed in experiment are PO₂, PO₂^-, P₂O, OPOPO, P₄, and higher oxides.

Full text of DOI:10.1021/jp993623b

3566
J. Phys. Chem. A 2000, 104, 3566-3571
A Study of the Products of the Reaction of Phosphorus and Dioxygen†
Charles W. Bauschlicher, Jr.*
NASA Ames Research Center, Mail Stop 230-3, Moffett Field, California 94035
Mingfei Zhou and Lester Andrews*
UniVersity of Virginia, CharlottesVille, Virginia 22901
ReceiVed: October 11, 1999; In Final Form: NoVember 30, 1999
The products of the reaction of laser-ablated red phosphorus and dioxygen have been studied using experiment
and theory. The bands at 480.3 and 1273.3 cm-l, previously attributed to PO3 in the matrix isolation IR
-
-
experiments, are reassigned to PO3 . Also observed in experiment are PO2, PO2 , P2O, OPOPO, P4, and
higher oxides.
I. Introduction
consider the effect of isotopic substitution, and consider some
species not considered previously.
In 1988 Withnall and Andrews1 reported the infrared (IR)
spectra arising from the products of the reaction of PH3 with
atomic oxygen trapped in solid argon. They attributed bands at
480.3 and 1273.3 cm-1 to the a2′′ out-of-plane bend and e′ P-O
stretching modes of PO3, respectively. They also tentatively
assigned a band at 435.2 cm-1 as the e′ bending mode of the
same molecule. The assignment was based in large part on the
spectra with mixed 16,18O, which clearly showed that the a2′′
mode arose from a species with three equivalent oxygen atoms,
and on the fact that using PD3, instead of PH3, showed that the
species did not include any hydrogen.
II. Computational Methods
The geometries are optimized and the harmonic frequencies
computed using the hybrid5 B3LYP6 functional in conjunction
with the 6-31+G* and 6-31+G(2df) basis sets.7 The vertical
electronic excitation energies are computed using the time-
dependent B3LYP approach8 with the 6-31+G(d) basis set. The
harmonic frequencies are also determined using the coupled
cluster singles and doubles approach9 including the effect of
connected triples determined using perturbation theory,10 CCSD-
(T). All electrons are correlated in the CCSD(T) calculations.
The open-shell calculations are based on unrestricted Hartree-
Fock (UHF) wave functions. The 6-31G* and 6-31+G(2df)
basis sets are used in conjunction with the CCSD(T) calcula-
tions.
The harmonic frequencies are computed using both 16O and
18O. Errors in the computed values prevent a definitive
identification of the experimental bands using only the 160
computed frequencies. However, for each band, the ratio of the
frequencies determined using 16O to the frequencies determined
using 18O, denoted R(16/18), is also computed. This ratio is
more accurate than the frequencies and therefore is very helpful
in identifying the bands.
In 1989 Withnall, McCluskey, and Andrews2 reported the
electronic spectra of the species previously assigned as PO3.
They observed a band system starting at 695.5 nm with
progressions of about 900 and 525 cm-l. On the basis of
comparison with NO3 and SO3+, they assigned the observed
transition as 2E′ r X2A′, the 913 ( 10 cm-1 interval to the a1′
2
symmetric stretch in the ground state, and the 525 cm-1 interval
to the excited state.
As part of our recent study3 of the heats of formation of POn
and POnH, n ) 1-3, we computed the vibrational frequencies
of these species. The computed frequencies of all of the
molecules, except PO3, agreed with experiment. Because we
expected similar accuracy for all of the species, we looked for
an alternative assignment of the experimental IR bands. We
found that the computed a2′′ out-of-plane bend and the e′ stretch
The B3LYP calculations are performed using Gaussian 98,11
while the CCSD(T) calculations are performed using ACES II.12
The. B3LYP/6-31+G* geometries are given at http://ccf.
arc.nasa.gov/∼cbauschl/p2o5.geometry.
-
of PO3 agreed much better with the experiment than did the
computed PO3 results. Unfortunately, the computed results for
neither molecule agreed well with the 435.2 cm-1 band.
III. Experimental Methods
In this paper we report on the electronic spectra and on higher
level calculations for the IR spectra of PO3 and PO3-. New
The experiment for laser ablation and matrix isolation has
been described in detail previously.13 Briefly, the Nd:YAG laser
fundamental (1064 nm, 10 Hz repetition rate with 1-5 mJ pulses
of 10 ns width) was focused on a rotating red phosphorus
(Aldrich, lump) target. Laser-ablated phosphorus was codepos-
ited with oxygen (1%) in excess argon onto a 10 K CsI
cryogenic window at 2 mmol/h for l h. FTIR spectra were
recorded at 0.5 cm-1 resolution on a Nicolet 750 spectrometer
with 0.1 cm-1 accuracy using a HgCdTe detector. Matrix
samples were annealed at different temperatures and subjected
-
experiments are also performed to test the PO3 hypotheses.
