91238-61-8Relevant academic research and scientific papers
Trinuclear complexes of 1,3,5,7-tetraketonates. Synthesis, molecular structure, absorption spectra, and electrochemistry of several bis[1,7-diphenyl-1,3,5,7-heptanetetronato(3-)]bis[dioxouranium(VI)]metal(II)-4- pyridine complexes
Lintvedt,Schoenfelner,Ceccarelli,Glick
, p. 2867 - 2874 (2008/10/08)
Several heterotrinuclear complexes have been prepared with the ligand 1,7-diphenyl-1,3,5,7-heptanetetrone. Two UO22+ ions occupy the terminal coordination positions in the molecules, and a divalent transition-metal ion occupies the central position. Crystallization from pyridine yields compounds abbreviated as (UO2)2M(DBAA)2(py)4·2py, where M(II) = Zn, Cu, Ni, Co, Fe, Mn. The X-ray crystal structures of the compounds where M is Ni(II), Co(II), Fe(II), and Mn(II) are reported. The structures are isomorphous. All are in the monoclinic space group P21/c. There are two molecules in the unit cell of each. The lattice constants with esd's, arranged in the sequence a, b, c (all in A?), β (in degrees), and V (in A?3), are as follows: 13.436 (3), 24.011 (6), 10.566 (2), 108.12 (1), 3236 (1), for M = Ni; 13.45 (2), 23.93 (3), 10.62 (1), 108.3 (1), 3245 (8), for M = Co; 13.475 (2), 23.778 (3), 10.718 (1), 108.85(1), 3250 (1), for M = Fe; 13.473 (6), 23.507 (12), 10.834 (4), 109.08 (3), 3243 (2), for M = Mn. Cyclic voltammetric studies show that the U(VI) ions undergo quasi-reversible one-electron reductions in dimethylformamide with a platinum-disk electrode. The two ions yield two well-formed CV waves in the scan rate range of 0.020-2.000 V/s with a separation of 0.17-0.26 V. The separation is dependent upon the identity of the intervening transition metal. Differential pulse polarography was also employed to determine the peak separation values. The results were used to calculate conproportionality constants for the series. The values vary from about 2 × 103 to 2 × 104 in regular fashion going from Fe to Zn. The UV-visible spectral properties are also discussed.
