A purely vibrational insight on the tetragonal distortion of [Cu(DMF)6]2+

Raman spectra of N,N-dimethylformamide (DMF) solutions containing copper perchlorate at different compositions have been recorded. The spectral changes exhibited at the r(methyl) region of DMF, in the presence of the Cu(II) salt, were reported for the first time. A correlation with the delta(OCN) region is made. The quantitative Raman analysis performed at the r(methyl) region allowed the determination of an average number of 6 DMF molecules per Cu(II) in the first salvation shell. This value as combined to the spectral variations observed in both regions of DMF allow us to propose the existence of axial bond lengths longer than equatorial ones in the octahedron. The spectra also reveal that the counter-ion is not capable of affecting the stability of the [Cu(DMF)(6)](2+) complex for the whole investigated concentration range. (C) 2014 Elsevier B.V. All rights reserved.