Other bands are observed in these experiments, so additional
calculations are performed for PnOm, species to aid in the
identification of the observed bands. We should note that many
of the PyOx, species have been studied by Lohr and co-workers4
at the Hartree-Fock level. In this work, we use a higher level
of theory which results in more accurate frequencies; we also
† Part of the special issue “Marilyn Jacox Festschrift”.
10.1021/jp993623b CCC: $19.00 © 2000 American Chemical Society
Published on Web 01/21/2000

Products of the Reaction of P and O2
J. Phys. Chem. A, Vol. 104, No. 16, 2000 3567
TABLE 1: Summary of the PO3 Harmonic Frequencies
(cm-1), Intensities (km/mol), and Oxygen 16/18 Isotopic
Ratios
TABLE 3: Summary of the Vertical Excitation Energies
-
(eV) and f Values of PO3 and PO3
-
PO3
PO3
mode
ω
inten
R(16/18)
state
∆
f
state
∆
f
B3LYP/6-31+G*
2E′′
2E′
2E′
1.30
1.96
4.21
4.23
0.0000
0.0014
0.0040
0.0000
1A2′
1E′′
1A2′′
1E′
4.42
5.62
5.65
6.23
0.0000
0.0000
0.0000
0.0128
e′
142.3
410.1
994.4
7.8
57.2
0
1.0441
1.0226
1.0608
1.0389
a2′′
a1′
e′
2A′′
1
1083.2
63.6
1273.3 cm-1 band, where the computed PO3 value differs by
B3LYP/6-31+G(2df)
e′
142.8
10.3
54.7
0
1.0443
1.0226
1.0608
1.0388
-
more than 100 cm-1 with experiment, while the value for PO3
a2′′
a1′
e′
425.2
1015.6
1112.4
differs by much less. The experimental band at 435.2 cm-1 with
an isotopic ratio of 1.0340 does not correspond very well with
70.2
-
either PO3 or PO3
.
CCSD(T)/6-31G*
The in-plane O 2p orbitals perpendicular to the P-O bonds
form a2′ and e′ orbitals. The a2′ orbital is singly occupied in
neutral PO3, but doubly occupied in the anion. The one fewer
electron should reduce the O-O repulsion in the neutral and
e′
51.0
399.8
983.5
17.1
49.0
0
1.0432
1.0226
1.0608
1.0398
a2′′
a1′
e′
1055.9
131.7
may be responsible for the lower in-plane e′ bending frequency
-
TABLE 2: Summary of the PO3 Harmonic Frequencies
(cm-1), Intensities (km/mol), and Oxygen 16/18 Isotopic
Ratios
-
for PO3 than for PO3
.
The electronic spectra of PO3 and PO3- are computed using
the time-dependent B3LYP approach using the 6-31+G(d) basis
set at the PO3 B3LYP/6-31+G(2df) geometry, and the results
are summarized in Table 3. For PO3-, the first transition is at
4.42 eV, and the first allowed transition is at 6.23 eV. For PO3,
the computed transitions lie at 1.30, 1.96, 4.21, and 4.23 eV,
with the transitions at 1.96 and 4.21 eV being allowed. The
allowed transition at 1.96 eV agrees with the experimental value
of 1.78 eV to within the expected uncertainty ((0.3 eV) of the
theoretical method used. Since there are no other allowed
transitions in this region, we agree with Withnall, McCluskey,
and Andrews that the band they observe in experiment arises
mode
ω
inten
R(16/18)
B3LYP/6-31+G*
e′
462.9
458.0
971.7
71.7
60.7
0
1.0514
1.0226
1.0608
1.0320
a2′′
a1′
e′
1239.3
644.6
B3LYP/6-31+G(2df)
e′
474.0
477.2
996.0
64.9
55.3
0
1.0514
1.0226
1.0608
1.0317
a2′′
a1′
e′
1264.0
619.7
2
from PO3 and should be assigned as E′ r X2A′. The current
CCSD(T)/6-31G*
2
e′
483.3
471.9
990.5
68.0
60.7
0
1.0516
1.0226
1.0608
1.0316
results show that the progression at 525 cm-1 should be
attributed to the upper state as done by Withnall, McCluskey,
and Andrews. It is more difficult to assign the progression at
about 900 cm-1; the experimental value is similar to that of the
a1′ mode of the PO3 ground state, as suggested by Withnall,
McCluskey, and Andrews, but the difference between theory
and experiment is larger than expected. Given the size of the
difference between theory and experiment for the vibrational
frequency and the matrix temperature (12 K), we would be more
tempted to assign this to the upper state than to the ground state.
