[aimeerider]

Im having a really tough time describing the role of potassium cations and the water in the compound K4[Ni(NCS)6].4H2O, ive been trying to find the structure but im drawing a blank.

Any help would greatly be appreciated
 

[dipic]

The NCS has a -1 charge, Ni is 2+, so 4 K  are needed to balance the 4- charge. The K and water will sit in the crystal lattice associated with the central octahedral complex [Ni(NCS)6].  In this case isomerism may occur with the following: K4[Ni(H2O)(NCS)5](SCN).3H2O, K4[Ni(H2O)2(NCS)4](SCN)2 .2H2O etc.

Hope that helps.

[dipic]

I hope you also see that NCS can coordinate to Ni via the N or S. So isomerisation can occur that way as well.