Transition Metal Chemistry

Titanium Chemistry

• -Second in abundance of transition metals
• -Excellent corrosion resistance
• -High heat transfer efficiency
• -Good strength to weight ratio
• -Extraction:
• TiO2 + C + 2Cl2 --> TiCl4 + CO2 (Kroll process)
• TiCl4 + 2Mg --> Ti + 2MgCl2 (purified by distillation (b.p. 136oC)
• -Titanium Halides, prepared by direct reaction of Ti with the halogen gas:
• TiF4 - white liquid
• TiCl4 - colourless liquid
• TiBr4 - yellow solid
• TiI4 - violet/black solid
• For TiX3 - reduction of TiX4 and H2
• -Titanium oxides:
• --Prepared by hydrolysis of TiX4 or Ti(III) salts
• --TiO2 reacts with acids AND bases:
• TiOSO4 formed in H2SO4
• MTiO3 (M = CaTiO3 - perovskite) - metatitanates
• M2TiO4 - orthotitanates
• Complexes, good Lewis acid - forms adducts on reaction with Lewis bases
• 2PEt3 + TiCl4 --> TiCl4(PEt3)2
• 2MeCN +TiCl4 -->TiCl4(MeCN)2
• bipy + TiCl4 --> TiCl4(bipy)
• Solvolysis - if ionisable protons present in ligand
• 2NH3 + TiCl4 -->TiCl2(NH2)2 + 2HCl
• 4H2O +TiCl4 --> TiO2 +4HCl
• 2EtOH + TiCl4 --> TiCl2(OEt)2 + 2HCL

Vanadium Chemistry

• -Plays a number of roles in biological systems
• -Amanita Muscaria (a mushroom) can accumulate vanadium in the form of amavadin
• -Can exist in a wide number of oxidation states but the key ones are: +2, +3, +4 and +5
• -+2 and +3 are reducing but +4 is stable, +5 is slightly oxidising
• -Vanadium Oxides:
• -VO, V2O3, V2O4, & V2O5
• --V2O5 - amphoteric and aq chem. v complex and pH dependent
• --when dissolved in v. strong NaOH sol. a colourless solution containing VO43- (vanadate) formed.
• --When acid is added protons added and polymerisation occurs to produce diff. oxy ions
• [VO4]3-(pH12) --> [VO3.OH)2-(pH10) --> [V2O6.OH]3-(PH9) --> [V3O9]3-(pH7) --> [V5014]3-(pH6.5) --> V2O5(H20)n(pH2.2) --> [V10O28]6-(pH<1) [VO2]+ VANADYL
• -Vanadium Halides:
• -+5: Only +5 complex is VF5 - white solid, based on trigonal bipyramid in gas phase. Solid state is a fused octahedral:
• -2V + 5F2 --> 2VF5 (300oC)
• -+4: Halides more common, prepared via numerous routes
• -VF4 VCl4 and VBr4
• -VCl4 prepared by reacting with chlorinating agents i.e
• -Cl2, SOCl2 or COCl2
• TERTRAHALIDES tend to be disproportionate
• -2VCl4 --> 2VCl3 + Cl2 (at room temp.) (can't get VCl5)
• -Halides hydrolyse in water
• - VCl4 + H2O --> VOCl2 + HCl
• -+2/+3: all trihalides known and are reducing
• Compounds with formula VX3 crystallize from H2O giving, [VF3.(H2O)3] & for other halides [V(H2O)6]3+3X-
• -All VX2 soluble in H2O and form violet solutions containing
• [V(H2O)6]2+
• -Addition of NaOH precips. V(OH)2 but compounds strongly reducing and sol. readily oxidised by air to [V(H2O)6]3+ H2O to produce H2

Chromium Chemistry

• -Chromite (FeCr2O4) commercial ore
• -one method of extraction, reduction with coke in electric arc furnace
• --or converted to Cr2O3 & reduced by Al or Si
• -Cr2O3 + 2Al --> 2Cr + Al2O3
• -2CrO3 + 3Si --> 4Cr + 3SiO2
• Halides:
• -All CrX3 known and are coloured solids, prep. by reaction of Cr + X2. hexaqua produced when dissolved in H2O, violet
• -CrX2 known and produced by reducing trihalides with H2
• -CrCl2 gives sky-blue 2+hexaqua when dissolved in H2O - strong reducing agent
• Oxides
• --3 main oxides:
• Chromium sesquioxide:Cr2O3 (3+) green solid prep. by heating metal in air, by heating CrO3 or heating ammonium dichromate [NH4]2[Cr2O7] --> Cr2O3 + N2 + 4H2O(volcano experiment)
• Chromium dioxide: CrO2 +4 brown/black solid from CrO3 reduc.
• Chromium trioxide: CrO3 +4 deep red solid made by adding H2SO4 to Na2Cr2O7: H2SO4 + Na2Cr2O7 --> H20 + Na2SO4 + 2CrO3
• CrO3 strongly acidic & dissolves in NaOH aq to form discrete tetrahedral chromate [CrO4]2-: CrO3 + 2NaOH --> 2Na+ [CrO4]2- + H2O
• Acidification of [CrO4]2- (yellow) give [Cr2O7]2- (orange/red) by joining two tetras
• pH > 8 CrO42-
• pH 2-6 HCrO4- & Cr2O72-
• pH < 1 H2Cr2O7