While the assignment of the 480.3 and 1273.3 cm-1 bands
a2′′
a1′
e′
1286.6
448.5
CCSD(T)/6-31+G(2df)
e′
487.1
490.5
1006.5
1282.3
68.1
56.0
0
1.0514
1.0226
1.0608
1.0318
a2′′
a1′
e′
596.0
to photolysis using a medium-pressure mercury arc (Philips,
H39KB, 175 W) lamp.
-
to PO3 seems straightforward, it is disconcerting that the e′
IV. Results and Discussion
bending mode of PO3-, which has about the same intensity as
the a2′′ mode, cannot be assigned to any of the observed bands.
Also, given that the electronic spectra clearly show the existence
of PO3, it is disconcerting that e′ P-O stretching and a2′′ out-
of-plane bending modes of PO3 have not been observed.
Early experiments employed laser-ablated red phosphorus as
a reagent for dioxygen diluted in argon.14 Similar experiments
were done using lower oxygen concentration, lower laser power,
and a rotating red phosphorus target to minimize the amount
of ablated phosphorus and to favor the ablation of P atoms.
Representative spectra are shown in Figures 1-3, and the
absorptions are listed in Table 4; the related theoretical data
are presented in Tables 5-12.
-
We first consider the computational study of PO3 and PO3
,
which is summarized in Tables 1-3. We then describe the new
experimental work; these results are summarized in Table 4.
The additional calculations performed to support the experi-
mental study are summarized in Tables 5-12.
2
The ground state of PO3 is A′, which has D3h symmetry.
2
-
PO3 is a closed shell and also has D3h symmetry. The two
species have very similar bond lengths; for example, at the
CCSD(T)/6-31+G(2df) level, the P-O bond length in PO3- is
1.492 Å compared with 1.482 Å for PO3. At this level of theory,
the electron affinity of PO3 is 4.99 eV, which is similar to the
value of 4.77 eV found at the B3LYP/6-31+G(2df) level.
-
The computed PO3 and PO3 harmonic frequencies and
The strong sharp 1319.0 cm-1 absorption has been assigned
to the antisymmetric stretching fundamental (ν3) of PO2 in solid
argon.1,14-18 This absorption is red-shifted 8.5 cm-1 from the
gas-phase19 diode laser value of 1327.53 cm-l. The reaction
intensities are summarized in Tables 1 and 2. Excluding the e′
bending mode of PO3, all of the results are fairly independent
of the level of theory used. The experimental bands at 480.3
and 1273.3 cm-1 with 16O to 18O isotopic ratios (R(16/18)) of
1.0219 and 1.0314, respectively, agree better with the computed
with 18O2 displaces the 1319.0 cm-1 absorption to 1280.0 cm-1
.
The associated bending mode was observed at 386.8 cm-l in
other experiments using a grating instrument. Both infrared
-
results for PO3 than for PO3. This is especially true for the

3568 J. Phys. Chem. A, Vol. 104, No. 16, 2000
Bauschlicher et al.
TABLE 5: B3LYP/6-31+G* Harmonic Frequencies (cm-l),
Intensities (km/mol), and 16O to 18O Isotopic Ratios for
Species with One P Atoma
16O
18O
ω
I
ω
R(16/18)
PO
1181 (1172.8)
σ
1226 (1218.0)
53
1.0380 (1.0385)
PO2
376
995
1238 (1280.0)
a1
a1
b2
381
1047
1277 (1319.0)
31
4
101
1.0372
1.0520
1.0312 (1.0304)
-
PO2
a1
a1
b2
445
1031
1172 (1198.6)
38
84
351
427
986
1135 (1160.6)
1.0431
1.0460
1.0331(1.0327)
PO3
e′
142
410
994
8
57
0
136
401
937
1042
-
1.0441
1.0226
1.0608
1.0389
Figure 1. Infrared spectra in the 1500-445 cm-1 region for laser-
ablated red phosphorus and 1% O2 in argon: (a) sample codeposited
at 10 K for 1 h and (b) sample after annealing to 25 K.
a2′′
a1′
e′
1083
64
TABLE 4: Infrared Absorptions (cm-1) from Codeposition
of Laser-Ablated P with O2 in Excess Argon
PO3
e′
463
458 (480.2)
973
72
61
0
440
448 (469.9)
916
1.0514
1.0226 (1.0219)
1.0608
a2′′
a1′
e′
16O2
18O2
R(16/18)
assignment
1473.1
1449.5
1319.0
1270.3
1253.4
1247.8
1218.0
1198.6
1158.1
1007.5
859.3
1431.1
1407.7
1280.0
1234.1
1207.5
1203.9
1172.8
1160.6
1105.5
971.7
822.9
703.0
503.3
469.9
1.0293
1.0297
1.0304
1.0293
1.0380
1.0365
1.0385
1.0327
1.0476
1.0368
1.0442
1.0457
1.0205
1.0219
1.0442
O2PPO2
X(O2P-O-PO isomer)
PO2
1239
645
1201
1.0320
a The relevant experimental bands from Table 4 are given in
parentheses for comparison.
