Abstract The adiabatic ionization potential (IP) of NF x x 1-3 and the enthalpies of formation of NF x and NF ϩ x have been computed using the Gaussian-3 (G3) theory. The obtained values are generally found in very good agreement with the experimental ones. However, the G3 enthalpy of formation of N

F Grandinetti

M Aschi

CiteSeerX

The ionization potential of NF3: a G3 computational study on the
thermochemical properties of NFx and NF
1
x x 1–3
M. Aschia, F. Grandinettib,*
aDipartimento di Chimica, Universita` di Roma “La Sapienza”, P.le A. Moro, 5, 00185, Rome, Italy
bDipartimento di Scienze Ambientali, Universita` della Tuscia, Via S.C. De Lellis, 01100, Viterbo, Italy
Received 26 July 1999; accepted 23 August 1999
Abstract
The adiabatic ionization potential (IP) of NFx x 1–3 and the enthalpies of formation of NFx and NF1x have been computed
using the Gaussian-3 (G3) theory. The obtained values are generally found in very good agreement with the experimental ones.
However, the G3 enthalpy of formation of NF13 at 0 K, 261:7^ 0:9 kcal=mol; and the adiabatic IP of NF3, 12:63^ 0:04 eV;
differ appreciably from the experimental values of 269.6 kcal/mol and 13:00^ 0:02 eV; respectively, based on photoionization
mass spectrometry [J. Berkowitz, J.P. Greene, J. Foropoulos, Jr., O.M. Neskovic, J. Chem. Phys. 81 (1984) 6166] and
268.2 kcal/mol and 12:94^ 0:01 eV; respectively, based on photoelectron photoion coincidence spectroscopy [R. Ru¨ede, H.
Troxler, Ch. Beglinger, M. Jungen, Chem. Phys. Lett. 203 (1993) 477]. This confirms the discrepancy recently noted by Ricca
[A. Ricca, Chem. Phys. Lett. 294 (1998) 454] between the theoretical and the experimental adiabatic IP of NF3. q 2000 Elsevier
Science B.V. All rights reserved.
Keywords: G3 theory; Ionization potential; NF3
1. Introduction
The NFx and NF
1
x speciesx 1–3 are of consid-
erable fundamental interest in the inorganic chemistry
of nitrogen [1]. In addition, they play an active role in
the NF32 based plasma processing of materials
employed for the fabrication of electronic devices
[2–8]. It is therefore not surprising that the structure,
bonding, and thermochemistry of these simple
neutrals and ions are the focus of continuing experi-
mental and theoretical interest [9–14]. In particular,
the enthalpies of formation of the NFx and NF
1
x x
1–3 have been recently evaluated by Ricca [15,16]
using the coupled cluster theory (CCSD(T)) in
conjunction with extrapolation to the complete basis
set. The maximum error bar of the employed theore-
tical procedure was estimated as 2 kcal/mol and, in
fact, the computed enthalpies of formation at 298 K
of NFx and NF
1
x resulted in good agreement with the
experimental values [17,18]. The only exception was
the enthalpy of formation of NF13 ; whose computed
value of 262.88 kcal/mol resulted lower than the
experimental value by 5 kcal/mol. A detailed investi-
gation of the origin of this discrepancy revealed that it
likely reflects an experimental adiabatic ionization
potential (IP) of NF3, 13:00^ 0:02 eV [19,20],
which is probably too large by 0.2–0.3 eV. In fact,
at the CCSD(T) level of theory, using basis sets of
triple, quadruple, and quintuple-zeta quality, the adia-
batic IP of NF3 was computed as 12.64 eV, whereas,
Journal of Molecular Structure (Theochem) 497 (2000) 205–209
0166-1280/00/$ - see front matterq 2000 Elsevier Science B.V. All rights reserved.
PII: S0166-1280(99)00325-5
www.elsevier.nl/locate/theochem
* Corresponding author. Tel.:139-761-357116; fax:139-761-
357179.
E-mail address:fgrandi@unitus.it (F. Grandinetti).
at the same computational level and irrespective of the
