I could (and am) writing a book on just this topic. I am also conducting investigative research into the nature and generation of Brown's Gas and HHO. The basic elements pertaining to an answer to this question would include but are not limited to:
1) Frequencies of what? How? Why?
2) 99.99% of those seeking such information are not qualified to understand or apply the answer.
3) Obviously, there is MUCH MORE to the vibratory make-up and dissociation of water than a simple frequency. BTW, the so-called Keely Frequencies are and have been publicly available in the literature for over 115 years. See here. But unless one understands what Keely did and how and have a truer grasp of vibratory physics basics they are not going to be able to develop anything real as regards acoustic dissociation of water.
4) It is absurd to think water is "broken" or "loosened" by a single specific vibratory frequency or it would have already been done. And this is especially true of digitally developed square waves which Keely DID NOT have or use.
5) I've already written extensively about this on my web site. Please read and study it.
6) It is presumptuous to assume I would divulge any information to perfect strangers beyond what I'm already giving away for free through my books, lectures and web site. If you are serious and have legitimate business interests then contact me and we'll see what we can do together.
I could go on and on but you get the picture. There is not a simple solution to such a complex issue. If one truly seeks such information my suggestion is to read and study Keely and Russell's writings, my writings and lectures, conventional physics and watch all those YouTube videos on HHO, Joe Cells, Brown's Gas, electrolysis, etc. There is a certain power of discovery in what does not work.....