Titanium─ Titanium dioxide (p324) Main ores: ilmenite FeTiO3 and rutile TiO2 Δ Concentrated H2SO4 TiOSO4 + FeSO4 + H2O H2TiO3 Fe(s) + H2O Cooling H2O Δ filtrated TiOSO4 + FeSO4·7H2O(s) TiOSO4
Titanium─ Titanium dioxide (p324) Reducing agents:C, H2, Na, Ca, Mg TiO2 Ti High temperature Fused electric arc Ar or He FeTiO3 1173 K C(s) + Cl2 Spongy Ti TiCl4(l) 1273 K Volatilization Fractionated Molten Mg TiCl4(l) Spongy Ti Mg + MgCl2 1073 K
Titanium─ Titanium dioxide (p324) NaOH Na2TiO3 TiO2 HF CaTiO3 H2TiF6 H2SO4 ferroelectrics TiO(H2O2)2+ Ti(OH)(O2)+ TiOSO4 Zn H2O2 Ti(H2O)63+ violet Intense orange Ti Ti O O Structure of TiOSO4·H2O
Titanium─ Titanium dioxide (p324) • TiO2 mainly used in pigments • TiO2 now studied as catalyst, nanoparticle • Light activity
Titanium─ Titanium tetrachloride (p325) • A colorless liquid (bp 136 ºC) • Pungent odor, fumes strongly in air TiCl4 + H2O TiO2 + HCl • Form adducts (TiCl4L or TiCl4L2) with molecules containing oxygen, even OPCl3 or CH3COOC2H5 • Form alkoxides TiCl4 + 4ROH + 4R`NH2 Ti(OR)4 + 4R`NH3Cl
Titanium─ Titanium trichloride (p327) • As Ziegler-Natta catalyst for polymerization of alkenes
Vanadium (V) • Electron Configuration: 4s23d33d43d33d2 • Origin: Named after the Scandinavian goddess 'Vanadis‘ because of its beautiful multi-coloured compounds. . • Ores: • Vanadinite: Pb5Cl(VO4)3 • Patronite: VS4 • Roscoelite: K2V4Al2Si6O20(OH)4 • Carnotite: K2(UO2)2(VO4)2.H2O
Properties • Soft, ductile, bright white. • Main oxidation states: III, IV, & V • Uses • About 80% of the vanadium produced is used as a steel additive. • Less than 1% of vanadium and as little chromium make steel shock- and vibration-resistant. • Vandium(V) oxide is used in ceramics
Vanadium (V) Oxide (p329) Δ V2O5 containing V(IV) (NH4)3VO4 C. HCl Dilute H2SO4 V2O5 VOCl2 Conc. H2SO4 NaOH NaOH H+ VO2SO4 VO43– H2O2 V10O286– VO2(O2)+ yellow V(O2)3+ reddish-brown Polyacid, containing VO6 unit
Aqua solution chemistryRedox Reactions • Sulphur dioxide will reduce V(+5) to V(+4) only; zinc in hydrochloric acid will reduce V(+5) step by step to V(+2). The half equations and the overall equation is given for each of these reactions.
The aqueous chemistry of vanadium(V) is complex and depends on pH. Here we take strongly acidic solutions in which the yellow ion VO2+ is the species present. The colour changes for the complete reduction sequence are: • +5 +4 +3 +2 • yellow blue green lavender • VO2+ VO2+ [V(H2O)6]3+ [V(H2O)6]2+ • The water ligands are not shown in the equations below, but remember that they are there for V(+3) and V(+2).
Aqua solution chemistrycomplexes (p329) • Oxovanadium ions: VO2+ VO2+ • VO2+ forms angular (cis-) complexes: VO2Cl43– VO2edta3– VO2(ox)23– why ? d2sp3, dx2-y2 and dz2 dxz, dyz, dxy d-p πbond • VO2+ forms either five- or six-coordinate complex: VO(acac)2
Halides (p328) • V(V) Only VF5 is known, colorless liquid, high viscosity. VF6 unit, cis-V-F-V bridge • VCl4 is a dark red oil, violently hydrolyzed by water, giving VOCl2
Chromium (Cr) • Electron configuration: 4s13d53d53d43d3 • Ore: Chromite FeCr2O4 • Properties: • Hard, silvery metal with a blue tinge. Capable of taking a high polish. • Metal-metal quadruple bonds are possible. • Gives Ruby its color. • Main oxidation state: III
Uses: • Used in stainless steels (~13% Cr) in increase corrosion resistance. • Used for plating other metals. • Used chemically in pigments (vivid green, yellow, red and orange colors). • Tanning agents, catalysts, and oxidizing agents. • Chromium compounds are toxic.
Chromium Compounds • All compounds of chromium are colored (except Cr(CO)6 ?); the most important are the chromates of sodium and potassium and the dichromates and the potassium and ammonium chrome alums. The dichromates are used as oxidizing agents in quantitative analysis, also in tanning leather.
Chromium Compounds • Other compounds are of industrial value; lead chromate is chrome yellow, a valued pigment. Chromium compounds are used in the textile industry as mordants, and by the aircraft and other industries for anodizing aluminum.
Dichromate and chromate • Dichromate and chromate equilibria is pH dependent: • HCrO4- -> CrO42- + H+ K=10-5.9H2CrO4 -> HCrO4- + H+ K=10+0.26Cr2O72- + H2O -> 2HCrO4- K=10-2.2HCr2O7- -> Cr2O72- + H+ K=10+0.85
Chromium Chromium is obtained from the ore chromite铬铁矿, FeCr2O4. Chromium is used in steel alloys, including ferrochrome. FeCr2O4(s) + 4 C(s) Fe(s) + 2 Cr(s) + 4 CO(g) ferrochrome Pure chromium is obtained by reducing chromium (III) oxide with aluminum. The oxidation states of chromium in solution depend on the pH of the solution.
Strong oxidizing agent. Conversion from chromate to dichromate: 2 CrO42-(aq) + 2 H+ (aq) Cr2O72-(aq) + H2O (l) lower pH: Cr3O102-, Cr4O132-, CrO3. Polymerization. stronger in oxyacids of Mo and W. polymetallates 多酸 e.g. [Mo36O112]8-, [H2W12O42]10+ etc.
Heteropolymetallates [CoIIW12O40]6-, [NiIVMo9O32]6-, etc. Heterogeneous catalyst. aluminosilicate Similar behavior for some main group compounds: Zeolite Linde A: [Na12(Al2Si12O48)].27H2O
Chromium (II) Acetate red Cr2(OCOCH3)4.2H2O 2.35 Å cf: 2.58 Å in metal
MO theory of Metal-Metal Bond Formation anhydrous Cr2(OCOCH3)4 d(Cr-Cr) 1.98 Å: quadruple bond dx2-y2, s, px, py pz M-L bonds, five dz2 dxz, dyz dxy