employed basis set, the IPs of NF and NF2 were found
to be in very good agreement with the experimental
values of 12:26^ 0:01 [21] and 11:63^ 0:01 eV
[19], respectively. It has been noted by Ricca that
the experimental estimate of the IP of NF3 by Berko-
witz et al. [19,20] based on photoionization (PI) mass
spectrometry, 13:00^ 0:02 eV; probably suffers of
the difficulty of extrapolating the NF13 yield curve to
the adiabatic limit. It is, however, to be mentioned that
the ionization potential of NF3 has been repeatedly
measured by various techniques [22–29] and invari-
ably placed around 13.0 eV. In particular, the two
most recent estimates are 12:94^ 0:01 eV using
photoelectron photoion coincidence (PEPICO) spec-
troscopy [28] and 13:5^ 0:2 eV using electron
impact (EI) mass spectrometry [29]. Therefore, the
difference noted by Ricca between the experimental
and the theoretical adiabatic IP of NF3 marks a discre-
pancy, which deserves further investigation. As a part
of our continuing experimental and theoretical inter-
est in the gas-phase ion chemistry of NF3 [30–38], we
decided to use the Gaussian-3 (G3) theory recently
proposed by Pople and coworkers [39] to evaluate
the enthalpies of formation of NFx and NF
1
x and the
adiabatic IP of NFx x 1–3: The obtained results,
discussed in the present article, confirm the discre-
pancy noted by Ricca [15] between the theoretical
and the experimental IP of NF3.
2. Computational details
The total energies of NFx and NF
1
x have been
computed using the G3 theory [39], which is the
third and the more recent member in the series of
the methods proposed by Pople and coworkers and
referred to as Gaussian-n theories. With respect to
the previous G2 theory [40], G3 has been found to
make a significant improvement in the calculation of
the thermochemical properties of certain classes of
chemical compounds, including simple fluorinated
species such as CF4, SiF4 and NF3. In particular, we
note that the G3 enthalpy of formation of NF3 practi-
cally matches the experimental value of231.6 kcal/
mol [17]. This reinforces the expectation that G3 is
indeed adequate to predict the thermochemical prop-
erties of the presently investigated NFx neutrals and
ions. Like G1 and G2, the G3 theory is a composite
method which consists of a sequence of well defined
ab initio calculations used to calculate the total energy
of a species according to an additivity scheme, the
results of which are corrected by appending a small
higher-level empirical term (HLC). The full details of
the procedure involved in the calculation of the G3
total energies of atoms and molecules are given in
Ref. [39]. We simply report here the general expres-
sion used to calculate the G3 total energies (in
hartrees) at 0 K of a polyatomic species
E0G3  EMP4fc=6-31Gd1 DE1
1 DE2df; p1 DEQCI1 DEG3large
2 0:006386nb 20:002977na 2nb1ZPE
Here,na andnb are the number ofa andb valence
electrons, respectively, and ZPE is the zero-point
energy calculated at the HF/6-31G(d) level and scaled
by 0.8929 to take account of known deficiencies at
this level. The other terms are calculated as follows
by performing single-point calculations at the
MP2(full)/6-31G(d) equilibrium geometry (“full”
and “fc” denote the inclusion or not of the valence
electrons for the calculation of the correlation ener-
gies)
DE1  EMP4fc=6-31G1 d
2 EMP4fc=6-31Gd
DE2df ;p  EMP4fc=6-31G1 2df;p
2 EMP4fc=6-31Gd
DEQCI  EQCISDT=6-31Gd
2 EMP4fc=6-31Gd
DEG3large  EMP2full =G3large
2 EMP2fc=6-31G2df;p
2 EMP2fc=6-311 Gd
1 EMP2fc=6-311 Gd
We have also calculated the G3 total energies of the
M. Aschi, F. Grandinetti / Journal of Molecular Structure (Theochem) 497 (2000) 205–209206
