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

References
periods, when strongly electronegative groups such as halogen atoms are
attached to the metal atom (e.g. SiF! ~ ). The kinetic lability of SiC1 4 to hydrolysis, in
contrast to CC1 4 , may be associated with the presence of empty relatively low lying
( 3d?) orbitals in the former which can accept electrons from water in nucleophilic
attack. Where such electron-attracting groups are absent. however, as in Me 4 Si.
there is generally no tendency for the covalency of the metal atom to expand
above four. so that Me 4 Si is kinetically inert to thermal decomposition, oxidation
and hydrolysis at room temperature.
Thus kinetic stability of organometallic compounds may be associated with a closed shell
of electrons, often of essentially spherical symmetry, around the metal atom.
For compounds ofthe transition elements, however, empty valence shell ns, np
or (n-1 )d orbitals are often available and this can markedly decrease their kinetic
stability. This accounts for the ready thermal decomposition of many binary
alkyls by ':1.- or ţ)-hydrogen transfer referred to above. If ali the valence orbitals
are fully used and occupied a closed shell results, so that such facile hydrogen transfer
is inhibited. Generally a closed shell for transition elements consists of 18
electrons i.e. ns 2 , np 6 , (n-1)dl". These additional electrons can be supplied by
'spectator' ligands such as cyclopentadienyl, which themselves are not readily
displaced. Whereas WMe 6 decomposes below room temperature, sometimes
explosively. Cp 2 WMe 2 can be sublimed without decomposition at 12())C/
1 O~ 3 mm. In the former the tungsten atom has a configuration of only 12
electrons, whereas in the latter the closed shell of 1 8 electrons is attained.
Transition metal atoms are, like atoms of Group IA and IIA elements. inherently
electron deficient, and this electron deficiency must be satisfied ifthermally stable
organometallic compounds are to be formed. The 18-electron rule and related
ideas are discussed further in Chapters 5 and 6.
1.6 References
On account of limited space it is possible to list only a few relevant books and
review articles at the end of each chapter. Most of those chosen have appeared
since about 19 79. Readers who require detailed access to the literature, including
original research papers are referred to 'Comprehensive Organometallic Chemistry'.
This contains an exhaustive but quite readable treatment ofthe subject up to
and including the year 1980. Some of the texts listed below also include fairly
extensive bibliographies. In particular, the hardback edition of Haiduc and
Zuckerman's book contains 111 pages of references to the secondary literature
up to 1984 (books and reviews only).
Texts on organometallic chemistry
Atwood, J.D. (1985) Mechanisms of lnorganic and Organometallic Reactions. Brooks/Cole,
CA.
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