P2O
OPOPO
OPOPO
PO
-
PO2
O2PPO2
X(O2P-O-PO isomer)
OPOPO
735.1
513.6
480.2
479.4
?
?
PO3
-
459.1
465.8
O2PPO2
P4
465.8
active modes of PO2 are in satisfactory agreement with our
B3LYP calculations; compare the results in Tables 4 and 5.
The next strongest absorption at 1198.6 cm-l has been
assigned to the PO2- anion;14,16 the 18O2 counterpart appears at
1160.6 cm-1. Our yield is not sufficient to observe the bending
mode reported at 470 cm-1 in the gas phase.20 New experiments
were performed to investigate the effect of a CCl4 electron
trap21-24 on the relative yields of PO2 and PO2-. Figure 2 shows
that CCl4 doping reduces the absorptions of PO2 to 50%, of
PO2- to 40%, of P18O2- to 57%, and of P18O2- to 27% of their
values without CCl4. (Part of the overall reduction may be due
to a lower yield of P atoms as P4 was reduced to 65% in the
0.2% CCl4 doped 1% O2 experiment; this probably arises from
ablation out of the groove on the target used in the previous
experiment.) Annealing to 25 K reduced PO2 by 20% and the
Figure 2. Infrared spectra in the 1340-1140 cm-l region for laser-
ablated red phosphorus and 1% O2 in argon codeposited at 10 K for 1
h periods: (a) 1% O2 in argon, (b) 1% O2 and 0.2% CCl4 in argon, (c)
1% 18O2 in argon, and (d) 1% 18O2 and 0.2% CCl4 in argon.
they do not give in to CCl4 as readily as transition metal
-
carbonyls. Nevertheless, the decrease of PO2 absorptions
-
relative to PO2 bands is sufficient to confirm the PO2 anion
assignment.
q
Figure 3 shows the lower region containing the PO3 , O2-
PPO2, and P4 absorptions at 480.2, 479.4, and 465.8 cm-1
,
-
respectively, in the 1% O2 experiment.1,15,16 The 480.2 cm-1
absorption was particularly noteworthy as it gave the 1/3/3/1
quartet with statistical 16,18O2 characteristic of the nondegenerate
motion of three equivalent oxygen atoms.1 Doping with 0.2%
CCl4 reduced these band absorbances to 38%, 60%, and 65%
of yields in the experiment without CCl4. Annealing to 25 K
slightly decreased the PO3q band, tripled the O2PPO2, band, and
increased the P4 absorption by 8%. The effect of added CCl4 is
PO2 band by 50%. Annealing to 30-40 K further decreased
PO2 and markedly increased O2PPO2 absorptions (Table 4). In
+
addition, weak CCl3 radical, CCl3 cation, and Cl-CCl3
transient absorptions were observed.25-28
The effect of added CCl4 is to compete with PO2 for ablated
electrons and reduce the yield of anions relative to neutral
molecules. In transition metal carbonyl systems, doping with
10% as much CCl4 as CO present essentially eliminates the
transition metal carbonyl anions from the spectrum. However,
q
to reduce the PO3 absorption at 480.2 cm-1 sufficiently to
-
conclude that q ) -1. Reassignment of the 480.2 cm-1 band
to PO3- is indicated by the present calculations and experiments.
We do not observe any band that we can assign as the e′
with NO and NO2, CCl4 doping reduced NO2 to 50% and
(NO)2 bands to 30% of the yields without CCl4 added.29
-
Clearly, NO2 and PO2 are good electron traps themselves, and

Products of the Reaction of P and O2
J. Phys. Chem. A, Vol. 104, No. 16, 2000 3569
TABLE 7: B3LYP/6-31+G* Harmonic Frequencies (cm-l),
Intensities (km/mol), and 16O to 18O Isotopic Ratios for
a
P2O3
16O
18O
ω
I
ω
R(16/18)
1.0569
OdPOPdO (E ) 0.0 kcal/mol)
a
b
a
b
a
a
b
b
a
61
91
102
372
452
546
823 (859.3)
1248 (1247.8)
1264 (1253.4)
1
8
58
88
1.0391
4
55
22
3
1029
100
112
98
356
428
544
787 (822.9)
1201 (1203.9)
1218 (1207.5)
1.0336
1.0441
1.0548
1.0046
1.0461 (1.0442)
1.0392 (1.0365)
1.0385 (1.0380)
PO3P Tribridge (E ) 24.1 kcal/mol)
e′′
e′
a1′
a2′′
e′
355
512
700
726
750
860
0
67
0
342
489
687
703
717
826
1.0374
1.0474
1.0182
1.0329
1.0462
1.0419
Figure 3. Infrared spectra in the 485-455 cm-l region for laser-ablated
red phosphorus and 1% O2 in argon codeposited at 10 K for 1 h
periods: (a) 1% O2 in argon, (b) 1% O2 and 0.2% CCl4 in argon, and
(c) after annealing to 25 K.