investigated neutrals and ions at 298.15 K by adding
to E0(G3) a thermal correction calculated using the
scaled HF/6-31G(d) frequencies for the vibrations in
the harmonic approximation and the classical approx-
imation for translation3=2RT and rotation (RT for
linear species and3=2RT for non-linear species).
The G3 thermochemical data have been calculated
following the procedures already described in the
literature [41,42] and recommended in Ref. [39]. In
particular, the G3 enthalpies of formation at 0 K of the
NFx neutrals and ions, DH
0
f (NFx, 0 K) and
DH0f (NF
1
x ; 0 K), respectively, have been obtained
according to the following expressions:
DH0f NFx; 0 K  xDH0f F; 0 K1 DH0f N; 0 K
2 D0NFx 1
DH0f NF1x ; 0 K  xDH0f F; 0 K1 DH0f N1; 0 K
2 D0NF1x  2
where
D0NFx  xE0G3; F1 E0G3; N2 E0G3; NFx
D0NF1x   xE0G3; F1 E0G3; N1
2 E0G3; NF1x 
The values of DH0f (F, 0 K), DH
0
f (N, 0 K), and
DH0f (N
1, 0 K), 18.47, 112.53 and 447.69 kcal/mol,
respectively, have been taken from the Janaf Tables
[17], and theE0(G3) of N, 254.56434 hartrees, F,
299.68421 hartrees and N1, 2 54.03123 hartrees,
respectively, have been taken from Ref. [39]. The
ionization potentials at 0 K of the NFx neutrals have
been calculated according to the expression
IPNFx; 0 K  E0G3; NF1x 2 E0G3; NFx 3
All the calculations have been performed using the
Unix version of theGaussian 94 set of programs
[43] installed on a Compaq Alphaserver 1200 work-
station. We used the 6-31G(d), 6-31G(d), and 6-
31G(2df,p) basis sets standard in this program and the
G3large basis set introduced by Pople and coworkers
in conjunction with the G3 theory. The latter has been
downloaded from the website suggested in Ref. [39].
The 6-31G(d), 6-31G1 (d) and 6-31G(2df,p) basis
sets use six Cartesian d-functions (6d) while the
G3large basis set uses five “pure” d-functions (5d).
Both the 6-31G(2df,p) and G3large basis sets use a
set of “pure” 7f.
3. Results and discussion
The G3 total energies of NFx and NF
1
x reported in
Table 1 have been used to calculate the thermochemi-
cal properties at 0 K reported in Table 2. The G3
enthalpies of formation and ionization potentials
have been reported with the uncertainties of
0.9 kcal/mol and 0.04 eV, respectively, quoted by
M. Aschi, F. Grandinetti / Journal of Molecular Structure (Theochem) 497 (2000) 205–209 207
Table 1
G3 total energies (hartrees) of NFx and NF
1
x x 1–3
G3 (0 K) G3 (298.15 K)
NF 2 154.37119 2 154.36881
NF1 2 153.91991 2 153.91755
NF2 2 254.15821 2 254.15516
NF12 2 253.73010 2 253.72715
NF3 2 353.93272 2 353.92927
NF13 2 353.46862 2 353.46516
Table 2
Thermochemical properties (0 K) of NFx and NF
1
x x 1–3
(enthalpies of formation are given in kcal/mol and ionization poten-
tials in eV)
G3 theory Experiment
DH0f (NF) 54.0^ 0.9 55.6̂ 0.5
a
DH0f (NF
1) 336.8^ 0.9 338.3̂ 0.5a
IP(NF) 12.28̂ 0.04 12.26̂ 0.01b
DH0f (NF2) 8.0^ 0.9 8.3^ 0.5
a
DH0f NF12  277.3^ 0.9 276.5̂ 0.5a
IP(NF2) 11.65^ 0.04 11.628 ^ 0.01
a
DH0f (NF3) 2 30.2^ 0.9 2 30.2^ 0.2
c
DH0f NF13  261.7^ 0.9 269.6̂ 0.7d
268.2^ 0.4e
IP(NF3) 12.63^ 0.04 13.00̂ 0.02
a
12.94^ 0.01f
a Taken from Ref. [19].
b Taken from Ref. [21].
c By thermal correction at 0 K of the value at 298.15 K.
d Based on the IP of NF3 reported in Ref. [19].
e Based on the IP of NF3 reported in Ref. [28].
f Taken from Ref. [28].
Pople and coworkers [39] for the calculation of these
quantities. The experimental data reported in Table 2
have been selected as follows: the enthalpies of
formation at 0 K of NF, 55:6^ 0:5 kcal=mol; NF1,
338:3^ 0:5 kcal=mol; NF2, 8.3^ 0.5 kcal/mol; and
NF12 ; 276:5^ 0:5 kcal=mol; as well as the ionization
