Reversible geometry reorganisations are demonstrated by cis-3,5-diamino-trans-hydroxycyclohexane (cis,trans-DAHC) copper(II) fluoride complexes, with the concentration of water in the mother liquor controlling interconversion between blue crystals of 5-coordinate syn-[Cu(DAHC)2F](F)·2CH3OH·H2O and red crystals of 4-coordinate anti-[Cu(DAHC)2](F)2·2H2O.