Move files in C#

I suggest you to use '@' in order to escape slashes in a more readable way. Use also Path.Combine(...) in order to concatenate paths and PadLeft in order to have your filenames as your specifics.

for (int i = 1; i < n; i++)
{
    try
    {
        from = System.IO.Path.Combine(@"E:\vid\","(" + i.ToString() + ").PNG");
        to = System.IO.Path.Combine(@"E:\ConvertedFiles\",i.ToString().PadLeft(6,'0') + ".png");

        File.Move(from, to); // Try to move
        Console.WriteLine("Moved"); // Success
    }
    catch (IOException ex)
    {
        Console.WriteLine(ex); // Write error
    }
}

Why don't you use something like this?

var folder = new DirectoryInfo(@"E:\vid\"));

if (folder.Exists)
{
    var files = folder.GetFiles(".png");
    files.toList().ForEach(f=>File.Move(from,to));
}