{'fraction_non_alphanumeric': 0.023255813953488372, 'fraction_numerical': 0.004472271914132379, 'mean_word_length': 4.828125, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Electronic structure of monomeric methyl-lithium

In order to investigate the nature of the C—Li bond in alkyl-lithium compounds, ab initio calculations have been performed for the monomeric CH3Li molecule using spin-coupled theory. The eight singly occupied non-orthogonal valence orbitals have been fully optimized without symmetry constraints, and the complete spin space of 14 singlet spin functions has been employed. We found essentially four distorted sp3 hybrids on the carbon atom and three 1s orbitals on the hydrogen atoms. The eighth orbital can be described as the superposition of an s-type orbital on lithium and a p-type orbital on carbon, and it also has some amplitude on the hydrogen atoms. When compared with the situation expected for a normal covalent bond, the build-up of ‘overlap charge’ in the C—Li bond region appears to be quite limited. However, an examination of the valence contribution to the total electron density shown a residual peak on lithium. In this sense, the C—Li bond can be described as essentially ionic, although it does not correspond to the transfer of a whole electron.