It contains Preparation and properties of: Allyl derivatives of nickel, Sandwich compounds of Fe, Cr and half sandwich compounds of Cr, Mo.

1. PREPARATON AND PROPERTIES OF:
1. Allyl derivatives of Nickel
2. Sandwich compounds of Fe, Cr and
half sandwich compounds of Cr, Mo

2. Allyl derivatives of Nickel
Diallyl Nickel, Ni(η3C3H5)2 :
• Preparation:
NiCl2 + 2C3H5MgBr Ether , -10℃ η-(C3H5)2Ni + 2MgClBr

3. Properties:
• Physical properties:
1.Yellow, pyrophoric compound that melts at 10C.
2. At low temperature of -100C, it is in orange yellow crystalline
form and recrystallises from pentane.
• Chemical properties:
Insertion reaction: An organic or inorganic substrate is inserted
into the metal-carbon bond.
Ni(η3C3H5)2 + CO2 →[Ni(OCOC3H5)(η3-C3H5)] →
Diallyl nickel intermediate
γ-lactone
-Ni

4. Sandwich componds of Fe,Cr
Ferrocene: Fe(η5-C5H5)2 :
Preparation:
 First metallocene-T.J.Kealey and P.L.Pauson in 1951, were trying to
synthesize fulvalene by oxidation of cyclopentadienyl magnesium
bromide (Grignard reagent) with FeCl3. Instead they obtained orange
crystals containing Fe(II), C10H10Fe. Later on, named as ferrocene by
M.C.Whiting.

5. Fe+++ Fe++ [Fe(η5-C5H5)2]
Using sodium cyclopentadiene:
FeCl2 +2C5H5Na (η5-C5H5)2Fe + 2NaCl
Using cyclopentadiene with a metal halides:
2C5H6 + 2Et2NH + FeCl2 (η5-C5H5)2Fe + 2Et2NH+Cl-
Properties:
orange coloured crystalline compound, diamagnetic and thermally
stable.
M.P. is 173℃.
stable in air and water, decomposes above 500℃ in absence of air.
THF
THF
C5H5MgBr C5H5MgBr

6. insoluble in water but soluble in organic solvents.
alkalis and acids do not attack this complex.
gets oxidised to blue paramagnetic ferricinium ion
[(π-C5H5)2Fe(III)]+.
• Chemical properties: It is an aromatic compound and thus
undergo electrophilic subtitution.
Nitration:

7. Bromation:
Alkylation:

8. Acylation:
Mannich reaction:

9. Bis(benzene) chromium: [Cr(η6-C6H6)2]
Preparation:
• CrCl3+ ⅔Al + AlCl3+ 2C6H6 → [Cr(C6H6)2]AlCl4 + ⅔AlCl3
[Cr(C6H6)2]AlCl4 + 1/2Na2S2O4 → [Cr(C6H6)2]+ NaAlCl4 + SO2
• Metal vapour synthesis: condensed at 77K
Cr(g) + C6H6 → [Cr(η6-C6H6)2]
Properties:
 Dark brown solid
 M.P. is 284℃

10. do not undergo Friedel Craft acylation, sulphonation and nitration
weaker aromatic character
Chemical properties:
Arene displacement reaction:
Oxidation reaction:
2[Cr(η6-C6H6)2] + H2O + 1/2O2 → 2[Cr(η6C6H6)2]+OH-

11. Half sandwich compounds of Cr, Mo
• Cyclic polyhapto ligand bound to an MLn center where L is an
unidentate ligand, (η6-C6H6)ML3. Also known as two-legged
piano stool compounds
• Preparation:
M=Cr,Mo
[Cr(η6-C6H6)(CO)3]
[Mo(η6-C6H6)(CO)3]

12. • Properties:
Yellow solid
[Cr(η6-C6H6)(CO)3]- M.P. is 162℃
[Mo(η6-C6H6)(CO)3]- M.P. is 125℃
stable 18-electron coordination compounds with variety of
chemical and material applications
The X-ray data indicate that the plane of the benzene ring is
nearly parallel to the plane defined by oxygen atoms of the
carbonyl ligands and so the structure resembles a benzene seat
mounted on three carbonyl legs tethered by the metal atom and
are thus also known as piano stool complexes.

13. REFERENCES
 R.C.Mehrotra and A.Singh, Organometallic Chemistry-A unified
approach.
D.Banerjea, Coordination Chemistry.
Dr.Indrajeet Kumar, Organometallic Compounds.
www.wikipedia.com
www.youtube.com