densed, high nuclearity Cu 2 S complexes may stem from the inability of sulfide
ligands to adopt the higher coordination modes observed with Se
2À . This has led
to a much larger structural diversity with the latter, as well as the prevalence of
the much larger clusters, as described above. Indeed, only with [Cu 12 E 6 (PR 2 R
0 ) 8 ]
(E ¼ S, Se) does one observe topologically similar complexes between the two
series [31].
The factors controlling the selectivity of cluster formation using E(SiMe 3 ) 2
(E ¼ S, Se, Te) at low temperatures are numerous, and small changes in reaction
conditions can have a pronounced effect on product distribution. The products
obtained are highly variable and are dependent upon the reaction conditions used.
Extensive studies of the synthesis of XI–XVI clusters demonstrate that careful
Fig. 13.9. An illustration of the copper–sulfur cores observed
in [Cu 28 S 14 (P
t Bu 2 Me)] 11 (top) and [Cu 50 S 25 (P
t Bu 2 Me) 16 ] 12
(bottom) illustrating the structural relationships between the
two clusters [39].
13.3 Group XI Chalcogenides 429