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

Bis( arene )complexes
clusters of atoms) at low temperature. The metal vapour is cocondensed with a
large excess of a reactant such as an arene on the inner surface of a vessel cooled
in liquid nitrogen. When the mixture is allowed to warm up slowly, reaction
occurs under very mild conditions. An apparatus designed for these reactions is
illustrated in Fig. 1 0.1. For relatively volatile elements electrica! heating is
sufficient but for very high boiling elements such as Ti. Nb and W an electron gun
is employed. The method is suitable for the laboratory preparation of small
quantities ( 1-50 g). The experiment is carried out under reduced pressure
(ca. 1 O- 3 mm) to in crease the mean free path of the metal atoms after
vaporization so that they are trapped in a matrix of coreactant before they can
meet each other to reform bulk metal.
The metal atom synthesis was first applied to the preparation of
bis(arene)chromium derivatives by Timms. A wide range of complexes containing
functional groups such as F, Cl, OMe and COOR were obtained. By introducing
the arene in a solvent, compounds of relatively involatile ligands such as
Cr(naphthalene) 2 have been prepared. Green has extended the method to the
synthesis of compounds such as Ti(C 6 H 6 ) 2 • Zr(C 6H6 ) 2 PMe~. Nb(C 6 H 6 ) 2 and
Fig. 10.1 Metal atom reactor. A - Glass reaction vessel. B- Electron beam furnace, model
EBSI. G.V. Planer Ltd. C- Vapour beam of metal atoms. D-Ca-condensate of
metal and substrate vapours. E - Heat shield. F - Furnace cooling water pipes.
G - Electricallead for substrate solution dispersion device. H - Furnace electricalleads.
J- Substrate inlet pipe (vapour). K- Substrate inlet pipes (solution).
M - Rotation of reaction vessel. N - To vacuum rotating seal, service vacuum
lead troughs and pumping systems. O- Level of coolant (usually liquid
nitrogen). P- Capped joint for product extraction. Q- Substrate vapour
dispersion device. R- Substrate vapour beam. (From Green, M.L.H., 1980. J.
Organomet. Chem .. 300, 119.)
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