Greenwood & Earnshaw 2 nd Edition Chapter 7 uminium, Gallium, Indium and Thallium
Observations uminum is the most common metal, 8.3% wt. of the earth s crust. Ga, In, Tl are relatively rare. uminum is monoisotopic, excellent heat and electrical conductor. Gallium has anomalous melting point (but not boiling point) and anisotropic electrical resistivity: a 17.5, b 8.20, c 55.3; liquid is 25.8 F ohm-cm. Thallium has a very stable oxidation state of one and is very electropositive, corrodes in moist air. I : III oxidative equilibria dominates its chemistry.
The Trihalides of uminum polymeric solids, CN = 6, µ X dimeric CN = 4, 2 µ X alides once hydrated cannot be dehydrated. F 3 alone does not form a hexahydrate. 2 O 3 [( 2 O) 6 ] 3+ 3 - heat O(O)C 2 O + 3 2 O F 3 F 3 Cn 2 O n = 1, 3, 9 the affinity of for F O heat 2 O 3
Complex alides Cryolite Structure F 3 + 3 NaF Na 3 F 6 uminum Smelting Synthetic cryolite has the perovskite structure (CaTiO 3 ) a face-centered cubic structure. No F 6 3- ions occur. The is not clearly ionic since the Na-F and -F distances are nearly equal. l occupy octahedral sites; 1/3 Na occupy octahedral sites, 2/3 occupy 12 coordinate sites.
Trihalides of Ga, In, Tl & Complex alides The trichloride of is important as Friedal Crafts & isomerization Catylist. The trihalides of Ga resemble those of with some structural differences. The trihalides become less stable as one goes down the group. Ga 4 - In 4 - [Tl 2 9 ] 3- T d In 5 2- hydrolyses rapidly Other adducts vary between sq. pyd. & trig. bipyd. geometry. The trihalides of Tl are chemically quite distinct from the rest of the group. TlF 2 O 3 mp d 550 C Ga(II) ~ In(II) vs. Ga(I)Ga(III) Tl(I) Tl(III) TlI 3 is Tl + - I 3 Tl(O) 3 103.9E In + 3 F 246 pm 242 pm square pyramidal NaTlF 4 Na 3 TlF 6 Fluorite Str. Cryolite Str. Two regular Ti 6 octahedra sharing a common face. @2dioxane Ga Ga vs Ga+[Ga4]- but TlI 4-2- Ga Ga is Tl(III); Tl 2 I 4 is Tl + TlI 4-2-
Acidity of [M( 2 O) 6 ] 3+ ydrates, ydroxides and Oxides M Ga In Tl * pk a 4.95 2.6 3.7 1.15 * Needs "non-coordinating anion" (O) 3 (O) 3 Ga(O) 3 In(O) 3 TlO Acidic Amphoteric asic Strongly asic ~KO ~100 C 100-1500 atm 2 O 250-400 C ~100 C MO(O) layer lattice ~150 C InO(O) ~Rutile Str. Tl 2 O black platelets - O 2 ~1000 C SiO 2 Acid Oxide Acceptor M 2 O 3 In 2 O 3 Tl 2 O 3 structurally very complex See p 243 text CaO ase Oxide Donor asic 2 (SiO 3 ) 3 2 O 3 Ca(O 2 ) 2 O - Tl 3+
Important uminum Oxides α-umina 2 O 3 Corundum, Sapphire including very strong optical glass, Saffil fibres. γ-umina 2 O 3 Activated alumina, a defect spinel structure. Sodium-β-alumina Na 11 O 17 -Na 2 O @0.11 2 O 3 a solid electrolyte & Na + conductor, see Na/S battery applications, p 678 text. Tricalcium uminate Ca 3 2 O 6 Principal ingredient of Portland Cement.
Complex Metal ydrides ( 4 ) 3 70EC - 2 6 fluxional C 3 2 Me 6 N(C 3 ) 3 N(C 3 ) 3
ydrides:, Ga, In, & Tl + 3/2 2 no reaction 4 3 + 3 Li 4 4 3 ( 2 O) n + 3 Li α-3 has 6 O h 3c-2e µ-'s 6 d - = 324 pm, 6 d - = 445 pm, p = 141E, no - bonding. (C 3 ) 3 N N(C 3 ) 3 benzene reflux 4 3 Td 150-200EC 2 N(C 3 ) 3 F 3 LiGa 4 + Me 3 N@ Ga 3 @NMe 3 Ga 3 ydrides of In, Tl too unstable to isolate LiM 4 M = EC T dec = Ga In Tl 380E 100E 50E OE Viscous liq. T mp -15EC T dec ~25EC
, Ga, In, & Tl -- kyls & ydrides + 3 / 2 2 + 2 R 3 3 R 2 2 + 2 C C 2 cf. ydroboration 3 dimeric dimeric 3 ineffective 2 + 3 2 + 2 2 6 6 2 6 2 C C 2 3 2 6 2 + 3 2 + 6 (C 3 ) 2 C C 2 100EC 2 [C cat. amts. 2 C(C 3 ) 2 ] 3 [C 2 C(C 3 ) 2 ] monomeric 3 200 atm 2 (C 2 C(C 3 ) 3 Na (C 3 ) 3 CC 2 ) 3 [C 2 C(C 3 ) 2 ] 3 2- mp 40EC, diamagnetic TlX 3 + 2 RMgX R Tl R + X- linear cation, isoelectronic with R 2 g R = Me, soluble and stable in water.
uminum kyls The Growth Reaction 3 2 C C 2 150EC 100 atm 2 C 2 C 2 2 C C 2 150EC 100 atm (C 2 C 2 ) x (C 2 C 2 ) y (C 2 C 2 ) z 2 C C 2 C 2 C 2 2 C C 2 2 C C 2 C 2 C 2 C 2 C 2 C 2 C 2 etc C 2 C 2 C 2 C 2 C 2 C 2
uminum kyls Ziegler-Natta Catalysis Ti 4 + 2 6 assical Mechanism: alkane solvent Ti(III) n 3-n brown suspension L n Ti- 2 C C 2 2 C C 2 L n Ti L n Ti 2 C C 2 L n Ti C 2 C 2 2 C C 2 C 2 C 3 c. C 2 C 2 or C 2 C 2 L n Ti L n Ti C 2 C 3 C 2 C 2 L n Ti C2C3 2 C C 2 L n Ti C 2 C 2 C 2 C 3 L n Ti C 2 C 2 C 2 C 3 2 C C 2 C 2 C 2 L n Ti C 2 C 3 2 C C 2 2 C C 2 2 C C 2 2 C C 2
uminum kyls Ziegler-Natta Catalysis assical mechanism requires chain transfer of an ever increasing length chain, entropy consideration as polymer chains become very long. The concerted pathway was invoked to counter the entropy troubles above. Polypropylene is only head-to-tail, most valuable polymer produced by Z-N catalysis. The methyl groups alternate along the chain. Reactivity: terminal > geminal > internal olefins. Only homopolymerization feasible.
Some Interesting Organometallics TlO (aq) + C 5 6 Tl 241 pm Trialkyl derivatives of Ga, In, Tl are all monomeric. Those of Ga & Tl tend to be liquids or low mp. Tl Tl Tl gas phase crystalline phase Indium compound has similar structure d In-ring = 285 & 309 pm; pin 3 128E; pring 177E 3 C Ga 3 C 3 C C 3 C 3 C 3 + 3 C 3 C In 3 C 3 C C 3 C 3 + Ga r r Ga r r O Me O O O O Me +