Y. Binev et al. / Spectrochimica Acta Part A 59 (2003) 3041ꢁ
/3052
3051
(alpha) mutual disposition of the two cyano
groups in the title species.
strong IR spectral variations, caused by the
conversion of phenylmalononitrile into the carb-
anion. We believe the corresponding structural
changes, predicted by the same methods, would
also be adequate. Thus, we think the combined IR/
quantum-chemical approach, used in this work,
could further be applied successfully to follow
other chemical conversions of this kind.
4.4. Energy analysis
According to the calculations performed, the
total energies Etot of the species studied (in the
order HF; MP2; BLYP) are, as follows.
molecule 1a:
455.859225 hartree
carbanion 1b: 452.645610;
455.334146 hartree
ꢀ
/
453.186790;
ꢀ
/
454.633382;
ꢀ
/
Acknowledgements
ꢀ
/
ꢀ
/
454.096748;
ꢀ
/
The authors thank Prof. I.G. Binev, D.Sc, for
the useful discussion. The financial support by the
Bulgarian Council of Scientific Research for con-
tract Chem.-1213 is also politely acknowledged.
So, the relative energy of deprotonation ErDel
ꢂ
/
tot
carbanion
tot
molecule
E
ꢀ/E
in the case studied is: 1420.9
(HF), 1408.9 (MP2) and 1378.2 (BLYP) kJ molꢀ1
.
We can compare these data with the EDrel values of
1482.9, 1495.4 and 1457.4 kJ molꢀ1 (HF, MP2
and BLYP), calculated for malononitrile 3a [15],
the corresponding values of 1496.7, 1505.3 and
1525.6 kJ molꢀ1 (HF) for p-, o- and m-cyano-
phenylacetonitriles 2a [13], EDrel of 1574.9 kJ molꢀ1
for the unsubstituted phenylacetonitrile [11], as
well as with the corresponding values of 1682.5,
1687.6 and 1658.3 kJ molꢀ1 (HF, MP2 and
BLYP), calculated for acetonitrile [38]. We can
see that EDrel increases in the above order, starting
by phenylmalononitrile studied. The acidity of
References
[1] I.N. Juchnovski, Teoret. Eksp. Khim. (Kiev) 3 (1967) 410.
[2] C. Krueger, J. Organometal. Chem. 9 (1967) 125.
[3] R. Das, C.A. Wilkie, J. Am. Chem. Soc. 94 (1972) 4555.
[4] M. Kirilov, D. Ivanov, G. Petrov, G. Golemchinski, Bull.
Soc. Chim. Fr. (1973) 3053.
[5] G. Albagnac, B. Brun, B. Calas, L. Giral, Bull. Soc. Chim.
Fr. (1974) 1469.
[6] I.N. Juchnovski, I.G. Binev, J. Organometal. Chem. 99
(1975) 1.
[7] I.N. Juchnovski, I.G. Binev, Ts.M. Kolev, Tetrahedron
Lett. (1976) 1519.
these Cꢁ/H acids decreases in the same order, as
[8] I.N. Juchnovski, I.G. Binev, Ts.M. Kolev, Commun.
Depart. Chem. Bulg. Acad. Sci. 10 (1977) 76.
[9] G. Boche, M. Marsch, K. Harms, Angew. Chem. 98 (1986)
373.
follows (compound, pKa in DMSO): phenylmalo-
nonitrile, 4.2 [39]; malononitrile, 11.0 [39]; p-
cyanophenylacetonitrile, 16.0 [40]; m-cyanopheny-
lacetonitrile, 18.7 [40]; phenylacetonitrile, 21.9
[39,40], acetonitrile, 31.3 [39]. The pKa value of
4.2 characterizes phenylmalononitrile 1a as one of
[10] D. Croisat, J. Seyden-Penne, T. Strzalko, L. Wartski, J.
Corset, F. Froment, J. Org. Chem. 57 (1992) 6435.
[11] I.G. Binev, J.A. Tsenov, E.A. Velcheva, I.N. Juchnovski,
J. Mol. Struct. 344 (1995) 205.
the strongest Cꢁ
explains both the formation of moderately strong
(CH3)2Sꢂ HꢁC(CN)2C6H5 hydrogen bonds
/H acids [39] and this phenomenon
[12] T. Strzalko, J. Seyden-Penne, L. Wartski, J. Corset, M.
Castella-Ventura, F. Froment, J. Org. Chem. 63 (1998)
3287.
/
O
/
Á Á Á
/
/
[13] I.G. Binev, J.A. Tsenov, E.A. Velcheva, V.B. Radomirska,
I.N. Juchnovski, J. Mol. Struct. 378 (1996) 133.
[14] I.N. Juchnovski, V.B. Radomirska, I.G. Binev, Commun.
Depart. Chem. Bulg. Acad. Sci. 14 (1981) 147.
[15] Y.I. Binev, J.A. Tsenov, I.N. Juchnovski, I.G. Binev, J.
Mol. Struct. (Theochem) (2003), in press.
(Section 4.2.1) and the presence of self-dissociated
molecules of phenylmalononitrile in the solutions
before metalation (Fig. 1).
[16] I.G. Binev, Spectrochim. Acta Part A 53 (1997) 1795.
[17] Y.I. Binev, B.A. Stamboliyska, I.G. Binev, Spectrochim.
Acta Part A 57 (2001) 95.
5. Conclusion
The ab initio and DFT calculations were
performed and gave good descriptions of the
[18] I.G. Binev, Y.I. Binev, B.A. Stamboliyska, I.N. Juch-
novski, J. Mol. Struct. 435 (1997) 235.