354
229
0
a1′
O2PPO (E ) 34.2 kcal/mol)
TABLE 6: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
a
a
a
a
a
a
a
a
a
35
100
163
239
371
8
2
34
95
1.0384
1.0440
1.0437
1.0244
1.0246
1.0253
1.0489
1.0393
1.0314
Intensities (km/mol), and 16O to 18O Isotopic Ratios for PPO
a
and P2O2
20
46
74
7
82
105
169
156 .
233
362
473
1050
1188
1329
16O
18O
ω
I
ω
R(16/18)
1.0168
1.0166
1.0310 (1.0293)
485
PPO
161
645
1228 (1234.1)
1101
1234
1371
π
σ
σ
164
656
6
2
1266 (1270.3)
154
a The relevant experimental bands from Table 4 are given in
parentheses for comparison.
P2O2
b3u
b1u
ag
b3g
b2u
ag
432
556
606
700
725
870
33
28
0
0
104
0
416
535
601
671
697
828
1.0389
1.0389
1.0088
1.0421
1.0389
1.0515
previous work) were assigned to oxo-bridged P2O4 (i.e., O2P-
O-PO). These bands are not observed in the present experi-
ments, but the strongest calculated bands (Table 8) are
compatible with this assignment. The earlier studies16,18 also
produced a species X (see Figure 1) absorbing at 1450.0 and
1007.9 cm-1, which was attributed to structural isomers of oxo-
bridged P2O4; these bands are observed here at 1449.5 and
1007.5 cm-l, and they increase markedly on annealing (Figure
1).
Sharp absorptions observed here at 1473.2, 1158.2, 735.1,
and 479.4 cm-l (labeled V) increased markedly (×4) on annealing
to 25 K. These bands were assigned to P2O5 after formation in
six different phosphorus/oxygen experiments.1,14-18 The most
important diagnostic evidence is the triplet of triplets first
reported for the 1158.1 cm-l band using statistical isotopic
oxygen.1 This clearly indicates two equivalent PO2 groups each
with equivalent oxygen atoms. Furthermore, the 1473.2 and
1158.1 cm-1 bands show 16/18 isotopic ratios for antisymmetric
and symmetric P-O stretching modes in a phosphoryl subgroup.
The current P2O5 B3LYP calculations (see Table 9) and the
older HF/6-21G* calculations of Lohr4 find a C2 structure with
inequivalent O atoms and a splitting in the strong antisymmetric
O-P-O stretching mode. Furthermore, both calculations predict
the strongest band, the antisymmetric P-O-P stretching mode,
in the 900-1000 cm-1 region; no such band is observed in the
spectrum. Therefore, the calculations cast doubt on the earlier
P2O5 assignment.
a The relevant experimental bands from Table 4 are given in
parentheses for comparison.
in-plane bending mode of PO3-, which is computed to be a
strong transition and have a frequency very similar to that of
the a2′′ band. The question naturally arises of whether the a2′′
and e′ bands are strongly overlapped. While the band at 480.2
cm-1 is definitely two overlapped bands, one grows on annealing
-
and the other is the photosensitive band that we assign to PO3
.
Given their different behaviors, it is difficult to assign these
two components of the 480.2 cm-1 band to the same molecule.
Thus, we see no evidence supporting the idea that the a2′′ and
e′ bands are strongly overlapped.
The band at 1218.0 cm-1 is due to PO, and the B3LYP results
are in good agreement; see Tables 4 and 5. The band at 1270.3
cm-1 with an isotopic ratio of 1.0293 is in very good agreement
with the B3LYP results (1266 cm-1 and 1.0310) for the P-O
stretch in the linear PPO species, which is also computed to
have a large intensity; see Table 6.
We do not see any indication of P2O2 (planar with D2h
symmetry), which is computed to have a strong band at 724
cm-l; see Table 6. However, the bands at 1253.4, 1247.8, and
859.3 cm-1 should be assigned, as previously suggested,30 to
the OdPsOsPdO isomer of P2O3, which is the most stable
of the P2O3 isomers studied; compare the results in Tables 4
and 7. We do not see any evidence for the higher energy O2-
PPO isomer.
The next best possibility is O2PPO2, the D2d form of
symmetrical P2O4. The strongest band (e) calculated at 1432
cm-1 with a 1.0309 16/18 ratio is appropriate for the antisym-
metric PO2 mode and the 1106 cm-1 band for the out-of-phase
symmetric PO2 mode. The computed 16/18 ratios are in good
agreement with those determined experimentally. Scale factors
In previous P2 oxidation experiments from this laboratory,16,18
bands at 1438.4, 1168.1, and 955.4 cm-l (labeled Y in the

3570 J. Phys. Chem. A, Vol. 104, No. 16, 2000
Bauschlicher et al.
