Novel germanetellones: XYGeTe (X, Y = H, F, Cl, Br, I and CN) – structures and energetics. Comparison with the first synthetic successes
No stable germanetellone was described until Tbt(Dis)GeTe and Tbt(Tip)GeTe (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Dis = bis(trimethylsilyl)methyl and Tip = 2,4,6-triisopropylphenyl) were reported in 1997. Following these initial experiments, there has arisen considerable interest in GeTe systems. An obvious question is: why have the simple XYGeTe (X, Y = H, F, Cl, Br, I and CN) molecules not yet been isolated? In view of the present situation, theoretical information may be of great help for further advances in germanetellone chemistry. A systematic investigation of the XYGeTe molecules is carried out using the second order Møller−Plesset perturbation theory (MP2) and density functional theory (DFT). The structures and energetics, including ionization potentials (IPad and IPad(ZPVE)), four different forms of neutral–anion separations (EAad, EAad(ZPVE), VEA and VDE) and the singlet–triplet gaps, are reported. The electronegativity (χ) reactivity descriptor for the halogens (F, Cl, Br and I) and the natural charge separations of the GeTe moiety are used to assess the interrelated properties of germanetellone and its derivatives. The results are analyzed, discussed and compared with analogous studies of telluroformaldehyde, silanetellone and their derivatives. The thermodynamic viabilities of some of the novel germanetellones have also been evaluated in terms of the bond dissociation enthalpies of Tbt(Dis)GeTe and Tbt(Tip)GeTe. The simple mono-substituted germanetellones appear to be slightly more thermodynamically favored than Tbt(Dis)GeTe and Tbt(Tip)GeTe, since the bond dissociation enthalpies of these kinetically stabilized germanetellones are about 28 and 51 kcal mol−1 lower, respectively.