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Unusual Geometry of Azido Group and Syn Conformation in Trans-Diazidobis(2,2-Dimethyl-1,3-Ropanediamine) Chromium (Iii) Moiety

Moon D, Subhan MA and Choi JH

A new complex 1, trans-syn-[Cr(Me2tn)2(N3)0.8Cl1.2]ClO4 (Me2tn = 2,2-dimethyl-1,3- propanediamine) was prepared and its structure was determined from synchrotron radiation data at 95 K. The complex crystallized in the space group Pbca of the orthorhombic system with eight mononuclear formula units in a cell of dimensions a = 12.559(3), b = 15.078(3), and c = 20.726(4) Å. The chromium ion was in a distorted octahedral coordination with four N atoms of two chelating Me2tn ligands and two mixed Cl/N atoms in the trans axial position. The two six-membered rings in the complex cation adopted only syn chair-chair conformations with respect to each other. The mean Cr-N(Me2tn) and Cr-N(azido) bond lengths were 2.084 (9) and 1.815 (8) Å, respectively. Unusually short inner Nα-Nβ bond distances of azido groups resulted from the crystallographic disorder between the Nβ atom and chloride. The crystal lattice was stabilized by hydrogen bonding interactions among the oxygens of ClO4 -, nitrogens of N3 -, and NH groups of the Me2tn ligand.