[zeoblade]

When reacting Fe(II), Fe(III), Co(II) and Ni(II) with (NH₄)₂S I observed black precipitates for all and could not distinguish between any of them. I've tried searching online and in my textbook but I can't find any information or don't know the best keywords and terminology to find information on it.

I am wondering if any of those reactions are ionic or actually co-ordinate? I'm thinking they are ionic as below:

Co₂₊(aq) + (NH₄)₂S(l) --> CoS(s) + NH₄⁺

However, I have a feeling it may not be so simple.

[Borek]

Compare http://en.wikipedia.org/wiki/Qualitative_inorganic_analysis

[zeoblade]

Thanks, I wish I found this table before.

I am wondering if transition metal sulphides coordinate in a linear stereochemical complex arrangement so that each sulphide anion is directly opposing the other across the transition metal?

Or if the structure is bent?

But in Fe(III) I can't visualise how would the coordinate sulphide complex be?