LECTURE SCHEDULE EACH LECTURE TIME:

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1 LECTURE SCHEDULE Date Topic 1. Mon Review of Elements, Periodic Properties & Periodic Table 2. Wed Short Survey of the Chemistry of Main Group Elements 3. Fri Redox Chemistry (Mustonen) 4. Fri Transition Metals: General Aspects & Crystal Field Theory (Thomas) 5. Mon Ag, Au, Pt, Pd & Catalysis (Karttunen) 6. Fri Zn + Ti, Zr, Hf & Atomic Layer Deposition (ALD) 7. Mon V, Nb, Ta, Cr, Mo, W & Metal Complexes 8. Wed Mn, Fe, Co, Ni, Cu & Magnetism and Superconductivity (Mustonen) 9. Mon Resources of Elements & Rare/Critical Elements & Element Substitutions 10. Wed Lanthanoids + Actinoids & Luminescence 11. Fri Inorganic materials chemistry research EACH LECTURE TIME:

2 QUESTIONS: Lecture 7 Name the following metal complexes 1. K 3 [Fe(CN) 6 ] 2. Na[B(NO 3 ) 4 ] 3. [CoN 3 (NH 3 ) 5 ]SO 4 4. NH 4 [Cr(NCS) 4 (NH 3 ) 2 ] 5. [Cr(H 2 O) 6 ]Cl 3 6. [Al(OH)(H 2 O) 5 ] Na 2 [Fe(CN) 5 NO] 8. [Co(ONO)(NH 3 ) 5 ]SO 4

3 ISO- and HETEROPOLYANIONS Coordination compounds (V, Nb, Ta, Mo, W) First synthesized in 1826: [PMo 12 O 40 ] 3- Basic structure unit: MO 6 Isopolyanion (IPA): [M n O y ] p- Heteropolyanion (HPA): [X z M n O y ] q- (z n) (very complex structures)

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6 polyoxometallates

7 PREPARATION PROPERTIES M metals at their highest oxidation states M metals bonded to oxygen fi ionic bond multitude of isomeric compounds dissolve as distinct units APPLICATIONS many applications in chemistry and medicine use as catalysts (in oxidation reactions) tailoring of the properties straightforward

8 METAL CLUSTER COMPOUNDS Nb and Ta (lowest oxidation states) X general formula [M 6 X 12 ] n+ - metals (M) form octahedra - halides (X) at edges and bonded to two metals each basic unit can bond via halide atoms: - to four similar units average formula MX 2.3 diamagnetic - to six similar units 3D chains average formula MX 2.5 paramagnetic

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10 APPLICATIONS of NIOBIUM NbN, NbTi, Nb 3 Sn and Nb 3 Ge (T c = K) superconductors (used in practical applications) fi strong magnets fi e.g. MRI, NMR LiNbO 3 and LiTaO 3 : - distorted perovskite structure - ferroelectric (electrical dipole moment without external electric field) Bronzes: e.g. Sr x NbO 3 (x = ) - good electrical conductivity - A-cation deficient ABO 3 perovskite structure - ref. Na x WO 3 ABO 3 Additive in steels and metal alloys Low neutron absorption

11 Perovskite ABO 3-d Mineral Perovskite: CaTiO 3 Perovskite is named for a Russian mineralogist, Count Lev Aleksevich von Perovski. It was discovered and named by Gustav Rose in 1839 from samples found in Ural Mountains. A: large metal, e.g. Ca, Sr, Ba, RE B: small metal, e.g. Mn, Fe, Co, Ni, Cu O: oxygen (halogen)

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13 Perovskite Multifunctional structure Capasitor (high dielectric constant) BaTiO 3 Piezoelectric material Pb(Zr,Ti)O 3 Ion conductor La(Co,Ga)O 3 Electric insulator SrTiO 3 Perovskite ABO 3 Superconductor CuBa 2 YCu 2 O 6+z Magnetoresistor LaMnO 3 Metallic conductor LaCrO 3 Catalyst La(Co,Mn)O 3 Record-high melting point Ba 3 MgTa 2 O 9 Major constituent of earth MgSiO 3

14 Distortions and Imperfections in Perovskite Structure - often the source of the desired properties Changes in atomic positions Oxygen deficiency Ordering of cations fi Layered structure

15 CHROMIUM (and Mn): OXIDATION STATES Chromium: VI: stable (chromate and tendency towards polychromates) V and IV: unstable III: most stable II: strong reducing agent Manganese:VII: stable (permanganate MnO 4- ) VI, V and III: unstable IV: most stable in basic conditions II: most stable in asidic conditions

16 OXIDES Halfmetal for SPINTRONICS: Electrical conductor & ferromagnet Dry battery

17 CHROMATE potassium chromate K 2 CrO 4 lead chromate PbCrO 4 strong oxidizers, carcinogenes Electron transfer reaction: Cr(VI)-O(-II) fi Cr(V)-O(-I) 2CrO H + Cr 2 O 7 2 +H 2 O CrO 4 2 +H 2 O HCrO 4 +OH -

