Synthesis, molecular structure, and spectroscopic properties of tris[trans-diazidobis(2,2-dimethylpropane-1,3-diamine)chromium(III)]bis[tertaazido(2,2-dimethylpropane-1,3-diamine)chromium(III)] perchlorate

Abstract

Abstract A new double complex, [trans-Cr(N3)2(Me2tn)2]3[Cr(N3)4(Me2tn)]2ClO4 (Me2tn\u202f=\u202f2,2-dimethylpropane-1,3-diamine), was prepared, and its structure determined through single-crystal X-ray diffraction at 100\u202fK. The complex crystallizes in the space group C2/c of the monoclinic system with a\u202f=\u202f34.255 (7), b\u202f=\u202f11.067 (2), c\u202f=\u202f24.137 (5) A, and β\u202f=\u202f120.64 (3)o. The asymmetric unit contains one half of a centrosymmetric trans-anti-[Cr(N3)2(Me2tn)2]+ cation, one independent trans-syn-[Cr(N3)2(Me2tn)2]+ cation, one cis-[Cr(N3)4(Me2tn)]- anion, and one half of a perchlorate anion. In two independent complex cations, the CrIII ions are each coordinated by four N atoms of two chelating Me2tn and two N atoms of the azido group in a distorted octahedral geometry, whereas the CrIII ion in cis-[Cr(N3)4(Me2tn)]- has a distorted octahedral coordination with two N atoms of one Me2tn and four N atoms of the azido group. Interestingly, the six-membered rings in two trans-[Cr(N3)2(Me2tn)2]+ cations adopt anti and syn chair-chair conformations, independently. The Cr N (Me2tn) bond lengths vary from 2.0556 (15) to 2.0992 (19) A, whereas the Cr N (azido) bond lengths range from 2.0205 (16) to 2.0428 (16) A. The perchlorate anion is disordered over two sets of sites, and has a distorted tetrahedral geometry. The crystal lattice is stabilized through hydrogen bonding interactions between the nitrogen of N3− and the NH groups of the Me2tn ligand. The IR and electronic absorption spectral properties are also discussed herein.