TABLE 8: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
TABLE 9: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
Intensities (km/mol), and 16O to 18O Isotopic Ratios for
Intensities (km/mol), and 16O to 18O Isotopic Ratios for P2O5
a
P2O4
16O
18O
16O
18O
ω
I
ω
R(16/18)
ω
I
ω
R(16/18)
1.0596
O2POPO2 (E ) 0 kcal/mol)
O2POPO Trans (E ) 0.0 kcal/mol)
a
b
a
a
b
a
b
b
a
a
b
b
a
b
a
56
61
103
306
336
379
421
428
487
671
938
1129
1158
1445
1453
0
3
53
57
1.0608
1.0659
1.0540
1.0529
1.0396
1.0235
1.0344
1.0431
1.0434
1.0364
1.0551
1.0493
1.0472
1.0313
1.0308
a
a
a
a
a
a
a
a
a
a
a
a
28
81
1
0
6
27
77
1.0535
1.0346
1.0365
1.0414
1.0427
1.0416
1.0256
1.0504
1.0465
1.0389
1.0304
1
98
118
340
382
419
481
613
868
1139
1270
1429
114
328
367
402
462
597
826
1088
1222
1387
7
291
323
371
407
410
467
647
889
1076
1105
1401
1409
8
13
13
69
160
2
119
38
16
42
635
175
90
175
48
490
317
21
136
174
O2POPO cis (E ) 1.3 kcal/mol)
a
a
a
a
a
a
a
a
a
a
a
a
29
98
11
1
28
93
1.0339
1.0538
1.0536
1.0473
1.0325
1.0240
1.0446
1.0371
1.0520
1.0451
1.0388
1.0304
O2PO2PO (E ) 3.9 kcal/mol)
108
284
359
412
461
642
882
1143
1285
1423
6
103
271
348
403
442
619
839
1093
1237
1381
b2
b1
a2
a1
b1
b2
b1
b2
a1
a1
a1
b2
a1
a1
b1
88
102
5
4
84
96
1.0391
1.0604
1.0608
1.0495
1.0290
1.0333
1.0415
1.0542
1.0235
1.0534
1.0598
1.0350
1.0506
1.0304
1.0299
15
39
50
67
245
0
2
231
300
314
356
429
432
501
559
915
1046
1072
1376
1402
315
323
5
153
516
239
81
368
447
54
51
456
512
589
970
39
299
120
40
177
O2PPO2 D2d (E ) 24.5 kcal/mol)
1082
1126
1418
1443
148
154
220
182
b1
e
a1
e
b2
a1
b2
a1
e
35
143
250
343
0
26
0
42
188
0
33
1.0608
1.0525
1.0495
1.0197
1.0370 (1.0442)
1.0230
1.0522 (1.0476)
1.0481
136
238
337
407 (459.1)
528
422 (479.4)
541
1106 (1158.1)
1138
OPO3PO (E ) 15.0 kcal/mol)
e′
240
267
22
0
227
264
1.0578
1.0131
1.0602
1.0507
1.0329
1.0509
1.0381
1.0607
1.0349
1.0271
147
0
1051 (1105.5)
1085
e′′
e′′
e′
a1′
a2′′
e′
a1′
a2′′
a1′
409
585
603
0
96
0
386
556
584
1432 (1473.1)
279
1389 (1431.1)
1.0309 (1.0293)
a The relevant experimental bands from Table 4 are given in
parentheses for comparison.
657
869
880
236
459
0
625
837
830
1358
1438
442
0
1312
1401
that bring the B3LYP frequencies for these two modes into
agreement with experiment, 1.029 and 1.047, are comparable.
The computed band at 422 cm-1 is consistent with the
experimental band at 479.4 cm-1, but the differences bletween
the B3LYP and experiment are slightly larger than for the other
two bands. The O2PPO2 form of P2O4 is 24.5 kcal/mol above
the O2POPO form, but the formation process probably has more
to do with the approach geometry of the reactants than with
the relative energetics of the two isomers of P2O4. This
reassignment requires that the 735.1 cm-l band be due to another
species, which grows on annealing in this reactive system. This
absorption position and isotopic ratio are characteristic of the
PO3P tribridge (Table 7).
Finally, note the agreement between the B3LYP-calculated
frequencies and the five strongest bands assigned to P4O10 in
solid argon14 (1408, 1026, 767, 577, and 412 cm-1). Again the
calculated frequencies (see Table 10) must be scaled upward
(in contrast to HF calculations) with scale factors 1.026, 1.050,
1.046, 1.053, and 1.051 for these infrared bands. The size of
these scale factors is consistent with those found for O2PPO2.
