Individual Transition metals

Question 1

Scandium

Answer 1

Only important oxidation state is Sc3+
Colourless
Sc3+ Strong Lewis acid
Borderline TM

Question 2

Titanium

Answer 2

Most important OS is +4 (d=0), but exists in solution as complexes with oxygen
+4 is a strong acid, can be reduced to +3
+3 is a good reducing agent
TiCl2 reacts violently with water.

Question 3

Vanadium

Answer 3

+5 exists as VO43- at pH 14, VO2 + at pH 0
+5 cn be reduced to VO2+ (blue), V3+ (green), and V2+ (violet). All stable with respect to disproportionation
VO2+ complexes square pyramidal, can co-ordinate ligands in vacant axial position
V(III) anion [V2Cl9]2-, formed on reaction of VCl3 with CsCl- structure consisting of 2 face-sharing VCl6 octahedra
V2+ is strongly reducing, oxidised by air- need to us in inert environment.

Question 4

Chromium

Answer 4

CR(VI) strong oxidising agent. Exists as orange dichromate (CrO7 2-) in acidic solution and yellow chromate (CrO4)2- in alkaline solution
Cr(III) is d=3 so high CFSE- kinetically inert
Cr(II) strongly reducing
Carboxylates dimeric and contain Cr-Cr multiple bonding

Question 5

Manganese

Answer 5

Mn(VII) ie d=o is powerful oxidising agent. Exists as MnO4-, tetrahedral. LCMT gives it intense colour
Mn(III) d=4 is always distorted octahedral due to Jahn-teller effect
Mn(II) d=5 is pale colour as the d-d transitions are forbidden by all selection rules

Question 6

Iron

Answer 6

Fe3+ and Fe2+ readily interconverted
Fe3+ acidic in solution- polarisation of M-O bonds increases lability of protons
Fe2+ is stable in aqueous solution but Fe2+ slowly oxidises due to the presence of dissolved oxygen
Compounds containing both Fe 2+ and Fe 3+ very strongly coloured due to m–>m charge transfer bands

Question 7

Cobalt

Answer 7

Co(III) d=6 is a very strong oxidising agent but low spin complexes kinetically inert
N donor ligands such as NH3 greatly stabilise Co3+ with respect to reduction
Co(II) d=7- colour depends on geometry and is very characteristic

Question 8

NIckel

Answer 8

Ni(II) d=8 generally stable to oxidation or reduction

range of co-ordination geometries available: tetrahedral, sq planar, tbp, sq pyramidal, octahedral

Question 9

Copper

Answer 9

Important oxidation states are Cu2+ d=9 and Cu+ d=10
For Cu(II) range of geometries, octahedral always distorted due to J-T,
Cu(I) can be linear

Question 10

Zinc

Answer 10

Only important OS is Zn 2+ d=10
Colourless, with a wide range of geometries
Not really a TM