The difference between Such thing, such a thing, a such thing

Question

• Such thing.
• Such a thing.
• A such thing.

Are all of them grammatically correct? What's the difference between them?

Answer 1

As you may be able to deduce from the example sentences given by sayfriend, “such a thing” is used to mean “a thing like that” or “a thing of that type”, while “such thing” is used with either a positive verb statement plus “no” (“I will do NO such thing”) or a negated verb plus “any” (“I wouldn’t [or would never] say ANY such thing”) to exclude an event from the realm of possibility. (I cannot find, not do I recall as a native speaker of English who has lived 59 years in western USA ever hearing, any other usage of “such thing”).

I can confirm that I have never heard or seen “a such thing” and that it strikes me as ungrammatical, even though “such” is defined as an adjective and you might think that would be proper placement and use of an adjective; after all, you could certainly say “a small thing” or “a yellow thing.” But “such” is an odd kind of adjective, with special usage rules. It is often used as an intensifying determiner, similar to “very”: “she is such a good cook” means the same thing as “she is a very good cook.” Sometimes it is used to mean “to this degree”: “she is such a good cook that she was invited to teach at a culinary school.”

Sureshot’s answer here explains a lot about “such” as an intensifier/determiner, but his statement that “It is always used before the articles and demonstrative determiners” (as in “such a [thing]”) doesn’t account for the “no such thing” or “any such thing” constructions, nor for another usage, “such that” (very well explained here).

Another SE answer gives the OED definition of “such” as “an adjective meaning 'having the character that he (it) has, no more and no less; used chiefly with a depreciatory or contemptuous reference, or apologetically.'” What are the parts of speech for as, so, such?

Answer 2

My search about samples of using in literature:

1) Such thing:

No such thing. 
It was no such thing. 
But no such thing! 
“I said no such thing. 
"I have said no such thing. 
“It is no such thing. 
But there was no such thing. 
There is no such thing.’
“I do no such thing.”
She would do no such thing. 
What you just said is, there is not no such thing. 
“I know no such thing. 
“I did no such thing. 
“He did no such thing.”
"You did no such thing."
‘She did no such thing. 
“I will do no such thing!” 
‘You will do no such thing!’ 
“You can do no such thing.”
Or some such thing. 
"You know, and I know, that we don't think any such thing. 
"No such thing as too much. 
"I'm not going to do any such thing. 
We would never do any such thing.”
For a long time I didn't know there was any such thing. 
“I didn’t say any such thing. 
“It would do no good for me to tell her any such thing,” he said. 
‘I’ll do no such thing.’
"I'll say no such thing. 

2) Such a thing:

“Such a thing. 
“Is there such a thing?”
'Do you have such a thing?'
You would not do such a thing. 
I could not do such a thing.”
No one would he about such a thing. 
Who would do such a thing?”
'But who would do such a thing? 
"Who could do such a thing?
How could I do such a thing? 
"How could he do such a thing?"
“How could you do such a thing?”
“How would you know such a thing?”
“Can he do such a thing?” 
How can they do such a thing?”
There is no way to do such a thing.”
I didn't even know there was such a thing.'
‘How could you even think such a thing? 
“How can you even think such a thing? 
“I never said such a thing.”
I would never do such a thing. 
He would never do such a thing.’
She would never do such a thing.”
I had never said such a thing to him before.
I never see such a thing.”
Why would do such a thing?”
Why would I do such a thing?"
"Why would he do such a thing?"
Why would you do such a thing? 

3) A such thing:

NOT FOUND.