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

Transition metal chemistry
18-electron
,-A
-L ··.
~
;>---
16-electron 14-electron
~
~ ~
T etrahedron
+x+ -x+
Trigonal Linear
~p•oa
:f.:
y
y y
·--.1/--k'
Aor /
+L
~
-L
Squore
pyramid
u•J r-x•
>K
Octahedron
.,.) r-x•
Trigonal
bipyramid
~
y
~
Squore planor T-shaped
+XY
X -k
-L '
+L
~
+XY
or
Squore Trigonol
pyramid bipyramid
*
Capped
octahedron
~ Distorted
+L octahedron
Fig. 5.16 Substitution, addition and elimination reactions of transition metal complexes.
L = Lewis base, two electron ligand. X = one electron ligand, e.g. CI, H, R, COR,
SiR,. XY includes homonuclear species, e.g. H 2 , Cl 2 •
a further ligand. The 16 and 14-electron species are 'coordinatively unsaturated',
that is, they possess vacant coordination sites which are potentially available for
occupation by ligands. These additional ligands must provide the electrons
needed to reach a stable electron configuration. In general this requires a total of
18-electrons. Some square planar 16-electron complexes, especially those of Ni,
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