03 Fakultät Chemie

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Institute: search.filters.UBSInstitut.Institut für Theoretische ChemieAuthor: search.filters.author.Becker, Gerd

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    Coupled electron pair calculations for R–C≡E molecules (E = N, P, As or Sb)
    (1992) Schmidt, H. M.; Stoll, Hermann; Preuss, Heinzwerner; Becker, Gerd; Mundt, Otto
    The effect of substituents R (R = H, H 3 C, F or H 5 C 6) on C≡E groups in alkylidyne compounds R - C ≡ E (E = N, P, As or Sb) has been studied at the level of valence electron CEPA (coupled electron pair approximation) calculations. Although the reactivities of R-C ≡ E compounds differ widely (depending on E), the isolated molecules all have surprisingly similar electronic structures. For the H, H 3,C and F species, our calculated bond lengths r e,(R- C) and r e,(C ≡E) agree well with experimental values where such are known. Along with the force constants, some trends for the changes in bond strength emerge. A plausible dependence of the dipole moments on E is observed. For benzonitrile (H 5 C 6 - C ≡N), published experimental values of the C - C( ≡ N) bond length differ. The problem is explored using several basis sets and methods to obtain a value of 1.436(10)A. The C...C( ≡P) bond length in benxylidynephosphane (H 5,C6,-C≡P) is calculated to be 1.435(10)A. Possible uncertainties of some of the experimental values are discussed.
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    Influence of substituents on bond lengths
    (1988) Hayd, Helmut; Savin, Andreas; Stoll, Hermann; Preuss, Heinzwerner; Becker, Gerd
    Pseudopotential SCF calculations for Y3C-X, Y=H, F; X=H, F, Cl, PH2, PF2 and a simple model, simulating the substituents by a homogeneous, electric field, are presented in order to rationalize the substitution effect on the C-X bond.