The structures of zinc carbene ZnCH2and zinc carbyne HZnCH, and the conversion transition states between them are optimized at B3LYP/aug‐cc‐pVTZ, MP2/aug‐cc‐pVTZ, and CCSD/aug‐cc‐pVTZ levels of theory. The thermodynamic energies with CCSD(T) method are further extrapolated to basis set limit through a series of basis sets of aug‐cc‐pVXZ (X=D, T, Q, 5). The Zn−C bonding characteristics are interpreted by molecular plots, Laplacian of density plots, the integrated delocalization indices, net atomic charges, and derived atomic hardness. On the one hand, the studies demonstrated the efficiency of DFT method in structure optimizations and the accuracy of CBS method in obtaining thermodynamic energies; On the other hand, the density analysis of CCSD/aug‐cc‐pVDZ density demonstrates that both the sharing interaction and ionic interaction are important in ZnCH2ad HZnCH. The3B1state of ZnCH2is the global minimum and formed in visible light, but its small bond dissociation energy (47.0 kcal/mol) cannot keep the complex intact under UV light (79.4–102.1 kcal/mol). However, the3Σ−state of HZnCH can survive the UV light due to the greater Zn−C dissociation energy (100.7 kcal/mol). The delocalization indices of Zn…C in both3B1of ZnCH2(0.777) and the3Σ−state of HZnCH (0.785) are close to the delocalization index of the single C−C bond of ethane (0.841), i. e. the nomenclature of Zinc carbene and Zinc carbyne is incorrect. The stronger Zn−C bond in the3Σ−state of HZnCH than in the3B1state of ZnCH2can be attributed to the larger charge separation in the former. It was found that the Zn−C bonds in related Zinc organic compounds were also single bonds no matter whether the organic groups are CR, CR2, or CR3. The ionic interactions were discussed in terms of the atomic hardness that were in turn related to ionization energy and electron affinity. The unique combination of covalent and ionic characteristics in the Zn−C bonds of organic Zinc compounds could be the origin of many interesting applications of organic Zinc reagents.
The optimized geometries, vibrational frequencies, and dissociation energies from MP2 and CCSD(T) computations with large correlation consistent basis sets are reported for (H2S)2and H2O/H2S. Anharmonic vibrational frequencies have also been computed with second‐order vibrational perturbation theory (VPT2). As such, the fundamental frequencies, overtones, and combination bands reported in this study should also provide a useful road map for future spectroscopic studies of the simple but important heterogeneous H2O/H2S dimer in which the hydrogen bond donor and acceptor can interchange, leading to two unique minima with very similar energies. Near the CCSD(T) complete basis set limit, the HOH⋯SH2configuration (H2O donor) lies only 0.2 kcal mol−1below the HSH⋯OH2structure (H2S donor). When the zero‐point vibrational energy is included, however, the latter configuration becomes slightly lower in energy than the former by <0.1 kcal mol−1. © 2018 Wiley Periodicals, Inc.
more » « less- Award ID(s):
- 1664998
- NSF-PAR ID:
- 10078167
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Computational Chemistry
- Volume:
- 40
- Issue:
- 1
- ISSN:
- 0192-8651
- Page Range / eLocation ID:
- p. 229-236
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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