Presentation on theme: "Unless otherwise stated, all images in this file have been reproduced from: Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 2007 (John Wiley)"— Presentation transcript:
1 Unless otherwise stated, all images in this file have been reproduced from: Blackman, Bottle, Schmid, Mocerino and Wille, Chemistry, 2007 (John Wiley) ISBN:
2 CHEM1002 [Part 2] Dr Michela Simone Lecturer BSc (I Hons), MSc, D.Phil. (Oxon), MRSC, MRACIWeeks 8 – 13Office Hours: Monday 3-5, Friday 4-5Room: 412A (or 416)Phone:It is a good idea if all lecturers can make an appearance for the first lecture.Remind students we are IT for the rest of the semester.DEMOS for this lecture:EXP 2.3: “Charles law (2.3),EXP 2.1 “CO2 density (2.1)
3 Summary of Last Lecture Complexes IIFor octahedral complexes with formulae [MX2Y4], cis and trans geometrical isomers are possibleFor square planar complexes with formulae [MX2Y2], cis and trans geometrical isomers are possibleFor octahedral complexes with bidentate ligands, optical isomerism is also possibleMetal complex formation can greatly increase solubility
4 Complexes III Lecture 14 Transition Metals Electron Configuration Oxidation StatesColoursMagnetismBlackman Chapter 13, Sections 13.4 and 13.7Lecture 15Metals in Biological ProcessesEssential ElementsToxic ElementsMedicinal UsesBlackman Chapter 13
6 Electronic Configurations of Atoms In 4th row, 4s and 3d orbitals are available for electronsThere is one 4s orbital: it can accommodate 2 electronsThere are five 3d orbitals: each can accommodate 2 electrons, giving a total of 10 electronsFill 4s then 3denergy3d4s
7 Atomic Configurations Fill 4s then 3dGroup number gives number of valence electronsElectronic configurations:K: group 1 so [Ar](4s)1(3d)0Sc: group 3 so [Ar](4s)2(3d)1Mn: group 7 so [Ar](4s)2(3d)5Ni: group 10 so [Ar](4s)2(3d)8Zn: group 12 so [Ar](4s)2(3d)10[Ar](4s)x(3d)ywhere x + y = group
8 Electronic Configurations of Cations Fill 3d onlyGroup number gives number of valence electronsCation has (group number – oxidation number) electronsMn7+: group 7 and oxidation number 7 so has:(7 – 7) = 0 electrons: [Ar](3d)0Mn2+: group 7 and oxidation number 2 so has(7 – 2) = 5 electrons: [Ar](3d)5Ni2+: group 10 and oxidation number 2 so has(10 – 2) = 8 electrons: [Ar](3d)8Ni3+: group 10 and oxidation number 3 so has(10 – 3) = 7 electrons: [Ar](3d)7(4s always empty!)Demo Fe/Mn reaction
9 Electronic Configurations of Cations To minimize repulsion between electrons, they occupy d-orbitals singly with parallel spins until they have to pair up:Mn2+: [Ar](3d)53dNi2+: [Ar](3d)83dDemo Fe/Mn reactionIf the metal cation has unpaired electrons, the complex will be attracted to a magnet: paramagnetic
10 Aqueous Oxoanions of Transition Metals One of the most characteristic chemical properties of these elements is the occurrence of multiple oxidation numbers, often associated with different colours.Ion Ox. No. ColourVO yellowVO greenV blueV violet
11 Colourful ComplexesAqueous solutions of the Co(III) complexes (from left to right): [Co(NH3)5OH2]3+, [Co(NH3)6]3+, trans-[Co(en)2Cl2]+, [Co(en)2O2CO]+ and [Co(NH3)5Cl]2+.All contain Co(III): colour influenced by the ligandBlackman, Bottle, Schmid, Mocerino & Wille (2007). Wiley & Sons: FIGURE Aqueous solutions of the Co(III) complexes: (from left to right) [Co(NH3)5OH2]3+,[Co(NH3)6]3+, trans-[Co(en)2Cl2]+, [Co(en)2O2CO]+ and [Co(NH3)5Cl]2+. As the metal ion is the same inall cases, the variety of colours arises from the different ligands surrounding the Co(III) ion.
12 Absorbed and Observed Colours Unless the d-orbitals are empty, half full or full, electrons can be excited from one d-orbital to another: absorption of light which we see as colour
13 Summary: Complexes II Complete the worksheet Learning Outcomes - you should now be able to:Complete the worksheetWork out the electron configurations of atoms and cationsWork out the number of unpaired electronsAnswer review problems in BlackmanNext lecture:The Biological Periodic Table
14 Practice ExamplesHow many d-electrons and how many unpaired electrons are there in the following complexes?K2[NiCl4][Co(en)3]Cl3[CrCl2(OH2)4]+K2[Zn(OH)4][PtCl2(NH3)2]2. Consider the compound with formula [CoCl2(NH3)4]Br2H2O(i) Write the formula of the complex ion.(ii) Write the symbols of the ligand donor atoms.(iii) What is the d electron configuration of the metal ion in this complex?