Abstract#R##N##R##N#The expansion of germanium chemistry in recent years has been rapid. In anticipation of new experiments, a systematic theoretical investigation of the eight low lying electronic singlet GeC2H2 stationary points is carried out. This research used ab initio self-consistent-field (SCF), coupled cluster (CC) with single and double excitations (CCSD), and CCSD with perturbative triple excitations [CCSD(T)] levels of theory and a variety of correlation–consistent polarized valence cc-pVXZ and cc-pVXZ-DK (Douglas-Kroll) (where X = D, T, and Q) basis sets. At all levels of theory used in this study, the global minimum of the GeC2H2 potential energy surface (PES) is confirmed to be 1-germacyclopropenylidene (Ge-1S). Among the eight singlet stationary points, seven structures are found to be local minima and one structure (Ge-6S) to be a second-order saddle point. For the seven singlet minima, the energy ordering and energy differences (in kcal mol−1, with the zero-point vibrational energy corrected values in parentheses) at the cc-pVQZ-DK (Douglas-Kroll) CCSD(T) level of theory are predicted to be 1-germacyclopropenylidene (Ge-1S) [0.0 (0.0)] < vinylidenegermylene (Ge-3S) [13.9 (13.5)] < ethynylgermylene (Ge-2S) [17.9 (14.8)] < Ge-7S [37.4 (33.9)] < syn-3-germapropenediylidene (Ge-8S) [41.2 (37.9)] < germavinylidenecarbene (Ge-5S) [66.6 (61.6)] < nonplanar germacyclopropyne (Ge-4S) [67.8 (63.3)]. These seven isomers are all well below the dissociation limit to Ge (3P) + C2H2( 1Σ). This system seems particularly well poised for matrix isolation infrared (IR) experiments. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010
['Qiang Hao', 'Andrew C. Simmonett', 'Yukio Yamaguchi', 'De-Cai Fang', 'Henry F. Schaefer']
From acetylene complexes to vinylidene structures: The GeC2H2 system