{Evidence|Proof} for Low-valent Electronic Configurations in Iron–Sulfur Clusters
{Although|Even though|Though|Despite the fact that|While} biological iron-sulfur (Fe–S) clusters {perform|carry out|execute} {some of|a few of|a number of} {the most|probably the most|essentially the most|one of the most|by far the most} {difficult|tough|challenging|hard|tricky|complicated}…