18 HISTORY of COORDINATION COMPLEXES Prussian blue: KFe[Fe(CN) 6 ] - synthesized in 1704 in Berlin - used as a pigment in Prussian army uniform Tassaert 1798: CoCl 3 x 6 NH 3 - cobolt chloride + ammonia fi brownish red product Blomstrand-Jörgensen chain theory: - derived from organic chemistry: ammine-chains + chlorine at the ends

19 Alfred Werner ( ) Nobel 1913 WERNER COORDINATION THEORY Alfred Werner 1892 (University of Zurich) Two valences - primary valence (hauptvalenz)» oxidation state ( ) - secondary valence (nebenvalenz)» coordination number (-----)

20 MODERN COORDINATION THEORY Central cation Chloride ions within the brackets are in the coordination sphere (secondary valence 6) Chloride ions outside of the brackets (so-called counter ions) contribute to the oxidation state only (primary valence 3) Outside-of-brackets chloride-ions can be removed in water solutions Complexes different in colour and electrical conductivity

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22 COORDINATION CHEMISTRY Metal complex: [ML n ]X y tai A b [ML n ] Central atom (M): metal cation or neutral metal atom Ligands (L; lat. ligare = to bind = sitoa): - molecules or ions around the central atom - infinite/integer number (n) - ligands form the coordination sphere of the central atom Metal-ligand bond: M :L - each ligand gives an electron pair to the central atom - COVALENT COORDINATION BOND Coordination number (CN = n): - typically 4 (tetrahedron or square-plane) or 6 (octahedron) - sometimes 5 (pyramid or trigonal bipyramid) Counter ion: anion (X) or cation (A) Typical for metal complexes: bright colours & magnetism

23 DENTICITY and CHELATE EFFECT Monodentante: ligand bonds to the central atom via one atom Multidentante: ligand bonds to the central atom via multiple atoms Ambidentate (changing): depending on conditions, ligand may bond via different atoms to the central atom, e.g.: - CN (cyano) and NC (isocyano) - SCN (thiocyanato) and NCS (isothiocyanato) - NO 2 (nitro) and ONO (nitrito) Chelate: complex compound in which multidentante ligands CHELATE EFFECT: - chelates are unusually stable - e.g. [Ni(en) 3 ] 2+ ca. 10 times more stable than [Ni(NH 3 ) 6 ] 2+

24 Examples of 2-dentante ligands Ethylenediamine (en) Asetyleneacetonato (acac) Oxalato (ox) Phenantroline (phen)

25 EDTA dentante - extremely stable complexes with most of the transition metal - typically octahedral structures - bonds via 2 N-atoms and 4 negatively charged O-atoms

26 NAMING Ligand names: (1) negative ligand: o-ending F - fluoro Cl - chloro Br - bromo I - iodo O 2- oxo OH - hydroxo NO 2- nitro CN - cyano (2) neutral ligand: name of the molecule without changes (3) positive ligand: ium-ending (e.g. hydratsinium NH 2 NH 3+ ) (4) trivial names: - aquo H 2 O - ammine NH 3 - carbonyl CO - nitrosyl NO (5) ambidentante ligands: - nitro NO 2- and nitrito ONO - - thiocyanato SCN - and isothiocyanato NCS - (6) bridging ligands: m-

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28 Naming of complexes/complex compounds: (1) cation first, then anion (2) ligands in alphabetical order (prefix does NOT affect) before central atom (3) number of similar ligands: prefix: di-, tri-, tetra-, penta-, hexa- - monoatomic ligands - polyatomic ligands with short name - neutral ligands with trivial names prefix: bis-, tris-, tetrakis- - ligands with prefix di-, tri- - neutral ligands (no trivial name) - ionic ligands with very long names (4) anionic complex: central atom with ate-ending (cuprate, ferrate, ) (5) oxidation state of the central atom with Roman numerals in parentheses

29 EXAMPLES [Co(NH 3 ) 4 Cl 2 ]Cl - ligands in alphabetical order: NH 3 neutral (trivial) fi ammine Cl negative fi chloro - 4 ammine ligands and 2 chloro ligands fi tetraamminedichloro - Cl is anion, complex is cation, cobalt oxidation state +3 fi cobalt(iii) tetraamminedichlorocobalt(iii)chloride (NH 4 ) 2 [Pt(NCS) 6 ] - 6 negative NCS ligands (bonding via N) fi hexaisothiocyanato - NH 4 cation fi ammonium - complex is anion, platinum oxidation state +4 fi platinate(iv) ammoniumhexaisothiocyanatoplatinate(iv)

30 [Cu(NH 2 CH 2 CH 2 NH 2 ) 2 ]SO 4 bis(ethylenediamine)copper(ii)sulphate [Ag(CH 3 NH 2 ) 2 ] [Mn(H 2 O) 2 (C 2 O 4 ) 2 ] bis(methylamine)silver(i)diaquadioxalatomanganate(iii) OH [(NH 3 ) 4 Co-OH-Co(NH 3 ) 4 ](NO 3 ) 3 OH tetraamminecobalt(iii)-m-trihydroxotetraamminecobalt(iii)nitrate