Abstract
While sulfadiazine (HL
) is extensively used to elaborate complexes of intriguing biological applications (
topical antibiotic silvadene; silver sulfadiazine), the molecular structure modification of sulfadiazine or even other sulfa drugs by coordination to either η
-cymene Ru(ii) or η
-Cp* Rh(iii) motif has not been investigated. Here, half-sandwich organoruthenium(ii) and organorhodium(iii) compounds of the type [(η
-
-cymene)Ru(L
)
] (1) and [(η
-C
Me
)Rh(L
)
] (2) are synthesized, characterized and evaluated for their potential antimicrobial activity. Spectroscopic and single crystal X-ray analysis showed that L
is coordinated to Rh(iii)
both the sulfonamide and pyrimidine nitrogen atoms forming "piano-stool" geometry. In 2, the NMR equivalence clearly pointed to participation of two L
molecules in a fluxional process in which the third bond of the base of the stool is oscillating between two equivalent sulfonamide nitrogen atoms. While 1 was biologically inactive, complex 2 was potent against Gram-positive bacteria,
and
. Hen white egg lysozyme (HEWL), a model protein, reacted covalently with 2
the loss of one L
molecule, while compound 1 decomposed during the interaction with that protein.