Since bands associated with P4 are clearly seen in these
experiments, we have also considered P3O and P4O, which are
possible products of the reaction of P4 with oxygen. The results
of these calculations are summarized in Tables 11 and 12. We
have considered several structures for each system, but we have
TABLE 10: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
Intensities (km/mol), and 16O to 18O Isotopic Ratios for
a
P4O10
16O
18O
ω
I
ω
R(16/18)
e
238
251
257
320
387
392 (412)
523
548 (577)
684
733 (767)
794
0
0
51
0
0
77
0
28
0
432
0
225
241
247
307
381
383
508
530
646
716
767
780
949
1347
1366
1.0556
1.0393
1.0387
1.0422
1.0165
1.0248
1.0303
1.0347
1.0590
1.0238
1.0342
1.0229
1.0309
1.0223
1.0313
t1
t2
e
t1
t2
a1
t2
a1
t2
t1
e
798
0
t2
t2
a1
979 (1026)
1378 (1408)
1409
2099
1176
0
a The experimental values (McCluskey and Andrews14) are given in
parentheses for comparison.
not found any definitive evidence of these species in the present
experimental spectra.

Products of the Reaction of P and O2
J. Phys. Chem. A, Vol. 104, No. 16, 2000 3571
TABLE 11: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
Intensities (km/mol), and 16O to l8O Isotopic Ratios for
Species with Three P Atoms
transition is correctly assigned as the 2E′ r X2A2′ band system
of PO3. The new experimental work does not show any infrared
evidence for PO3, but we are able to identify bands associated
with PO2, PO2-, P2O, OPOPO, and O2PPO2. P4 is also observed
in experiment, but we are unable to observe any evidence for
the expected products such as P4O and P3O.
16O
18O
ω
I
ω
R(16/18)
P3O Rhombus (E ) 0.0 kcal/mol)
b1
b2
a1
a1
b2
a1
162
368
409
533
641
730
0
13
3
6
18
67
157
368
405
533
615
792
1.0307
1.0000
1.0109
1.0003
1.0413
1.0395
Acknowledgment. L.A. thanks the National Science Foun-
dation (Grant CHE 97-00116) for financial support.
References and Notes
OdPP2 (E ) 13.1 kcal/mol)
(1) Withnall, R.; Andrews, L. J. Phys. Chem. 1988, 92, 4610.
(2) Withnall, R.; McCluskey, M.; Andrews, L. J. Phys. Chem. 1989,
93, 126.
(3) Bauschlicher, C. W. J. Phys. Chem. A 1999, 103, 11126.
(4) Lohr, L. L. J. Phys. Chem. 1984, 88, 5569. Lohr, L. L; Boehm, R.
C. J. Phys. Chem. 1987, 91, 3203. Lohr, L. L. J. Phys. Chem. 1990, 94,
1807. Lohr, L. L. J. Phys. Chem. 1992, 96, 119.
b1
b2
a1
b2
a1
a1
208
257
328
490
555
9
12
3
204
249
1.0189
1.0294
1.0045
1.0010
1.0125
1.0336
327
490
4
11
171
548
1213
1254
(5) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.
(6) Stephens, P. J.; Devlin, F. J.; Chabalowski, C. F.; Frisch, M. J. J.
Phys. Chem. 1994, 98, 11623.
(7) Frisch, M. J.; Pople, J. A.; Binkley, J. S., J. Chem. Phys. 1984, 80,
3265 and references therein.
TABLE 12: B3LYP/6-31+G* Harmonic Frequencies (cm-1),
Intensities (km/mol), and 16O to 18O Isotopic Ratios for
Species with Four P Atoms and Zero or One Oxygena
(8) Stratmann, R. E.; Scuseria, G. E.; Frisch, M. J. J. Chem. Phys.
1998, 109, 8218.
(9) Bartlett, R. J. Annu. ReV. Phys. Chem. 1981, 32, 359.
(10) Raghavachari, K.; Trucks, G. W.; Pople, J. A.; Head-Gordon, M.
Chem. Phys. Lett. 1989, 157, 479.
16O
18O
ω
ω
I
R(16/18)
P4
e
t2
a1
365
0
5
0
(11) Gaussian 98, Revision A.6: M. J. Frisch, G. W. Trucks, H. B.
Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, V. G. Zakrzewski,
J. A. Montgomery, Jr., R. E. Stratmann, J. C. Burant, S. Dapprich, J. M.
Millam, A. D. Daniels, K. N. Kudin, M. C. Strain, O. Farkas, J. Tomasi,
V. Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S.
Clifford, J. Ochterski, G. A. Petersson, P. Y. Ayala, Q. Cui, K. Morokuma,
D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J.
