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(μ-Cl)]2 and mononuclear [CdL(μ-NO3)2]. Unique intramolecular
Zn-selenoether and Cd-diselenide bonds are reported for [ZnL(μ-NO3)2] and [CdL*(μ-NO3)2], respectively. In addition, a cocrystal of
[CdL(μ-NO3)2] and [CdL*(μ-NO3)2] is structurally characterized. The intermolecular pyridyl
π-interactions observed in these diverse structures are highlighted.