Electronic and steric control over Au••• Au, C-H••• O and C-H••• π interactions in the crystal structures of mononuclear triarylphosphinegold( I) carbonimidothioates:: R3PAu[SC(OMe) = NR′] for R′ = Ph, o-tol, m-tol or p-tol, and R′ = Ph, o-tol, m-tol, p-tol or C6H4NO2-4

The structures of R3PAu[ SC( OMe) =NR'], for R Ph, o-tol, m-tol or p-tol,and R'= Ph, o-tol, m-tol, p-tol or C6H4NO2- 4, feature linear P-Au-S coordination geometries with intramolecular Au center dot center dot center dot O or Au center dot center dot center dot pi interactions depending on the substitution patterns of the R and/ or R' groups. For R= Ph, intramolecular Au center dot center dot center dot O interactions are observed exclusively but when R = p-tol, intramolecular Au center dot center dot center dot pi interactions are found unless precluded by steric crowding, i. e. in the case when R'= m-tol, or by electronic reasons such as the presence of an electron withdrawing nitro group, i. e. when R'= C6H4NO2-4. In the latter case, aurophilic interactions (Au center dot center dot center dot Au =3.0872( 4)angstrom) are formed, uniquely amongst the series. The mode of coordination of the thiolate ligands in these complexes, arising from either steric or electronic factors or both, has a profound influence on the supramolecular aggregation patterns operating in their crystal structures. In the solvent-free systems that feature intramolecular Au center dot center dot center dot O interactions, columns of molecules stack so that the thiolate residues interdigitate to a greater or lesser extent leaving the aryl groups of the phosphine ligands facing each other, forming phenyl embraces in the Ph3P species or being connected by C-H center dot center dot center dot pi contacts involving methyl-H atoms in the isomeric tolyl(3)P structures. In structures featuring intramolecular Au center dot center dot center dot p interactions, the methoxy-O atom is more accessible for the formation of C-H center dot center dot center dot O contacts. Finally, in the cases where the nitro sub-stituent is present, at least one of the nitro-O atoms is involved in C-H center dot center dot center dot O intercations. In summary, subtle changes in electronic character and/ or steric profile of the phosphine and thiolate ligands are seen to influence, systematically, the crystal packing.