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GATE 2025 CY – Question 11

Inorganic Chemistry · Main Group Elements: Shapes and structures of molecules using VSEPR postulates, Hydrides, halides, oxides, oxoacids, nitrides, sulfides - shapes and reactivity. Structure and bonding of boranes, carboranes, silicones, silicates, boron nitride, borazine and phosphazenes: electron counting in polyhedral boranes, isolobal analogy. Allotropes of carbon, phosphorus and sulfur. Industrial synthesis of compounds of main group elements such as NH3, H2SO4 and HNO3. Chemistry of noble gases and interhalogen compounds. Acid-base concepts and principles (Lewis, Brønsted, HSAB and acid-base catalysis). · 1 mark · Multiple choice

The phosphazene compound that acts as a superbase is

Four phosphazene structures.
  1. Option A in the figure
  2. Option B in the figure
  3. Option C in the figure
  4. Option D in the figure

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Correct answer: (C) Option C in the figure

Explanation

The acyclic phosphazene C has a strongly basic imino nitrogen and a conjugate acid stabilized by the amino substituents. The cyclic phosphazenes and chlorophosphazene do not give the same superbase motif.