The use of thermotropic liquid crystals in organometallic chemistry. Synthesis of new mercury, silver and gold complexes with 4,4′-disubstituted azob
作者:Jose' Vicente、María Dolores Bermúdez、Francisco J. Carrión、Ginés Martínez-Nicolas
DOI:10.1016/0022-328x(94)87107-8
日期:1994.10
Liquid crystalline 4-XC6H4N=NC6H4X-4' [X = C4H9 (1a), C10H21 (1b), OC4H9 (1c), OC8H17 (1d)] can be easily prepared in high yields from the corresponding anilines. In order to study the influence of metals on the thermal properties of these materials, we have obtained adducts [AuCl3(4-C4H9OC6H4N=NC6H4OC4H9-4')] (2) and [Ag(OClO3)L2] [L = 4-XC6H4N=NCH4X-4'; X = OC4H9 (3a), OC8H17 (3b)]. The silver adducts show thermotropic behaviour. Mercuriation of dialkylazobenzenes 1a-b takes place with [Hg(OAc)2] and LiCl to give [Hg(R)Cl] [R = C6H3(N=NC6H4X-4')-2, X-5; X = C4H9 (bpap) (4a), C10H21 (dpap) (4b)] while dialkoxyazobenzenes 1c-d require [Hg(OOCCF3)2] to obtain [Hg(R)Cl] [R = C6H3(N=NC6H4X-4')-2, X-5, X = OC4H9 (bxpap) (4c), OC8H17 (4d)]. 4a-c react with NaI to give [HgR2] [R = bpap (5a), dpap (5b), bxpap (5c), oxpap (5d)]. Both chloroaryl-, 4a and 4c, and diaryl-mercurials, 5a and 5c, act readily as transmetallating agents towards [Me4N] [AuCl4] in the presence of [Me4N]Cl to give [Au(eta2-R)Cl2] [R = bpap (6a), bxpap (6b)]. After reaction of [AuCl3(tht)] (tht = tetrahydrothiophene) with [Me4N]Cl and 4b (1:2:1), [Me4N][Au(dpap)Cl3] (7) can be isolated. C-H activation of acetone by 6a-b leads to [Au(eta2-R)CH2C(O)Me}Cl][R = bpap (8a), bxpap (8b)]. None of the complexes 4-8 shows mesomorphic behaviour.