Is the t-butyl carbocation more stable than the benzyl carbocation?

Question

Various authors have different views regarding stability order of the benzyl and *t*-butyl carbocations. $$\\ce{PhCH2+ ; (CH3)3C+}$$ In my opinion, resonance effect dominates, so the benzylic carbocation should be more stable. But in the other case, both the inductive and hyperconjugation are present which stabilize the intermediate carbocation. What should is the correct stability order? Especially when you consider them an S_N1 reactions, and what their effect on the rate is.

Answer 1

Experimental date indicates tert-butyl cation is more stable. Specifically, the benzylic cation releases more energy when combined with hydride, indicating that it is less stable. This is called "hydride affinity", a term you could google. This seems to go against the rule of thumb that ions with conjugation are more stable than ions only stabilized by hyperconjugation.

https://en.wikipedia.org/wiki/Carbocation <--This link talk a bit about hydride affinity.

I recall reading somewhere that some experimental results can seem inconsistent with hydride affinity. But generally this is what people refer to first when assessing carbocation stability.