I need some help, in explaining how to know what kind of d-metal complex a molecule is. For example, I have: 1. [Cr(H2O)6]2+ 2. [Cr(CN)6]4- I know that #1 is d4, and #2 is d3, but that's just because it says so in my paper. How do I "calculate" it if that information is not given? Many thanks! (My english sucks, hope you understand what I mean).