  Spin-crossover has a wide range of applications from memory devices to
sensors. This has to do mainly with the nature of the transition, which may be
abrupt, gradual or incomplete and may also present hysteresis. This transition
alters the properties of a given sample, such as magnetic moment, color and
electric resistance to name some. Yet, a thorough understanding of the
phenomenon is still lacking. In this work a simple model is provided to mimic
some of the properties known to occur in spin-crossover. A detailed study of
the model parameters is presented using a mean field approach and exhaustive
Monte Carlo simulations. A good agreement is found between the analytical
results and the simulations for certain regions in the parameter-space. This
mean field approach breaks down in parameter regions where the correlations and
cooperativity may no longer be averaged over.
