[en] Highlights: • Binding energies in Au_n–CH₂ are higher than in Au_n–SCH₃ by 57–175 kJ/mol. • Crucial role in the Au_n–CH₂ bonding play two singly occupied orbitals of CH₂. • Low spin BEs in Au_n–CH₂ and Au_n–SCH₃ are higher than high spin BEs by 87–158 kJ/mol. • CH₂ prefers the bonding with two gold atoms of Au_n (bridge structures). • In Au_n–SCH₃ is the S atom mostly bound to a single Au atom (on top interactions). We compare DFT binding energies (BEs) of Au and small gold clusters interacting with CH₃S and CH₂ ligands (Au_n–L complexes, n = 1–4). The spin state and the binding mechanism in Au_n–L varies with the participation of singly occupied non-bonding orbitals or doubly occupied lone-pair orbitals of a ligand and on the number of atoms (even or odd) of Au_n. The highest BE, 354 kJ/mol, exhibits the Au₃–CH₂ complex with the covalent bond in which participate two singly occupied orbitals of the triplet state of CH₂. With CH₃S the highest BE (277 kJ/mol) is calculated for Au₃–SCH₃ with the single Au–S bond.