Crystal structure of bis[trans-dichloridobis-(propane-1,3-diamine-κ2N,N'chromium(III)] dichromate from synchrotron data.

The structure of the title compound, [CrCl₂(tn)₂]₂[Cr₂O₇] (tn = propane-1,3-diamine; C₃H₁₀N₂), has been determined from synchrotron data. The asymmetric unit contains one Cr^III complex cation and half a [Cr₂O₇]^2- anion. In the complex cation, the Cr^III ion is coordinated by the four N atoms of two propane-1,3-diamine (tn) ligands in the equatorial plane and by two Cl atoms in a trans configuration, displaying a distorted octahedral coordination sphere. The two six-membered rings in the complex cation have an anti chair-chair conformation with respect to each other. The mean Cr-N(tn) and Cr-Cl bond lengths are 2.09 (1) and 2.320 (2) Å, respectively. The slightly bent dichromate anion is disordered over two sets of sites (occupancy ratio = 0.7:0.3) and has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the NH₂ groups of the tn ligands as donors and the O atoms of the [Cr₂O₇]^2- anion and chlorido ligands as acceptors. [ABSTRACT FROM AUTHOR]