As some others have said, both are correct, and it is not wrong to say
I tried to not do that.
However, that is not the full story. Searching the Corpus of Contemporary American for various phrases (not to hold vs to not hold; not to know vs to not know; not to go vs to not go) reveals that the not to <verb> form is far more common:
| Verb | Not to <verb> | To not <verb> | % |
| Hold | 97 | 6 | 94 |
| Know | 1130 | 69 | 94 |
| Go | 452 | 57 | 88 |
(Note that I didn't search for "not to [any verb]", because that also picks up certain fixed expressions such as "not to mention ..." which might distort the picture.)
So it's clear that the not to <verb> form is far more common. Furthermore, looking at the context of a sample of the to not <verb> examples, most of them appeared to be in speech (either on the radio, or quoted in a magazine), or very informal writing.
Searching the British National Corpus gives an even clearer bias - there, not to <verb> dominates by about 99%.
So in general usage, it is clear that not to <verb> is preferred by most writers.
Why is this? And when should one choose one expression or the other? Naturally this is rather subjective, so take the following explanation as my personal view on the matter, but note that it is consistent with what a lot of other people think.
- Putting the not in between the to and its verb disrupts the expected flow, creating a slightly jarring effect - the to primes the reader/listener to expect a verb, and so it is a little surprising to find another word there.
- While the so-called rule against "splitting infinitives" is entirely false, there are nonetheless a sizeable proportion of educated people who believe it is an absolute rule, and will be irritated (or at least, think you poorly educated/stupid) if you do. One should never let this fact scare one into writing awfully clumsy sentences to avoid such disapproval, but in cases where there is nothing to be gained by splitting the infinitive, it's a good idea not to, and that is often the case here.
So when might one want to say to not <verb>?
- Occasionally this can avoid ambiguity: My aim is not to kill him could either mean I'm not aiming to kill him (i.e. my aim is something other than killing him), or I'm aiming not to kill him (i.e. my aim is keeping him alive). Saying My aim is to not kill him definitely means I'm aiming not to kill him. (In this case I would personally just say I'm aiming not to kill him - but in other circumstances it might not be so easy to rephrase.)
- As I mentioned in the first bullet point above, putting the not after the to goes against the listener's expectations. This can sometimes be used for effect, especially if you want to put particular emphasis on the not.
AHD has this to say about whether or not 'This is able to be said' is allowable:
Usage Note:
The construction able to takes an infinitive to show the subject's
[referent's] ability to accomplish an action:
We were able to get a grant for the project.
The new submarine is able to dive twice as fast as the older model.
Some people think it should be avoided when the subject does not
have an ability, as in sentences with passive constructions involving
forms of the verb be:
The problem was able to be solved by using a new lab technique.
The reasoning here is that since the problem has no ability to
accomplish an action, it is not able to do anything, and therefore
able to should not be used.
Presumably this ban would apply to similar words like capable and to
negative words like unable and incapable. In such cases one can
usually avoid the problem by using can or could:
The problem could be solved....
Keep in mind, however, that passives with get ascribe a more active
role to their subjects, and here one can use able to:
He was able to get accepted by a top law school.
Best Answer
While it is valid, it would be considerably rarer than placing the not before the to:
It splits the infinitive. Now, the "rule" against splitting the infinitive is of course utter nonsense, but there are still people out there who believe in it and so they would avoid it, and one might as well follow suit when it makes no difference, rather than have to defend one's choice.
Also, while it is not a matter of a rule, keeping the infinitive together is the more common pattern even by those of us who know we've the option of doing otherwise.
However, it's also common to have the to appear after a verb. Consider:
In this case the meaning is pretty much the same. The first would be preferable to a no-split-infinitive stickler, but the second certainly seems more natural to me in the "[verb] to" pattern.
There can also be a difference in just what is negated.
"I played, but winning was not my goal, but I wouldn't have objected winning" or "I played, with not winning as a goal". We could argue the second meaning, but the first seems the much more likely meaning.
"I played, with not winning as a goal" seems the only possible interpretation.
Often though, the forms would be equivalent. "To be or not to be" wouldn't differ in meaning from "To be or to not be"; any subtle difference in what is logically meant amounts to the same thing. Since there's no reason to favour the latter such as the previous examples quote, the not seems unnecessarily emphasised in the latter, just by dint of not being quite where we might expect it.
As used in your dictionary, there are two good reasons for favouring the "to not [verb]" pattern: