Why does iron(III) form the trithiocyanate complex instead of the triisothiocyanate one?

[![enter image description here](https://i.stack.imgur.com/a7owQ.png)](https://i.stack.imgur.com/a7owQ.png)


As far as I know, $\ce{Fe^{3+}}$ is a hard acid, and thus shouldn't it favor complexation with the nitrogen's lone pair rather than the softer S? 


