A series of Rh III and Ir III half-sandwich compounds of the type [(η 5 -Cp* R )M(β-diketonato)Cl] were synthesized and characterized, including 17 X-ray crystallographic structures. In general, the complexes were synthesized in short reaction times and in good yield. The antimicrobial properties of these complexes were tested against a variety of microbes, and several complexes were found to have good activity against Mycobacterium smegmatis.