The capacity for the 5-coordinate structure to accommodate an
additional ligand can be demonstrated by dissolving the compound
in coordinating solvents such as pyridine or solutions
containing aqueous ammonia or sodium carbonate. Coordination
of a sixth ligand changes the color compared to solutions in
noncoordinating solvents such as chloroform or dichloromethane.
Given the workup that we use, the catalyst is not easily
collected and recycled.