Dicyanogermylenes: A Tale of Isomers and Interconversions

Abstract

A systematic investigation is carried out using the B3LYP, BLYP, and BHLYP functionals and MP2 level of theory to characterize the low-lying electronic singlet and triplet GeC2N2 isomers. The basis sets used are of double-ζ plus polarization quality with additional s- and p-type diffuse functions, DZP++. Three bent isomers Ge(CN)2, CNGeCN, and Ge(NC)2 are located on the singlet and triplet potential energy surfaces. In visualizing the reaction pathways for the singlet isomerization of the bent isomers, two three-membered [Ge, C, N] cyclic systems, with exocyclic -C-C≡N and -C-N≡C bonding, appear on the energy surface. Four types of electron affinities reported are: the adiabatic electron affinity, the zero-point vibrationally corrected electron affinity, the vertical electron affinity, and the vertical detachment energy of the anion. The ionization energies and singlet-triplet gaps for all isomers are also reported. The energetic ordering (kcal mol(-1)) (B3LYP) with zero-point vibrational energy corrections for the singlet ground state isomers follows: Ge(CN)2 (global minimum) < CNGeCN (2.3) < Ge(NC)2 (3.3) < Cyc_exo_CCN (15.3) < Cyc_exo_CNC (30.6). All the bent and cyclic isomers are found to be below the dissociation limit to Ge ((3)P) + C2N2 ((1)Σg). The rate constants for all interconversions are evaluated using transition state theory.

Which triatomic monohalosilylenes, monohalogermylenes, and monohalostannylenes (HMX) fluoresce or phosphoresce and why? An ab initio investigation

“…Finally, in two papers, Bundhun et al used density functional theory (DFT) methods to predict the ground and excited triplet state geometries and energies of a variety of HMX species including HGeX 22 and HSnX. 23 The reader is referred to the original references for a more complete background to the various diverse theoretical studies of HMX molecules. We are not aware of any theoretical studies of the HMX molecules that directly address the role of excited state dissociation processes in the spectroscopy.…”

Diatomic Silylynes, Germylynes, Stannylynes, and Plumbylynes: Structures, Dipole Moments, Dissociation Energies, and Quartet-Doublet Gaps of EH and EX (E = Si, Ge, Sn, Pb; X = F, Cl, Br, I)

“…29−34 Stannylynes have proved to be important in understanding new organometallic chemistry. 35 However, isolated low-valence stannylynes R-Sn(I) are rarely observed since usually they are assumed to be unstable species. Practically speaking, R-Sn radicals are usually intermediates in transformations to the stable Sn(IV) or Sn(II) compounds.…”

Toward unsaturated stannylenes Y2ZSn: and related compounds with triplet electronic ground states

“…The relative changes in the geometrical parameters and the predicted singlet-triplet gaps obtained with the different functionals used are found to be reasonably consistent. The BHLYP values are used in discussions within this paper, since this functional appears better than the other functionals employed in the prediction of geometries, harmonic vibrational frequencies, and singlet-triplet splittings, 28 for related molecules.…”