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LCAO MO SCF calculations on ClO2F3
Volume 16, nirmber 1
CHEhlICAL
Receiwd
Semi-cmpiriwl
15 September
PHYSICS LETI’ERS
1372
12 June 1972
SCF calculntions fCNDO/7-) of the trigonnl-bipyramidal molecule ClOzF3 proved the Czv cont$,ustrtbilizntion, in accord wiih empirical rules, and with an interpretation of the IR sFecrntm first preparation of th!; compound.
ration to hnvc the highest
of :1 wry recent
1. lritroduction
Quantum chemical treatment of the mo!ecule CtOzF3 appeared of interest in view of the possible csistcnce of several configurations of thir trigonal&pyramidal molecule. MO cakulations should lead to ~nfornlation about the relative! stabifity of the various configurations and facilitate general conclusions in regard to similar problems. An analogous compound of iodine, IO,F,, has Lzecnprcpszed recently [i] , but B detinite determination uf its configuration has not yet been possible. However, MO cakuiations of IOzF, cannot be performed, owing to the fact that the system is too large, and appropriate wavcfunctions for iodine are not svailable. The moiecu!e investigated here is suitable for quantum cflemicaf treatment by means of semi-empirical SCF calculations. We therefore chose the CNDO/:! method [2--41, which has been tested before for severd well known good agreement
a modified version, which computes autortlaticaIl~1 geometrical parameters for lowest total energy. All bond lengths and angles reported here are CNDO/? n~inirn~~rnvalues.
3. Results Four possible configurations have to be considered for the basically trigonal-bipyramidal molecule C102F3 (fig. 1). Calculations were carried out for all four of them. For configuration If no minimum could be obtained. It shows continuous stabilization for increasing F/Cl/F and decreasing
O/Cl/O
angle, leading
IIf. This agrees with Gillespie’s rule, predicting that
the more electronegative atoms prefer axial positions in pyramidal molecules [S] . Aillong the configurations I, III and IV the C,,,
compounds of chlorine and has led to with experirnentai values.
2. Method of computation
All calculations have been Ixrried out by the CNDO/Z method in its cxiginal parametrization [4]. The program QC?E 141*, adapted td the CDC 3300 computer
of the University
of’ Innsbruck,
was used in
to configuration
Fig. 1.
Volume 16, number 1 Table 1
Electronic, total and binding enegies for difrerent confiiurations of C102F3 (in atomic units) Symmetry
Electronic
TotJ
Binding
energy
energy
energy
Dzh
-314.084343
-136.129296
-1.271271
Czv
-315.71023S
-136.225097
-1.367073
Cs
-315.361846
-136.160109
-1.302084
symmetry
(III) proved
by C, (IV) and D,, In the meantime
15 September
CHEMICAL PHYSICS LETTERS
to be the most stable,
(0. Christe
aration of the compound
[6] succeeded
1972
A further reason to favour the CzLvsymmetry may be the fact that the smallest charge transfer from chlorine to fluorine and oxygen atoms respectively, occurs in this configuration.
Acknowledgement
followed
in the prep-
The authors are greatly indebted to the “Rechenzentrum” of the University of Innsbruck for generously supplying
them with computer
time.
C102F3. The infrared spec-
tra indicate
the C,, configuraGon (111) in accord with our quantum chemical treatment. The calculated values for electronic, total and bind: ing energies are collected in table 1. Minimum geometries, charge densities and dipole moments are listed in table 2. The stabilization of C 2v symmetry appears to be mainly an effect of electronic energy contributions. Nuclear repulsion ener,v increases in the order D3h < C, < Czv, but electronic energy decreases to a
larger extent at the same time, leading to a net decrease of the total ener,q.
Geomerries, Configuration
(1)
(III)
chagc
References [I] A. Engelbrecht and P. Peterfy, Angew. Chern. 81 (1969) 753: Angew. Chem. Intern. Ed. 8 (1969) 768. [Zj J.A. Pople, D.P. Santiy and G.A. Scgal, J. Chem. Phys. 43 (1965) 129. [3] J.A. Pople and G.A. Sgal, J. Chcm. Phys. 43 (1965) 136. [4] J.A. Poplc and C.A. Se@, J. Chem. Phys. 44 (1966) 3289. [5] R.J. Gillespie, Arqw. Chem. 79 (1967) 885; Angew. Chem. Intern. Ed. 6 (1967) 819. [6] K.O. Christe, Inorg. Nucl. Chem. Letters 8 c.1972) 457.
Table 2 den&es and dipolc moments Charge density (esu)
Dipole moment (dcbyes)
rCl_F = 1.524 A rCl_0 = 1.520 A
Cl : 6.1699 F : 7.1294 0 : 6.2209
u=o
ra-0 = 1.497 1-i ‘Cl--F,:, = 1.536 8, ‘Cl -Fe4 = 1.513 A
Cl: 6.2238 0 : 6.1764 Fax : 7.1623 Feg : 7.0987
Geometry
p - 1.403
4a/Cl/o = 131.1” liF&ClP,, = 170.5”
(Iv)
‘CLO,q
= 1.500 A
‘Cl-O,, ’ = 1.525 a ‘Cl-Feq = 1.519A ‘Q-F = 1.530.4 dFcq/%/Fq = 108.4” 4O,,/Cl/F,, = 189.5”
Cl : 6.2138 Ocq : 6.1623 O,, : 6.2647 Fq : 7.1077 F, : 7.1439
/.I = 3.342
?
