Structural diversity of supramolecular networks formed between polycyanometalates and sulfur-based chalcogen bond donors

The co-crystallization of S-(CF3)-dibenzothiophenium ("Umemoto" - abbreviated Ume) cations and polycyanometalates with different coordination geometries yields a large structural variety of supramolecular assemblies. In the case of [Ume+]2[Ni(CN)4]2-<middle dot>CH2Cl2 all four cyanide groups of the square-planar dianion act as chalcogen bond acceptors whereas the sulfur atoms of the Umemoto cations act as biaxial chalcogen bond donors. For tetrahedral [Zn(CN)4]2- a more complex assembly of four Umemoto cations and two dianions is observed. In the case of [Ume+]3[Fe(CN)6]3-<middle dot>CH2Cl2 one Umemoto cation even acts as a triaxial chalcogen bond donor whereas only 4 out of the 6 cyanide groups act as chalcogen bond acceptors. For [Ume+]3[W(CN)8]3- a polymeric chain structure is observed in which all Umemoto cations act as biaxial chalcogen bond donors. DFT investigations focus on the physical nature of the chalcogen bonds, encompassing energetic assessments, MEP surface plots, QTAIM, and NBO analysis, shedding light on the nature of chalcogen donor-acceptor interactions. The energetic results evidence that total contributions of chalcogen bonds in different synthons range from -7.6 to -16.3 kcal mol-1, surpassing that of hydrogen bonds that range from -4.9 to -11.8 kcal mol-1. Polycyanometalates can act as polydentate chalcogen bond acceptors when combined with sulfonium cations.