| Abstract | Binuclear phosphanegold(i) complexes of a bipodal thiocarbamate dianion, (R<inf>3</inf>PAu)<inf>2</inf>L, R = Et (1), Ph (2) and Cy (3), where LH<inf>2</inf> is {1,4-[MeOC(S)N(H)]<inf>2</inf>C<inf>6</inf>H<inf>4</inf>}, have been synthesised, and characterised spectroscopically (NMR and IR) and by X-ray crystallography. The gold atoms are linearly coordinated within a P-,S-donor set, and are oriented toward the central ring to form intramolecular Au ⋯π(aryl) interactions, rather than the intramolecular Au ⋯O interactions normally observed in mononuclear analogues. This phenomenon has been investigated by theory (LC-ωPBE-XDM) for 1 which revealed that the geometry optimised species with two Au ⋯π(aryl) interactions is more stable by at least 12 kcal mol-1 compared to conformations having one or more Au ⋯O interactions instead. The disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods were used to observe the inhibitory effect of complexes 1-3. The disk diffusion results demonstrated that 1 exhibited a broad spectrum of anti-bacterial activity toward 24 strains of Gram-positive and Gram-negative bacteria. By contrast, the anti-bacterial activity of 2 and 3 was limited to Gram-positive bacteria. Further evaluation showed that 1 exhibited marked bactericidal activity against B. cereus, B. subtilis, E. faecalis, L. monocytogenes, S. aureus, S. saprophyticus and methicillin resistant S. aureus cf. standard antibiotics tetracycline and chloramphenicol. |
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