Phosphine, :PH3, and carbon monoxide, :CO, are monodentate ligands found in some transition element complexes.

1. (a)(i)Define monodentate ligand.[1]
2. (a)(ii)Define transition element complex.[1]
3. (a)(iii)Explain why transition elements form complexes.[1]
4. (b)(i)The formulae of six complexes are given in Table 6.1. The abbreviation en is used for 1,2-diaminoethane. The abbreviation dien is used for the tridentate ligand H2NCH2CH2NHCH2CH2NH2. The dien ligand forms three bonds to the gold ion in [Au(dien)(H2O)2Cl]2+ and Au(dien)Cl3. These three bonds all lie in the same plane. The CO ligand coordinates through the carbon atom in [Rh(CO)2Cl2]+. Table 6.1 formula isomerism shown geometry [Rh(en)2Cl2]+ yes [Rh(CO)2Cl2]+ yes [Au(dien)(H2O)2C1]2+ Au(dien)Cl3 no octahedral Ni(PH3)2Cl2 no [Ni(H2O)2(NH3)4]2+ yes Complete Table 6.1 to state the geometry of the first three complexes. Each complex is either square planar, tetrahedral or octahedral.[1]
5. (b)(ii)Use complexes [Au(dien)(H2O)2Cl]2+ and Au(dien)Cl3 to write an equation showing ligand exchange.[1]
6. (b)(iii)Draw the three-dimensional structure of Au(dien)Cl3 in the box. The dien ligand can be drawn as N N N Au [Figure for drawing box][1]
7. (b)(iv)Draw the three-dimensional structure of Ni(PH3)2Cl2 in the box. Ni [Figure for drawing box][1]
8. (b)(v)One of the complexes, [Rh(en)2Cl2]+ or [Rh(CO)2Cl2]+, can exist in three isomeric forms. Identify this complex and the types of isomerism shown.[1]
9. (b)(vi)Draw the three-dimensional structures of the two isomers of [Ni(H2O)2(NH3)4]2+ in the boxes and identify the type of isomerism shown. Ni Ni type of isomerism shown ............................................[2]

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