CIE Mar 2016 v2 Paper 4 Q3

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(a) Complete the electronic structures of the following species. Co [Ar]Co2+ [Ar]PMT [2] (b) In an isolated transition metal atom the five d orbitals have the same energy. When a transition metal ion forms a tetrahedral complex the d orbitals are split into two groups of different energies. Complete an orbital energy diagram to show this, indicating the number of orbitals in each group. increasing energy isolated transition metal ion tetrahedral complex [1] (c) Cobalt(II) forms a six co-ordinate complex containing three water molecules and three chloride ions. (i) Write the formula of this complex showing the overall charge, if appropriate.[1] (ii) Explain, with the aid of diagrams, how many isomers of the complex in (i) exist. (d) Platinum(II) forms a four co-ordinate complex containing two ammonia molecules and two chloride ions. (i) Write the formula of this complex showing the overall charge, if appropriate.[1] [2]UCLES 2016 9701/42/F/M/16<br /> (ii) This complex exists as two isomers. Draw the structure of these isomers and give their names. PMT[3] (iii) One of the isomers in (ii) is an important anticancer drug. State which isomer this is and explain why this isomer is effective. isomerreason[2] (e) Transition metal ions often exist as hexa-aqua complexes in aqueous solution. The reactions which involve ligand exchange are reversible. [Cu(H2O)6]2+ + 4NH3 [Cu(NH3)4(H2O)2]2+ + 4H2O (i) Write an expression for the stability constant, Kstab, for this equilibrium. Give its units. Kstab = units =[2] (ii) The numerical value for Kstab for this equilibrium at 298 K is 1.201013. Explain how this value relates to the relative stabilities of the two complexes.[1]UCLES 2016 9701/42/F/M/16 [Total: 15] [Turn over<br />

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