Spin crossover in co-crystallised 2 ratio 1 cisratiotrans [Fe(II)(pldpt)(2)(NCS)(2)] occurs only in (1/3) of the iron centres.

The first spin crossover (SCO) active sample of co-crystallised stereoisomers (cisratiotrans, 2 ratio 1) is fully high spin (HS) at room temperature but displays temperature mediated SCO in which only a third of the iron(ii) centres change spin state.