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 Au-3-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 klimol) is calculated for Au-3-SCH3 with the single Au-S bond. (C) 2017 Elsevier B.V. All rights reserved.