Q7(a)(i). Metal carbonyls; how they are formed; tetrahedral Ni(CO)₄
What are carbonyls? How are they formed? Show that the molecule Ni(CO)₄ has a tetrahedral structure.
Answer in brief
Metal carbonyls are compounds of metals in low oxidation states (often 0) with CO bound through carbon by σ donation and π back-donation. They are formed by direct reaction of the metal with CO, by reductive carbonylation of metal salts, or from other carbonyls by heat or light. Ni(CO)₄: Ni(0) d¹⁰, sp³, 18 e, diamagnetic; its IR and Raman C–O bands coincide (no centre of symmetry) and electron diffraction shows four equal Ni–C bonds at 109.5°: tetrahedral.
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Coversback-donationlow oxidation statesMond process
All parts of Question 7
- 7(a)(i) Metal carbonyls; how they are formed; tetrahedral Ni(CO)₄10 marks
- 7(a)(ii) Structure of Fe₂(CO)₉ and the 18-electron rule10 marks
- 7(b) Ferredoxin: structure and role in photosynthesis10 marks
- 7(c) Isomers of [CoCl₂(en)₂]⁺; is there a meso form?10 marks