Structure of Bismuth Cluster Bi₅³⁺ to Bi₅⁺

CSIR-NET: JUNE 2017

Addition of two electrons to the bismuth cluster Bi₅⁺³ results in a change of structure from
A. Closo to Nido
B. Nido to Arachno
C. Closo to Arachno
D. Arachno to Hypo

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The addition of two electrons to the bismuth cluster Bi₅⁺³ results in a change of structure from Closo to Nido.

For Bi₅⁺³ (Initial Cluster):
Total Valence Electrons = (5 × 5) - 3 = 22
Skeletal Electrons= 22 - 10 = 12 electrons.
Skeletal Electron Pairs (SEP) = 12 / 2 = 6 pairs.
Formula for n = 5 vertices
The SEP count is n + 1 = 5 + 1 = 6
According to Wade's rules, an n + 1 count corresponds to a Closo structure (specifically a trigonal bipyramid).

For Bi₅⁺ (After adding 2 electrons):
Valence Electrons = 22 + 2 = 24 electrons.
External Lone Pairs = Still 10 electrons.
Skeletal Electrons = 24 - 10 = 14 electrons.
Skeletal Electron Pairs (SEP) = 14 / 2 = 7 pairs.
Formula for n = 5 vertices
The SEP count is n + 2 = 5 + 2 = 7
This corresponds to a Nido structure (derived from an octahedron with one vertex removed, forming a square pyramid).

According to Wade's rule, the cluster type and geometry of Sn₉⁴⁻ respectively are-
A. Closo and Tricapped trigonal prismatic
B. Nido and Monocapped square antiprismatic
C. Arachno and Heptagonal bipyramidal
D. Closo and Monocapped square antiprismatic

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Answer: Try to solve

B. Nido and Monocapped square antiprismatic