Order of Ligands in Coordination Compounds (9c.3)

[Ishpreet Kaur 3C]

I know this has been asked a lot but is there a specific order in which the ligands are supposed to be arranged when writing the formula (not the name) of the coordination compound? The textbook does say to arrange the ligands in alphabetical order based on the chemical symbol but the solutions manual for 9c.1(c) has the formula listed as [Co(NH3)4(H2O)2]Br3, which isn't alphabetically ordered. Also, why is it written H2O and not OH2? I thought we were supposed to write it as OH2 to emphasize the oxygen atom binds to the metal atom.

[Lily Dabrowski 2G]

Within the brackets, the metal atom is written first, followed by the ligands. Ligands are written in order of negative, neutral, then positive. If more than one of a type of ligand exists, then they are written alphabetically. I think the order of the formula (like OH2 vs H2O) would only change when writing out the structure/diagram, so you could draw out that the O binds to the central metal atom like you said. But that isn't done when writing the formula out in the brackets.