The use of thermotropic liquid crystals in organometallic chemistry. Synthesis of new mercury, silver and gold complexes with 4,4'-disubstituted azobenzenes

Article abstract of DOI:10.1016/0022-328X(94)87107-8

Liquid crystalline 4-XC6H4N=NC6H4X-4' 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 (2) and .The silver adducts show thermotropic behaviour.Mercuriation of dialkylazobenzenes 1a-b takes place with and LiCl to give while dialkoxyazobenzenes 1c-d require to obtain . 4a-c react with NaI to give .Both chloroaryl-, 4a and 4c, and diaryl-mercurials, 5a and 5c, act readily as transmetallating agents towards in the presence of Cl to give 2-R)Cl2> < R = bpap (6a), bxpap (6b)>.After reaction of (tht = tetrahydrothiophene) with Cl and 4b (1:2:1), (7) can be isolated.C-H activation of acetone by 6a-b leads to 2-R)Cl> .None of the complexes 4-8 shows mesomorphic behaviour. Key words: Gold; Silver; Mercury; Aryl; Transmetallation; Orthometallated complexes