Report No xxxx - Instytut Fizyki JÄ drowej PAN

data for Cβ-nonplanar model 3 are in agreement with 2 J PαHβ’ = 12.1 and 2 J PγHβ’ = 1.3 Hz evaluated
analogously for the lowest found energy conformer of the near Cβ-planar ylide 2 [7]; an
opposite J assignment would be practically impossible, see Fig. 1. The lacking small coupling
2 J PγHβ’ ≅ 0.5 Hz was determined very recently [10].
∆E DFT
FC term
energy
minimum
-50 -30 -10 10 30 50
-10
Torsion angle X-P-C-H, ϕ ( o )
-20
Fig. 1 DFT/FPT results for 2 J PH in 3
50
40
30
20
10
0
Relative DFT energy (kJ/mol) and
the FC contribution to 2 J PH (Hz)
Calculational Details. Fermi-contact (FC)
terms are usually dominant contributors to total
J couplings, including interactions with a P
nucleus [11]. According to works by Del
Bene et al. [12], the trans-H bond hn J AB (n = 2,
3) coupling is also dominated by the distance
dependent FC term, at least for N−N, N−O,
O−O, Cl−N and N−P(V) systems of the type
A−H···B and A−H···O−B, respectively. So, to
economically recover these most probably
leading FC contributions to J couplings discussed
here, a finite perturbation theory (FPT)
method of Pople et al. [13] was solely used,
which has been reintroduced recently by
Barfield and co-workers [14]. All DFT/FPTcomputed
J values are based on the FC output
of the FIELD option of Gaussian 98W, obtained for free molecules of (Z)-1, 2 and 3 at the
UB3LYP/6-31G**//B3LYP/6-31G** level of theory. The parameter λ = 0.01 and the tight
SCF convergence criterion were applied as giving calculational results in a reasonable agreement
with the n J XY (XY = CH, PC or PP) couplings measured for above compounds in
solution. Differently designed conformers of 3 were geometrically optimised under the C S
symmetry constraint.
References
1. Nazarski, RB; Gralak, DK; Kudzin, ZH Bull. Pol. Acad. Sci., Chem. 2000, 48, 27-33.
2. (a) Gralak, DK; Kudzin, ZH; Nazarski, RB, poster presented at the Symposium on Application
of Magnetic Resonance in Chemistry and Related Areas, Warszawa, June 25-27, 1997; abstract
P-35. (b) Gralak, DK, Master Thesis, University of Łódź, 1997.
3. Mishima, M; Hatanaka, M; Yokoyama, S; Ikegami, T; Wälchli, M; Ito, Y; Shirakawa, M.
J. Am. Chem. Soc. 2000, 122, 5883-5884.
4. Löhr, F; Mayhew, SG; Rüterjans, H J. Am. Chem. Soc. 2000, 122, 9289-9295.
5. Czernek, J; Brüschweiler, R J. Am. Chem. Soc. 2001, 123, 11079-11080.
6. Alkorta, I; Elguero, J Int. J. Mol. Sci. 2003, 4, 64-92.
7. Chęcińska, L; Kudzin, ZH; Małecka, M.; Nazarski, RB; Okruszek, A Tetrahedron, 2003, 59,
7681-7693.
8. Schmidbaur, H; Buchner, W; Scheutzow, D Chem. Ber. 1973, 106, 1251-1255.
9. Mitzel, NW; Brown, DH; Parsons, S; Brain, PT; Pulham, CR; Rankin, DWH Angew. Chem. Int.
Ed. 1998, 37, 1670-1672 and refs therein.
10. Nazarski, RB, unpublished results.
11. Malkina, OL; Salahub, DR; Malkin, VG J. Chem. Phys. 1996, 105, 8793-8800 and refs therein.
12. Del Bene, JE; Perera, SA; Bartlett, RJ, Elguero, J; Alkorta, I; López-Leonardo, C; Alajarin, M.
J. Am. Chem. Soc. 2002, 124, 6393-6397 and refs therein.
13. Pople, JA; McIver, JW Jr.; Ostlund, NS J. Chem. Phys. 1968, 49, 2960-2964, 2965-2970.
14. Onak, T; Jaballas, J; Barfield, M. J. Am. Chem. Soc. 1999, 121, 2850-2856.
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