From acetylene complexes to vinylidene structures: The GeC(2) H(2) system

Area of Science:

• Organometallic Chemistry
• Computational Chemistry
• Quantum Chemistry

Background:

• Germanium chemistry is rapidly expanding, necessitating theoretical investigations into novel germanium-carbon-hydrogen (GeC2H2) species.
• Understanding the potential energy surface (PES) of GeC2H2 is crucial for predicting and synthesizing new germanium compounds.

Purpose of the Study:

• To systematically investigate the eight low-lying electronic singlet stationary points of GeC2H2.
• To determine the global minimum and relative energies of GeC2H2 isomers using high-level theoretical methods.

Main Methods:

• Ab initio calculations including self-consistent-field (SCF), coupled cluster with single and double excitations (CCSD), and CCSD with perturbative triple excitations [CCSD(T)].
• Utilized correlation-consistent polarized valence basis sets (cc-pVXZ and cc-pVXZ-DK) with X = D, T, and Q.
• Calculated energy differences, including zero-point vibrational energy corrections.

Main Results:

• 1-germacyclopropenylidene (Ge-1S) is confirmed as the global minimum on the GeC2H2 PES.
• Seven out of eight investigated singlet stationary points are identified as local minima, with one being a second-order saddle point.
• Detailed energy ordering of the seven stable isomers is provided, all lying below the dissociation limit.

Conclusions:

• The theoretical landscape of GeC2H2 isomers is well-defined, with 1-germacyclopropenylidene being the most stable.
• The predicted stability and energy differences offer valuable insights for experimental chemists.
• The GeC2H2 system is highly promising for matrix isolation infrared (IR) spectroscopy experiments.