potential of NF2, 11:628 ^ 0:01 eV; have been taken
from Berkowitz et al. [19]. The enthalpy of formation
at 0 K of NF3, 230:2^ 0:2 kcal=mol; has been
obtained by correcting the enthalpy of formation at
298 K, 231.6 kcal/mol [17], for the enthalpy differ-
ence between 0 K and 298 K of NF3 (taken from Ref.
[23]). The enthalpy of formation of NF13 at 0 K has
been obtained combining the enthalpy of formation of
NF3 at 0 K with the corresponding adiabatic IP. We
decided to quote both the value of 269: ^
0:7 kcal=mol based on the IP of NF3 reported by
Berkowitz et al. [19,20], 13:00^ 0:02 eV; and the
value of 268:2^ 0:4 kcal=mol based on the IP of
NF3 reported by Ru¨ede et al. [28], 12:94^ 0:01 eV:
We first note from Table 2 that, within their combined
uncertainties, the G3 enthalpies of formation at 0 K of
NF, 54:0^ 0:9 kcal=mol; NF1, 336:8^ 0:9 kcal=mol;
NF2, 8:0^ 0:9 kcal=mol and NF
1
2 ; 277:3^
0:9 kcal=mol; are in very good agreement with the
experimental values. However, our calculated
enthalpy of formation of NF13 ; 261:7^
0:9 kcal=mol; significantly differs from the experimen-
tal values of 269.6 and 268.2 kcal/mol. In line with the
conclusion by Ricca [15], our G3 calculations indicate
that the discrepancy between the experimental and the
theoretical enthalpy of formation of NF13 arises from
an appreciable difference between the experimental
and the theoretical adiabatic IP of NF3. In fact,
whereas the G3 enthalpy of formation of NF3 at 0 K,
230:2^ 0:9 kcal=mol; practically matches the experi-
mental value, the G3 adiabatic IP of NF3, 12:63^
0:04 eV; is larger than the two reported experimental
values by ca. 0.3–0.4 eV. It is important to note that
the G3 adiabatic ionization potentials of NF and NF2,
12:28^ 0:04 and 11:65^ 0:04 eV; practically match
the experimental values of 12:26^ 0:01 and 11:628 ^
0:01 eV; respectively.
In conclusion, the G3 adiabatic IP of NF3, 12:63^
0:04 eV; is practically coincident with the accurate
theoretical estimate of 12.64 eV recently reported by
Ricca [15] but larger than the most accurate available
experimental values by ca. 0.3–0.4 eV. This reinforces
the expectation that additional experimental work on
the thermochemistry of ionized NF3 could result in the
appreciable refinement of the IP of this molecule.
Conversely, if the currently accepted IP of NF3 should
be confirmed by further experiments, the theoretical
estimate of this quantity would emerge as a challen-
ging test case even for highly accurate computational
procedures.
Acknowledgements
The authors wish to thank the financial support
from the Italian Ministero della Ricerca Scientificae
Tecnologica (MURST) and Consiglio Nazionale delle
Ricerche (CNR).
References
[1] H.H. Sisler, in: R. Bruce King (Ed.), Encyclopedia of Inor-
ganic Chemistry, Wiley, New York, 1994, p. 2516.
[2] V.M. Donnelly, D.L. Flamm, W.C. Dautremont-Smith, D.J.
Werder, J. Appl. Phys. 55 (1984) 242.
[3] J.I. Steinfel, Chem. Rev. 89 (1989) 1291.
[4] M. Konuma, E. Bauser, J. Appl. Phys. 74 (1993) 62.
[5] A. Jenichen, Surf. Sci. 331 (1995) 1503.
[6] A. Jenichen, J. Phys. Chem. 100 (1996) 9820.
[7] J.B. Casady, E.D. Luckovski, M. Bozack, D. Sherida, R.W.
Johnson, J.R. Williams, J. Electrochem. Soc. 143 (1996) 1750.
[8] E. Meeks, R.S. Larson, S.R. Vosen, J.W. Shon, J. Electro-
chem. Soc. 144 (1997) 357.
[9] K.A. Peterson, R.C. Mayrhofer, E.L. Sibert III, R.C. Woods, J.
Chem. Phys. 94 (1991) 414.
[10] A. Gobbi, G. Frenking, Bull. Chem. Soc. Jpn 66 (1993) 3153.
[11] Z.-L, Cai, Chem. Phys. Lett. 202 (1993) 70.
[12] A. Papakondylis, A. Mavridis, Chem. Phys. Lett. 216 (1993)
167.
[13] M.E. Jacox, W.E. Thompson, J. Chem. Phys. 102 (1995) 6.
