One of the difficulties in preparing accurate ambient-temperature model complexes for heme proteins, particularly in the ferric state, has been the generation of mixed-ligand adducts: complexes with different ligands on either side of the heme. The difference in the accessibility of the two sides of the heme in the H93G cavity mutant of myoglobin (Mb) provides a potential general solution to th...

In this Perspective, we highlight the non-innocent behaviour of the bridging ligand in organometallic polynuclear metallic complexes displaying metal-carbon σ bonds between the metallic units and a strongly coupled conjugated carbon-rich bridging ligand. With the help of representative experimental and theoretical studies on polymetallic systems, but also on monometallic complexes, we point out...