Mind the gap: A complete, cooperative spin transition for a mononuclear MnIII complex is reported with an 8 K hysteresis window. Raman spectra collected at a single temperature in warming and cooling modes confirm the electronic bistability within the hysteresis loop. The source of the cooperativity is a disconnection in the hydrogen-bonded 1D chains that connect adjacent cations owing to an order-disorder transition in the PF 6 - counterion. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.