A hydrated cobalt(III) complex, A, is heated in a crucible to remove the water of crystallisation. The anhydrous complex B is formed. The experimental results are shown below:
The anhydrous complex B is analysed and found to have a molar mass of 478.9 g mol-1 and to contain the following percentage composition by mass:
Co, 12.30%; C, 15.05%; N, 17.55%; H, 5.05%; Br, 50.05% \text{Co, } 12.30\%; \text{ C, } 15.05\%; \text{ N, } 17.55\%; \text{ H, } 5.05\%; \text{ Br, } 50.05\% Co, 12.30%; C, 15.05%; N, 17.55%; H, 5.05%; Br, 50.05%The anhydrous complex B contains a cation C comprising Co\text{Co}Co, C\text{C}C, N\text{N}N and H\text{H}H only.
Cation C is six-coordinate, contains three molecules of the bidentate ligand D, and exists as optical isomers.
Determine the formula of A, B, C and D and show the 3D structures for the optical isomers of C.
Show all your working.
48 exam-style questions on OCR A A Level Chemistry Transition elements. Each one has a worked solution and a mark scheme showing where the marks go.