Discuss and explain the factors that contribute to the preference of a first row transition metal octahedral complex forming a high spin or low spin complex. Explain how you would experimentally determine this. Use examples of octahedral complexes to illustrate your answers.

Identify complexes that can have low and high spin configurations and rationalize why they adopt a particular configuration using a strong field / weak field ligand argument based on the spectrochemical series.

An octahedral complex having the formula [M(dien)(NH3)(OH2)F] has a total of 15 isomers. In the sum formula “dien” represents the tridentate diethylenetriamine ligand, which can adopt meridional or facial coordination modes. Draw structures of 8 possible isomers, clearly showing any pairs of enantiomers. The tridentante ligand may be abbreviated as below for simplicity.