Manganese chemistry

• -MnO2/Mn3O4 reduced with Al in blast furnace: 3MnO2 + 4Al --> 3Mn + 2Al2O3
• Halides: All halides known, most common --> MnF2, pale pink, MnF3,red/purple, MnF4,blue, MnCl2,pink,MnCl3, MnBr2,pink,MnI2,pink.
• Dihalides prep. by adding acid to MnCO3
• MnCO3 + 2HX --> MnX2 + CO2 + H2O
• -Or heat MnO2 with HCl to get MnCl2:
• MnO2 + 4HCl --> MnCl2 + 2H2O + Cl2
• Oxides: diff. oxides dep. on ox. state of metal centre - Mn2O7,+7,green oil,MnO4,4+,Black solid,Mn2O3,+3,Black solid,Mn3O4,+2/3,black solid,MnO,+2,grey-green solid
• -oxi. of fused MnO2 with NaOH in air(or KNO3 as oxi agent) generates dark green manganate ion [MnO4]2-,+4, only stable in strongly alkali sols. & disproportionates in neutral/acidic sol
• --3[MnO4]2- + 4H+ --> 2[MnO4]- + MnO2 + 2H2O
• --manganate --> permanganate(purple) due to transfer band not d-d transition good oxi agent
• --Redox properties of [MnO4]-:
• Strong base: [MnO4]- + e- --> [MnO4]2- fast, [MnO4]2- + 2H2O --> MnO2 + 4OH - slow
• Modeate Base: [MnO4]2- + 2H2O + 3e- --> MnO2 + OH-
• Dil. H2SO4: [MnO4]- + 8H+ + 5e- --> Mn2+ + 4H2O

Iron Chemistry

• Obtained from blast furnace: Fe2O3 + 3CO --> 2Fe + 3CO2
• Halides: get tri and di: tri - Fe + 3X2 -->2FeX3, di - Fe + HX --> FeX2
• --Oxides: Fe2O3,3+, red/brown, hematite, prep. heating alkaline sols. of Fe3+ & dehydrating solid formed; Fe3O4,2/3+, Black, magnetite; FeO,2+.
• Movement of Cl into alk. sol. of hydrated ferric oxide(Fe2O3), generates red/purple sol. that contains [FeO4]2- (ferrate), stronger oxidising agent that permanganate. Only stable in strongly alk. sol and decompose in water/acid
• [FeO4] 2- + 4H+ --> Fe3+ + O2 + 2H2O
• General Fe Chem.
• Fe3+ strongly acidic:
• [Fe(OH2)6]3+ + H2O --> [Fe(OH2)5(OH)]2+ + H3O+ pKa 3.1.
• [Fe(OH2)5(OH)]2+ + H2O --> [Fe(OH2)4(OH)2]+ + H3O+ pKa 3.3.
• --Rust:
• 2Fe --> 2Fe2+ + 4e-
• O2 + 2H2O + 4e- --> 4HO-
• overall: 2Fe + O2 + 2H2O --> 2Fe(OH02

