The Student Room Group
Da Mouse

In the following complexes identify the central ion, and the ligand/s
[CrCl(H2O)5] 2+
Co(OH)2(H2O)5]2+

[CrCl(H2O)5] 2+
Central ion = Cr2+, ligands = H2O

Co(OH)2(H2O)5]2+
Central ion = Co2+, ligands = OH and H2O

Da Mouse
Given the co-ordination number, write down the formulae and names of the complex ions formed between:
Fe3+ and CN- (C.N=6)
Ni2+ and Cl- (C.N.=4)

Fe3+ and CN- (C.N=6)
Formula = [Fe(CN)6]3-

Ni2+ and Cl- (C.N.=4)
Formula = [Ni(Cl)4)]2-
I don't know how to name them but I found this site: http://www.chemistry.wustl.edu/~edudev/LabTutorials/naming_coord_comp.html
Reply 3
Cr3+ is central ion with 5 water ligands
Co ia central metal ion. I think you got the formula wrong though ie there should be 1 OH... H2O and OH- ligands.

[Fe(CN)6]3-. Coordination number is 6. Hexacyanoferrate (III) ions.
[NiCl4]2-. tetrachloronickelate(II). Coordination number 4.