Page 7 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

C O O R D I N A T I O N C O M P O U N D S IR-9.3

Examples:
1. 4
1 1

SPY-5-43
3 2

2. 1
Br
2 2
t
Bu PhP PPhBu t 2
2
Pd
Br PPhBu t 2
1 2
(SPY-5-12)-dibromidotris[di-tert-butyl(phenyl)phosphane]palladium

IR-9.3.3.6 Bipyramidal coordination systems (TBPY-5, P BPY-7, H BPY-8 and HBPY-9)

The configuration index for bipyramidal coordination systems follows the appropriate
polyhedral symbol, and consists o f t wo segments separated by a h yphen, except for
the trigonal b ipyramid where the second segment is not required a nd is therefore omitted.
The first segment has two digits which are the priority numbers of the ligating atoms on the
highest order rotational s ymmetry axis, the reference axis. T he lower number is cited first.
The second s egment consists of the priority numbers of the ligating atoms in the plane
perpendicular to the reference axis. The first digit is the priority number for the preferred
ligating atom, i.e. the lowest priority number in the plane. The r emaining priority numbers
are cited in sequential order proceeding around t he projection o f t he structure either
clockwise or anticlockwise, in whichever direction gives t he lower numerical sequence. The
lowest numerical sequence is that having the lower number at the first point of difference
when the numbers are compared d igit by digit from one end to the other.

Examples:

1. Trigonal bipyramid (TBPY-5)

2 1
1 PPh 3 2
2 CO
3
OC Fe
2
4 CO
PPh 3
5
1

TBPY-5-25 ( TBPY-5-11)-tricarbonylbis(triphenylphosphane)iron

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