Magnesium Cyclam complexes with a Mg2(Bn2Cyclam) core: Structural characterization of Mg2(Bn2Cyclam)I2 and Mg2(Bn2Cyclam){μ-H}{μ-F-C6F4}2BC6F5

Abstract

This work describes the crystal structures of two Mg dimers supported by dianionic trans-disubstituted Bn2Cyclam ligands (1,8-dibenzyl-1,4,8,11-tetraazacyclotetradecane). Mg2(Bn2Cyclam)I2 (1) crystallizes in the monoclinic space group P21/c with half-molecule in the asymmetric unit. The two metal centers and the two Namido donors of the cyclam ring define a four-member Mg2N2 metallacycle. The metals’ coordination spheres are completed by one amine of the macrocycle and one iodide defining a trigonal pyramidal coordination geometry. Mg2(Bn2Cyclam){μ-H}{μ-F-C6F4}2BC6F5 (2) crystallizes in the monoclinic space group P21/c with half-molecule in the asymmetric unit. Compound 2 is a rare example of a zwitterionic species of the type [Mg2(Bn2Cyclam)]2+ with two [HB(C6F5)3]− anions coordinating in a k3-H,F,F tridentate fashion. This compound also displays bridging Namido ligands that bind the two Mg atoms in a Mg2N2 arrangement analogous to 1, promoting a capped square pyramidal coordination geometry. At a supramolecular level C–H⋯I and C–H⋯F hydrogen bonds as well as CH/π and F⋯F interactions are responsible for the crystal packing.