Depends on what you are trying to do - and it isn't clear from your description.
To match your "whitespace" collection is easy:
[\s\\/]
will match any character which is any one of them, and
[^\s\\/]
will match any character which is none of them.
But there isn't a code which says "ignore these characters, regardless of where they are in the string" - for that kind of thing, you are better off using string.Replace in C# to remove them before passing the data to a Regex for matching.
And if you are going to work with regexes, then get a copy of
Expresso [
^] - it's free, and it examines and generates Regular expressions. I use it a lot!