[14] S.S. Xantheas, T.H. Dunning Jr., A. Mavridis, J. Chem. Phys.
106 (1997) 3280.
[15] A. Ricca, Chem. Phys. Lett. 294 (1998) 454.
[16] A. Ricca, Chem. Phys. Lett. 300 (1999) 80.
[17] M.W. Chase Jr., C.A. Davies, J.R. Downey Jr., D.J. Frurip,
R.A. McDonald, A.N. Syverud, J. Phys. Chem. Ref. Data 11
(Suppl. 1) (1985).
[18] S.G. Lias, J.A. Bartmess, J.F. Liebman, J.L. Holmes, R.D.
Levin, W.G. Mallard, J. Phys. Chem. Ref. Data 17 (Suppl.
1) (1988).
[19] J. Berkowitz, J.P. Greene, J. Foropoulos Jr., O.M. Neskovic, J.
Chem. Phys. 81 (1984) 6166.
[20] J. Berkowitz, J.P. Greene, J. Chem. Phys. 81 (1984) 3383.
[21] J.M. Dyke, N. Jonathan, A.E. Lewis, A. Morris, J. Chem. Soc.
Faraday Trans. 2 78 (1982) 1445.
M. Aschi, F. Grandinetti / Journal of Molecular Structure (Theochem) 497 (2000) 205–209208
[22] R.M. Reese, V.H. Dibeler, J. Chem. Phys. 24 (1956) 1175.
[23] V.H. Dibeler, J.A. Walker, Inorg. Chem. 8 (1969) 1728.
[24] J. Muller, K. Fenderl, Chem. Ber. 104 (1971) 2207.
[25] P.J. Basset, D.R. Lloyd, J. Chem. Soc. Dalton Trans. (1972)
248.
[26] A.V. Dubin, A.V. Baluev, L.N. Gorochov, Bull. Acad. Sci.
USSR, Div. Chem. Sci. 28 (1979) 1996.
[27] H. Baumgärtel, H.-W. Jochims, E. Ru¨hl, H. Bock, R. Dammel,
J. Minkwitz, R. Nass, Inorg. Chem. 28 (1989) 943.
[28] R. Rüede, H. Troxler, Ch. Beglinger, M. Jungen, Chem. Phys.
Lett. 203 (1993) 477.
[29] V. Tarnovsky, A. Levin, K. Becker, R. Basner, M. Schmidt,
Int. J. Mass Spectrom. Ion Processes 133 (1994) 175.
[30] F. Grandinetti, J. Hrusa´k, D. Schröder, S. Karrass, H. Schwarz,
J. Am. Chem. Soc. 114 (1992) 2806.
[31] F. Cacace, F. Grandinetti, F. Pepi, Angew. Chem. Int. Ed.
Engl. 33 (1994) 123.
[32] M. Aschi, F. Cacace, F. Grandinetti, F. Pepi, J. Phys. Chem. 98
(1994) 2713.
[33] M. Aschi, F. Grandinetti, F. Pepi, Int. J. Mass Spectrom. Ion
Processes 130 (1994) 117.
[34] F. Cacace, F. Grandinetti, F. Pepi, J. Chem. Soc. Chem.
Commun. (1994) 2173.
[35] F. Cacace, F. Pepi, F. Grandinetti, J. Phys. Chem. 98 (1994)
8009.
[36] F. Cacace, F. Grandinetti, F. Pepi, Inorg. Chem. 34 (1995)
1325.
[37] F. Grandinetti, F. Pepi, A. Ricci, Chem. Eur. J. 2 (1996) 495.
[38] M. Aschi, F. Grandinetti, V. Vinciguerra, Chem. Eur. J. 4
(1998) 2366.
[39] L.A. Curtiss, K. Raghavachari, P.C. Redfern, V. Rassolov,
J.A. Pople, J. Chem. Phys. 109 (1998) 7764.
[40] L.A. Curtiss, K. Raghavachari, G.W. Trucks, J.A. Pople, J.
Chem. Phys. 94 (1991) 7221.
[41] L.A. Curtiss, K. Raghavachari, P.C. Redfern, J.A. Pople, J.
Chem. Phys. 106 (1997) 1063.
[42] L.A. Curtiss, P.C. Redfern, K. Raghavachari, J.A. Pople, J.
Chem. Phys. 109 (1998) 42.
[43] M.J. Frisch, G.W. Trucks, H.B. Schlegel, P.M.W. Gill, B.G.
Johnson, M.A. Robb, J.R. Cheeseman, T.A. Keith, G.A.
Petersson, J.A. Montgomery, K. Raghavachari, M.A. Al-
Laham, V.G. Zakrzewski, J.V. Ortiz, J.B. Foresman, J.
Cioslowski, B.B. Stefanov, A. Nanayakkara, M. Challacombe,
C.Y. Peng, P.Y. Ayala, W. Chen, M.W. Wong, J.L. Andres,
E.S. Replogle, R. Gomperts, R.L. Martin, D.J. Fox, J.S. Bink-
ley, D.J. Defrees, J. Baker, J.P. Stewart, M. Head-Gordon, C.
Gonzalez, J.A. Pople,Gaussian 94, Revision E.2, Gaussian
Inc., Pittsburgh, PA, 1995.
M. Aschi, F. Grandinetti / Journal of Molecular Structure (Theochem) 497 (2000) 205–209 209


The ionization potential of NF 3 : a G3 computational study on the thermochemical properties of NF x and NF ϩ x x 1-3

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=7C62F118C56AD97DD8933C7928C58F35?doi=10.1.1.1076.4528&rep=rep1&type=pdf

The ionization potential of NF 3 : a G3 computational study on the thermochemical properties of NF x and NF ϩ x x 1-3

Abstract

Similar works

Full text

Available Versions

CiteSeerX