Q5(a). A face-capped trinickel carbonyl cluster
The compound [Ni₃(C₂H₅)₃(CO)₂] has a single CO stretching absorption at 1761 cm⁻¹. The IR data indicate that all C₅H₅ ligands are pentahapto and probably in identical environments. (i) On the basis of these data, propose a structure. (ii) Does the electron count for each metal in the structure agree with the 18e⁻ rule?
Answer in brief
Reading C₂H₅ as C₅H₅, propose a Ni₃ triangle capped above and below by μ₃-CO with one η⁵-Cp on each Ni; the 49-electron cluster does not strictly satisfy the 18-electron rule.
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Covers18-electron rulenickel carbonyl clusterμ3-CO face-cappingCp2Ni3(CO)2cluster electron count
All parts of Question 5
- 5(a) A face-capped trinickel carbonyl cluster10 marks
- 5(b) Balancing nuclear capture products10 marks
- 5(c) Magnetite from an ignited iron oxide residue10 marks