A new chromium (III) coordination compound of 2-amino-3-carbomethoxy-4,5,6,7-tetrahydrobenzo[b]thiophene (ACTT) (3) with Cr(NO3)3.9H2O in methanol at room temperature for 48 hours has been prepared. The composition of the new complex compound (4) has been confirmed by a number of instrumental methods including IR, NMR, MS and elemental analysis. It was found that the ACTT ligand behaves as bidentate chelating agent and coordinates to the central metal ion through the nitrogen atom of the amino-group and the oxygen atom of the carbonyl function of the ester group. The results showed that in the coordination sphere of the complex, the metal ion is coordinated by three chelating ACTT ligands. In the structure of the cation core [Cr(ACTT)3] 3+ , the three ACTT ligands are linked to the chromium ion through three Cr-N and three Cr-O bonds forming a square bipyramidal geometry. The metal complex and the ACTT ligand were screened for their antimicrobial activities against several strains of bacteria (Staphylococcus aureus ATCC25923, Escherichia coli S2 (1), Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa ATCC27853, Shigella flexneri SDINT) and fungi (Candida albicans ATCC10231, Candida tropicalis PK233, Cryptococcus neoformans H99). The chromium complex showed promising antimicrobial activity against the microorganisms with minimum inhibitory values between 4 and 16 μg/mL.

A novel bismuth(III) complex with 2-amino-3-carbomethoxy-4,5,6,7-tetrahydrobenzo[b]thiophene (ACTT) as a ligand have been synthesized. The novel complex was characterized on the basis of its IR, NMR, elemental analysis and MS spectral data. It was found that the ligand behaves as a monodentate chelating agent and bonds to the metal ion through the nitrogen atom of the amino group to form the [Bi III (ACTT) 6 ]Cl 3 complex. The new complex compound displayed significant antimicrobial activity (MIC = 8-32 μg/mL) against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Shigella flexneri, Candida albicans, Candida tropicalis and Cryptococcus neoformans.