Hi Dr.Bob,

Question

Which is the correct formula for
dinitrobis(ethylenediamine)cobalt(III) nitrate?
I'm not sure which is the correct one out of these two:
a)[Co(en)2(NO2)2]NO3 or
b)[Co(NO2)2(en)2]3(NO3)3 ?

At the instance, I've choosen option a). Is my naming correct?

Answer 1

I would go with a also. b appears to be just the trimer of a and unless we know the compound is a trimer (and thus the molecular formula instead of the empirical formula) I think the empirical formula is the way to go. You know we write NaCl even though it really is NaxClx.