Staging Bonding between Group 12 Metal Ions and Neutral Selenium Donors: Intermolecular Interactions of Mixed N,Se Donor Ligands and Anions

The versatile pyridyl synthons of mixed N,Se donor ligands bis(pyridin-2-ylmethyl)selane (L) and 1,2-bis(pyridin-2-ylmethyl)diselane (L*) served the dual roles of metal chelating anchors and mediators of supramolecular associations in a crystallographic approach to documenting uncommon bonding between divalent Group 12 metal ions and neutral selenium functionalities. Five new molecular species with diverse ligand configurations and conformations were structurally characterized. Two macrocyclic polymorphs of [ZnLCl2] have intermolecular Se-Cl interactions rather than the desired intramolecular Zn-Se binding. Rare examples of Cd(II)-selenoether bonding are provided by tricoordinate L in dinuclear [CdLCl(mu-Cl)](2) and mononuclear [CdL(mu-NO3)(2)]. Unique intramolecular Zn-selenoether and Cd-diselenide bonds are reported for [ZnL(mu-NO3)(2)] and [CdL*(mu-NO3)(2)], respectively. In addition, a cocrystal of [CdL(mu-NO3)(2)] and [CdL*(mu-NO3)(2)] is structurally characterized. The intermolecular pyridyl pi-interactions observed in these diverse structures are highlighted.