Schiff bases derived from mercury(II)-aminothiolate complexes as metalloligands for transition metals

Mercury(II) complexes of aromatic aminothiolate ligands of formula [Hg(n-SC 6H4NH2)(2)], n = 3 (1) or 4 (2) and [RHg(n-SC6H4NH2)], R = Me, n = 3 (3) or 4 (4); R = Ph, n = 3 (5) or 4 (6) have been obtained and characterized by infrared and H-1, C-13 acid Hg-199-NMR spectroscopies. The latter indicates that, in solution, complexes 1-6 have an essentially linear coordination a bout Hg(II). Unprecedented Schiff bases containing the Hg-S(thiolate) bond have been synthesized from 3-6 and saticylaldehyde yielding complexes of fo rmula [RHg(n-SC6H4N=CHC6H4OH)], R = Me, n = 3 (7) or 4 (8); R = Ph, n = 3 ( 9) or 4 (10). The template reaction of 3 and 4 with M(CH3COO)(2), M = Zn(II ), Cd(II), and salicylaldehyde has afforded trimetallic complexes of formul a [M-11{MeHg(n-SC6H4N=CHC6H4O)}(2)], M = Zn, n = 3 (11) or 4 (12). M = Cd, n = 3 (13) or 4 (14). Complexes 7-14 have also been explored by use of infr ared and NMR spectroscopies. The crystal structure determination of 2, 3, 5 , 7 and 8 by X-ray diffraction shows that Hg(II) has an essentially linear coordination. The presence of additional secondary Hg . . .S interactions i n all these complexes leads to an increase in the coordination number of cg to 4 or 5. In 2, the interaction of each S-Hg-S unit with three neighbouri ng units gives rise to a polymeric chain, which can be considered as being formed by pairs of fused incomplete cubanes. In 3, 5, 7 and 8, secondary Hg . . .S bonds between pairs of C-Hg-S fragments yield Hg2S2 dimers. In 3, t hese dimers afford two-dimensional sheets by means of additional Hg . . .N secondary interactions. The crystal packing of the Hg,Sz dimers in 5, 7 and 8 is very similar and gives rise to one-dimensional chains by means of add itional HgS bonds. The resulting polymeric zig-zag ladders can be described as formed by Hg4S4 pseudo-cubanes sharing opposite faces. (C) 2001 Elsevie r Science B.V. All rights reserved.