Citation:
Abstract:
The air oxidation of the cluster compounds [Li2E((NBu)-Bu-t)(3)](2) (E = S, Se) in toluene produces deep blue (E = S) or green (E = Se) solutions. The ESR spectra of these solutions consist of a septet (1:3:6:7:6:3:1) of decuplets. The simulation of these spectra shows that the secondary hyperfine splitting results from interaction of the unpaired electron with three equivalent Li-7 ions consistent with the formation of the neutral radicals {Li-3[E((NBu)-Bu-t)(3)](2)}(.) (4a, E = S, g = 2.0039, a(N-14)= 5.69 G, a(Li-7) = 0.82 G; 4b, E = Se, g = 2.00652, a(N-14) = 5.41 G, a(Li-7) = 0.79 G). Over a period of 25 h the seven line pattern of 4b is replaced first by a five line (1:2:3:2:1) spectrum (g = 2.009, a(N-14) = 13.4 G) and, subsequently, by a three line (1:1:1) spectrum (g = 2.00946, a(N-14) = 15.4 G, a(Se-77) = 3.3 G), neither of which exhibit 7Li hyperfine splitting. These spectra are tentatively assigned to the radical anions SeO((NBu)-Bu-t)2(.-) and SeO2((NBu)-Bu-t)(.-), respectively. The cluster (Li-2[O2S((NBu)-Bu-t)]), (3) is prepared by the reaction of sulfur dioxide with 2 equiv of (LiNHBu)-Bu-t in toluene. The air oxidation of toluene solutions of {Li-2[OS((NBu)-Bu-t)(2)]}(6) (2a) or 3 produces deep blue species. In the former case the initial ESR spectrum is a 1:2: 3:2:1 quintet (g = 2.009, a(N-14) = 13.3 G) which, after 16 h, evolves into a 1:1:1 triplet (g = 2.008X, a(N-14) = 15.9 G). The same triplet is observed in the ESR spectrum of oxidized solutions of 3 leading to the assignments OS((NBu)-Bu-t)(2)(.-) and O2S((NBu)-Bu-t)(.-) for the quintet and triplet, respectively. The disproportionation 2OS((NBu)-Bu-t)(2)(.-) --> OS((NBu)-Bu-t)(.-) + S((NBu)-Bu-t)(3)(.-) is indicated by the changes observed for the ESR spectra of oxidized solutions of 2a.
Notes:
Times Cited: 24Brask, JK Chivers, T McGarvey, B Schatte, G Sung, R Boere, RT