How many possible isomers are there of an octahedral complex having the formula M(ABC)(N...

How many possible isomers are there of an octahedral complex having the formula M(ABC)(NH₃)(H₂O)Br, where BC is the tridentate ligand How many of these consist of pairs of enantiomers? Sketch all isomers, showing clearly any pairs of enantiomers. The tridentate ligand may be abbreviated as N—P—As for simplicity.