The structure of (NH₃)₃CrO₄ is:

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DSSSB PGT Chemistry (Female) Official Paper (Held On: 06 Jul, 2018 Shift 1)

Answer 1

CONCEPT:

The structure of coordination compounds

The geometry of a coordination compound is determined by the arrangement of ligands around the central metal atom or ion, based on the coordination number.
In coordination chemistry, the coordination number refers to the number of ligand donor atoms directly bonded to the central metal atom or ion.
Common geometries include tetrahedral, octahedral, trigonal bipyramidal, and pentagonal bipyramidal, depending on the coordination number and electronic configuration of the central atom.

EXPLANATION:

The given compound is (NH₃)₃CrO₄.
In this compound:
- Chromium (Cr) is the central metal atom.
- There are 3 ammonia (NH₃) ligands and 1 oxo (O₄) group bonded to the chromium atom.
- The coordination number of chromium is 7 (3 from NH₃ ligands and 4 from the oxo group).

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Coordination number 7 typically leads to a pentagonal bipyramidal geometry.
In a pentagonal bipyramidal structure:
- Five ligands form a pentagonal plane around the central atom.
- Two additional ligands are positioned axially, perpendicular to the pentagonal plane.

Therefore, the structure of (NH₃)₃CrO₄ is pentagonal bipyramidal.