Rules for counting the number of skeletal electrons provided by each vertex atom need to be established in order to determine the number of skeletal electrons in polygonal and polyhedral clusters of the post-transition elements. The rules discussed above for polyhedral boranes can be adapted to bare post-transition metal vertices as follows [Pg.19]

Mingos rules. This hypoelectronicity or electron poverty (fewer than the Wade-Mingos 2n + 2 skeletal electrons) in the bare metal cluster anions Enz (z < n + 2) leads to deltahedra not only different from those in the deltahedral boranes but also different from those in hypoelectronic metal carbonyl clusters of metals such as osmium. [Pg.22]

Butterfly. While Tl2Te22- has a (2)(1) + (2)(4) + 2 = 12 skeletal electron count isoelectronic and isolobal with neutral cyclobutadiene, it undergoes a different Jahn-Teller-like distortion to the butterfly structure discussed by Bums and Corbett [81]. [Pg.20]

Application of this procedure to post-transition metal clusters indicates that bare Ga, In, and Tl vertices contribute one skeletal electron bare Ge, Sn, and Pb vertices contribute two skeletal electrons bare As, Sb, and Bi vertices contribute three skeletal electrons and bare Se and Te vertices contribute four skeletal electrons in two- and three-dimensional aromatic systems (see Chapter 1.1.3). Thus, Ge, Sn, and Pb vertices are isoelectronic with BH vertices and As, Sb, and Bi vertices are isoelectronic with CH vertices. [Pg.19]

Seven-vertex Structures. As73- and Sb73- have the C3v structure depicted in Figure 1-7 and the correct (4) (3) + (3)(1) + 3 = 18 skeletal electron count for [Pg.20]

Balakrishnarajan and Jemmis [32, 33] have very recently extended the Wade-Mingos rules from isolated borane deltahedra to fused borane ("conjuncto ) delta -hedra. They arrive at the requirement of n I m skeletal electron pairs corresponding to 2n + 2m skeletal electrons for such fused deltahedra having n total vertices and m individual deltahedra. Note that for a single deltahedron (i.e., m = 1) the Jemmis 2n + 2m rule reduces to the Wade-Mingos 2n I 2 rule. [Pg.8]

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