Cobalt Chemistry

• Extracted from sulphide by conversion to oxide then red. with H2/C:
• 2Co2O3 +3C --> 4Co + 3CO2
• Halides: dihalides exist;
• CoF2,pink
• CoCl2,blue
• CoBr2,green
• CoI2,blue-black.
• CoCO3 + 2HX -->CoX2(aq) + CO2 + H2O
• Heat to get solid.
• Some other higher ox. state halides known:
• 2CoCl2 + 3F2 --> 2CoF3 + 2Cl2
• 3 oxides:Co2O3,3+, prep by oxi. of Co(OH)2;Co3O4,2/3+,CoO,2+
• +2 oxi. state: Hydrated salts of Co2+ pink/red, octahedrally coord
• Co(II) chloride tests for H2O as on dehydration pink Co hexaqua turns to blu tetrahedral ion.
• colour change due to crystal field splitting of E levels diff in oct and tetra cases. Though Co2+ more stable than Co3+ many Co(II) complexes readily oxidised to corresponding Co(III) complexes. Bc CFSE for Co(III) -d6 higher than for Co(II0 - d7 main reason for observation
• 3+ oxi state: many stable Co(III) inert to ligand sub: Yellow [Co(NH3)6]3+,Pink[Co(NH3)5(OH2)]3+,Purple[Co(NH3)5(Cl)]2+, Purple[Co(NH3)4(CO3)]+,Yellow[Co(NH3)3(NO2)3],violet[Co(CN)6]3-, yellow[Co(NO2)6]3-
• Linkade isomerism: can prep. nitrito ONO complex (red) but can be converted to yellow nitro NO2 complex by acid

Nickel Chemistry

• Extraction: Ni occurs as Nis, NiAs2, & NiSb: sulphides roasted in air & converted to oxides. Oxides then red. to metal by C in smelter
• Halides: all Ni(II) halides known. NiCl2 when added to water forms, [Ni(OH2)6]2Cl- which is green
• Oxide: Oxide of Ni is NiO. when Ni reacts with fused NaOH in presence of O2, sodium nickelate - NaNi(III)O2 formed
• Coordination complexes:
• Dominated by Ni(II). Wide range of geometries possible, including oct, square planar, tetra, trig bipy and square based pyramidal structures
• complexes with NH3, ethylene diamine oct and blue in colour, paramagnetic. Strong ligand i.e. CN-square planar complex formed: these are generally red, brown or yellow and are diamagentic
• Ni(III) complexes less common: oxi. of Ni(OH)2 in alk. sol. with Br2 gives Ni2O3.2H2O as black solid which decomposes to NiO on dehydration.
• Macrocyclic ligand complexes capable of supporting 3+ oxi state

Copper Chemistry

• Extraction: Cu occurs as CuFeS2, Cu2S & CuS in earth's crust. Sulfide ores conc. then roasted in air
• 4CuFeS + 5O2 --> 2CuS + 2Fe2O3 + 2SO2
• Sand added to remove Fe as Fe2(SiO3)3
• 2Cu2S + 3O2 --> 2Cu2O + 2SO2
• Cu2S + 2Cu2O --> 6Cu + SO2
• Halides: Cu(I) halides cuprous, known (the F not been produced in pure state), colourless & diamagnetic. Cl and Br salts produced by boiling acidic sol of Cu(II) ion and excess of Cu. Upon dil. white CuCl or CuBr precip.
• Oxides: Cu(I) more stable than Cu(II) oxides at high temp. Cuprous oxide be prod. in controlled reaction of alk Cu(II) sol. Can also be prep by heating CuO at High Temp.
• CuO,2+ - Black solid, Cu2O,+ - red solid
• Coordination complexes:
• In +1 ox state complexes diamagnetic and colourless as consequence of d10 config.
• Iodide ions reduce Cu2+ to CuI and I2 - cna be used to estimate Cu volumetrically as I easily titrated with Nathiosulphate:
• 2Cu2+ + 4I- --> 2CuI + I2
• +2 ox state most stable and common for Cu. d9 config mans complexes paramagnetic and coloured. Hexaqua distorted oct with 2 long Cu-OH2 & 4 short Cu-OH2 bonds (Jahn-Teller Distortion)
• Aq Cu2+ sol form many complexes with amines ranging from: [Cu(OH2)5NH3]2+
• [Cu(OH2)4(NH3)2]2+
• [Cu(OH2)3(NH3)3]2+
• [Cu(OH2)2(NH3)4]2+
• Anhydrous CuF2 & CuSO4 white as ligands weak & don't cause big ligand field splitting energy. Most other Cu(II) complexes blue/green. tetra[CuCl4]2- orange & Square planar[CuCl2]2- yellow

Zinc Chemistry

• Extraction: Zinc occurs as ZnFeS & ZnS - to extract and purify, suphide taken to oxide and then reduced with C
• Halides: ZnX2. Zinc salts usually hydrated & dissolve in H2O to make 2+ hexaqua. Acidic due to eq
• [Zn(OH2)6]2+ --> [Zn(OH2)5(OH)]+ + H+
• Oxides: only ZnO - yellow when hot and white when cold
• Colour not a d-d transition as completed shell - colour due to defects in solid structure
• Coordination complexes: Zinc(II) forms complexes with range of ligands inc. cyanide ammonia amines and halides. coord no.s 4 and 6 are common for Zn(II)