Abstract
The structure of the title compound, [Cr(tacn)2]2[ZnCl4]3·H2O (tacn is 1,4,7-tri-aza-cyclo-nonane; C6H15N3), has been determined from synchrotron X-ray data. Each CrIII cation is coordinated by the six N atoms from the two tacn ligands, displaying a distorted octa-hedral geometry. Three distorted tetra-hedral [ZnCl4]2- anions and one lattice water mol-ecule lie outside this coordination sphere. The Cr-N bond lengths are in the range 2.0621 (11) to 2.0851 (12) Å, while the mean inner N-Cr-N bond angle is 82.51 (5)°. The crystal packing is stabilized by hydrogen-bonding inter-actions with the N-H groups of the tacn ligands and the water O-H groups acting as donors, and the O atoms of the water mol-ecules and Cl atoms of the [ZnCl4]2- anions as acceptors. Overall these contacts lead to the formation of a three-dimensional network.
Highlights
The structure of the title compound, [Cr(tacn)2]2[ZnCl4]3ÁH2O, has been determined from synchrotron X-ray data
The Cr—N bond lengths are in the range 2.0621 (11) to 2.0851 (12) A, while the mean inner N—Cr—N bond angle is 82.51 (5)
The crystal packing is stabilized by hydrogen-bonding interactions with the N—H groups of the tacn ligands and the water O—H groups acting as donors, and the O atoms of the water molecules and Cl atoms of the [ZnCl4]2À anions as acceptors
Summary
The 1,4,7-triazacyclononane (tacn, C6H15N3) ligand can coordinate facially to many transition metal ions in various oxidation states (Chaudhuri & Wieghardt, 1987). The crystal structure of [Cr(tacn)2]Br5Á5H2O (Scarborough et al, 2011) has been reported, but a [Cr(tacn)2]3+ complex with a [ZnCl4]2À counter-anion is not known. The CrIII cation in both [Cr1A(tacn)2]3+ and [Cr2B(tacn)2]3+ is coordinated by the six N atoms from the two tacn ligands, displaying a distorted octahedral geometry. The mean N—M— Nintra, N—M—Ntrans and N—M—Ninter for [Cr1A(tacn)2]3+ are 82.35 (5), 178.60 (5) and 97.64 (5) while the three corresponding angles for [Cr2B(tacn)2]3+ are 82.66 (5), 177.13 (5) and 97.36 (5), respectively. Each ZnCl42À anion has a slightly distorted tetrahedral coordination geometry because of the influence of hydrogen bonding on the Zn—Cl lengths and the Cl—Zn–Cl angles. The Zn—Cl bond lengths involved in hydrogen bonds were all found to have longer bonds than those not involved
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
