Why are the coordination compounds representated by arrows? Is it necessary to write every coordination compounds with the arrow side of the bond facing the metal ion and the other part the ligand?
Historically, coordination compounds have been depicted in various ways.
According to the Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008), bonds representing coordination from one atom to a single other atom should be represented as normal plain single bonds. The use of dative bonds (i.e. arrows pointing to the central atom) to represent coordination is not acceptable.