_P.-Powell-auth.-Principles-of-Organometallic-Chemistry-Springer-Netherlands-1988

Complexes of arenes
Problems
1. Ferrocene was heated under reflux with mesitylene (1, 3, 5-
trimethylbenzene) in the presence of aluminium powder and aluminium(III)
chloride for several hours. The aqueous layer obtained by hydrolysis of the
reaction mixture was treated with aqueous NH 4 PF 6 • A yellow solid A
(C 14 H 1 l 6 FeP) was precipitated. The 1 H n.m.r. spectrum of A consisted of singlets
(<5 6.30, 5.07 and 2.52 ppm relative to Me 4 Si). Compound A gave a bright red
product B (C 14 H 18 Fe) on treatment with NaBH 4 • B with Ph 3 C+BF; in dichloromethane
afforded C (C 14 H 17 BF 4 Fe).
Suggest structures for compounds A, B and C.
2.
O:~HMe 2
Cr(C0) 6 C13H14Cr0 3 ( G)
CqHqCrN 3 0 3 ( F)
u(CO) 1915 1 1790 cm-1
u(CO) 1991,1921,1893 cm-1
1 , 8-bis (dimethylominonaphthalene)
[J+][PF6]
HPF 6
u(CO) 2066,2021 cm-1
K
u(CO) 1985,1931 , 1905 cm-1
Proton n.m.r. (<>relative to TMS, relative intensity, multiplicity).
rPF;: 6.5 7, 6H, multiplet; 3.23, lH, septet G = 7 Hz); 1.46, 6H, doublet
(J = 7Hz)
K 5. 78, 2H, triplet (J = 9 Hz); 4.64, 2H, triplet (J = 9 Hz); 4.08, 2H,
doublet (J = 9 Hz); 1.56, 6 H, singlet
Propose structures for F, G, r and K. Discuss how the spectroscopic data are
compatible with the proposed structures.
(Royal Holloway College).
3. Suggest how the following conversions could be effected using arenetricarbonylchromium
complexes as intermediates.
(a) PhF ---PhNMe2
( b) PhH ---Ph-<) ( (p.4') PhCHO)
(c) Ph(CH2l4CN ---+ J)o
~CN
H
332
PhCMe2C02Me