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

Problems
accessible temperatures. The compound has an infrared spectrum showing the
characteristic frequencies of a vinyl group.
(b) Diallylpalladium gives an 1 H n.m.r. spectrum at low temperatures with three
groups of resonances, intensity ratio 2: 2: 1. At room temperature the two
stronger resonances merge into a single rather broad peak.
(c) Two isomeric forms can be isolated for the n-allyl compound
Co(C0) 3 (CHCH 3 CHCH 2 ).
(University of East Anglia).
2. M is a First Transition Series element. It forms a carbonyl F of empirica!
formula M(CO), which reacts with sodium amalgam in tetrahydrofuran to give a
solution G. Treatment of G with 3-chloro-1-propene gives a compound H of
molecular formula C 8 H 5 0 5 M. The infrared spectrum of H shows carbonyl
stretching bands between 2110 and 2004cm- 1 , the 1 H n.m.r. spectrum of H
indicates protons in faur chemically distinct environments.
On heating H to 1 00°C one mole of carbon monoxide is eliminated to give I,
C 7 H 5 0 4 M [v(CO) between 2110 and 1950cm- 1 ]. The 1 H n.m.r. spectrum of I
indicates protons in three chemically distinct environments.
(a) Identify the metal M.
(b) Propose and draw structures for the compounds F. H and I and for the species
present in solution G.
(c) Interpret the 1 H n.m.r. features of H and 1.
Give a qualitative sketch of the spectrum of I. clearly labelling the protons which
give rise to each group ofresonances. Discuss the spin-spin couplings which are
observed. (Coupling through more than three bonds can be ignored).
(d) Discuss the bonding of the organic ligand to M in compound I.
(Royal Holloway and Bedford New College ).
3. Treatment of an aqueous methanolic solution of Na 2 PdCI 4 with 2-methylallyl
chloride, CH 2 =C(CH 3 )CH 2 Cl. under a CO atmosphere yields the dimeric
complex [C 4 H 7 PdCl1z. (C). The 1 H n.m.r. spectrum of C at 298 K shows three
singlets at b 2.2. 2.9 and 3.8 with relative intensities of 3:2:2 respectively.
Addition of 2 moles of AsPh 1 to 1 mole of dimer ( i.e. moi ar ratio As: Pd = 1 : 1)
yields another complex D.
The 1 H n.m.r. spectrum of Dat 193 K shows fi ve singlets at 6 2.1. 2. 7. 3.2, 3.6
and 4. 5 with relative intensities of 3: 1: 1: 1: 1 respectively in addition to the
phenyl proton resonances. On warming the solution of D to 3 2 3 K the 1 H n.m.r.
spectrum changes in profile to show two singlets at b 2.1 and 3.5 relative
intensities of 3:4 respectively in addition to the phenyl proton resonances.
Suggest structures for the compounds C and D. interpret the 'H n.m.r. data. and
describe briefly the type of bonding occurring between the organic group and the
palladium atom in C.
(University of Warwick).
4. The reaction between H 2 C=C(CH 2 Ci) 2 and Fe 2 (C0) 9 was found to yield a
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