post html as string through ajax

I have a tinymce wysiwyg and i want to post the html from it to my action method:

   $("#save").click(function () {
            var ed = tinymce.get('wysiwyg');
            var id = $("#destinationId").val();
            var PostContent = JSON.stringify({ 'content': ed.getContent(), 'destinationId' : id });
            console.log(PostContent);


            $.ajax({
                url: '@Url.Action("SaveDestinationContent", "Home")',
                type: 'POST',
                dataType: 'JSON',
                cache: false,
                data: PostContent,
                success: function (data) {

                },
                error: function (xhr, error) {
                },
            });

I always get null in my action method that looks like this:

[HttpPost]
    public ActionResult SaveDestinationContent(string content, string destinationId)
    {
        return Json("TRUE");
    }

i have tried to do this in a couple of different ways:

   $("#save").click(function () {
            var ed = tinymce.get('wysiwyg');
            var PostContent = ed.getContent();
            console.log(ed.getContent());
            var id = $("#destinationId").val();

            $.ajax({
                url: '@Url.Action("SaveDestinationContent", "Home")',
                type: 'POST',
                dataType: 'JSON',
                cache: false,
                data: {
                    content: PostContent.toString(), destinationId: id
                },
                success: function (data) {

                },
                error: function (xhr, error) {
                },
            });

but none of them work!