27
CHEhlICAL
Receiwd
Semi-cmpiriwl
15 September
PHYSICS LETI’ERS
1372
12 June 1972
SCF calculntions fCNDO/7-) of the trigonnl-bipyramidal molecule ClOzF3 proved the Czv cont$,ustrtbilizntion, in accord wiih empirical rules, and with an interpretation of the IR sFecrntm first preparation of th!; compound.
ration to hnvc the highest
of :1 wry recent
1. lritroduction
Quantum chemical treatment of the mo!ecule CtOzF3 appeared of interest in view of the possible csistcnce of several configurations of thir trigonal&pyramidal molecule. MO cakulations should lead to ~nfornlation about the relative! stabifity of the various configurations and facilitate general conclusions in regard to similar problems. An analogous compound of iodine, IO,F,, has Lzecnprcpszed recently [i] , but B detinite determination uf its configuration has not yet been possible. However, MO cakuiations of IOzF, cannot be performed, owing to the fact that the system is too large, and appropriate wavcfunctions for iodine are not svailable. The moiecu!e investigated here is suitable for quantum cflemicaf treatment by means of semi-empirical SCF calculations. We therefore chose the CNDO/:! method [2--41, which has been tested before for severd well known good agreement
a modified version, which computes autortlaticaIl~1 geometrical parameters for lowest total energy. All bond lengths and angles reported here are CNDO/? n~inirn~~rnvalues.
3. Results Four possible configurations have to be considered for the basically trigonal-bipyramidal molecule C102F3 (fig. 1). Calculations were carried out for all four of them. For configuration If no minimum could be obtained. It shows continuous stabilization for increasing F/Cl/F and decreasing
O/Cl/O
angle, leading
IIf. This agrees with Gillespie’s rule, predicting that
the more electronegative atoms prefer axial positions in pyramidal molecules [S] . Aillong the configurations I, III and IV the C,,,
compounds of chlorine and has led to with experirnentai values.
2. Method of computation
All calculations have been Ixrried out by the CNDO/Z method in its cxiginal parametrization [4]. The program QC?E 141*, adapted td the CDC 3300 computer
of the University
of’ Innsbruck,
was used in
to configuration
Fig. 1.
Volume 16, number 1 Table 1
Electronic, total and binding enegies for difrerent confiiurations of C102F3 (in atomic units) Symmetry
Electronic
TotJ
Binding
energy
energy
energy
Dzh
-314.084343
-136.129296
-1.271271
Czv
-315.71023S
-136.225097
-1.367073
Cs
-315.361846
-136.160109
-1.302084
symmetry
(III) proved
by C, (IV) and D,, In the meantime
15 September
CHEMICAL PHYSICS LETTERS
to be the most stable,
(0. Christe
aration of the compound
[6] succeeded
1972
A further reason to favour the CzLvsymmetry may be the fact that the smallest charge transfer from chlorine to fluorine and oxygen atoms respectively, occurs in this configuration.
Acknowledgement
followed
in the prep-
The authors are greatly indebted to the “Rechenzentrum” of the University of Innsbruck for generously supplying
them with computer
time.
C102F3. The infrared spec-
tra indicate
the C,, configuraGon (111) in accord with our quantum chemical treatment. The calculated values for electronic, total and bind: ing energies are collected in table 1. Minimum geometries, charge densities and dipole moments are listed in table 2. The stabilization of C 2v symmetry appears to be mainly an effect of electronic energy contributions. Nuclear repulsion ener,v increases in the order D3h < C, < Czv, but electronic energy decreases to a
larger extent at the same time, leading to a net decrease of the total ener,q.
Geomerries, Configuration
(1)
(III)
chagc
References [I] A. Engelbrecht and P. Peterfy, Angew. Chern. 81 (1969) 753: Angew. Chem. Intern. Ed. 8 (1969) 768. [Zj J.A. Pople, D.P. Santiy and G.A. Scgal, J. Chem. Phys. 43 (1965) 129. [3] J.A. Pople and G.A. Sgal, J. Chcm. Phys. 43 (1965) 136. [4] J.A. Poplc and C.A. Se@, J. Chem. Phys. 44 (1966) 3289. [5] R.J. Gillespie, Arqw. Chem. 79 (1967) 885; Angew. Chem. Intern. Ed. 6 (1967) 819. [6] K.O. Christe, Inorg. Nucl. Chem. Letters 8 c.1972) 457.
Table 2 den&es and dipolc moments Charge density (esu)
Dipole moment (dcbyes)
rCl_F = 1.524 A rCl_0 = 1.520 A
Cl : 6.1699 F : 7.1294 0 : 6.2209
u=o
ra-0 = 1.497 1-i ‘Cl--F,:, = 1.536 8, ‘Cl -Fe4 = 1.513 A
Cl: 6.2238 0 : 6.1764 Fax : 7.1623 Feg : 7.0987
Geometry
p - 1.403
4a/Cl/o = 131.1” liF&ClP,, = 170.5”
(Iv)
‘CLO,q
= 1.500 A
‘Cl-O,, ’ = 1.525 a ‘Cl-Feq = 1.519A ‘Q-F = 1.530.4 dFcq/%/Fq = 108.4” 4O,,/Cl/F,, = 189.5”
Cl : 6.2138 Ocq : 6.1623 O,, : 6.2647 Fq : 7.1077 F, : 7.1439
/.I = 3.342
?
27