Some transition element complexes can show stereoisomerism. State two types of stereoisomerism shown by transition element complexes. 1 2

1. (a)Some transition element complexes can show stereoisomerism. State two types of stereoisomerism shown by transition element complexes. 1 2[1]
2. (b)The complexes [Pt(NH3)2C2] and [Pt(en)₂]2+ have the same geometry (shape) around the metal ion. [Pt(NH3)2C2] exists as two stereoisomers whereas [Pt(en)2]2+ only has one possible structure. State the geometry around the metal ion.[1]
3. (c)The complex [Cr(en)3]2+ exists as two stereoisomers whereas the complex [Cr(OCH2CH2NH2)3] exists as four stereoisomers. Complete the three-dimensional diagrams in Fig. 2.1 to show the four stereoisomers of [Cr(OCH2CH2NH2)3]¯. Represent the ligand ¯OCH2CH2NH2 by using [Figure 2.1][3]
4. (d)(i)The complex [Cr(OCH2CH2NH2)3] is formed by reacting Cr²+(aq) with the conjugate base of 2-aminoethanol. A synthesis of 2-aminoethanol is shown in Fig. 2.2. [Figure 2.2] Suggest the mechanism for step 1 of the reaction of oxirane with ammonia in Fig. 2.3. Include all relevant curly arrows, lone pairs of electrons, charges and partial charges. Draw the structure of the organic intermediate. [Figure 2.3][3]
5. (d)(ii)A small amount of by-product E, shown in Fig. 2.4, is produced during the reaction shown in Fig. 2.2. [Figure 2.4] Suggest how the formation of by-product E can be minimised.[1]
6. (d)(iii)Compound F, C4H9NO, can be formed from the reaction of by-product E, C4H11NO2, with concentrated H2SO4. Compound F is a saturated and basic organic compound. Suggest a structure for compound F. State the type of reaction undergone by E to form F.[2]

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