Create a DocumentSet in host web using REST API

I need to create a DocumentSet in the Hostweb from inside the App.

I have tried this:

    var info = {
        __metadata: { 'type': 'SP.DocumentSet' },
        AllowContentTypes: true,
        ContentTypesEnabled: true,
        ContentTypeID: '0x0120D520',
        Description: 'new documentset',
        Title: 'new documentset',
    }

    $.ajax(
    {
        url: appweburl + "/_api/SP.AppContextSite(@target)/web/getFolderByServerRelativeUrl('/Shared Documents')?@target='" + hostweburl + "'",
        type: "POST",
        data: JSON.stringify(
            {
                'parameters': info
            }
        ),
        headers: {
            "X-HTTP-Method": "POST",
            "accept": "application/json;odata=verbose",
            "content-type": "application/json;odata=verbose",
            "X-RequestDigest": $("#__REQUESTDIGEST").val()
        },
        success: function (site) {
         },
        error: function (error) {
        }

With no success, any suggestion?