Cioslowski, J. V. Ortiz, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz,
I. Komaromi, R. Gomperts, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-
Laham, C. Y. Peng, A. Nanayakkara, C. Gonzalez, M. Challacombe, P. M.
W. Gill, B. Johnson, W. Chen, M. W. Wong, J. L. Andres, C. Gonzalez,
M. Head-Gordon, E. S. Replogle, and J. A. Pople, Gaussian, Inc., Pittsburgh,
PA, 1998.
(12) ACES II is a computational chemistry package especially designed
for coupled cluster and many body perturbation calculations. The SCF,
transformation, correlation energy, and gradient codes were written by J.
F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, and R. J. Bartlett. The
two-electron integrals are taken from the vectorized MOLECULE code of
J. Almlo¨f and P. R. Taylor. ACES II includes a modified version of the
ABACUS integral derivatives program, written by T. Helgaker, H. J. Jensen,
P. Jørensen, J. Olsen, and P. R. Taylor, and the geometry optimization and
vibrational analysis package written by J. F. Stanton and D. E. Bernholdt.
(13) Burkholder, T. R.; Andrews, L. J. Chem. Phys. 1991, 95, 8697.
(14) McCluskey, M.; Andrews, L. J. Phys. Chem. 1991, 95, 3545.
(15) Andrews, L.; Withnall, R. J. Am. Chem. Soc. 1988, 110, 5606.
(16) Andrews, L.; McCluskey, M.; Mielke, Z.; Withnall, R. J. Mol.
Struct. 1990, 222, 95.
461 (465.8)
604
P4O (Ring) (E ) 0.0 kcal/mol)
a2
b1
b2
a1
a1
a1
b2
a1
b2
207
297
313
426
458
521
550
620
768
0
6
2
207
286
312
418
454
521
550
604
734
1.0000
1.0394
1.0007
1.0183
1.0074
1.0002
1.0001
1.0266
1.0462
5
14
5
9
39
25
P4O (Edge) (E ) 12.7 kcal/mol)
b1
a1
a2
b1
a1
b2
a1
b2
a1
315
327
336
412
421
441
537
637
717
6
0
0
5
1
9
6
303
325
336
411
418
441
537
612
690
1.0386
1.0053
1.0000
1.0001
1.0073
1.0002
1.0007
1.0400
1.0394
35
68
OdPP3 (E ) 29.0 kcal/mol)
(17) Mielke, Z.; McCluskey, M.; Andrews, L. Chem. Phys. Lett. 1990,
165, 146.
(18) McCluskey, M.; Andrews, L. J. Phys. Chem. 1991, 95, 2988.
(19) Qian, H.-B.; Davis, P. B.; Hamilton, P. A. J. Chem. Soc., Faraday
Trans. 1995, 91, 2993.
(20) Xu, C.; de Beer, E.; Neumark, D. M. J. Chem. Phys. 1996, 104,
2749.
e
e
a1
e
a1
a1
228
323
397
496
548
26
0
222
323
393
496
543
1.0291
1.0000
1.0110
1.0008
1.0085
1.0330
0
18
0
183
1221
1182
(21) Illenberger, E. Ber. Bunsen-Ges. Phys. Chem. 1982, 86, 252;
Matejcik, S.; Kiendler, A.; Stamatovic, A.; Mark, T. D. Int. J. Mass.
Spectrom. Ion Processes. 1995, 149/150, 311.
a The relevant experimental bands from Table 4 are given in
parentheses for comparison.
(22) Zhou, M. F.; Andrews, L. J. Am. Chem. Soc. 1998, 120, 11499.
(23) Zhou, M. F.; Chertihin, G. V.; Andrews, L. J. Chem. Phys. 1998,
109, 10893.
V. Conclusions
(24) Zhou, M. F.; Andrews, L. J. Phys. Chem. A 1999, 103, 2964.
(25) Andrews, L. J. Chem. Phys. 1968, 48, 972.
(26) Jacox, M. E.; Milligan, D. E. J. Chem. Phys. 1971, 54, 3935.
(27) Prochaska, F. T.; Andrews, L. J. Chem. Phys. 1977, 67, 1091 and
references therein.
(28) Maier, G.; Reisenauer, H. P.; Hu, J.; Hess, B. A., Jr.; Schaad, L. J.
Tetrahedron Lett. 1989, 30, 4105.
(29) Zhou, M. F.; Andrews, L. J. Chem. Phys. 1999, 111, 6036.
(30) McCluskey, M.; Andrews, L. J. Phys. Chem. 1991, 95, 2679.
The computed frequencies and experiment suggest that the
band at 480.3 cm-1 should be reassigned to PO3-. The computed
results show that the related band at 1273.3 cm-1 also agrees
much better with PO3 than PO3. This reassignment is a clear
example of the synergistic effect of applying both theory and
experiment to the identification of IR bands.
-
The computed results also suggest that the observed electronic